Imagine you fly home from vacation with your one-and-a-half-year-old son who is traveling for free as a “lap child.” In the airport parking lot, you put him into his forward-facing car seat, where he sits much more contentedly than he did in the rear-facing one that was mandatory until his first birthday. After he falls asleep on the way home, you transfer him to his crib without waking him, lowering the side rail so you can lift him in more easily. (...) -/- Many parts of this idyllic parenting picture are deemed unacceptably risky according to recent child safety proposals. While these proposals all aim to improve child safety, their possible impact is unclear because there has been little discussion of the absolute risk and risk reduction involved in each. And while precise figures are lacking, rough estimates indicate that the magnitudes are quite small. I will argue that this risk and benefit data raises important questions about the proposals, including whether parents might reasonably believe that the small absolute risk reduction offered by the proposed changes does not justify the attendant burdens. This possibility—termed the “prevention paradox” in other contexts—highlights ethical and theoretical challenges in this area of public health. (shrink)

Architecture and Deconstruction Case of Peter Eisenman and Bernard Tschumi -/- Introduction Towards deconstruction in architecture Intensive relations between philosophical deconstruction and architecture, which were present in the late 1980s and early 1990s, belong to the past and therefore may be described from a greater than before distance. Within these relations three basic variations can be distinguished: the first one, in which philosophy of deconstruction deals with architectural terms but does not interfere with real architecture, the second one, in (...) which a collaboration between Jacques Derrida and a group of architects interested in his concepts is commenced, and the third one, in which completed or only designed objects or new concepts of deconstruction created by architects gain their supremacy over philosophy. The following book analyses these three possible ways, first of all with the reference to Peter Eisenman and Bernard Tschumi. -/- Peter Eisenman -/- Misreading… and Other Errors -/- The issue of relations between Peter Eisenman’s work and philosophy of deconstruction may be referred to his activity more than ten years preceding his direct collaboration with Jacques Derrida (in 1985) and organisation of the exhibition Deconstructivist Architecture at Museum of Modern Art in New York (in 1988). As soon as at the stage of designing the first houses (House I-III, 1967-1970), which almost entirely inscribed in formalistic aesthetics of Modernism, the architect analysed the problem of architecture dependence on its assumptions. All his later designs may be treated as consequence of this initial interest in relations between practice and theory, and at the same time as an introduction to manipulations later on led at the level of metaphysics of architecture. Beginning with the issue of presence, considered in comments to House VI (1972), the number of ideas having their analogies in philosophy of deconstruction increased. The text entitled The End of the Classical: The End of the Beginning, The End of the End (1984), in which Eisenman criticised questions of representation in architecture, its delusive strive for truth and comparably unattainable attempts at ultimate definition of elementary rules, should be acclaimed the breaking point. This attitude was extended by numerous strategies disturbing architecture rules defined at metaphysical level in an essay Moving Arrows, Eros, and Other Errors: an Architecture of Absence (1986). The issue of Eisenman’s passage from formalism to deconstruction has already been much discussed in the literature (Rosalind Krauss, Thomas Patin among others), still it should be mentioned that the threads similar to Derrida’s concept included in Eisenman’s writing reveal untranslatability of architecture and philosophy. -/- Choral Works or Separate tricks -/- In 1985-1986 a series of seven disputes between Jacques Derrida and Peter Eisenman took place. The pretext for them were designs concerning Parc de la Villette in Paris. The situation of many months of collaboration between a notable philosopher of the second half of the 20th c. and an architect that already had a huge theoretical oeuvre, ended up with a publication of a large volume entitled Chora L Works and it became at the same time a vast study area for historians of contemporary architecture and philosophers. Derrida’s contribution to concept works were his considerations over the idea of chôra, the properties related to this concept were about to be reflected in shapes of the park. Therefore, Chora L Works became an example of the abilities of contemporary art, both in its capability of translation from philosophical ideas to artistic forms and its resistance to tradition of representing in architecture some phenomena and values originating outside this discipline. In the final period of their collaboration both interlocutors started to polemicise with each other more decidedly, what became a separate part of their thought exchange. The exchange of letters between Derrida and Eisenman at the turn of 1989 ended up the period of their direct contacts, nevertheless, at this time precisely a large group of experts in issues of deconstruction joined the discussion and extended the revealed in the former dispute problems into more than ten years of further considerations and publications. Except for a long text by Jeffrey Kipnis, who had participated in the meetings of the philosopher and the architect, there appeared also comments of researchers of artistic theories (K. Michael Hays, Thomas Patin), philosophers (Andrew Benjamin), and even experts in Greek literature (Maria Theodorou or Ann Bergren). Following these debates a contemporary reflection on architecture has saturated with indeed numerous concepts originating in philosophy of deconstruction. -/- Architecture which imitates mute philosophy -/- The series of Jacques Derrida and Peter Eisenman meetings, which took place in the period of 1985-1987, induced many authors to make comments. Some of them (Jeffrey Kipnis, Ann Bergren, Maria Theodorou) developed the subject of chôra which was introduced to the discussion by Derrida. The problem that was about to be solved was the question of tying up the concept of chôra with architecture, including Eisenman’s architecture and the series of meetings within frames of Chora L Works project. Kipnis on this occasion paid attention to chôra and its character of anachronia which infects any being created within chôra. In other words any event has its counterpart (analogon) in another, earlier event. He demonstrated the similarity of structure of many events and statements from the times of Derrida and Eisenman’s meetings to the almost identical behaviour of figures in Plato’s dialogue Timaeus. The loss of beginning present in this phenomenon was appropriate to both features of chôra and the effects of typical analyses of philosophy of deconstruction. Bergren’s analyses focused on accentuating gender of chôra, which, according to this author, had been neglected hitherto in discussions. She collated chôra descriptions with characteristics of women in myths, early Greek epic and philosophy and she arrived at a conclusion that chôra has features of a single woman and a married one at the same time. And yet Theodorou’s studies showed that in the Homeric epics chôra is not treated as an idea but is related with single things and events. The other part of the comments (represented by Andrew Benjamin and K. Michael Hays’ utterances) concerns Eisenman’s attitude to tradition which was treated as a variety of iteration understood philosophically. Benjamin commenced his considerations at the point of closeness between a definition of tradition and a concept of chôra understood as perpetuation (placement). A problematic issue was for him Eisenman’s complex relation to tradition based on its contest and affirmation at the same time. Overcoming the simple subordination to tradition – according to Benjamin – was based on awareness of the role of repetition in culture not known before. Hays made an attempt to explain the pleasure and torment of repetition with the support of Sigmund Freud and Roland Barthes’ concepts. According to Hays repetitions are attempts of a single being to a certain primal state perceived as free of any tension. In a similar way Rosalind Krauss explained a motif of a grate present in Modernistic art and also exceptionally frequent in Eisenman’s work. -/- Annex Architecture is still writing Balzac novels. Peter Eisenman and literature -/- Architecture’s approach to writing, script or literature, present within Peter Eisenman’s work, is an exceptional phenomenon, furthermore a complex one. The article considers four possible relations. The first one relates to Eisenman’s characteristics as a person extremely gifted with the ability to wordplay, which very ‘play’ reveals skills to create architectural images. In the second approach the attention has been paid to Eisenman’s interests – in the first period of his oeuvre – in linguistic works by Noam Chomsky and his transformational-generative grammar. The third kind of relations applied to overcoming the need for autonomy of architecture (and of modernist aesthetics at the same time) and renew interests in questions of meaning in architecture. The fourth sort of relations occurred when Eisenman started to create reflections of historic or literary narrations in architecture – ‘stone stories’ and architectural fictions of their kind. -/- Bernard Tschumi -/- From perversion to deconstruction In Bernard Tschumi’s writings from the 1970s and 1980s we can find a transposition of important threads of post-structuralist ideas deriving from Georges Bataille, Roland Barthes and Jacques Derrida’s works. The analysis of the architect’s writings also shows roots in Phillippe Sollers, Michel Foucault and Denis Hollier’s works. The analysis of borrowed elements from the beginnings of Tschumi’s theoretical activity may be helpful in explaining the contents of his later writings motre inspired by philosophy of deconstruction. The set of his earliest views was inspired by Marxism, Neo Marxism and French Structuralism, mainly by the writings of Henri Levebre and Guy Debord. From the thought of Levebre Tschumi took interest for city as not only a question of urbanistics but also a political issue. From Debord’s concepts he borrowed a conviction about the role of situational violation for changes in the society structure. Some of these beliefs were preserved in his own concepts of architecture as an event. From this period derived also his will to change conservative elements of social structure not by means of political revolution but of theoretical and creative activity. Tschumi acknowledged that the effective way of the proceedings towards achieving his aims would be accepting the role of both a critical intellectualist and architecture expert who would not hide away his left-wing orientation. The speculations defined by the architect as ‘revolting analyses’ were about to characterise contradictions which tear the society apart, penetrate architecture and constitute the basis of culture. Spreading away of the conscience of false assumptions hidden away in various disciplines could have weakened cohesion of a conservative society and influence the will to change among the elites. This way the beginnings of political revolution were rooted in philosophy of architecture. In 1977 Tschumi published his text entitled The Pleasure of Architecture inspired by Roland Barthes’s The Pleasure of the Text, it also included some concepts derived from Georges Bataille and Jacques Derrida. First of all the author used Barthes’s concept which made an assumption that literary activity is pervaded by the spirit of resistance towards social rules, and Tschudi transferred this remark onto architecture. From the ideas of Bataille, acquainted via Holier’s work, he derived his belief that two concepts of space, a conceptual one (defined as Pyramid) and a sensual one (defined as Labirynth), not losing their distinct features, they join in the concept of experienced space which exceeds contradictions. The exceeding itself was defined as the basic rule of architecture and it was referred to situations in which architecture not only negates social needs, but also disavows its own tradition. Crossing the borders applies not only to political issues or permanent rules of the very discipline but also interfering with other fields (especially literature and film). The fact that architecture is associated with organising events turned Tschumi’s attention to questions of violence that result from upsetting architectural order of a given building by its users and the one hand, and on the other from forcing the users to specific acts imposed by this very order. The analysis of the concepts used by Tschumi in his early writings indicates that they are close to definitions that would occur in his reflection in the following years influenced by philosophy of deconstruction. -/- Approaching deconstruction Tschumi in his theories developed in the 1980s presumed that the current social world had undergone a deep process of decay, and the reaction against which ought to be based on ordering-up actions, and also preserving the main outline of disintegration of the whole and its elements in the state of conflict. The statements concerning the nature of the contemporary to Tschumi social relations were applied by him to the world of architecture, this led him to coming up with designing strategies that took into consideration the destabilised character of conditions in which works of architecture were created. New ways of conduct invented by Tschumi drew their inspiration from literature and research on literature, psychoanalysis, structural linguistics, structuralism and post structuralism, and eventually also deconstruction philosophy. The proposed methods were opposed by their author both to functionalism continuity trends and postmodern architecture. Tschumi’s proposals contradicted any forms of conservatism or traditionalism in political sphere as well as in reference to tendencies in architecture. They were not simple contradictions of social or architectural rules, they intrude them from the inside, weaken or escalate the already existing incongruities, they move the boundaries between the areas. Revolutionary illusions about the possibility of radical changes were replaced with strategies which completed, tainted or test former rules in the series of formal games of permutation and combination. Quite different from avant-garde formalism Tschumi’s games were not about maintaining the autonomy of a given area, but on the contrary – polluting it with other areas’ influences. Tschumi enjoyed demonstrating illusions of architecture concerning simple relations between form and function, or between form and meaning. Making use of Freud, Lacan and Foucault’s research he introduced a category of “madness” into architecture allowing an observation that the recognised norms are nothing but merely ones of many possible principles of behaviour, and their recognised status resulted from unjustified hindering innovativeness which is crucial for architecture. To reborn architecture’s capability of changing Tschumi also made use of Barthes’s discoveries concerning rules of narration and works by writers who applied in their writing knowledge on linguistics. Making a work’s author unclear by various mechanical transformations of its elements was however apparent only, and formal rigours imposed on the process of designing liberated possibilities difficult to obtain in more traditional creative action. Another mode of acting introduced by Tschumi was combining his work of elements deriving from outside architecture; joining space records with notation of motion and events accompanying architectural objects among others. These architectural and extra-architectural elements were not unified, on the contrary their heterogenous and conflictual character was stressed. This is how shock, anxiety and instability, typical for live in great metropolises, infiltrated architecture. Taking some ideas of deconstruction philosophy as a pattern Tschumi also took into critical consideration in his essays traditional in architecture oppositions between form and figuration, or theory and practice. By combining various inspirations he eventually worked out an idea of architectural event, which he understood as a series of actions contesting its own field, redefining its sources, principles and elements. An event, understood in this way, was not so much producing works as rather creating conditions of their production and at the same time designing the society different from a hierarchic one. -/- Park of deconstruction Among numerous philosophical strategies of deconstruction most frequently used was questioning the practice of strong opposition of two reasons. In many cases Bernard Tschumi’s writings just consider functioning of the conflict juxtaposition of the ideas of structure and ornament or theory and practice in history of architecture. Violation of traditional relations between terms of this kind, both old and modern, raised Jacques Derrida’s objections, when he was induced for the first time to co-operate with architects’ milieu. During this long lasting thought exchange the philosopher eventually acknowledged Bernard Tschumi’s arguments for reasoning the encroachment of architecture’s fundamental rules. Deconstruction applied in architecture was not a simple transposition or analogy of practices that had been applied by philosophy of deconstruction. We may even say that considering architectural terms became an important formula of deconstruction. Architecture understood in philosophical way became something beyond the practice and theory of its own discipline, a sort of metaphysics of both philosophy and architecture. The deliberate encroachment of simplicity of dividing architecture into theory and practice, for the first time became a clear aim for Tschumi in his drawings and texts entitled The Manhattan Transcripts. The contents of this series of works was a record of characteristic features of this New York district in such a way that not only objects were the subject of the record but also relations between objects, people and events. The record was about to take into consideration a conflict character of elements of this representation and at the same time to avoid applying to them the rule of mimetism. The record became a form of reflection over the very record by an increased control over the ways of representation. Architecture which was considered in the The Manhattan Transcripts was not directed to fulfill the needs of inhabitation or production, it was rather related with hitherto usually marginalised liminal situations: building ostentatiously big monuments, religious cult, war etc. Architecture operating in these relations focused also the attention on the included in it continuous tendency to overpass its own restrictions, the role of violence as its not recognised factor, or the meaning of excess and shock in its operation. Architecture moving from reason towards madness became even more visible in the design of Parisian Parc de la Villette, whose pavilions were defined as folies (in French it means both small park buildings and follies). The park was supposed to be on the one hand a reflection of traditional society disintegration while on the other it questioned basic rules of producing a work of architecture. The traditional rules of designing, based on ordering up, were replaced with the strategies of dysfunction and dissociation. In Tschumi’s opinion methods of this kind may be equivalent of what Derrida named différance. Instead of aiming at mergence, any diversity, plays or variations were strengthen. Tschumi’s texts, in which he explained his attitude, were completed by Derrida’s extent statement entitled Point de folie – Maintenant l’architecture. Derrida’s article is the most significant of all his statements on architecture as a form of thinking and activity. According to the philosopher, architecture should divide space (in French defined as espacement), what enables both thinking and action – it arranges the space of an event. Tschumi’s buildings, defined as folies, in an essential way destabilise any created order, and at the same time they refresh it. Derrida’s statement suggests that architecture may become both metaphor of an order merging a language or a society but also of inner forces which deconstruct and reconstruct it. Therefore architecture is at the same time a construction, a deconstruction and a reconstruction. Parc de la Villette stands out in this system with its attempt to step beyond the scheme of an easy repetition and its heading for chances of achieving more radical otherness. -/- Conclusion Destruction as construction. Paradoxes of deconstruction in architecture -/- Scepticism about persistence and common importance of fundamental values of human culture evinced in philosophers and writers’ works as early as in Greek antiquity, nevertheless it was not expressed so strongly as in the second half of the 20th century. Especially in Heidegger’s work Being and Time (although originated in 1927, still influential in all later philosophy) the following states were characterised: the state of losing the ground (Abgrund), of being out of sight (Unheimlichkeit) and of being out of dwelling (Un-zuhause-sein) – as the basis of self-confidence of conscious being there (Dasein). The entire criticism of philosophy of home and dwelling draws the inspiration from this early writing of the German philosopher, it combines crisis of basic terms of metaphysics with social conditions which are dictated by living in large metropolis. The crisis of both metaphysical foundation and home appears to be similar to the situation of weakening the relations between a man and his dwelling in extensively expanding cities. Whereas philosophy, as well as many disciplines of social sciences, have diagnosed for a long time the destabilisation of fundamental ideas of Western culture and crucial changes in the ways of dwelling, architecture itself occurred to be “the last fortress of metaphysics” (J. Derrida). Among contemporary architects, Peter Eisenman and Bernard Tschumi were the ones who engaged most decidedly in the issues of critical analysis of architecture foundation and its social role. Both the architects noticed new formulas of contemporary social and individual existence, tremendously different from the entire history, and at the same time they affirmed lack of adequacy of architecture concepts to new situations. Both Eisenman and Tschumi used to describe the existing architecture as a tool for consolidation of highly integrated and hierarchised societies, and also as a discipline extremely uncoincidental with the current character of social life based on ideas of freedom and diversity. The means to transform architecture and make a factor of further social changes out of it, was a concept that accentuated revealing the inner contradictions of this discipline, and considering them in designing strategies. Eisenman’s activity, in regard of what has just been noticed, was focused on questioning the basic rules of traditionally comprehended architecture, especially the rule of purpose. The American architect noticed that the concept of architecture as fulfilment the need of location, hides away the fact that the location has to be constantly reconsidered, and hence it is overtaken by change (dislocation). Therefore new concept of architecture propounded architectural activity to translocate the concept of location – more than before – but also to change its status perpetually. Such comprehended architecture should claim, as its main purpose, the constant revision of this purpose and create itself anew permanently. Even Eisenman’s earliest designs of houses nos. I-IV broke with such values as the sense of safety, closeness and familiarity, and just on the contrary they accentuated senses of strangeness, homelessness and loss of confidence. The contradictions within architecture noticed by Tschumi referred to combination of intellectual and sensual values in architecture, when their non-appropriation was defeated by an additional condition, namely the way of experience based on pleasure of excess, marked by insanity. The features of folly were especially visible in his designs of gardens, where the order of planning was mixed with sensual experience introduced by particular elements (both the ones created by nature, and the buildings defined as folies). Parc de la Villette designed by the French architect in Paris put in question not only the common understanding of purpose in architecture but also the ideas of order and integrity, as its plan was based on the combination of independent layers with records of grids of points, various lines and planes. The architecture that collides inadequate elements with each other was supposed to be a kind of an event with no beginning and no end. The architecture treated as an event became a form of a space weakened articulation that maintains its diversity and lack of accordance of the elements building it up. The analyses of Eisenman and Tschumi’s theoretical writings indicate how much the aims of architecture have actually changed; instead of supporting social persistence, the architecture is rather intensifying contradictions, and instead of providing people with the sense of safety, it sublimes danger. From simple acts of defamiliarisation, increasing the distance to itself and enhancing the role of theory, through discomfort, anxiety, not feeling someone at home, weirdness, excess, shock and violence, architecture reached the edge of stability and uncertainty, only to make an attempt at penetrating what is impossible and unutterable, and recording what cannot become the subject of any records. -/- . (shrink)

In the traditional sense, a work of art creates an illustration of the outside world, or of a certain text or doctrine. Sometimes it is considered that such an illustration is not literal, but is an interpretation of what is visible, or an interpretation of a certain literary or ideological message. It can also be assumed that a work of art creates its own visual world, a separate story or a separate philosophical statement. The Parc de La Villette represents the (...) last of these possibilities: it is a philosophical statement that develops the premises derived from poststructuralist philosophies and the philosophy of deconstruction. The uniqueness of its being status, however, is that it does so not only at the level of the theoretical assumptions, but also through its functioning as an active philosophical work. This means that a park is a happening philosophy. Its activity, however, does not refer only to the present tense, but is also an attempt to penetrate the future, all otherness and impossibility. This kind of activity assumes that the work, in a sense, does not yet fully exist, but is also still produced in the processes of its interpretation. The theoretical foundations of the park included texts by Bernard Tschumi, in which he questioned traditional ways of creating a work of architecture, postulating in return the use of a long series of negations, which were comparable to the crisis of metaphysics characteristic of contemporary philosophy. It is therefore no coincidence that the publication containing Tschumi’s theoretical text on Parc de La Villette was accompanied by an essay by Jacques Derrida developing some of the architect’s concepts. The next step in integrating philosophy into the process of park design was a series of discussions between Peter Eisenman and Derrida, who completely moved the creation of the park into the world of thoughts, without accentuating the need for their realization in the material reality. The main topic of these discussions was the problem of the chôra, which was taken up by later commentators and used to interpret the park as a work in which the philosophy of the beginning is manifested relating to issues of politics, morality and religion. The park was therefore interpreted as a space of invention within the scope of creating new rules of functioning of the community and democracy. Thinking about the political future may, however, exceed the horizon of ordinary expectations. Although philosophical thought is always connected with contemporary problems and metaphysics sometimes intertwines with current politics, yet at the same time the customs of philosophy also include crossing horizons and thinking about absolute otherness and impossibility. Initially, the chôra, différance, Absolute Otherness (tout autre) and the Impossibile were concepts of pure philosophy of atheistic character, but with the further development of the discussion, more and more theological motifs began to emerge. One of the reasons for this phenomenon was the fact that radical negations of all being, which were contemplated in contemporary philosophy (by Heidegger and Derrida, among others), had previously been manifested in negative and apophatic theologies (by Master Eckhart, among others). Also the category of the “Other”, taken from Emmanuel Levinas, was clearly connected with the thought about God. A further reason for connecting the chôra with the theological thought was the interest in the philosophy of deconstruction expressed by some theologians. Caputo in particular managed to persuade Derrida to participate in discussions on the current status of religion. In the late period of Derrida’s writing, further statements on religious topics appeared. All these reasons led to posing a question about the identity of the chôra and God. Although there were no satisfactory conclusions on this issue, the discussion was also important to create an interpretation of the park as a place of worship. The chôra, representing, according to Plato, the preoriginal emptiness is the place of every beginning, but it turns out that it is not neutral to the being created in it. The chôra deposits itself in every being as an irremovable beginning that interferes with its stability. The chôra, therefore, forces us into a palintropical movement, but it also turns out to be a pure compulsion, an erring necessity and a fundamental force from which, in the human perception, motifs useful to the individual and to the community are extracted. All definitions of this force, including its anthropomorphisation, are formulated in such a way that they allow for building private and collective morality upon them. Such definitions are changed depending on variable political situations. It is difficult to determine whether in the processes of changes in the formulation of “God’s names” any essential value is retained, which is not subject to change. The current definitions of the chôra (God?), which can be found, for example, in the philosophy of Caputo, stress that she is a combination of various and contradictory forces. This characteristic inherits much of Plato’s concept, reminds us of Master Eckhart’s views on Gottheit and, at the same time, is not unfamiliar to Tschumi, whose essays were an apologia of contradictions. The current concept of chôra, transferred into the sphere of politics, is the praise of social diversity and the protection of the difference from the forces of order. In the Parc de La Villette, the future community and democracy were elevated as a system of safe existence of individuals in all their singularity. The park is a temple of a future community in which individual beings have nothing in common. (shrink)

In the texts that presented the theoretical assumptions of the Parc de La Villette, Bernard Tschumi used a large number of terms that contradicted not only the traditional principles of composing architecture, but also negated the rules of social order and the foundations of Western metaphysics. Tschumi’s statements, which are a continuation of his leftist political fascinations from the May 1968 revolution, as well as his interest in the philosophy of French poststructuralism and his collaboration with Jacques Derrida, prove that (...) terms such as disruption, dissociation, disfunction, disjunctions and dispersion not only referred to architectural problems but also applied to political criticism and the deepest foundations of thinking itself. His collaboration with Derrida manifested itself primarily in the publication La Case Vide: La Villette, 1985, in which the architect’s design drawings and texts explaining his concepts related to the Park de La Villette were accompanied by an extensive essay by Derrida, which included theoretical problems taken up by Tschumi in a philosophical context. Architectural and philosophical issues were also combined during seven discussion meetings organised by Peter Eisenman, invited by Tschumi to collaborate on the design of the Parc de La Villette. Eisenman, who, like Tschumi, invited Derrida to participate in the design of the park and also led to the publication of Chora L Works: Jacques Derrida and Peter Eisenman, in which his ideas were confronted with Derrida’s philosophical text. In this case, Derrida’s essay was not a direct commentary on the architect’s concepts, but rather a reflection on the question of the chôra presented by Plato in Timaeus. During the discussion and in his essay, Derrida pointed out that the chôra is a component of the created world, yet it does not belong to it, but precedes it. The originality of the chôra is so radical that she also precedes all the factors of creating the world, including ideas and the Demiurge. Thus a thesis appeared in the metaphysics of the West that the chôra is a form of active abyss, in relation to which all beings are secondary, both those perfect (as ideas or God) and those created, such as the world, things, people or language. This leads to the conclusion that the chôra does not exist, because all existence is a derivative of the chôra. Nor could the chôra be described, since it is a form of developing a space that is preceded by a lack of space characteristic of the chôra. Derrida intended the chôra to be an instance with an exceptional degree of transcendentalism, an anti-metaphysical instance, but also an a-theological one. However, this attempt failed, both in the field of secular philosophy and in the field of theology. Derrida’s characteristics of the chôra to strengthen its transcendentalism and negation of metaphysics had to be expressed in a language that immediately produces new concepts and a new metaphysics that reproduces the categories of the beginning, the origin or the foundation known from earlier philosophical traditions. All forms of criticism of metaphysics are also inspired by negative, apophatic and mystical theology. The undermining of many concepts of permanent meaning and the introduction of new concepts of unstable meaning, characteristic of the philosophy of deconstruction, had many features of originality, but it was directed towards problems whose solutions repeat, with the use of new vocabulary, the findings known in culture since Democritus. Thus, if apophatic philosophy can be regarded as deconstruction avant la lettre, then deconstruction itself in its late versions began to take on the features of a new religion. The exchange of inspiration between theology and deconstruction was manifested in a series of scientific conferences and publications in which Derrida’s philosophical concepts were interpreted within the scope of religious thought. Theological threads began to be found in such concepts of deconstruction as différance or the chôra, while at the same time Derrida himself undertook in his philosophy to study problems such as the Other (L’Autre) or Impossible (Impossible), which belonged to newer theological traditions. As a consequence of the new problems, the deconstruction became closer to the features of a new religion. Philosophy, at least from Kant’s time, has tried to create a system that would take over from religion the tasks of setting moral and political goals. Similarly, Derrida has directed his interest towards the problems of democracy and ethics, which would enable their renewal. Attempts to create a new religion (cleared of old metaphors), a new community or a new democracy bring problems and threats which may be no less troublesome than the previous systems. All promises of freedom carry with them threats, the greater the more they strive for perfection. The renewal of existential orders, sometimes carried out by means of violent changes, is a certain repetitive feature of human cultures. Deep changes, however, do not protect against the return of both old gods and old demons. Tschumi and Derrida were shaped in their youth by the atmosphere of leftist rebellion against the moral and political limitations of ossified communities and the imperfections of democracy. The ethical theme distinguishes many of their works, including the Parc de La Villette. The opposition to the metaphysical traditions of philosophy and architecture contained in this park was prompted by specific political situations and resulted from bringing political issues to the level of philosophical considerations. Achievements made at the level of pure concepts were then subject to elevation, to a kind of sacralization, which made them religious concepts. The deconstruction reached for the stratus of the new religion especially when it found its followers and began to generate moral obligations. In the new situation, terms such as the chôra, l’autre or the Impossible were absolutized and in relation to them a cult and attitude of adoration emerged. The Parc de La Villtette then gained new post-secular meanings, which allow it to be assigned the function of a Temple of Otherness (L’Autre) and Impossible. (shrink)

GAMETOGÊNESE -/- Emanuel Isaque Cordeiro da Silva Instituto Agronômico de Pernambuco Departamento de Zootecnia – UFRPE Embrapa Semiárido -/- • _____OBJETIVO -/- Os estudantes bem informados, estão a buscando conhecimento a todo momento. O estudante de Veterinária e Zootecnia, sabe que a Reprodução é uma área de primordial importância para sua carreira. Logo, o conhecimento da mesma torna-se indispensável. No primeiro trabalho da série fisiologia reprodutiva dos animais domésticos, foi abordado de forma clara, didática e objetiva os mecanismos de diferenciação (...) sexual dos embriões em desenvolvimento, quais os genes envolvidos nesse processo e tudo mais. Nesse segundo trabalho, a abordagem será teórica, mas também clara, sobre a formação primordial dos gametas femininos e masculinos, através da ovogênese nas fêmeas e a espermatogênese nos machos. Esse trabalho visa levar a importância do processo de formação dos gametas e a produção hormonal das gônadas, bem como o entendimento sobre as interações com o eixo hipotálamo-hipofisário. -/- •____INTRODUÇÃO -/- A reprodução sexual é um processo mediante a qual dois organismos da mesma espécie unem seu material genético para dar lugar a um organismo fixo com combinação única de genes; para isso, cada organismo produz células que contém a metade do material genético característico da espécie. Essas células haploides (1n) são denominadas gametas; ao combinar-se um gameta masculino com um feminino produz-se uma célula diploide (2n) (zigoto ou ovo) a partir da qual se forma o embrião. A grande maioria das espécies com reprodução sexual são anisogâmicas, o que significa que produzem dois tipos de gametas diferentes: os gametas masculinos são microscópios, móveis e produzem-se em grande quantidade, enquanto que os femininos são grandes, imóveis e produzem-se em menor quantidade. O tipo de gameta que um indivíduo produz é o que define seu sexo; sobre os animais o macho é o indivíduo que produz grandes quantidades de espermatozoides e a fêmea produz uma menor quantidade de óvulos, enquanto que nas plantas as gônadas masculinas são as produtoras pólen e as femininas produzem oosferas. Os gametas são diferentes do resto das células do organismo, as quais se chamam células somáticas; essas últimas são diploides porque contém dois pares de cromossomos, um par herdado do pai do indivíduo e o outro da mãe. As células somáticas, ademais, se dividem por mitose, ao qual os cromossomos se duplicam antes de cada divisão celular e cada uma das células filhas recebe um complemento diploide idêntico dos cromossomos, logo todas as células somáticas de um indivíduo possuem o mesmo material genético, embora cada tipo celular expresse diferentes combinações de genes. Em contraponto, os gametas são células haploides porque possuem somente um par de cromossomos e a metade do material genético característico da espécie. Cada um dos cromossomos em um gameta é resultado da recombinação dos genes contidos nos cromossomos paterno e materno do indivíduo que originam o gameta, e cada um destes possuem uma combinação única de genes. Os gametas se formam a partir das células germinais, que são células que em sua origem são diploides e elas de “comprometem” a manter-se como uma linha celular especial que em determinado momento sofrerá o processo de meiose para dar origem aos gametas haploides, sejam óvulos ou espermatozoides segundo o sexo do animal. Como descrito no trabalho sobre a diferenciação sexual, as células germinativas primordiais originam-se no epiblasto do embrião, e migram desde o saco vitelino até colonizar as cristas gonodais, onde, por sua vez, proliferam-se e se organizam junto com as células somáticas da gônada primitiva para formar o testículo ou o ovário. As células germinais masculinas e femininas tem a mesma origem embrionária. As gônadas indiferenciadas em um embrião possuem três tipos celulares: as células que dão origem aos gametas (ovogonia ou espermatogonia), as precursoras de células que nutrem os gametas em desenvolvimento (células da granulosa no ovário; células de Sertoli no testículo) e as precursoras de células que secretam hormônios sexuais (células da teca no ovário; células de Leydig no testículo). As células germinais são as únicas estruturas do organismo que têm a capacidade de dividir-se por meiose sofrendo uma redução no número de seus cromossomos, sendo responsável pela transmissão da carga genética aos descendentes. Em contraste, as células somáticas somente se dividem por mitose. A formação dos gametas compreende fases sequenciais de mitose, meiose e pós-meiose. Esses processos são altamente organizados e necessitam de um preciso e bem coordenado programa de expressão genética. Uma das características importantes da gametogênese é a redução cromossômica, que através da meiose, reduz pela metade o número de cromossomos e produz células distintas entre si, devido a trocas de material genético entre os pares de cromossomos provenientes do pai e da mãe, o que ocorre no processo de “crossing over” durante a primeira fase da meiose. A gametogênese é o processo mediante o qual as células germinais de cada sexo se multiplicam, dividem e diferenciam até formar os gametas. No caso da formação dos gametas masculinos o processo recebe o nome específico de espermatogênese, e para os gametas femininos é denominado como ovogênese. Embora os dois processos alcancem o objetivo comum de produção das células haploides, por onde compartilham algumas características, existem diferenças marcadas entre eles devido a necessidade de produzir um número muito distinto de gametas, de tamanho diferente, e com características de motilidade também distintas. -/- •___ESPERMATOGÊNESE -/- A espermatogênese é o processo mediante o qual se produz os gametas masculinos denominados espermatozoides. Durante a vida fetal as células germinais e as células somáticas do testículo em formação organizam-se em túbulos seminíferos que se derivam dos cordões sexuais primários e conformam a maior parte da medula do testículo. Na etapa fetal cada tubo seminífero é delimitado por uma membrana basal, recoberta na parte interior pelas células precursoras das células de Sertoli (um tipo de células somáticas). No exterior do túbulo localizam-se as células precursoras das células de Leydig ou intersticiais (figura 1), que também são células somáticas. Entre a membrana basal e as células de Sertoli encontram-se algumas células germinais denominadas espermatogonias de reserva A0 (denominadas gonócitos) que serão o único tipo de células germinais presentes no testículo enquanto o animal não alcançar a puberdade. As células de Sertoli estabelecem na região basal uniões oclusoras entre si, formando parte da barreira hemato-testicular. As espermatogonias A0 localizam-se por dentro da membrana basal do túbulo seminífero, embora fora da barreira hemato-testicular. Figura 1: fase neonatal. Nota-se a grande infiltração de tecido intersticial em quase 50% da seção originando que os túbulos sejam pequenos e redondos em sua maioria. O citoplasma e núcleo das células pré-Leydig são notadas claramente por essa ser uma espécie suína onde o tecido intersticial está claramente diferenciado. Hematoxilina-eosina (X 220.5). Fonte: Embrapa. -/- O número de células de Sertoli no testículo depende da influência do hormônio folículo estimulante (FSH) presente durante a vida fetal e as primeiras etapas de vida pós-natal. A população de células de Sertoli ao chegar a puberdade se manterá fixa durante o resto da vida do animal; existe uma relação positiva entre o tamanho e a população de células de Sertoli e a capacidade de produção de espermatozoides do testículo. As células de Sertoli são as únicas células somáticas que estão no epitélio seminífero, e sua função é a nutrição, sustentação e controle endócrino das células germinais. As células de Sertoli participam ativamente no processo de liberação dos espermatozoides para a luz do túbulo. Nesse momento, as células de Sertoli realizam a fagocitose de parte do citoplasma do espermatozoide dos chamados corpos residuais. As células de Sertoli também fagocitam as células germinais que se degeneram no curso normal da espermatogênese. Essas células ainda sintetizam grande quantidade de proteínas, como por exemplo as proteínas ABP (androgen hinding protein), que transportam andrógenos para todo o aparelho reprodutivo, transferrinas, que transportam ferro para a respiração celular das células germinais e também às inibinas, que regulam a liberação de FSH pela hipófise, através de um sistema de retroalimentação (feedback) negativa (figura 2). Figura 2: epitélio seminífero, células de Sertoli (flecha) (400 X). Fonte: Embrapa. -/- Antes da puberdade dos túbulos seminíferos observam-se ao corte como estruturas de diâmetro pequeno, sem luz, e conformados unicamente pelas células de Sertoli e espermatogonias de reserva e rodeados por abundante tecido intersticial, ao que estão presentes as células precursoras das células de Leydig. Ainda antes da puberdade, a diferenciação celular manifesta-se primeiro pela presença de espermatócitos primários, os quais se degeneram em geral na fase de paquíteno, por falta de estimulação hormonal. A partir de que o animal chega a puberdade inicia-se o processo de espermatogênese, que se manterá durante toda a vida do animal, exceto em espécies de animais silvestres muito estacionais, ao qual pode se suspender durante a época não reprodutiva para voltar e ser retomada na época ou estação reprodutiva. Depois da puberdade, os túbulos seminíferos possuem um diâmetro muito maior; em seu interior observa-se um grande número de células germinais de todos os tipos, diferentes estádios de divisão, e em seu lúmen contém líquido e espermatozoides. Ainda sobre o alcancei da puberdade, as espermatogonias começam a dividir-se aceleradamente por mitose, enquanto que no espaço intersticial as células mesenquimais também começam a se diferenciar e a dar origem as células de Leydig (figura 3). A partir dessa etapa as células de Leydig (totalmente diferenciadas) são também evidentes no exterior do túbulo, junto com as células mioides ou peritubulares que o rodeiam o que ao contrair-se são responsáveis por controlar o avanço dos fluidos e as células presentes no lúmen do túbulo. As células mioides estão situadas ao redor do túbulo, e é creditado a elas a promoção da contração e da integridade estrutural do túbulo. Esse tipo celular apenas se diferencia na puberdade pela ação dos andrógenos (figura 4). As interações entre as células de Sertoli e as mioides parecem ter um papel importante na manutenção das funções do testículo. Durante o processo de espermatogênese, as espermatogonias de reserva dividem-se periodicamente e enquanto algumas células fixas permanecem como espermatogonias de reserva, outras proliferam e sofrem uma seção de divisões mitóticas durante as quais se vão diferenciando até formarem espermatócitos primários (espermatocitogênese ou fase de mitose), logo sofrem divisões especiais mediante as quais reduzem seu número de cromossomos (fase de meiose), e ao final trocam de forma para converter-se em espermatozoides (espermatocitogênese) (figura 5). Cada uma dessas etapas da espermato- gênese será descrito detalhadamente adiante, antes é necessário a explicação de algumas características das células de Sertoli e de Leydig que ajudarão a entender seu papel durante a espermatogênese. Figura 3: células de Leydig no espaço intersticial do testículo bovino adulto PAS (400 X). Fonte: Embrapa. -/- Figura 4: o estabelecimento da puberdade pela presença de espermatozoides no túbulo. Hematoxilina-eosina (400 X). Fonte: Embrapa. Figura 5: fases mitóticas das espermatogonias (A0 e B) para formação de um espermatócito primário e as duas fases de meiose que se sucedem antes da espermatogênese. Fonte: ZARCO, 2018. -/- Ao início da espermatocitogênese as uniões oclusoras entre as células de Sertoli se abrem por etapas (como as comportas de um submarino) para permitir a passagem das espermatogonias em direção ao centro do túbulo seminífero sem que se estabeleça uma continuidade entre o exterior e o interior da barreira hemato-testicular. Uma vez ultrapassada essa barreira, as sucessivas gerações de espermatogonias, espermatócitos, espermátides e espermatozoides irão se localizar em direção ao interior do túbulo seminífero, em estreita associação com as células de Sertoli. Em consequência, as células de Sertoli dividem o túbulo seminífero em dois compartimentos; o compartimento basal (debaixo das uniões oclusoras das células de Sertoli), ao qual residem as espermatogonias de reserva, e o compartimento adluminal (em direção ao centro do túbulo), cujos espaços entre as células de Sertoli desenvolvem o resto do processo de espermatogênese (meiose e espermatocitogênese). Esse feito é importante porque durante a vida fetal as únicas células germinais existentes eram as espermatogonias de reserva, pelo que os antígenos expressados por gerações mais avançadas (espermatogonias intermediárias, secundárias, espermátides e espermatozoides) não são reconhecidos como próprios do corpo pelo sistema imunológico. Logo, o anterior implica que deve existir uma barreira entre eles e o sangue para evitar um ataque imunológico. Em todas as etapas da espermatogênese, as células de Sertoli atuam como células de suporte para as células germinais, que sempre permanecem recoberta pela membrana das células de Sertoli. Também atuam como células nutricionais já que proporcionam o meio em que as células germinais se desenvolvem e maturam, assim como as substâncias que regulam e sincronizam as sucessivas divisões e transformações das células germinais. As células de Sertoli produzem hormônios, como estrógenos e inibina que atuam sobre a hipófise para regular a secreção das gonadotropinas que controlam a espermatogênese. As células de Leydig que residem no exterior do túbulo seminífero também são importantes para a espermatogênese: produzem a testosterona que estimula e mantém a espermatogênese, bem como serve como substrato sobre o qual atua como aromatizador das células de Sertoli para transformá-las em estrógenos. Como supracitado, para seu estudo podemos dividir a espermatogênese em três fase: espermatocitogênese, meiose e espermiogênese (figura 6). Agora, serão descritas cada uma dessas etapas. Em algumas espécies, incluindo no homem, os macrófagos representam o segundo tipo celular intersticial mais numeroso no testículo, depois das células de Leydig. Os macrófagos e vários subtipos de linfócitos são identificados nós testículos de ovinos e ratos. Eles estão intimamente associados com as células de Leydig e atuam juntamente na regulação da esteroidogênese. Figura 6: fluxograma da espermatogênese. -/- Espermatocitogênese -/- A espermatocitogênese, também chamada de etapa proliferativa ou de mitose, consiste numa série de divisões mitóticas sofridas pelas células descendentes de uma espermatogonia de reserva. Uma vez que a célula se divide, abandona o estado de reserva e começa um processo de diferenciação. As espermatogonias de reserva (denominadas espermatogonias A0 na rata ou As nos humanos) são células que existem desde a vida fetal e que permanecem mitoticamente inativas durante a infância. Uma vez que alcançam a puberdade começam a dividir-se em intervalos regulares, e as células filhas podem permanecer como espermatogonias de reserva ou abandonar a reserva e ingressar na dita espermatocitogênese. Uma vez abandonada a reserva, as células filhas que vão se formando em cada divisão permanecem unidas por pontes citoplasmáticas, constituindo um clone que se divide sincronicamente. As células que se formam depois de cada divisão continuam sendo espermatogonias, porém cada geração é ligeiramente diferente da anterior. Na rata, por exemplo, as espermatogonias tipo A0 ao dividir-se originam espermatogonias do tipo A1, que em sucessivas divisões formam espermatogonias dos tipos A2, A3 e A4, as quais, por sua vez, sofrem outra mitose para formar espermatogonias intermediárias e uma mais para formar espermatogonias do tipo B. Essas últimas se diferenciam (sem se dividir) em espermatócitos primários, processo em que termina a fase de espermatocitogênese, que literalmente significa processo de geração de espermatócitos. As espermatogonias tipo A0 são a fonte para a contínua produção de gametas. A metade delas se dividem e formam células iguais (as chamadas células tronco) e a outra metade forma as espermatogonias A1, que sofre novas divisões mitóticas e formam os tipos 2, 3 e 4. O tipo A4 sofre mitose para formar a intermediária (A In), que por mitose, forma a tipo B (figura 6). Esses tipos de espermatogonias podem ser identificadas em evoluções histológicas de acordo com sua organização topográfica na membrana basal dos túbulos seminíferos ou mediante seu conteúdo de heterocromatina. Outra maneira de diferenciação se baseia em marcadores moleculares específicos que distinguem as espermatogonias tronco (A0) das demais, com os fins de isolamento, desenvolvimento in vitro e transplante. As tipo B passam por mitose para formarem os espermatócitos primários; estes iniciam a primeira etapa da meiose formando os espermatócitos secundários; na segunda etapa da divisão meiótica, cada espermatócito secundário se divide e formam as chamadas espermátides. Quando o testículo alcança seu desenvolvimento total, a meiose completa-se e as espermátides originadas se convertem em espermatozoides. Um dos maiores sinais característicos desse fenômeno é o alargamento das espermátides e sua migração em direção ao lúmen do túbulo seminífero (figuras 4, 7 e 8). Figura 7: espermatogonias marcadas por imuno-histoquímica, anticorpo monoclonal TGFa (400 x). Figura 8: fases de divisões meióticas (M), espermatócitos em paquíteno (PA) e espermatócitos secundários (ES). -/- Figura 9: estádio posterior a liberação dos espermatozoides na luz do túbulo. Hematoxilina-eosina (400 x). Mediante as seis divisões mitóticas que ocorrem durante a espermatocitogênese se forma potencialmente um clone de 64 espermatócitos primários a partir de cada espermatogonia A que ingressa sobre o processo. Não obstante, algumas células sofrem apoptose em cada uma das etapas do processo, ao qual o número real formado é menor. Em outras espécies produzem-se um transcurso similar de divisões mitóticas sucessivas durante a espermatocitogênese, embora a nomenclatura utilizada possa ser distinta, por exemplo nos bovinos as duas últimas divisões mitóticas dão origem as espermatogonias de tipo B1 e B2. -/- Meiose -/- Uma vez que as espermatogonias B se diferenciam em espermatócitos primários, esses iniciam a etapa de meiose, com uma nova divisão; desta vez a divisão é do tipo meiótica. Ao completar-se a primeira divisão meiótica (meiose I) se obtém os espermató-citos secundários, que ao sofrer a segunda divisão meiótica (meiose II) dão origem as espermátides. Vale salientar que a meiose é o processo mediante o qual reduz-se a metade do número de cromossomos, pelo que as espermátides que se obtém são células haploides (1n). Os espermatócitos secundários que se formam depois da primeira divisão meiótica contém a metade do número normal de cromossomos, porém a mesma quantidade de DNA já que cada cromossomo é duplo. As espermátides formadas na conclusão da segunda divisão meiótica (figura 7), por sua vez, contém a metade dos cromossomos, e esse já não são duplos, já que se trata de células 1n. Também deve-se enfatizar que durante a meiose é relevante o entrecruzamento dos cromossomos homólogos, pelo que cada espermátide possui uma combinação única e diferente de genes paternos e maternos. Outro ponto que deve ser levado em consideração é que cada espermátide somente possui um cromossomo sexual; a metade das espermátides contém o cromossomo X herdado da mãe do macho que está levando a cabo a espermatogênese e a outra metade contém o cromossomo Y herdado de seu pai. Para cada espermatócito primário que entra no processo de meiose obtém-se cerca de quatro espermátides, pelo qual ao ser completada a meiose potencialmente se poderiam formar até 256 espermátides por cada espermatogonia que abandona a reserva e ingressa na espermatocitogênese. -/- Espermiogênese -/- Durante a espermiogênese, também chamada de fase de diferenciação, as esper-mátides sofrem, sem se dividir, uma metamorfose que as transforma em espermatozoides, os quais finalmente são liberados das células de Sertoli em direção ao lúmen do túbulo seminífero. A espermiogênese é um processo complicado e longo já que a espermátide deve sofrer complexas trocas nucleares, citoplasmáticas e morfológicas que resultam na forma-ção dos espermatozoides. Algumas dessas mudanças incluem a condensação do material nuclear para formação de um núcleo plano e denso, a eliminação do citoplasma para a constituição de uma célula pequena, a formação de uma estrutura especializada denomi-nada acrossomo ou tampa cefálica, e a formação do pescoço e da cauda (flagelo) do esper-matozoide, do que depende a sua motilidade. Durante a maior parte da espermiogênese, as espermátides se mantém com uma estreita associação com as células de Sertoli; logo, chega-se a observar, então, flagelos que se projetam em direção a luz do túbulo que pare-cem sair das células de Sertoli, sendo na realidade os flagelos dos espermatozoides que ainda não tinham sido liberados pelo lúmen. Ao liberar os espermatozoides em direção a luz do túbulo, as células de Sertoli realizam a fagocitose de parte do citoplasma dos espermatozoides (corpos residuais). Também fagocitam os restos de todas as células germinais que sofrem apoptose ou degeneram-se durante a espermatogênese. Credita-se que ao realizar essas funções as células de Sertoli podem fazer uma monitoração eficiente da espermatogênese, o que lhes permitiria emitir sinais para colaborar na regulação desse processo em nível gonodal e a nível sistêmico através da secreção de hormônios como a inibina e o estradiol. Além da inibina e activina, as células de Sertoli sintetizam outras proteínas, como a ABP (proteína ligadora de andrógenos) que serve como uma molécula de transporte de andrógenos dentro dos túbulos seminíferos, ductos deferentes e epidídimo, ou a transfer-rina, que transporta o ferro necessário para a respiração celular. -/- Resultados da espermatogênese -/- O resultado da espermatogênese não significa apenas uma simples multiplicação das células germinais (até 256 espermatozoides a partir de cada espermatogonia A1), senão que através dela são produzidos gametas haploides pequenos, móveis e com grande diversidade genética entre eles, ao mesmo tempo que se mantêm uma reversa de células mãe (espermatogonias A0) a partir das quais se poderiam originar novos ciclos de esper-matogênese durante o resto da vida do animal. -/- Controle hormonal da espermatogênese -/- Como mencionado, o FSH reproduz um importante papel para o estabelecimento das células de Sertoli durante a vida fetal e início da vida pós-natal. O começo da esper-matogênese também é estimulado pelo FSH, que atua sobre as células de Sertoli para estimular sua função e a ativação de sinais dessas células em direção as células germinais, incluindo-as a abandonar a reserva e ingressar na espermatogênese. O FSH, assim mesmo, estimula a mitose durante o resto da espermatogênese e aumenta a eficiência do processo, já que reduz a apoptose e a degeneração de espermatogonias intermediárias e do tipo B. O FSH também estimula as células de Sertoli para produzirem inibina e ABP. Uma vez iniciada a espermatogênese somente requerem níveis baixos de FSH para se mantê-la. As células de Sertoli também devem ser estimuladas pela testosterona para funcio-nar de maneira adequada; se requer também do LH hipofisário: hormônio que estimula as células de Leydig para produzir testosterona. Por sua vez, a secreção de LH e FSH é regulada pelo GnRH hipotalâmico: esse neurohormônio também faz parte do mecanismo de regulação da espermatogênese. A espermatogênese também é modulada em nível local mediante a produção de determinados fatores e interações entre as células. Dentro dos fatores locais podemos mencionar o fator de crescimento parecido com a insulina 1 (IGF-1), o fator de crescimen-to transformante beta (TGF- β), activina, ocitocina e diversas citocinas. Entre as intera-ções celulares existem tanto uniões de comunicação entre as células de Sertoli e as células germinais, como pontes citoplasmáticas entre todas as células germinais que formam o clone de células descendentes de uma espermatogonia A1. Uma vez que as células de Sertoli iniciam sua função na puberdade é possível manter experimentalmente a espermatogênese somente com testosterona, sem ser requeri-dos nenhum outro hormônio. A quantidade de espermatozoides produzidos, no entanto, é maior quando há presença do FSH. Abaixo do estímulo do FSH as células de Sertoli produzem estradiol e inibina, hormônios que geram uma retroalimentação sobre o eixo hipotálamo-hipofisário para a regulação da secreção de gonadotropinas. Em particular, a inibina reduz a secreção de FSH, pelo qual é factível que sirva como um sinal que evite uma excessiva estimulação as células de Sertoli. -/- Ciclo do epitélio seminífero -/- Em cada espécie as espermatogonias de reserva iniciam um novo processo de divi-sões celulares em intervalos fixos: a casa 14 dias no touro; 12 dias no garanhão e a cada 9 dias no cachaço (reprodutor suíno). A nova geração de células que começam a proliferar sobre a base do tubo deslocam-se em direção ao centro do túbulo a geração anterior, que por sua vez deslocam-se as gerações anteriores. Devido as mudanças que vão sofrendo cada geração celular se ajustam a tempos característicos de cada etapa, já que rodas as células em uma determinada seção do túbulo estão sincronizadas entre si pelas células de Sertoli; em cada espécie somente é possível encontrar um certo número de combinações celulares: 14 diferentes combinações no caso da rata, 8 no touro e 6 no ser humano. A sucessão de possíveis combinações até regressar a primeira combinação se conhece como o ciclo do epitélio seminífero. Na maioria das espécies os espermatozoides que são libera-dos em direção a luz do túbulo provém das células que entraram no processo de esperma-togênese quatro gerações antes que a geração que está ingressando nesse momento, pelo que a espermatogênese no touro dura ao redor de 60 dias e um pouco menos em outras espécies domésticas. Significa que os efeitos negativos das alterações na espermatogêne-se podem estar presentes até dois meses depois de que se produziram essas alterações. Como supracitado, geralmente se observa a mesma combinação celular em toda a área de uma determinada secção transversal do túbulo seminífero. No entanto, se fizermos uma série de secções, observa-se que ao longo do túbulo há uma sucessão ordenada de combinações (a primeira em uma determinada secção; a segunda combinação na seguinte secção, e assim sucessivamente em secções subsequentes até regressar a primeira combi-nação. Teremos, então, que ao início da divisão das espermatogonias A1 se produz de forma sincronizada em uma secção do túbulo, e vai-se transmitindo como uma onda peristáltica as secções adjacentes. Esse processo é denominado como onda do epitélio seminífero e graças à esse túbulo seminífero sempre tem secções em todas as etapas da espermatogênese, com o que se alcança uma produção constante de espermatozoides. -/- Alterações da espermatogênese -/- Nas espécies estacionais a espermatogênese, como já mencionado, pode reduzir-se ou inclusive suspender sua atividade fisiológica durante a época não reprodutiva dessas espécimes, porém esse processo fisiológico não pode ser considerado como uma altera-ção. No entanto, a espermatogênese só pode ser alterada pelas enfermidades ou por fatores externos. A principal causa de alterações na espermatogênese é o aumento da temperatura testicular. Por isso, os testículos são localizados na saco escrotal e são “caídos” para fora do corpo como pode-se observar nos bovinos, caprinos, ovinos, caninos e no próprio homem. A temperatura testicular deve estar cerca de 2 a 6 °C abaixo da temperatura corporal normal. As células germinais masculinas são sensíveis ao calor, pelo qual na maioria dos mamíferos os testículos se encontram fora da cavidade abdominal e existe um sofisticado sistema de termorregulação para mantê-los a uma temperatura menor que a corporal. Se a temperatura corporal for elevada ou se os testículos permanecerem na cavidade abdominal, ou ainda se os sistemas termorreguladores do testículo sejam afetados por fatores inflamatórios como edema ou falta de mobilidade testicular dentro do escroto, a temperatura do tecido testicular aumentará e a espermatogênese sofrerá alterações proporcionais ao excesso de temperatura e a duração da elevação. A espermatogênese também pode ser afetada pela exposição a hormônios ou a outras substâncias. É possível que a causa mais comum (sobretudo no homem) seja o uso de esteroides anabólicos, que elevam a concentração de andrógenos na circulação, provo-cando um feedback negativo sobre a secreção de gonadotropinas. Ao deixar de estimular-se o testículo pelas gonadotropinas, este deixará de produzir testosterona, e as concentra-ções de andrógeno exógeno nunca alcançará as altíssimas concentrações de testosterona que normalmente estão presentes a nível do tecido testicular por ser o local onde se produz o hormônio. Também se supõe que diversas substâncias com propriedades estrogênicas derivadas de processos industriais (indústria dos plásticos, hidrocarbonetos etc.) e presentes no ambiente (fatores xenobióticos) podem ser responsáveis pelas alterações na espermatogênese em diversas espécies, entre as quais se inclui o ser humano. -/- • OVOGÊNESE E FOLICULOGÊNESE -/- A ovogênese é o processo seguido pelas células germinais da fêmea para a forma-ção dos óvulos, que são células haploides. Durante a vida fetal as células germinais proliferam-se no ovário por mitose, formando um grande número de ovogonias, algumas das quais se diferenciam em ovócitos primários que iniciam sua primeira divisão meiótica para deter-se na prófase da divisão. Somente alguns desses ovócitos primários retornarão e concluirão a primeira divisão meiótica em algum momento da vida adulta do animal, dando origem a um ovócito secundário e a um corpo polar. O ovócito secundário inicia a sua segunda divisão meiótica, a qual volta a ficar suspensa até receber um estímulo apropriado, já que somente os ovócitos secundários que são ovulados e penetrados por um espermatozoide retornam e concluem a segunda divisão meiótica, dando origem a um óvulo (figura 10). O processo de ovogênese é realizado dentro dos folículos ovarianos, que também tem que sofrer um longo transcurso de desenvolvimento e diferenciação denominado foliculogênese pelo que a ovogênese como tal realiza-se dentro do marco desse último processo. Por essa razão, na seguinte seção descreverei tanto a ovogênese como a folicu-logênese, e a relação que existe entre ambos. Figura 10: representação da ovogênese. Na etapa de proliferação, as células germinais se diferen-ciam por mitose. A meiose I se caracteriza por uma prófase prolongada, ocorrendo a duplicação do DNA. Nas duas divisões, que ocorrem antes da ovulação e depois da fertilização, a quantidade de DNA é reduzida a 1n, com o fim de que a fusão dos pronúcles (singamia) pós-fertilização, seja gerado um zigoto com um número de cromossomos de 2n (diploide). -/- Geração de ovócitos primários e folículos primordiais Tanto a ovogênese como a foliculogênese iniciam-se durante a vida fetal, quando as células germinais primordiais provenientes do saco vitelino colonizam a gônada primitiva e, junto com as células somáticas z organizam-se para a formação dos cordões sexuais secundários, que se desenvolvem principalmente no córtex do ovário. Nesse período, as células germinais que colonizaram o ovário sofrem até 30 divisões mitóticas, proliferando-se até formar milhares ou milhões de ovogonias, que inicialmente formam “ninhos” constituídos cada um deles por um clone de várias ovogonias que descendem da mesma célula precursora e que se mantêm unidas por pontes citoplasmáticas, sincronizan-do suas divisões mitóticas. Nessa etapa alcança-se a máxima população de células germinais no ovário, que antes de nascer se reduzirá drasticamente por apoptose. No ovário do feto humano chegam a haver até sete milhões de células germinais que ao nascimento se reduzem a dois milhões. Os ovários fetais do bovino, de maneira análoga, chegam a ter até 2.100.000 células germinais, que ao nascimento reduzem para 130.000 aproximadamente. A redução no número de ovogonias produz-se ao mesmo tempo que essas células, que vêm dividindo-se por mitose e estão agrupadas em ninhos, iniciam sua primeira divisão meiótica para se transformarem em ovócitos primários: células germinais que se encontram em uma etapa de suspensão (diplóteno) da prófase da primeira divisão meiótica. Nesse período produz-se uma grande proporção de células germinais; as células somáticas dos cordões sexuais, por sua vez, emitem projeções citoplasmáticas que separam a isolam os ovócitos primários sobreviventes, ficando cada um deles rodeados por uma capa de células aplanadas da (pré) granulosa. Ao mesmo tempo em que se forma uma membrana basal entre as células da granulosa e o tecido intersticial do ovário. Ao ovócito primário rodeado de uma capa de células da (pré) granulosa aplanadas e delimita-das por uma membrana basal denomina-se de folículo primordial (figura 11). Nas vacas os folículos primordiais bem formados já estão presentes nos ovários a partir do dia 90 da gestação. A maioria dos folículos primordiais com os que nasce uma fêmea se manterão inativos durante um longo tempo; muitos deles durante toda a vida do animal. Nos folículos primordiais inativos tanto os ovócitos primários como as células da granulosa conservam sua forma original e mantém um metabolismo reduzido estritamente ao mínimo necessário para manter-se viáveis. Por essa razão, ao realizar um corte histológico de qualquer ovário as estruturas mais numerosas que se observam serão os folículos primordiais. No entanto, cada dia da vida de um animal, inclusive desde a vida fetal, um certo número de folículos primordiais reiniciam seu desenvolvimento, e a partir desse momento um folículo exclusivamente pode ter dois destinos: o primeiro, prosseguir seu desenvolvi-mento até chegar a ovular, e o segundo (que é muito mais frequente) encontrar em algum momento condições inadequadas que fazem fronteira com ele para parar seu desenvolvi-mento, levando-o a sofrer atresia e degenerar até desaparecer do ovário. Figura 11: sequência da foliculogênese apresentando as diferentes estruturas que podemos encontrar em cada fase. Fonte: ZARCO, 2018. Culminação da ovogênese A ovogênese somente se completará quando um ovócito primário reinicia a meio-se; completa sua primeira divisão meiótica para formar um ovócito secundário e um primeiro corpo polar e, quando, finalmente sofrer uma segunda divisão meiótica para formar um óvulo e um segundo corpo polar. Os óvulos são as células 1n que constituem os gametas femininos, pouco numerosos, grandes e imóveis. A grande maioria dos ovóci-tos primários, como veremos mais adiante, nunca retomam a meiose e, em consequência, não chegam a formar ovócitos secundários, e muitos dos ovócitos secundários tampouco sofrem uma segunda divisão meiótica, pelo que não chegam a formar os óvulos. Ao longo da vida de uma fêmea, na maioria das espécies, menos de 0,1% dos ovócitos primários (um a cada mil) chega a terminar a ovogênese, dando origem a um óvulo. O supracitado deve-se a que a ovogênese somente pode retomar-se e ser completa-da em ovócitos primários que se encontram dentro dos folículos primordiais que (uma vez ativados) vão alcançando diversas etapas de seu desenvolvimento em momentos precisos aos que encontram as condições ideais de oxigenação, nutrição, vascularização e exposição a fatores parácrinos e a exposição a concentrações de hormônios que se requerem para que o folículo continue em cada etapa de seu desenvolvimento com o processo de foliculogênese até chegar a ovular. Qualquer folículo que não esteja nessas condições ao longo do desenvolvimento sofrerá degeneração e atresia, pelo que o ovócito primário em seu interior nunca chegará ao ponto em que pode retomar a primeira divisão meiótica. No que resta da presente seção revisaremos o processo de foliculogênese em cujo marco se desenvolve a ovogênese; havemos que tomar de conta que essa última se limita ao que ocorre nas células germinais (ovogonia, ovócito primário, secundário e óvulo), pelo qual depende intimamente do desenvolvimento do folículo de que essas células formam parte. Em um princípio a ativação do folículo primordial e o desenvolvimento folicular são independentes das gonadotropinas: não se conhecem os mecanismos precisos median-te os quais um folículo primordial se ativa e reinicia seu desenvolvimento, nem como se decide quais folículos, dentre as dezenas de milhares de ou centenas de milhares presentes em um ovário se reativarão em um dia em particular. A reativação trata-se de uma liberação de influência de fatores inibidores, já que os folículos primordiais se reativam espontaneamente quando cultivados in vitro, isolados do resto do tecido ovariano. Uma vez que um folículo primordial se ativa, inicia-se um longo processo de desenvolvimento que somente depois de vários meses (ao redor de cinco meses no caso dos bovinos) o levará a um estádio em que seu desenvolvimento posterior requer a presença das gonado-tropinas; daí que se diz que as primeiras etapas do desenvolvimento são independentes das gonadotropinas. Durante a fase independente de gonadotropinas, um folículo primordial que tenha sido ativado e tenha começado a crescer; passará primeiro para a etapa de folículo primá-rio, caracterizada por conter um ovócito primário que está rodeado, por sua vez, por uma capa de células da granulosa, que não são planas, e sim cúbicas. Depois, se o folículo continuar crescendo se transformará em um folículo secundário, ao qual as células da granulosa começam a proliferar (aumentando em número) e se organizam em duas ou mais capas que rodeiam o ovócito primário. Entre o ovócito e as células da granulosa que o rodeiam se forma nesta uma zona pelúcida; ainda assim o ovócito mantém contato direto com essas células, mediante o estabelecimento de pontes citoplasmáticas que atravessam a zona pelúcida. Através dessas pontes citoplasmáticas as células da granulosa podem passar nutrientes e informação ao ovócito primário. O volume e o diâmetro do ovócito primário aumentam ao mesmo tempo que as células da granulosa proliferam-se, para incrementar as capas ao redor do ovócito. De maneira gradual o citoplasma do ovócito primário aumenta até 50 vezes seu volume e a proliferação das células continua. Esses folículos que possuem cada vez mais células e portanto mais capas de células da granulosa se denominam folículos secundários. Para evitar confusões, há a necessidade de nomen-clatura ao qual o folículo vá mudando de nome de primordial a primário e logo, de secun-dário, a terciário, por sua vez, o ovócito que encontra-se em seu interior, a todo momento, segue sendo um ovócito primário. Durante a etapa dependente de gonadotropinas, os folículos secundários começam a formar um espaço cheio de líquido, o antro folicular, desse modo se convertem em folí-culos terciários. Com a utilização de outra nomenclatura, a formação do antro marca a transição entre folículos pré-antrais (sem antro) e folículos antrais (com antro). Em algum momento dessa transição entre folículo secundário e terciário, também aparece a depen-dência de folículos em direção as gonadotropinas, pelo qual somente podem seguir crescendo na presença do hormônio luteinizante (LH) e do hormônio folículo estimulante (FSH). Nos bovinos e em outras espécies (para seu estudo), os folículos antrais são dividi-dos em pequenos, médios e grandes. Embora todos eles possuam um antro folicular, dependendo do seu grau de desenvolvimento requerem diferentes concentrações de gona-dotropinas para continuar o crescimento. Os folículos antrais mais pequenos somente re-querem concentrações baixas de LH e FSH, pelo qual podem continuar crescendo em qualquer momento do ciclo estral inclusive em animais que não estão ciclando (fêmeas em anestro pré-puberal, gestacional, lactacional, estacional). Nas etapas posteriores os folículos antrais requerem primeiro concentrações elevadas de FSH, e nas etapas finais somente podem continuar crescendo na presença de pulsos frequentes de LH, pelo qual somente os folículos que encontram-se sob concentrações apropriadas desses hormônios podem seguir crescendo. Por essa razão, nos animais que se encontram em anestro de qualquer tipo somente é possível encontrar folículos antrais pequenos ou médios, segundo a espécie, e nos animais que se encontram ciclando (estro) o maior tamanho folicular encontrado em um determinado dia do ciclo dependerá das concentrações de FSH e LH presentes nesse momento e nos dias anteriores. Um folículo que chega ao estado máximo de desenvolvimento, conhecido como folículo pré-ovulatório, ao final, somente chegará a ovular se for exposto a um pico pré-ovulatório de LH. Como supracitado, cada dia na vida de uma fêmea inicia seu desenvolvimento um certo número de folículos; a grande maioria sofrem atresia, mas depois da puberdade em cada dia do ciclo estral um ou vários folículos vão encontrando ao longo do seu desenvol-vimento concentrações hormonais que lhes permite chegar na etapa de folículo pré-ovula-tório. Somente nestes folículos, e como consequência de um pico pré-ovulatório de LH, se reinicia e completa-se a primeira divisão meiótica do ovócito primário, produzindo duas células distintas. Uma delas é o ovócito secundário, que retém praticamente todo o citoplasma. Contém, assim mesmo, em seu núcleo um par de cromossomos duplos, a outra é o primeiro corpo polar, que é exclusivamente um núcleo com uma quantidade mínima de citoplasma. Na maioria das espécies ovula-se um ovócito secundário que se encontra, então, suspendido na segunda divisão meiótica. Esta segunda divisão meiótica somente reinicia-rá e completarar-se uma vez que o espermatozoide começa a penetrar sob o ovócito secundário. Ao concluir-se a divisão se forma o segundo corpo polar e completa-se a ovogênese com o qual se obtém o óvulo, célula 1n que constitui o gameta feminino. No entanto, o óvulo existe pouco tempo como tal, já que em poucos minutos/horas (depen-dendo da espécie) se produzirá a fusão do núcleo do mesmo (pró-núcleo feminino) com o do espermatozoide (pró-núcleo masculino), com o qual se completa a fertilização e se forma um novo indivíduo (o ovo ou zigoto). -/- Ondas foliculares -/- Como mencionado supra, todos os dias um determinado número de folículos pri-mordiais se ativam e começam a crescer, os quais crescem em um ritmo característico em cada espécie. Isso provoca que em qualquer momento existam nos ovários folículos pri-mordiais (que começam a crescer em alguns dias ou semanas), assim como folículos secundários em diversas etapas do desenvolvimento, os quais iniciaram seu desenvolvi-mento em semanas ou inclusive meses (segundo o grau de desenvolvimento atual). Também em qualquer momento poderá haver folículos antrais nas etapas iniciais de seu desenvolvimento (com antros que já se podem detectar em cortes histológicos mas não são visíveis macroscopicamente). Todos esses folículos chegaram até seu estado de de-senvolvimento atual (primário, secundário ou antral pequeno), independente da etapa do ciclo estral em que sejam observados ou encontrados. Nos bovinos, os folículos que chegam ao início da etapa antral iniciaram seu desenvolvimento cinco meses antes, e todavia requerem ao redor de 42 dias para chegar ao estado pré-ovulatório. Para continuar seu desenvolvimento, os folículos antrais pequenos devem encon-trar concentrações altas de FSH, que os estimulam para prosseguir o crescimento. Cada vez que se produz uma elevação nas concentrações de FSH, esse hormônio estimula o desenvolvimento de um grupo de folículos antrais pequenos, que começaram a crescer muito tempo antes e que o dia da elevação de FSH tenha alcançado o grau de desenvolvi-mento preciso para responder com eficiência a este hormônio, o qual atuará através de seus receptores nas células da granulosa para estimular a produção de estradiol, a secreção de inibina, a produção de líquido folicular e a proliferação das células da granulosa. Um grupo de folículos antrais pequenos é assim recrutado pelo FSH para acelerar seu cresci-mento e aumentar sua produção de estradiol e inibina (figura 12). Mediante um seguimento ultrassonográfico dos ovários é possível identificar pou-cos dias depois um certo número de folículos, que por haver sido recrutados começam um período de crescimento acelerado. Durante alguns dias vários folículos crescem juntos, porém depois um deles é selecionado para continuar crescendo, enquanto que o restante do grupo deixam de fazê-lo e terminam sofrendo atresia. Através da ultrassom é possível identificar o folículo selecionado, agora chamado folículo domi-nante, já que sua trajetória de crescimento sofre um desvio com respeito a seguida pelo restante do grupo. Os folículos que não foram selecionados deixam de crescer e sofrem atresia já que deixam de possuir o suporte gonadotrópico de FSH, uma vez que as concentrações desse hormônio são suprimidos pela inibina e o estradiol produzidos pelo conjunto de folículos que conformam a onda folicular (figura 12), porém o folículo mais desenvolvido do grupo se converterá em dominante. A inibina atua diretamente a nível hipofisário para reduzir a secreção de FSH. Figura 12: onda folicular e relação dos níveis de FSH, estradiol e LH. Fonte: ZARCO, 2018. -/- Figura 13: Recrutamento, seleção e dominação folicular na espécie ovina e influência do FSH e LH nas fases. Fonte: SILVA, E. I. C. da, 2019. -/- A razão pela qual o folículo dominante é capaz de continuar seu desenvolvimento apesar da baixa nas concentrações de FSH é que o folículo é o único que alcançou o grau de progresso necessário para que apareçam os receptores para LH em suas células da granulosa. Esse processo permite ao folículo dominante ser estimulado pela LH, e que requeira baixas concentrações de FSH para manter seu desenvolvimento. A secreção de LH em forma de pulsos de baixa frequência (um pulso a cada quatro a seis horas), característica da fase lútea do ciclo estral; é suficiente para permitir que um folículo dominante continue crescendo por mais dias depois da sua seleção e que mais tarde mantenha-se viável durante alguns dias embora não aumentem de tamanho. Contu-do, se durante o período viável desse folículo não seja finalizada a fase lútea e não diminuam as concentrações de progesterona, o folículo terminará sofrendo atresia devido a exigência de um padrão de secreção acelerada de LH (aproximadamente um pulso por hora) durante o desenvolvimento pré-ovulatório, que somente pode ser produzido com a ausência da progesterona. Uma vez que um folículo dominante sofre atresia deixa de produzir inibina, pelo qual as concentrações de FSH podem elevar-se novamente para iniciar o recrutamento de outro grupo de folículos a partir da qual se origina uma nova onda folicular. Durante o ciclo estral de uma vaca podem gerar-se dois ou três ondas foliculares; somente em raros casos quatro. A etapa de dominância folicular da primeira onda na grande maioria dos casos não coincide com a regressão do corpo lúteo, pelo qual o primei-ro folículo dominante quase invariavelmente termina em atresia. Em algumas vacas o fo-lículo dominante da segunda onda ainda está viável quando se produz a regressão do corpo lúteo e acelera-se a secreção de LH, pelo qual esse segundo folículo dominante se converte em folículo pré-ovulatório e, ao final ovula. Em outros animais o segundo folícu-lo dominante também perde a sua viabilidade antes da regressão do corpo lúteo, por onde nesses animais se inicia uma terceira onda folicular, da qual surge o folículo que finalmen-te ovulará depois de produzir-se a regressão do corpo lúteo. Sem importar a onda em que se origine, uma vez que um folículo dominante é ex-posto a alta frequência de secreção de LH que se produz depois da regressão do corpo lúteo, aumenta ainda mais sua secreção de estradiol até que as altas concentrações desse hormônio comecem a exercer um feedback positivo para a secreção do LH. Isso provoca-rá a aceleração da frequência de secreção do LH até que os pulsos são tão frequentes que começam a ficar por cima e produzir-se o pico pré-ovulatório de LH, que é responsável pela realização da ovulação e a maturação final do ovócito. -/- •___DIFERENÇAS ENTRE ESPERMATOGÊNESE E OVOGÊNESE -/- Enquanto que na fêmea a ovogênese inicia-se durante a vida fetal, no macho a es-permatogênese começa na puberdade. Na fêmea, a partir de um ovócito primário se origi-na um óvulo; no macho, de um espermatócito primário se produzem, teoricamente, quatro espermatozoides. Outra característica interessante é que enquanto a fêmea já conta desde o nasci-mento com todos os ovócitos que necessitará na vida adulta, o macho necessitará chegar a puberdade para iniciar o desenvolvimento das células sexuais, já que ao nascer somente possui gonócitos precursores das células germinais, células de Sertoli e intersticiais. Na vida adulta de uma fêmea, o número de células germinais desaparece paulati-namente. Uma vez iniciada a espermatogênese no macho, a cada ciclo do epitélio seminí-fero as células germinais são renovadas mantendo a provisão para toda a vida reprodutiva. Na fêmea, a meiose sofre duas interrupções em seu transcurso, e no macho é ininterrupta. Figura 14: representação em diagramação comparativa do desenvolvimento da gametogênese. -/- Principais pontos abordados sobre as diferenças entre a gametogênese masculina e feminina: ❙ Na ovogênese a meiose contêm-se em duas ocasiões esperando acontecimentos externos para prosseguir. Já na espermatogênese não existe a suspensão da meiose. ❙ A espermatogênese é um processo contínuo, enquanto que a ovogênese pode completar exclusivamente um óvulo em cada ciclo estral; já que só pode ser completada por mais de um nas espécies que ovulam vários ovócitos no caso das porcas, cadelas, gatas etc. ❙ Na espermatogênese existem células de reserva que permitem a continuação du-rante toda a vida, enquanto que na ovogênese o número de ovócitos primários é limitado. A fêmea somente conta com os que nasceu, e eles não se dividem. ❙ Na espermatogênese obtém-se até 256 espermatozoides para cada espermatogo-nia que inicia o processo, enquanto que na ovogênese somente se obtém um óvulo a partir de cada ovócito primário. ❙ Durante a espermatogênese se produz uma metamorfose que transforma as es-permátides em espermatozoides. Na ovogênese não ocorre um processo análogo. ❙ Na espermatogênese, durante a meiose produzem-se quatro espermátides a partir de cada espermatócito primário. Na ovogênese se produz somente um óvulo a partir de cada ovócito primário; produz, ademais, dois corpos polares. ❙ Todos os óvulos que se produzem durante a ovogênese contém um cromossomo X, enquanto que a metade dos espermatozoides possuem um cromossomo Y e a outra metade um cromossomo X. ❙ Na espermatogênese produzem-se centenas ou dezenas de milhões de esperma-tozoides por dia, enquanto que na ovogênese se produz um ou alguns óvulos a cada ciclo estral. ❙ A espermatogênese produz gametas macroscópicos e com motilidade própria, enquanto que a ovogênese produz gametas grandes e imóveis. -/- REFERÊNCIAS BIBLIOGRÁFICAS -/- ABDEL-RAOUF, Mohammed et al. The postnatal development of the reproductive organs in bullswith special reference to puberty.(Including growth of the hypophysis and the adrenals). Acta endocrinologica, n. Suppl No. 49, 1960. ADONA, Paulo Roberto et al. Ovogênese e foliculogênese em mamíferos. Journal of Health Sciences, v. 15, n. 3, 2013. AERTS, J. M. J.; BOLS, P. E. 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Coordinated regulation of follicle development by germ and somatic cells. Reproduction, Fertility and Development, v. 22, n. 1, p. 1-12, 2009. CHIARINI-GARCIA, Helio; RUSSELL, Lonnie D. High-resolution light microscopic characterization of mouse spermatogonia. Biology of reproduction, v. 65, n. 4, p. 1170-1178, 2001. CHOUDARY, J. B.; GIER, H. T.; MARION, G. B. Cyclic changes in bovine vesicular follicles. Journal of animal science, v. 27, n. 2, p. 468-471, 1968. CLERMONT, Yves; PEREY, Bernard. Quantitative study of the cell population of the seminiferous tubules in immature rats. American Journal of Anatomy, v. 100, n. 2, p. 241-267, 1957. COSTA, DEILER SAMPAIO; PAULA, T. A. R. Espermatogênese em mamíferos. Scientia, v. 4, 2003. CUNNINGHAM, James. Tratado de fisiologia veterinária. Elsevier Health Sciences, 2011. CUPPS, Perry T. (Ed.). Reproduction in domestic animals. Elsevier, 1991. DA SILVA, Emanuel Isaque Cordeiro. Fisiologia Clínica do Ciclo Estral de Vacas Leiteiras: Desenvolvimento Folicular, Corpo Lúteo e Etapas do Estro. 2020. Acervo pessoal. DA SILVA, Emanuel Isaque Cordeiro. Fisiologia da Reprodução Animal: Ovulação, Controle e Sincronização do Cio. 2020. Acervo pessoal. DUKES, Henry Hugh; SWENSON, Melvin J.; REECE, William O. Dukes fisiologia dos animais domésticos. Editora Guanabara Koogan, 1996. EPIFANO, Olga; DEAN, Jurrien. Genetic control of early folliculogenesis in mice. Trends in Endocrinology & Metabolism, v. 13, n. 4, p. 169-173, 2002. ERICKSON, B. H. Development and senescence of the postnatal bovine ovary. Journal of animal science, v. 25, n. 3, p. 800-805, 1966. REFERÊNCIAS BIBLIOGRÁFICAS -/- FELDMAN, Edward C. et al. Canine and feline endocrinology-e-book. Elsevier health sciences, 2014. FUSCO, Giuseppe; MINELLI, Alessandro. The Biology of Reproduction. Cambridge University Press, 2019. GALINA-HIDALGO, Carlos Salvador. 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HYTTEL, Poul; SINOWATZ, Fred; VEJLSTED, Morten. Embriologia veterinária. São Paulo: Elsevier Brasil, 2012. JOHNSON, Martin H. Essential reproduction. Nova Jersey: John Wiley & Sons, 2018. JONES, Richard E.; LOPEZ, Kristin H. Human reproductive biology. Academic Press, 2013. KIERSZENBAUM, Abraham L.; TRES, Laura L. Primordial germ cell‐somatic cell partnership: A balancing cell signaling act. Molecular Reproduction and Development: Incorporating Gamete Research, v. 60, n. 3, p. 277-280, 2001. MATZUK, Martin M. et al. Intercellular communication in the mammalian ovary: oocytes carry the conversation. Science, v. 296, n. 5576, p. 2178-2180, 2002. MCLAREN, Anne. Germ and somatic cell lineages in the developing gonad. Molecular and cellular endocrinology, v. 163, n. 1-2, p. 3-9, 2000. MCKINNON, Angus O. et al. (Ed.). Equine reproduction. John Wiley & Sons, 2011. MERCHANT-LARIOS, Horacio; MORENO-MENDOZA, Norma. Onset of sex differentiation: dialog between genes and cells. 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Follicle growth in the immature mouse ovary. European Journal of Endocrinology, v. 62, n. 1, p. 117-132, 1969. PINEDA, Mauricio H. et al. McDonald's veterinary endocrinology and reproduction. Iowa state press, 2003. ROSER, J. F. Endocrine and paracrine control of sperm production in stallions. Animal Reproduction Science, v. 68, n. 3-4, p. 139-151, 2001. RUSSELL, Lonnie D. et al. Histological and histopathological evaluation of the testis. International journal of andrology, v. 16, n. 1, p. 83-83, 1993. RÜSSE, I.; SINOWATZ, F. Gametogenese. Lehrbuch der Embryologie der Haustiere, p. 42-92, 1991. SAITOU, Mitinori; BARTON, Sheila C.; SURANI, M. Azim. A molecular programme for the specification of germ cell fate in mice. Nature, v. 418, n. 6895, p. 293-300, 2002. SALISBURY, Glenn Wade et al. Physiology of reproduction and artificial insemination of cattle. WH Freeman and Company., 1978. SAWYER, Heywood R. et al. Formation of ovarian follicles during fetal development in sheep. 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The Shadow of God in the Philosopher’s Garden. The Parc de La Villette in Paris in the context of the philosophy of chôra I Bernard Tschumi’s project of the Parc de La Villette could have won the competition and was implemented thanks to the political atmosphere that accompanied the victory of the left-wing candidate in the French presidential elections in 1981. François Mitterand’s revision of the political programme and the replacement of radical reforms with the construction of prestigious architectural objects (...) and urban assumptions in the French capital gave Tschumi a unique opportunity to realise ideas that polemicised with traditional forms of social life, questioned the basic principles of architecture and included architectural work in the philosophical disputes over the issues of metaphysics. Tschumi’s theoretical assumptions put forward during the design of the Parc de La Villette highlighted the questions of conflict between the main components of the project and suggested that the intensification of differences was analogous to Jacques Derrida’s creation of the concept of différance. It was this philosopher who in a special commentary to Derrida’s project also introduced the concept of maintenant, which aimed at demonstrating that the architect’s polemical inclinations remain in a hidden balance with his inclinations to affirmation of architectural principles. During the discussion between Derrida and Peter Eisenman, who was to take part in the design of the Parisian park, the concept of the chôra was also put forward, which in the course of the debate led to an additional confusion of architectural and philosophical problems. II In the period from the Antiquity to the Renaissance, the dialogue Timaeus was the most frequently commented work of Plato. At present, the most frequently discussed is the issue of the chôra included in it, which aroused fascination among philosophers, researchers of rhetoric, religion, feminism, but also architecture. The work on the chôra also influenced the development of the interpretation of the Parc de La Villette, among which the topics related to the beginning and the change were highlighted. In early uses of the word chôra in Greek, as in Homer’s 18th Book of Iliad, it meant both dancing and a place to dance. On this occasion, it can be seen that it is not possible to determine which phenomenon took precedence in the creation of the name. It cannot be denied, however, that the word concerned a specific movement, as if circular and returning to an indefinable beginning. Despite gaining more and more general meanings, the word chôra has retained its connection with the dance of people on the threshing floor, the dance of bees (choros meliton) or the dance of stars (choros astron). In Timaeus, the chôra is a space filled with movement with an effect similar to shaking the sieve to husk the grain: it separates similar elements from the dissimilar ones. The juxtaposition of the Parc de La Villette and the chôra already at this stage leads to the suggestion that the park was treated by the architect as a place of dynamic changes leading to the establishment of new social solutions. In his statements, the architect confirmed that the park was to be a space of new politics and ethics. The book by Julia Kristeva La Révolution du langage poétique contributed to the spread of the belief that works of art can play a role as factors of political revolution. In this work, the author put forward the thesis that the chôra is a kind of space, the character of which has a destructive influence on attempts to conclude language games. The chôra gives beginning to words, but at the same time, by leaving a trace of this beginning it forces us to renew their meanings. The chôra understood in this way, turns out to be an irremovable beginning, to which one has to return all the time. Kristeva found manifestations of the chôra’s activity in avant-garde French poetry, to which she attributed the role of a mediator between criticism of metaphysics and aspirations for social change. The chôra, violating the language, introduces some voids into it, as if traces of the abyss, which direct the consciousness towards understanding the necessity of political changes. The Parc de La Villette was to pursue similar objectives in the city space. In his essays, Tschumi considered the problems of creating spaces that would give rise to a radical democracy. The proposed rebellious spaces should have the characteristics of a void, in which contradictory forces would occur as forms of pure activity. The means of achieving this goal was to concentrate contradictions and make them visible. The Parc de La Villette was supposed to collect differences as indelible and at the same time by showing them it was supposed to raise awareness of the social world as a conglomerate of differences. Saturation of the space of the park with subversive values results from the character of this space suppressed in the consciousness, as well as from the social diversity which has not been taken into account so far. The main contradictions contained in space relate to the division that exists between its presentation as a mental problem and a sensual one. The park was the deliberate creation of a place that transcends such a division and creates a separate space for negotiation between architectural theories and its practical applications. The purpose of the park was to become a place of future events, which would not hide their conflicting character coming from diversity of both space and society. The method of composition usually aimed at achieving a harmonious whole has been replaced by Tschumi with a system of juxtaposition of non-coherent elements or those resulting from variations and transformations. Tschumi did not seek direct influence on politics in the Parc de La Villette, but made room for thinking about the possibilities of the future. He introduced problems rather than showed solutions to them. The task of the park was to put the principles of architecture into a kind of vibration that would inspire users to participate in the new community. III Tschumi believes that the quality of architecture depends on the theoretical factor it contains. Such a view led to the creation of architecture that would achieve visibility and comprehensibility only after its interpretation. On his way to creating such an architecture he took on a purely philosophical reflection on the basic building block of architecture, which is space. In 1975, he wrote an essay entitled Questions of Space, in which he included several dozen questions about the nature of space. The questions he formulated could be regarded as analogous to the situation in the philosophy of the time, in which the interest in questioning the most obvious forms of understanding the world and intellectual categories increased. The research on space is an area common to many fields of natural sciences, humanities and artistic creation, but it also deals with other problems, such as issues of experience. The concept of space-time continuum proposed by Hermann Minkowski drew attention to the identity of time and space with the events taking place. Probably regardless of the postulates of physicists commenting on Albert Einstein’s discoveries, also in philosophy it increased the importance of the concept of the event which became dominant in Martin Heidegger’s latest work Contributions of Philosophy: Of the event. Furthermore, Tschumi’s reflections on space entered into relation with the problem of experience, which aroused the interest of a group of French philosophers trying to assimilate Georges Bataille’s concept of “inner experience”. Both Tschumi and Derrida referred to Bataille because his views could be used not only to modify the concept of the subject, but also to change the understanding of what constitutes the area of architecture. The discussion on experience has led to the recognition that the subject is not sovereign, but actually a form of what is on their outside. Such insights make it possible to treat the area of the Parc de La Villette as existing mainly when it is organised by its users. The decisive features of the park are its assumptions, according to which it is a variety of active void that leads to agreeing new social relations with it. The park does not force to participate in already existing moral or political communities, but tries to move into an unknown future in which the scope of free functioning of individuals will be increased. Doubts about the principles of functioning of the individual self and its discovery as a whole composed of non-coherent parts, as well as its dependence on its own depth full of disordered forces, influenced the understanding of architecture as a set of contradictions whose source is a fundamental void anticipating the empty phenomenal space. The use of this phenomenal void in architecture, as well as the rejection of the whole and unity, had a specific political purpose and drew its inspiration from political analyses. In the Parc de La Villette, metaphysics and politics were brought closer together because the philosophy of void was used to create new conditions for community action. It can be argued that the source of this philosophy was the perception of errors in existing societies dependent on the shortcomings of traditional metaphysics. Spacing (espacement) was one of the key terms in Derrida’s philosophy, which was also combined with the concepts of différance and chôra. The study of the nature of space, especially its transition from the level of pure possibility to the level of sensual phenomenon, also contributes to understanding how well designed space can have an impact on its audience. This explanation is based on Tschumi’s assumption that the space of the Parc de La Villette contradicts the integrating approaches and instead exposes contradictions, but it does so in a way that combines incompatible properties into a single piece of architecture. The specificity of such integration is similar to the invention of a musical phrase, which is an ideological message: moral and political. Such a thesis may raise doubts, however, if both the clearly adopted assumptions and those deduced from the work allow for their logically ordered presentation then to a limited extent it may be assumed that the work has achieved a connection between a specific philosophy of space and its practical application. Derrida combined the problem of spatiality with the problem of transcendental imagination in the philosophy of Immanuel Kant, who in the first version of Critique of Pure Reason assumed that pure imagination precedes the appearance of time and space, even in their transcendental forms. The imagination in such a situation can be described as a factor activating time and space, which indicates what function is played by movement in this activity. This leads us to recognize that the ultra originary source of pure forms of sensual intuition is movement, which in early Greek philosophy was identified with void and its lack of resistance to phenomena occurring in it. Derrida’s philosophy in search of a certain super-transcendental source of time and space pointed to différance which, like void or the chôra, does not have material features or even any other form of being. Différance is the primary cause of the disruption of motionlessness and the introduction of activity into motionless time and space, thus its activity can be described as spacing (espacement). Derrida’s discoveries in this respect are not entirely original, because Georg Wilhelm Friedrich Hegel already pointed out when examining the present that it is primarily a differential relation (differente Beziehung), which, being seemingly neutral, influences the present with supernatural force and makes it unidentifiable with itself. Differente Beziehung must similarly influence the originary space, negating its initial character by multiplying its divisions and expanding its boundaries. Différance acts by revealing contradictions wherever there is apparent undifferentiation. Tschumi, composing the Parc de La Villette as a variety of void and a set of incompatible layers, followed the rules of différance or the chôra: he made void visible together with its saturation with contradictions. If space can be considered to be the result of the activity of difference, such activity has a certain regularity, which influences the behaviour of its observers. Differences or contradictions fall into a certain rhythm, which can be considered a manifestation of transcendent order. The problem is that what can be considered the source of such order, namely the logos or God, is partly disorder and error. According to descriptions contained in Timaeus, the world is a combination of forces that drive to order with forces of erroneous necessity that resounds in every order and forces it to return to disorder. Derrida denied the possibility of understanding différance as a theological value, even if it were a negative or apophatic theology, but no categorical denial could be perfect. The assumption that différance or the chôra are not endowed with any substance properties cannot deny their activity, and thus a certain force. Already since Democritus, philosophy has multiplied the names of such a force and the contradictory variety of its manifestations, never forgetting also the necessity for reason to withdraw from the possibility of giving its correct characteristics. Such a withdrawal may be interpreted as an expression of respect and, in certain situations, as a cult of the force that precedes reasonableness. The Parc de La Villette, which is an artistic divagation about the contradictions and forces behind them, can be considered as a place of their sublimation, and therefore as a variation of the temple of what differs from order and disorder. IV In the texts that presented the theoretical assumptions of the Parc de La Villette, Tschumi used a large number of terms that contradicted not only the traditional principles of composing architecture, but also negated the rules of social order and the foundations of Western metaphysics. Tschumi’s statements, which are a continuation of his leftist political fascinations from the May 1968 revolution, as well as his interest in the philosophy of French poststructuralism and his collaboration with Derrida, prove that terms such as “disruption”, “dissociation”, “disfunction”, “disjunction” and “dispersion” not only referred to architectural problems but also applied to political criticism and the deepest foundations of thinking itself. His collaboration with Derrida manifested itself primarily in the publication La Case Vide: La Villette 1985, in which the architect’s design drawings and texts explaining his concepts related to the Parc de La Villette were accompanied by an extensive essay by Derrida, which included theoretical problems taken up by Tschumi in a philosophical context. Architectural and philosophical issues were also combined during seven discussion meetings organised by Eisenman, invited by Tschumi to collaborate on the design of the Parc de La Villette. Eisenman, who, like Tschumi, invited Derrida to participate in the design of the park and also led to the publication of Chora L Works: Jacques Derrida and Peter Eisenman, in which his ideas were confronted with Derrida’s philosophical text. In this case, Derrida’s essay was not a direct commentary on the architect’s concepts, but rather a reflection on the question of the chôra presented by Plato in Timaeus. During the discussion and in his essay, Derrida pointed out that the chôra is a component of the created world, yet it does not belong to it, but precedes it. The originality of the chôra is so radical that she also precedes all the factors of creating the world, including ideas and the Demiurge. Thus athesis appeared in the metaphysics of the West that the chôra is a form of active abyss, in relation to which all beings are secondary, both those perfect (as ideas or God) and those created, such as the world, things, people or language. This leads to the conclusion that the chôra does not exist, because all existence is a derivative of the chôra. Nor could the chôra be described, since it is a form of developing a space that is preceded by a lack of space characteristic of the chôra. Derrida intended the chôra to be an instance with an exceptional degree of transcendentalism, an anti-metaphysical instance, but also an a-theological one. However, this attempt failed, both in the field of secular philosophy and in the field of theology. Derrida’s characteristics of the chôra to strengthen its transcendentalism and negation of metaphysics had to be expressed in a language that immediately produces new concepts and a new metaphysics that reproduces the categories of the beginning, the origin or the foundation known from earlier philosophical traditions. All forms of criticism of metaphysics are also inspired by negative, apophatic and mystical theology. The undermining of many concepts of permanent meaning and the introduction of new concepts of unstable meaning, characteristic of the philosophy of deconstruction, had many features of originality, but it was directed towards problems whose solutions repeat, with the use of new vocabulary, the findings known in culture since Democritus. Thus, if apophatic philosophy can be regarded as deconstruction avant la lettre, then deconstruction itself in its late versions began to take on the features of a new religion. The exchange of inspiration between theology and deconstruction was manifested in a series of scientific conferences and publications in which Derrida’s philosophical concepts were interpreted within the scope of religious thought. Theological threads began to be found in such concepts of deconstruction as différance or the chôra, while at the same time Derrida himself undertook in his philosophy to study problems such as the Other (L’Autre) or the Impossible (Impossible), which belonged to newer theological traditions. As a consequence of the new problems, the deconstruction became closer to the features of a new religion. Philosophy, at least from Kant’s time, has tried to create a system that would take over from religion the tasks of setting moral and political goals. Similarly, Derrida has directed his interest towards the problems of democracy and ethics, which would enable their renewal. Attempts to create a new religion (cleared of old metaphors), a new community or a new democracy bring problems and threats which may be no less troublesome than the previous systems. All promises of freedom carry with them threats, the greater the more they strive for perfection. The renewal of existential orders, sometimes carried out by means of violent changes, is a certain repetitive feature of human cultures. Deep changes, however, do not protect against the return of both old gods and old demons. Tschumi and Derrida were shaped in their youth by the atmosphere of leftist rebellion against the moral and political limitations of ossified communities and the imperfections of democracy. The ethical theme distinguishes many of their works, including the Parc de La Villette. The opposition to the metaphysical traditions of philosophy and architecture contained in this park was prompted by specific political situations and resulted from bringing political issues to the level of philosophical considerations. Achievements made at the level of pure concepts were then subject to elevation, to a kind of sacralization, which made them religious concepts. The deconstruction reached for the status of the new religion especially when it found its followers and began to generate moral obligations. In the new situation, terms such as the chôra, l’Autre or the Impossible were absolutized and in relation to them a cult and attitude of adoration emerged. The Parc de La Villtette then gained new post-secular meanings, which allow it to be assigned the function of a Temple of Otherness (L’Autre) and Impossible. V In the traditional sense, a work of art creates an illustration of the outside world, or of a certain text or doctrine. Sometimes it is considered that such an illustration is not literal, but is an interpretation of what is visible, or an interpretation of a certain literary or ideological message. It can also be assumed that a work of art creates its own visual world, a separate story or a separate philosophical statement. Parc de La Villette represents the last of these possibilities: it is a philosophical statement that develops the premises derived from poststructuralist philosophies and the philosophy of deconstruction. The uniqueness of its being status, however, is that it does so not only at the level of the theoretical assumptions, but also through its functioning as an active philosophical work. This means that a park is a happening philosophy. Its activity, however, does not refer only to the present tense, but is also an attempt to penetrate the future, all otherness and impossibility. This kind of activity assumes that the work, in a sense, does not yet fully exist, but is also still produced in the processes of its interpretation. The theoretical foundations of the park included texts by Tschumi, in which he questioned traditional ways of creating a work of architecture, postulating in return the use of a long series of negations, which were comparable to the crisis of metaphysics characteristic of contemporary philosophy. It is therefore no coincidence that the publication containing Tschumi’s theoretical text on Parc de La Villette was accompanied by an essay by Derrida developing some of the architect’s concepts. The next step in integrating philosophy into the process of park design was a series of discussions between Eisenman and Derrida, who completely moved the creation of the park into the world of thoughts, without accentuating the need for their realization in the material reality. The main topic of these discussions was the problem of the chôra, which was taken up by later commentators and used to interpret the park as a work in which the philosophy of the beginning is manifested relating to issues of politics, morality and religion. The park was therefore interpreted as a space of invention within the scope of creating new rules of functioning of the community and democracy. Thinking about the political future may, however, exceed the horizon of ordinary expectations. Although philosophical thought is always connected with contemporary problems and metaphysics sometimes intertwines with current politics, yet at the same time the customs of philosophy also include crossing horizons and thinking about absolute otherness and impossibility. Initially, the chôra, différance, absolute otherness (tout autre) and the Impossible were concepts of pure philosophy of atheistic character, but with the further development of the discussion, more and more theological motifs began to emerge. One of the reasons for this phenomenon was the fact that radical negations of all being, which were contemplated in contemporary philosophy (by Heidegger and Derrida, among others), had previously been manifested in negative and apophatic theologies (by Master Eckhart, among others).Also the category of the “Other”, taken from Emmanuel Levinas, was clearly connected with the thought about God. A further reason for connecting the chôra with the theological thought was the interest in the philosophy of deconstruction expressed by some theologians. John Caputo in particular managed to persuade Derrida to participate in discussions on the current status of religion. In the late period of Derrida’s writing, further statements on religious topics appeared. All these reasons led to posing a question about the identity of the chôra and God. Although there were no satisfactory conclusions on this issue, the discussion was also important to create an interpretation of the park as a place of worship. The chôra, representing, according to Plato, the preoriginal emptiness is the place of every beginning, but it turns out that it is not neutral to the being created in it. The chôra deposits itself in every being as an irremovable beginning that interferes with its stability. The chôra, therefore, forces us into a palintropical movement, but it also turns out to be a pure compulsion, an erring necessity and a fundamental force from which, in the human perception, motifs useful to the individual and to the community are extracted. All definitions of this force, including its anthropomorphisation, are formulated in such a way that they allow for building private and collective morality upon them. Such definitions are changed depending on variable political situations. It is difficult to determine whether in the processes of changes in the formulation of “God’s names” any essential value is retained, which is not subject to change. The current definitions of the chôra (God?), which can be found, for example, in the philosophy of Caputo, stress that she is a combination of various and contradictory forces. This characteristic inherits much of Plato’s concept, reminds us of Master Eckhart’s views on Gottheit and, at the same time, is not unfamiliar to Tschumi, whose essays were an apologia of contradictions. The current concept of chôra, transferred into the sphere of politics, is the praise of social diversity and the protection of the difference from the forces of order. In the Parc de La Villette, the future community and democracy were elevated as a system of safe existence of individuals in all their singularity. The park is a temple of a future community in which individual beings have nothing in common. (shrink)

Suppose that scientific realists believe that a successful theory is approximately true, and that constructive empiricists believe that it is empirically adequate. Whose belief is more likely to be false? The problem of underdetermination does not yield an answer to this question one way or the other, but the pessimistic induction does. The pessimistic induction, if correct, indicates that successful theories, both past and current, are empirically inadequate. It is arguable, however, that they are approximately true. Therefore, scientific realists overall (...) take less epistemic risk than constructive empiricists. (shrink)

Many realists argue that present scientific theories will not follow the fate of past scientific theories because the former are more successful than the latter. Critics object that realists need to show that present theories have reached the level of success that warrants their truth. I reply that the special theory of relativity has been repeatedly reinforced by unconceived scientific methods, so it will be reinforced by infinitely many unconceived scientific methods. This argument for the special theory of relativity overcomes (...) the critics’ objection, and has advantages over the no-miracle argument and the selective induction for it. (shrink)

Scientific realists argue that present theories are more successful than past theories, so present theories will not be superseded by alternatives, even though past theories were superseded by alternatives. Alai (2016) objects that although present theories are more successful than past theories, they will be replaced by future theories, just as past theories were replaced by present theories. He contends, however, that past theories were partly true, and that present theories are largely true. I argue that Alai’s discrimination between past (...) and present theories is subject to his own criticism against realists’ discriminations between past and present theories, and also subject to other criticisms that philosophers have raised against scientific realism and pessimism. (shrink)

The pessimistic induction holds that successful past scientific theories are completely false, so successful current ones are completely false too. I object that past science did not perform as poorly as the pessimistic induction depicts. A close study of the history of science entitles us to construct an optimistic induction that would neutralize the pessimistic induction. Also, even if past theories were completely false, it does not even inductively follow that the current theories will also turn out to be completely (...) false because the current theories are more successful and have better birth qualities than the past theories. Finally, the extra success and better birth qualities justify an anti-induction in favor of the present theories. (shrink)

Throughout the COVID-19 pandemic, shortages of scarce healthcare resources consistently presented significant moral and practical challenges. While the importance of vaccines as a key pharmaceutical intervention to stem pandemic scarcity was widely publicized, a sizable proportion of the population chose not to vaccinate. In response, some have defended the use of vaccination status as a criterion for the allocation of scarce medical resources. In this paper, we critically interpret this burgeoning literature, and describe a framework for thinking about vaccine-sensitive resource (...) allocation using the values of responsibility, reciprocity, and justice. Although our aim here is not to defend a single view of vaccine-sensitive resource allocation, we believe that attending critically with the diversity of arguments in favor (and against) vaccine-sensitivity reveals a number of questions that a vaccine-sensitive approach to allocation should answer in future pandemics. (shrink)

I criticize the following three arguments for moral objectivism. 1. Since we assess moral statements, we can arrive at some moral truths (Thomson, 2006). 2. One culture can be closer to truths than another in moral matters because the former can be closer to truths than the latter in scientific matters (Pojman, 2008). 3. A moral judgment is shown to be true when it is backed up by reason (Rachels and Rachels, 2010). Finally, I construct a dilemma against the view (...) that there are moral truths and we can move toward them. (shrink)

Healey (2019a) makes four comments on my (Park, 2019a) objections to van Fraassen’s positions. The four comments concern the issues of whether ‘disbelief’ is appropriate or inappropriate to characterize van Fraassen’s position, what the relationship between a theory and models is for van Fraassen, whether he believes or not that a theory is empirically adequate, and whether destructive empiricism is tenable or not. I reply to those comments in this paper.

Some stories of moral exemplars motivate us to emulate their admirable attitudes and behaviors, but why do some exemplars motivate us more than others? We systematically studied how motivation to emulate is influenced by the similarity between a reader and an exemplar in social or cultural background (Relatability) and how personally costly or demanding the exemplar’s actions are (Attainability). Study 1 found that university students reported more inspiration and related feelings after reading true stories about the good deeds of a (...) recent fellow alum, compared to a famous moral exemplar from decades past. Study 2A developed a battery of short moral exemplar stories that more systematically varied Relatability and Attainability, along with a set of non-moral exemplar stories for comparison. Studies 2B and 2C examined the path from the story type to relatively low stakes altruism (donating to charity and intentions to volunteer) through perceived attainability and relatability, as well as elevation and pleasantness. Together, our studies suggest that it is primarily the relatability of the moral exemplars, not the attainability of their actions, that inspires more prosocial motivation, at least regarding acts that help others at a relatively low cost to oneself. (shrink)

Bird argues that scientific progress consists in increasing knowledge. Dellsén objects that increasing knowledge is neither necessary nor sufficient for scientific progress, and argues that scientific progress rather consists in increasing understanding. Dellsén also contends that unlike Bird’s view, his view can account for the scientific practices of using idealizations and of choosing simple theories over complex ones. I argue that Dellsén’s criticisms against Bird’s view fail, and that increasing understanding cannot account for scientific progress, if acceptance, as opposed to (...) belief, is required for scientific understanding. (shrink)

Surprisingly little has been written about hedged assertion. Linguists often focus on semantic or syntactic theorizing about, for example, grammatical evidentials or epistemic modals, but pay far less attention to what hedging does at the level of action. By contrast, philosophers have focused extensively on normative issues regarding what epistemic position is required for proper assertion, yet they have almost exclusively considered unqualified declaratives. This essay considers the linguistic and normative issues side-by-side. We aim to bring some order and clarity (...) to thinking about hedging, so as to illuminate aspects of interest to both linguists and philosophers. In particular, we consider three broad questions. 1) The structural question: when one hedges, what is the speaker’s commitment weakened from? 2) The functional question: what is the best way to understand how a hedge weakens? And 3) the taxonomic question: are hedged assertions genuine assertions, another speech act, or what? (shrink)

YouTube has been implicated in the transformation of users into extremists and conspiracy theorists. The alleged mechanism for this radicalizing process is YouTube’s recommender system, which is optimized to amplify and promote clips that users are likely to watch through to the end. YouTube optimizes for watch-through for economic reasons: people who watch a video through to the end are likely to then watch the next recommended video as well, which means that more advertisements can be served to them. This (...) is a seemingly innocuous design choice, but it has a troubling side-effect. Critics of YouTube have alleged that the recommender system tends to recommend extremist content and conspiracy theories, as such videos are especially likely to capture and keep users’ attention. To date, the problem of radicalization via the YouTube recommender system has been a matter of speculation. The current study represents the first systematic, pre-registered attempt to establish whether and to what extent the recommender system tends to promote such content. We begin by contextualizing our study in the framework of technological seduction. Next, we explain our methodology. After that, we present our results, which are consistent with the radicalization hypothesis. Finally, we discuss our findings, as well as directions for future research and recommendations for users, industry, and policy-makers. (shrink)

Putnam (1975) infers from the success of a scientific theory to its approximate truth and the reference of its key term. Laudan (1981) objects that some past theories were successful, and yet their key terms did not refer, so they were not even approximately true. Kitcher (1993) replies that the past theories are approximately true because their working posits are true, although their idle posits are false. In contrast, I argue that successful theories which cohere with each other are approximately (...) true, and that their key terms refer. My position is immune to Laudan’s counterexamples to Putnam’s inference and yields a solution to a problem with Kitcher’s position. (shrink)

Vigorous debate over the moral propriety of cognitive enhancement exists, but the views of the public have been largely absent from the discussion. To address this gap in our knowledge, four experiments were carried out with contrastive vignettes in order to obtain quantitative data on public attitudes towards cognitive enhancement. The data collected suggest that the public is sensitive to and capable of understanding the four cardinal concerns identified by neuroethicists, and tend to cautiously accept cognitive enhancement even as they (...) recognize its potential perils. The public is biopolitically moderate, endorses both meritocratic principles and the intrinsic value of hard work, and appears to be sensitive to the salient moral issues raised in the debate. Taken together, these data suggest that public attitudes toward enhancement are sufficiently sophisticated to merit inclusion in policy deliberations, especially if we seek to align public sentiment and policy. (shrink)

Despite the recent proliferation of scientific, clinical, and narrative accounts of auditory verbal hallucinations, the phenomenology of voice hearing remains opaque and undertheorized. In this article, we outline an interdisciplinary approach to understanding hallucinatory experiences which seeks to demonstrate the value of the humanities and social sciences to advancing knowledge in clinical research and practice. We argue that an interdisciplinary approach to the phenomenology of AVH utilizes rigorous and context-appropriate methodologies to analyze a wider range of first-person accounts of AVH (...) at 3 contextual levels: cultural, social, and historical; experiential; and biographical. We go on to show that there are significant potential benefits for voice hearers, clinicians, and researchers. These include informing the development and refinement of subtypes of hallucinations within and across diagnostic categories; “front-loading” research in cognitive neuroscience; and suggesting new possibilities for therapeutic intervention. In conclusion, we argue that an interdisciplinary approach to the phenomenology of AVH can nourish the ethical core of scientific enquiry by challenging its interpretive paradigms, and offer voice hearers richer, potentially more empowering ways to make sense of their experiences. (shrink)

Psychopaths are brutal individuals, having no empathetic concern for others. Initially, the existence of psychopaths seems to be a mystery from an evolutionary point of view. On close examination, however, it can be accommodated by evolutionary theory. Brutal individuals excelled meek individuals in the desperate circumstances where they had to fight their competitors over natural resources for survival and reproduction. This evolutionary explanation of psychopaths receives support from Pinker's observation of the history of brutality. We have good reasons for predicting (...) that psychopaths are likely to die out in the future. (shrink)

Nearly all success is due to some mix of ability and luck. But some successes we attribute to the agent’s ability, whereas others we attribute to luck. To better understand the criteria distinguishing credit from luck, we conducted a series of four studies on knowledge attributions. Knowledge is an achievement that involves reaching the truth. But many factors affecting the truth are beyond our control and reaching the truth is often partly due to luck. Which sorts of luck are compatible (...) with knowledge? We find that knowledge attributions are highly sensitive to lucky events that change the explanation for why a belief is true. By contrast, knowledge attributions are surprisingly insensitive to lucky events that threaten but ultimately fail to change the explanation for why a belief is true. These results shed light on our concept of knowledge, help explain apparent inconsistencies in prior work on knowledge attributions, and constitute progress toward a general understanding of the relation between success and luck. (shrink)

Certain passages in Kaplan’s ‘Demonstratives’ are often taken to show that non-vacuous sentential operators associated with a certain parameter of sentential truth require a corresponding relativism concerning assertoric contents: namely, their truth values also must vary with that parameter. Thus, for example, the non-vacuity of a temporal sentential operator ‘always’ would require some of its operands to have contents that have different truth values at different times. While making no claims about Kaplan’s intentions, we provide several reconstructions of how such (...) an argument might go, focusing on the case of time and temporal operators as an illustration. What we regard as the most plausible reconstruction of the argument establishes a conclusion similar enough to that attributed to Kaplan. However, the argument overgenerates, leading to absurd consequences. We conclude that we must distinguish assertoric contents from compositional semantic values, and argue that once they are distinguished, the argument fails to establish any substantial conclusions. We also briefly discuss a related argument commonly attributed to Lewis, and a recent variant due to Weber. (shrink)

Experimental philosophers have gathered impressive evidence for the surprising conclusion that philosophers' intuitions are out of step with those of the folk. As a result, many argue that philosophers' intuitions are unreliable. Focusing on the Knobe Effect, a leading finding of experimental philosophy, we defend traditional philosophy against this conclusion. Our key premise relies on experiments we conducted which indicate that judgments of the folk elicited under higher quality cognitive or epistemic conditions are more likely to resemble those of the (...) philosopher. We end by showing how our experimental findings can help us better understand the Knobe Effect. (shrink)

A formulational debate is a debate over whether certain definitions of scientific realism and antirealism are useful or useless. By contrast, an epistemological debate is a debate over whether we have sufficient evidence for scientific realism and antirealism defined in a certain manner. I argue that Hilary Putnam’s definitions of scientific realism and antirealism are more useful than Bas van Fraassen’s definitions of scientific realism and constructive empiricism because Putnam’s definitions can generate both formulational and epistemological debates, whereas van Fraassen’s (...) can generate only formulational debates. (shrink)

Constructive empiricism implies that if van Fraassen does not believe that scientific theories and his positive philosophical theories, including his contextual theory of explanation, are empirically adequate, he cannot accept them, and hence he cannot use them for scientific and philosophical purposes. Moreover, his epistemic colleagues, who embrace epistemic reciprocalism, would not believe that his positive philosophical theories are empirically adequate. This epistemic disadvantage comes with practical disadvantages in a social world.

This paper examines the possibility of parenting as a queer practice. Examining definitions of “queer” as resistant to presumptions and practices of reprosexuality and repro-narrativity (Michael Warner), bourgeouis norms of domestic space and family time (Judith Halberstam), and policies of reproductive futurism (Lee Edelman), I argue that queer parenting is possible. Indeed, parenting that resists practices of normalization are, in part, realized by certain types of postmodern families. However, fully actualizing the possibility of parenting queerly—and thus teaching our children the (...) values of non-normativity--requires engaging political struggles for distributive justice. These are, thus, the struggles that should be at the center of queer politics, rather than the current struggles for gay marriage and homoparental rights. (shrink)

This paper critically examines two objections and raises a new objection against the besire theory of moral judgment. Firstly, Smith (1994) observes that a belief that p tends to expire whereas a desire that p tends to endure on the perception that not p. His observation does not refute the sophisticated version of the besire theory that to besire that p is to believe that p and to desire to act in accordance with the belief that p. Secondly, Zangwill (2008) (...) claims that the strength of motivation may vary while the degree of belief remains constant. Besirists would reply that a besire admits of both degree and strength. Finally, I argue that the belief that p endures while the desire to act on the belief that p expires with the introduction of a new bodily condition, and hence that the belief and the desire are distinct mental states. (shrink)

Having an agreed-upon definition of character education would be useful for both researchers and practitioners in the field. However, even experts in character education disagree on how they would define it. We attempted to achieve greater conceptual clarity on this issue through a prototype analysis in which the features perceived as most central to character education were identified. In Study 1 (N = 77), we asked character education experts to enumerate features of character education. Based on these lists, we identified (...) 30 features. In Study 2 (N = 101), experts assessed which features were central to character education through a categorization task. In Study 3 (N = 166), we assessed the extent of centrality using scalar items. We conclude by offering practical advice for the development of future character education studies and programs rooted in what is deemed central to such programs. (shrink)

Experiments in particle physics have hitherto failed to produce any significant evidence for the many explicit models of physics beyond the Standard Model (BSM) that had been proposed over the past decades. As a result, physicists have increasingly turned to model-independent strategies as tools in searching for a wide range of possible BSM effects. In this paper, we describe the Standard Model Effective Field Theory (SM-EFT) and analyse it in the context of the philosophical discussions about models, theories, and (bottom-up) (...) effective field theories. We find that while the SM-EFT is a quantum field theory, assisting experimentalists in searching for deviations from the SM, in its general form it lacks some of the characteristic features of models. Those features only come into play if put in by hand or prompted by empirical evidence for deviations. Employing different philosophical approaches to models, we argue that the case study suggests not to take a view on models that is overly permissive because it blurs the lines between the different stages of the SM-EFT research strategies and glosses over particle physicists' motivations for undertaking this bottom-up approach in the first place. Looking at EFTs from the perspective of modelling does not require taking a stance on some specific brand of realism or taking sides in the debate between reduction and emergence into which EFTs have recently been embedded. (shrink)

I attempt to rebut the following standard objections against cultural relativism: 1. It is self-defeating for a cultural relativist to take the principle of tolerance as absolute; 2. There are universal moral rules, contrary to what cultural relativism claims; 3. If cultural relativism were true, Hitler’s genocidal actions would be right, social reformers would be wrong to go against their own culture, moral progress would be impossible, and an atrocious crime could be made moral by forming a culture which approves (...) of it; 4. Cultural relativism is silent about how large a group must be in order to be a culture, and which culture we should follow when we belong to two cultures with conflicting moralities. (shrink)

The wider the gap between rivaling positions, the more there can be debates between rivaling interlocutors. The gap between the respective formulations of scientific realism and antirealism that invoke the Prussian conception of rationality is wider than the gap between the respective formulations of scientific realism and antirealism that invoke the English conception of rationality. Therefore, scientific realists and antirealists should choose the former over the latter as the framework of their debate.

Lyons (2016, 2017, 2018) formulates Laudan’s (1981) historical objection to scientific realism as a modus tollens. I present a better formulation of Laudan’s objection, and then argue that Lyons’s formulation is supererogatory. Lyons rejects scientific realism (Putnam, 1975) on the grounds that some successful past theories were (completely) false. I reply that scientific realism is not the categorical hypothesis that all successful scientific theories are (approximately) true, but rather the statistical hypothesis that most successful scientific theories are (approximately) true. Lyons (...) rejects selectivism (Kitcher, 1993; Psillos, 1999) on the grounds that some working assumptions were (completely) false in the history of science. I reply that selectivists would say not that all working assumptions are (approximately) true, but rather that most working assumptions are (approximately) true. (shrink)

I raise the following six moral objections to the way God evaluates us. (i) He violates the human right to free thought. (ii) He makes the dubious assumption that it is praiseworthy and blameworthy, respectively, to believe and disbelieve that he exists. (iii) He excessively rewards believers and excessively punishes disbelievers. (iv) He only assigns to his evaluatees the two extreme grades: eternal bliss and eternal damnation. (v) He overlooks diverse factors related to the belief of God. (vi) He is (...) silent on the issue of whether to evaluate animals. Therefore, God, who is allegedly omnipotent, omniscient, and omnibenevolent, does not exist. (shrink)

Nickles (2017) advocates scientific antirealism by appealing to the pessimistic induction over scientific theories, the illusion hypothesis (Quoidbach, Gilbert, and Wilson, 2013), and Darwin’s evolutionary theory. He rejects Putnam’s (1975: 73) no-miracles argument on the grounds that it uses inference to the best explanation. I object that both the illusion hypothesis and evolutionary theory clash with the pessimistic induction and with his negative attitude towards inference to the best explanation. I also argue that Nickles’s positive philosophical theories are subject to (...) Park’s (2017a) pessimistic induction over antirealists. (shrink)

As new communication technologies transform everyday life in the 21st century, personal, family, and other social relations are transformed with it. As a way of exploring the larger question, "how exactly does communication technology transform love and how love is lived?" here I explore the cell phone, instant messaging and other communication technologies as electronic extensions of maternal bodies connecting (cyber)mother to (cyber)children. -/- Feminist explorations of the marketing and use of cell phones, as well as other communication technologies, have (...) largely remarked on the pernicious gender ideologies intertwined with technological innovation and application. If, however, we take seriously Haraway’s (1991) claim that postmodern humans are cyborgs, the distinction between human animals and machines breaks down in ways that invite us to revision the questions we ask about technology. Thus instead of inquiring about the oppression engendered by the production and consumption of communication technologies, here I explore the ways in which technology functions as an extension and modification of human embodiment that transforms our experiences of intimacy and our ability to create, maintain and transform loving relationships with others. More specifically, I examine cyborg mothering as transformative of loving relationships between women and children. (shrink)

A scientific theory is successful, according to Stanford (2000), because it is suficiently observationally similar to its corresponding true theory. The Ptolemaic theory, for example, is successful because it is sufficiently similar to the Copernican theory at the observational level. The suggestion meets the scientific realists' request to explain the success of science without committing to the (approximate) truth of successful scientific theories. I argue that Stanford's proposal has a conceptual flaw. A conceptually sound explanation, I claim, respects the ontological (...) order between properties. A dependent property is to be explained in terms of its underlying property, not the other way around. The applicability of this point goes well beyond the realm of the debate between scientific realists and antirealists. Any philosophers should keep the point in mind when they attempt to give an explanation of a property in their field whatever it may be. (shrink)

A distorted representation of one's own body is a diagnostic criterion and core psychopathology of both anorexia nervosa (AN) and bulimia nervosa (BN). Despite recent technical advances in research, it is still unknown whether this body image disturbance is characterized by body dissatisfaction and a low ideal weight and/or includes a distorted perception or processing of body size. In this article, we provide an update and meta-analysis of 42 articles summarizing measures and results for body size estimation (BSE) from 926 (...) individuals with AN, 536 individuals with BN and 1920 controls. We replicate findings that individuals with AN and BN overestimate their body size as compared to controls (ES= 0.63). Our meta-regression shows that metric methods (BSE by direct or indirect spatial measures) yield larger effect sizes than depictive methods (BSE by evaluating distorted pictures), and that effect sizes are larger for patients with BN than for patients with AN. To interpret these results, we suggest a revised theoretical framework for BSE that accounts for differences between depictive and metric BSE methods regarding the underlying body representations (conceptual vs. perceptual, implicit vs. explicit). We also discuss clinical implications and argue for the importance of multimethod approaches to investigate body image disturbance. (shrink)

In everyday life and in science we acquire evidence of evidence and based on this new evidence we often change our epistemic states. An assumption underlying such practice is that the following EEE Slogan is correct: 'evidence of evidence is evidence' (Feldman 2007, p. 208). We suggest that evidence of evidence is best understood as higher-order evidence about the epistemic state of agents. In order to model evidence of evidence we introduce a new powerful framework for modelling epistemic states, Dyadic (...) Bayesianism. Based on this framework, we then discuss characterizations of evidence of evidence and argue for one of them. Finally, we show that whether the EEE Slogan holds, depends on the specific kind of evidence of evidence. (shrink)

In Western political philosophy, democracy is generally the dominant view regarding what the best form of government is, and this holds even in respect to promoting minority rights. However, I argue that there is a better theory for satisfying minority interests and rights. I amass numerous studies from the social sciences demonstrating how democracy does poorly in accounting for minority interests. I then contend that a particular hybrid view that fuses a meritocracy with democracy can do a better job than (...) democracy in accounting for minority interests and in having more equal rights and fair policies coming from the legislative and executive branches. Finally, I defend this thesis from numerous counters. (shrink)

According to some psychological studies, women approaching ovulation feel the increased desire to have short-term sexual affairs with “sexy cads” while they are in long-term relations with “good dads.” I argue that this psychological property is a vestige of our evolutionary history. Early hominid females occasionally acquired good genes from top-ranking males while they were in long-term relations with low-ranking males. The Paleolithic living conditions indicate that women with the foregoing psychological trait were more likely to have viable children than (...) those without it. Sexy cads are the descendents of the top-ranking males, and good dads are the descendents of the low-ranking males. Sexy cads and good dads will continue to coexist in the future, developing better methods to detect cheaters and to escape detection. (shrink)

Causal platonism asserts that mathematical objects cause neural states in human brains. I raise the following four objections to it. (i) Quantum entanglement does not show that one object can causally affect another, although one is nontemporal, nonspatial, and unchanging. (ii) Causal platonism can neither be justified a posteriori nor a priori. (iii) To postulate mathematical media to flesh out mathematical causation is to multiply mysteries beyond necessity. (iv) To say that mathematical causation is unintelligible and inexplicable is not to (...) complain about causation in general. (shrink)

Scientific realists and antirealists believe that a successful scientific theory is true and merely empirically adequate, respectively. In contrast, epistemic reciprocalists believe that realists’ positive theories are true, and that antirealists’ positive theories are merely empirically adequate, treating their target agents as their target agents treat other epistemic agents. Antirealists cannot convince reciprocalists that their positive theories are true, no matter how confident they might be that they are true. In addition, reciprocalists criticize antirealists’ positive theories exactly in the way (...) that antirealists criticize their epistemic colleagues’ theories. Reciprocalism is a better epistemic policy than realism and antirealism in the epistemic battleground in which we strive to be epistemically safe vis-à-vis our epistemic colleagues’ theories and strive to convince our epistemic colleagues that our theories are true. (shrink)

In 1968, Jürgen Habermas claimed that, in an advanced technological society, the emancipatory force of knowledge can only be regained by actively recovering the ‘forgotten experience of reflection’. In this article, we argue that, in the contemporary situation, critical reflection requires a deliberative ambiance, a process of mutual learning, a consciously organised process of deliberative and distributed reflection. And this especially applies, we argue, to critical reflection concerning a specific subset of technologies which are actually oriented towards optimising human cognition. (...) In order to create a deliberative ambiance, fostering critical upstream reflection on emerging technologies, we developed the concept of a mutual learning exercise. Building on a number of case studies, we analyse what an MLE involves, both practically and conceptually, focussing on key aspects such as ambiance and expertise, the role of ‘genres of the imagination’ and the profiles of various ‘subcultures of debate’. Ideally, an MLE becomes a contemporary version of the Socratic agora, providing a stage where multiple and sometimes unexpected voices and perspectives mutually challenge each other, in order to strength-en the societal robustness and responsiveness of emerg-ing technologies. (shrink)

We shall focus on moral theories that are solely concerned with promoting the benefits (e.g., wellbeing) of individuals and explore the possibility of such theories ascribing some priority to benefits to those who are worse off—without this priority being absolute. Utilitarianism (which evaluates alternatives on the basis of total or average benefits) ascribes no priority to the worse off, and leximin (which evaluates alternatives by giving lexical priority to the worst off, and then the second worst off, and so on) (...) ascribes absolute priority to the worse off (i.e., favors even a very small benefit to a worse off person over very large benefits to large numbers of better off people). Neither extreme view, we assume, is plausible. (shrink)

Understanding everyday behavior relies heavily upon understanding our ability to improvise, how we are able to continuously anticipate and adapt in order to coordinate with our environment and others. Here we consider the ability of musicians to improvise, where they must spontaneously coordinate their actions with co-performers in order to produce novel musical expressions. Investigations of this behavior have traditionally focused on describing the organization of cognitive structures. The focus, here, however, is on the ability of the time-evolving patterns of (...) inter-musician movement coordination as revealed by the mathematical tools of complex dynamical systems to provide a new understanding of what potentiates the novelty of spontaneous musical action. We demonstrate this approach through the application of cross wavelet spectral analysis, which isolates the strength and patterning of the behavioral coordination that occurs between improvising musicians across a range of nested time-scales. Revealing the sophistication of the previously unexplored dynamics of movement coordination between improvising musicians is an important step towards understanding how creative musical expressions emerge from the spontaneous coordination of multiple musical bodies. (shrink)