In her book Specifications Grading, Linda B. Nilson advocates for a grading regimen she claims will save faculty time, increase student motivation, and improve the quality and rigor of student work. If she is right, there is a strong case for many faculty to adopt some version of the system she recommends. In this paper, we argue that she is mostly right and recommend that faculty move away from traditional grading. We begin by rehearsing the central features of specifications grading (...) and providing two examples of how to implement it in philosophy classes. In light of the examples, we argue that specifications grading fulfills two of Nilson’s central desiderata but not the third. Since specifications grading generates two benefits that when combined increase student learning, without adding or increasing burdens, we conclude that student learning increases when courses are revised to include aspects of specifications grading. (shrink)

Nursing Theories and Nursing Practice, 2nd Edition, shows your undergraduate and graduate students how theory will help them improve the ways in which they practice nursing. It contains contributions by the original theorists, including discussion of how theories can be used in practice and examples of implementation written by nurses themselves. to help your students develop critical thinking skills, clear explanations of multiple ways of knowing are detailed, in addition to reflective practice, and background information on the process of theory (...) development. (shrink)

In the remainder of this article, we will disarm an important motivation for epistemic contextualism and interest-relative invariantism. We will accomplish this by presenting a stringent test of whether there is a stakes effect on ordinary knowledge ascription. Having shown that, even on a stringent way of testing, stakes fail to impact ordinary knowledge ascription, we will conclude that we should take another look at classical invariantism. Here is how we will proceed. Section 1 lays out some limitations of previous (...) research on stakes. Section 2 presents our study and concludes that there is little evidence for a substantial stakes effect. Section 3 responds to objections. The conclusion clears the way for classical invariantism. (shrink)

It has recently been argued that a person’s moral judgments (about both their own and others’ actions) are constrained by the nature and extent of their relevant ignorance and, thus, that such judgments are determined in the first instance by the person’s epistemic circumstances. It has been argued, in other words, that the epistemic is logically prior to other normative (e.g., ethical, prudential, pecuniary) considerations in human decision-making, that these other normative considerations figure in decision-making only after (logically and temporally) (...) relevant ignorance has constrained the decision-maker’s menu of options. If this is right, then a person’s moral judgments in some set of circumstances should vary with their knowledge and ignorance of these circumstances. In this study, we test the hypothesis of the logical priority of the epistemic. We describe two experiments in which subjects’ knowledge and ignorance of relevant consequences were manipulated. In the second experiment, we also compared the effect of ignorance on moral judgments with that of personal force, a factor previously shown to influence moral judgments. We found broad empirical support for the armchair arguments that epistemic considerations are logically prior to normative considerations. (shrink)

This essay considers how scholarly approaches to the development of molecular biology have too often narrowed the historical aperture to genes, overlooking the ways in which other objects and processes contributed to the molecularization of life. From structural and dynamic studies of biomolecules to cellular membranes and organelles to metabolism and nutrition, new work by historians, philosophers, and STS scholars of the life sciences has revitalized older issues, such as the relationship of life to matter, or of physicochemical inquiries to (...) biology. This scholarship points to a novel molecular vista that opens up a pluralist view of molecularizations in the twentieth century and considers their relevance to current science. (shrink)

Does the Ship of Theseus present a genuine puzzle about persistence due to conflicting intuitions based on “continuity of form” and “continuity of matter” pulling in opposite directions? Philosophers are divided. Some claim that it presents a genuine puzzle but disagree over whether there is a solution. Others claim that there is no puzzle at all since the case has an obvious solution. To assess these proposals, we conducted a cross-cultural study involving nearly 3,000 people across twenty-two countries, speaking eighteen (...) different languages. Our results speak against the proposal that there is no puzzle at all and against the proposal that there is a puzzle but one that has no solution. Our results suggest that there are two criteria—“continuity of form” and “continuity of matter”— that constitute our concept of persistence and these two criteria receive different weightings in settling matters concerning persistence. (shrink)

In this paper I’ll examine whether we could be justified in attributing consciousness to artificial intelligent systems. First, I’ll give a brief history of the concept of artificial intelligence (AI) and get clear on the terms I’ll be using. Second, I’ll briefly review the kinds of AI programs on offer today, identifying which research program I think provides the best candidate for machine consciousness. Lastly, I’ll consider the three most plausible ways of knowing whether a machine is conscious: (1) an (...) AI demonstrates a sufficient level of organizational similarity to that of a human thinker, (2) an inference to the best explanation, and (3) what I call “punting to panpsychism”, i.e., the idea that if everything is conscious, then we get machine consciousness in AI for free. However, I argue that all three of these methods for attributing machine consciousness are inadequate since they each face serious philosophical problems which I will survey and specifically tailor to each method. (shrink)

It has recently been argued that a person’s moral judgments (about both their own and others’ actions) are constrained by the nature and extent of their relevant ignorance and, thus, that such judgments are determined in the first instance by the person’s epistemic circumstances. It has been argued, in other words, that the epistemic is logically prior to other normative (e.g., ethical, prudential, pecuniary) considerations in human decision-making, that these other normative considerations figure in decision-making only after (logically and temporally) (...) relevant ignorance has constrained the decision-maker’s menu of options. If this is right, then a person’s moral judgments in some set of circumstances should vary with their knowledge and ignorance of these circumstances. In this study, we test the hypothesis of the logical priority of the epistemic. We describe two experiments in which subjects’ knowledge and ignorance of relevant consequences were manipulated. In the second experiment, we also compared the effect of ignorance on moral judgments with that of personal force, a factor previously shown to influence moral judgments. We found broad empirical support for the armchair arguments that epistemic considerations are logically prior to normative considerations. (shrink)

Description In this paper, we propose an advanced mathematical framework centered around the Energy Number Field (E), which fundamentally avoids the conventional concept of zero by introducing a neutral ele- ment, νE. Through this approach, we redefine core mathematical constructs, including limits, continuity, differentiation, integration, and series summation, ensuring they operate seamlessly within a zero-less paradigm. We address and redefine matrix operations, topology, metric spaces, and complex analysis, aligning them with the principles of E. Additionally, we explore non-mappable properties of (...) energy numbers in the context of symmetry groups, non-standard fields, fractional calculus, and non-Euclidean geometries. By employing νE as the central element, our framework resolves conventional zero-related sin- gularities and computational anomalies, offering a novel perspective that bridges advanced mathematical theories with practical applications in physics, computational algorithms, and topological transforma- tions. This work paves the way for future research to experimentally validate these formulations and explore potential applications in advanced physics, quantum mechanics, and beyond. (shrink)

Using artificial intelligence (AI) to make decisions in human resource management (HRM) raises questions of how fair employees perceive these decisions to be and whether they experience respectful treatment (i.e., interactional justice). In this experimental survey study with open-ended qualitative questions, we examine decision making in six HRM functions and manipulate the decision maker (AI or human) and decision valence (positive or negative) to determine their impact on individuals’ experiences of interactional justice, trust, dehumanization, and perceptions of decision-maker role appropriate- (...) ness. In terms of decision makers, the use of human decision makers over AIs generally resulted in better perceptions of respectful treatment. In terms of decision valence, people experiencing positive over negative decisions generally resulted in better perceptions of respectful treatment. In instances where these cases conflict, on some indicators people preferred positive AI decisions over negative human decisions. Qualitative responses show how people identify justice concerns with both AI and human decision making. We outline implications for theory, practice, and future research. (shrink)

We recall, "a priori," numeric energy expression: -/- Energy Numbers -/- $\begin{gathered}\mathcal{V}=\left\{f \mid \exists\left\{e_1, e_2, \ldots, e_n\right\} \in E \cup R\right\} \\ \mathcal{V}=\left\{f \mid \exists\left\{e_1, e_2, \ldots, e_n\right\} \in E, \text { and }: E \mapsto r \in R\right\} \\ \mathcal{V}=\left\{E \mid \exists\left\{a_1, \ldots, a_n\right\} \in E, E \not \neg r \in R\right\}\end{gathered}$ -/- We now introduce the set of optimized energy numbers: -/- ($H_a \in \mathcal{H}$ or $P^n = NP$ or $(P,\mathcal{L},F) = NP$). -/- Based on our formulation of (...) the bi-objective optimization task, we can make the following mathematical inferences: -/- 1. If the optimized energy numbers set $\mathcal{N}_H$ is equal to the original energy numbers set $\mathcal{E}$, i.e. $\mathcal{N}_H = \mathcal{E}$, then the maximum optimization score is achieved, i.e. the bi-objective optimization task is solved. This implies that there exists at least one solution to the optimization problem and $H_a \in \mathcal{H}$, where $H_a$ is the hypothesis that states the existence of an efficient algorithm to solve the problem. -/- 2. If the optimized energy numbers set $\mathcal{N}_H$ is a subset of the original energy numbers set $\mathcal{E}$, i.e. $\mathcal{N}_H \subset \mathcal{E}$, then the optimization score is less than the maximum score. This indicates that there may exist more efficient algorithms to solve the problem, and the hypothesis $H_a$ is still possible. -/- 3. If the optimized energy numbers set $\mathcal{N}_H$ is a superset of the original energy numbers set $\mathcal{E}$, i.e. $\mathcal{N}_H \supset \mathcal{E}$, then the optimization score is higher than the maximum score. This implies that the optimization problem may be easier than initially thought, and $P^n = NP$, or at least some form of $NP$-completeness. -/- 4. If the optimized energy numbers set $\mathcal{N}_H$ is a strict subset of the original energy numbers set $\mathcal{E}$, i.e. $\mathcal{N}_H \subsetneq \mathcal{E}$, and $P^n \neq NP$, then it can be concluded that the optimization problem is complex but there may exist algorithms that can efficiently approximate the solution. -/- 5. If the optimized energy numbers set $\mathcal{N}_H$ is empty, i.e. $\mathcal{N}_H = \emptyset$, then it can be inferred that the optimization problem is infeasible, i.e. no efficient algorithm exists to solve it, and $H_a$ is false. -/- 6. Comparing the two objectives in the bi-objective optimization task, we can make the following statements: -/- - The first objective, $\frac{\delta_{v(f)}(\mathbf{v}, \mathbf{w_{max}})} {\langle \mathbf{v_f}, \mathbf{1_f}\rangle}$, measures the efficiency of the algorithm and its ability to find low energy numbers. - The second objective, $\rho(\mathcal{N}_H)$, measures the accuracy of the algorithm in terms of loss and perplexity on the HyperLanguageModel. - Therefore, by optimizing both objectives simultaneously, we aim to find an efficient algorithm that also minimizes the loss and perplexities on the HyperLanguageModel. - If the optimization task is successfully solved, then the algorithm achieves both high efficiency and high accuracy. This would imply that the algorithm is able to find low energy numbers effectively and also generalize well on the HyperLanguageModel. -/- The optimized energy numbers aim to find a set of numbers $\mathbf{v}$ that maximize the bi-objective optimization task, while also minimizing the loss and perplexity of the HyperLanguageModel. This is achieved by finding the set of numbers that have the highest delta value and the lowest perplexity, resulting in a more optimized and efficient set of energy numbers. -/- By comparing the optimized energy numbers to the original set, we can see that the optimized set may have a higher delta value and a lower perplexity, indicating that it is a better set of numbers for the given task. This shows that the optimized energy numbers have successfully achieved their goal of maximizing efficiency while minimizing loss and perplexity. (shrink)

G.E.M. Anscombe famously remarked that an adequate philosophy of psychology was needed before we could do ethics. Fifty years have passed, and we should now ask what significance our best theories of the psychology of agency have for moral philosophy. My focus is on non-moral conceptions of autonomy and self-governance that emphasize the limits of deliberation -- the way in which one's cares render certain options unthinkable, one's intentions and policies filter out what is inconsistent with them, and one's resolutions (...) function to block further reflection. I argue that we can expect this deliberative "silencing" to lead to moral failures that occur because the morally correct option was filtered out of the agent's deliberation. I think it follows from these conceptions of self-governance that we should be considered culpable for unwitting acts and omissions, even if they express no ill will, moral indifference, or blameworthy evaluative judgments. The question is whether this consequence is acceptable. Either way, the potential tradeoff between self-governance and moral attentiveness is a source of doubt about recent attempts to ground the normativity of rationality in our concern for self-governance. (shrink)

G.E.M. Anscombe famously claimed that ‘the Hebrew-Christian ethic’ differs from consequentialist theories in its ability to ground the claim that killing the innocent is intrinsically wrong. According to Anscombe, this is owing to its legal character, rooted in the divine decrees of the Torah. Divine decrees confer a particular moral sense of ‘ought’ by which this and other act-types can be ‘wrong’ regardless of their consequences, she maintained. There is, of course, a potentially devastating counter-example. Within the Torah, Abraham is (...) apparently commanded by God to slaughter and set fire to his innocent son, Isaac. For attempting to do so, he is praised in the Biblical passage and by later Jewish and Christian commentators. This paper examines rabbinic and early Christian analyses of the story and finds that it was not unambiguously held by these interpreters that God absolutely prohibits killing the innocent, until the time of Augustine, whose position on the story evolved over time. (shrink)

We apply the analysis that we have developed over the course of several publications on the significance of ignorance for decision-making, especially in surrogate (and, thus, in political) contexts, to political decision-making, such as it has been, during the COVID-19 pandemic (see Scheall 2019; Crutchfield and Scheall 2019; Scheall and Crutchfield 2020; Scheall 2020). Policy responses to the coronavirus constitute a case study of the problem of policymaker ignorance. We argue that political responses to the virus cannot be explained by (...) assuming that the interests of policymakers were at loggerheads with those of their constituents at the beginning of the crisis. In order to explain the responses of policymakers, it is necessary to recognize the effects of relevant ignorance on their incentives to pursue different policy objectives. We discuss the knowledge that policymakers required at the start of the pandemic in order to deliberately realize the goal of limiting overall human suffering and the spontaneous forces that could have facilitated the realization of this goal. The problem of policymaker ignorance implies that policymakers have not earnestly pursued the goal of limiting overall suffering due to the novel coronavirus, but have repeatedly resorted to the pursuit of relatively less epistemically burdensome goals. The problem of policymaker ignorance explains why policymakers have focused primarily on limiting one kind of suffering – physical suffering due to the virus – and have mostly ignored related kinds of suffering, i.e., the economic, sociological, psychological, and physical suffering caused by policies to limit physical suffering from the virus. The problem of policymaker ignorance also helps to explain why policymakers relied on the relatively blunt instrument of economic lockdown rather than more focused protection policies, and why they continue to resort to lockdowns, despite the emerging scientific evidence of their ineffectiveness at mitigating physical suffering due to the virus. (shrink)

The concept of stage presence in performing arts is generally understood as the ability of the skilled performer to capture the attention of the audience, a prerogative of the talented actor, who occupies a position of power in respect to the audience. This work challenges the classic model of stage presence as an intrinsic quality of the performer and proposes instead a cognitive ecological ethnographic framework which considers the role played by various social actors — the public and the performers, (...) embedded in specific historical, cultural, and social environments — in shaping the performance event. Through an ethnographic and phenomenological analysis of the concept of stage presence in different performative contexts, this work proposes a cognitive ecological approach to the study of stage presence, suggesting possible methodological directions. (shrink)

One could argue that the use, extraction, and development of natural resources for human purposes, i.e. resource exploitation, constitutes a form of instrumentalization of the ecosystems from which these resources are derived. Moreover, that such instrumentalization may be carried out in a way that has adverse social and environmental impacts. Given that a number of ecosystems are indispensable for the satisfaction of human interests and needs, their instrumentalization may nevertheless be justified. In this context, if the amount and rate of (...) instrumentalization of ecosystems leads to their depletion, people whose well-being depends on the ecosystems’ existence may be profoundly harmed. Those instrumentalization practices and actions that lead to states of depletion are generally considered as harmful, but only to those whose interests and needs are frustrated as a result of such practices and actions. In this paper, I argue that the way in which ecosystems are instrumentalized, and not just the quantity and rate, may also cause a philosophically relevant form of harm, and not necessarily to humans: A given ecosystem may be meaningfully harmed not only when it is depleted, but also when its functioning is altered in such a way that it cannot retain core capacities it had before it was instrumentalized. (shrink)

Observational learning can enhance the acquisition and performance quality of complex motor skills. While an extensive body of research has focused on the benefits of synchronous (i.e., concurrent physical practice) and non-synchronous (i.e., delayed physical practice) observational learning strategies, the question remains as to whether these approaches differentially influence performance outcomes. Accordingly, we investigate the differential outcomes of synchronous and non-synchronous observational training contexts using a novel dance sequence. Using multidimensional cross-recurrence quantification analysis, movement time-series were recorded for novice dancers (...) who either synchronised with (n = 22) or observed and then imitated (n = 20) an expert dancer. Participants performed a 16-count choreographed dance sequence for 20 trials assisted by the expert, followed by one final, unassisted performance trial. Although end-state performance did not significantly differ between synchronous and non-synchronous learners, a significant decline in performance quality from imitation to independent replication was shown for synchronous learners. A non-significant positive trend in performance accuracy was shown for non-synchronous learners. For all participants, better imitative performance across training trials led to better end-state performance, but only for the accuracy (and not timing) of movement reproduction. Collectively, the results suggest that synchronous learners came to rely on a realtime mapping process between visual input from the expert and their own visual and proprioceptive intrinsic feedback, to the detriment of learning. Thus, the act of synchronising alone does not ensure an appropriate training context for advanced sequence learning. (shrink)

We compare the definition of virtue in philosophy with the definition and operationalization of virtue in psychology. We articulate characteristics that virtue is presented as possessing in the perennial western philosophical tradition. Virtues are typically understood as (a) dispositional (b) deep-seated (c) habits (d) that contribute to flourishing and (e) that produce activities with the following three features: they are (f) done well, (g) not done poorly, and (h) in accordance with the right motivation and reason. We form a definition (...) from these characteristics and defend our exclusion of some other characteristics from the definition. Using our definition as a rubric, we evaluate conceptions of virtue in psychology, showing how many fall short at operationalizing at least one component of the philosophical notion of virtue. (shrink)

Forms of Artificial Intelligence (AI) are already being deployed into clinical settings and research into its future healthcare uses is accelerating. Despite this trajectory, more research is needed regarding the impacts on patients of increasing AI decision making. In particular, the impersonal nature of AI means that its deployment in highly sensitive contexts-of-use, such as in healthcare, raises issues associated with patients’ perceptions of (un) dignified treatment. We explore this issue through an experimental vignette study comparing individuals’ perceptions of being (...) treated in a dignified and respectful way in various healthcare decision contexts. Participants were subject to a 2 (human or AI decision maker) x 2 (positive or negative decision outcome) x 2 (diagnostic or resource allocation healthcare scenario) factorial design. We found evidence of a “human bias” (i.e., a preference for human over AI decision makers) and an “outcome bias” (i.e., a preference for positive over negative outcomes). However, we found that for perceptions of respectful and dignified interpersonal treatment, it matters more who makes the decisions in diagnostic cases and it matters more what the outcomes are for resource allocation cases. We also found that humans were consistently viewed as appropriate decision makers and AI was viewed as dehumanizing, and that participants perceived they were treated better when subject to diagnostic as opposed to resource allocation decisions. Thematic coding of open-ended text responses supported these results. We also outline the theoretical and practical implications of these findings. (shrink)

Cognitive flexibility, the adaptation of representations and responses to new task demands, improves dramatically in early childhood. It is unclear, however, whether flexibility is a coherent, unitary cognitive trait, or is an emergent dimension of task-specific performance that varies across populations with divergent experiences. Three-to 5-year-old English-speaking U.S. children and Tswana-speaking South African children completed two distinct language-processing cognitive flexibility tests: the FIM-Animates, a word-learning test, and the 3DCCS, a rule-switching test. U.S. and South African children did not differ in (...) word-learning flexibility but showed similar age-related increases. In contrast, U.S. preschoolers showed an age-related increase in rule-switching flexibility but South African children did not. Verbal recall explained additional variance in both tests but did not modulate the interaction between population sample (i.e., country) and task. We hypothesize that rule-switching flexibility might be more dependent upon particular kinds of cultural experiences, whereas word-learning flexibility is less cross-culturally variable. (shrink)

Martin E. Rosenberg -/- The Gift of Silence: Towards an Anthropology of Jazz Improvisation as Neuro-Resistance. -/- ABSTRACT: -/- This essay addresses how the complex processes that occur during jazz improvisation enact behaviors that resemble the logic of gift exchange first described by Marcel Mauss. It is possible to bring to bear structural, sociological, political economical, deconstructive or even ethical approaches to what constitutes gift exchange during the performance of jazz. Yet, I would like to shift from focusing this analysis (...) of jazz improvisation with reference to the language of music as symbolic action (which all of these approaches require), to grounding improvisation in embodied and distributed cognition, the performance of which begins with a ritual gift of silence. By silence, I refer to the embodied, yet shared pure duration as felt synchrony within an individual performer, that extends to the members of an ensemble. Thus, I refer to both aesthetic and micro-political implications of embodied, yet also distributed musical cognition in real time. -/- For jazz musicians, embodied silence becomes the initial condition for processes of cognitive bifurcation. For it is bifurcation that attracts us to jazz in the first place. Here I expand my previous work establishing similarities in the behavior of bifurcating systems in physical and cognitive sciences to the unfolding of ambiguity in real time during improvisation with respect to polyphony, polytonality and polyrhythms in the history of jazz from Charlie Parker to Ornette Coleman. We can therefore re-conceptualize jazz improvisation as a subversive antidote for processes of determination identified in a sub-discipline of cultural studies called “cognitive capitalism.” By examining silence from this anthropological perspective, we can conceive of jazz performance as a ritualized resistance to top-down cognitive control immanent with social and digital networks. The ritual enactment that is jazz improvisation points towards an aesthetics of bifurcation that is simultaneously a micro-politics of neuro-resistance. In other words, I argue that freedom of thought requires freedom from thought as an initial condition. -/- Yet, I emphasize the empirical rather than mystical grounds to this gift of silence. The valorization of silence by jazz musicians is not simply etiquette, an ethics of reciprocity for performers exchanging “riffs,” but an initial condition that jazz performers (and, I would argue, listeners) experience in their bodies, thus linking embodied cognition to a collective field of cultural production that emerges from each embodied individual, and yet also pervades the ensemble in ways reminiscent of feedback loops in complex systems. The recent and remarkable research on music and the brain has demonstrated that it is now possible to describe jazz improvisation as possessing both embodied and distributed cognitive properties. The emergent neuronal ensemble behavior within the individual that is visible in jazz improvisors, discovered by the neuroscientists at Johns Hopkins led by Charles Limb, bears striking resemblance to the interactive behaviors of the jazz ensemble itself. Thus, it is by recourse to recent research by myself and others into the cognitive neuroscience of music generally, and jazz improvisation specifically, that the empirical grounds for an anthropology of neuro-resistance become visible. (shrink)

When the French philosopher Sarah Kofman committed suicide in 1994 she left behind an impressive oeuvre in which both the autobiographical genre and the treatment of women play a central role. Her theoretical re ections on both topics situate themselves in the interstices between psychoanalysis, feminism and deconstruction and share a common concern: the respect of alterity in all its guises. Kofman's resistance to the authoritative claim of the retrospective closure underlying traditional autobiographies is closely related to her celebration (...) of an e ®criture parricide, a mode of writing which undoes the repression of multiplicity and otherness. Shortly before her death Kofman published an autobiographical account of her own childhood years after the deportation and death of her father in a concentration camp. This article addresses the striking discrepancies between the theoretical positions Kofman defends throughout her philosophical writings and the autobiographical turn of her own last words. (shrink)

Sarah Kane's theatre is one of the most at the same time disturbing and profound representation of the collapses of the human soul. Nevertheless her theatre doesn't only stage the horrors of the pain, but it could be an epistemologically useful tool to decrypt the actual human condition: in this paper my goal is to extend her playworks in a pregnantly ontological and existential instance.

DESENVOLVIMENTO EMBRIONÁRIO E DIFERENCIAÇÃO SEXUAL -/- E. I. C. da Silva Departamento de Agropecuária – IFPE Campus Belo Jardim Departamento de Zootecnia – UFRPE sede -/- 1.1 INTRODUÇÃO O sexo foi definido como a soma das diferenças morfológicas, fisiológicas e psicológicas que distinguem o macho da fêmea permitindo a reprodução sexual e assegurando a continuidade das espécies. Os processos de diferenciação sexual são realizados durante o desenvolvimento embrionário, onde ocorre a proliferação, diferenciação e maturação das células germinativas e primordiais, precursoras (...) de ovócitos e espermatozoides em fêmeas e machos, respectivamente. Assim, os embriões machos e fêmeas iniciam o seu desenvolvimento de forma semelhante, de modo que em ambos os sexos se estabelecem em estruturas idênticas a partir das quais se formarão os órgãos reprodutores correspondentes a cada sexo. O conhecimento da origem e do desenvolvimento do aparelho genital é indispensável para entender sua função e as alterações que produzem infertilidade ou esterilidade. 1.2 DETERMINAÇÃO DO SEXO CROMOSSÔMICO Nos mamíferos, o sexo cromossômico é determinado no momento da fertilização, quando um óvulo, que contém um cromossomo X, é fecundado por um espermatozoide portador de um cromossomo X ou um cromossomo Y. No primeiro caso, o complemento cromossômico seria XX, o que originaria uma fêmea (sexo homogamético), e no segundo daria como resultado um macho com a fórmula cromossômica XY (sexo heterogâmico). 1.3 A GÔNADA INDIFERENCIADA A primeira manifestação das gônadas se aprecia no embrião em forma de um par de eminências longitudinais chamadas cristas ou dobras gonodais, situadas em ambos os lados da linha média entre os mesonefros (rins em desenvolvimento) e do mesentério dorsal. Nos embriões dos mamíferos, as células germinativas primordiais (CGP) manifestam-se em estágios precoces do desenvolvimento, podendo ser detectadas pela primeira vez na metade da gastrulação. As CGP são células grandes, de citoplasma claro e núcleo grande e redondo, localizadas na parede do saco vitelino, perto do alantoide. Essas células possuem grande capacidade de proliferação e vão migrar desde o endoderma do intestino e o epitélio do saco vitelino, através do mesentério, até as cristas gonodais. Isso ocorre por volta do 26° dia da gestação no bovino. Sua migração realiza-se graças aos movimentos de translocação passiva e deslocamento ameboide ativo. Desconhece-se o mecanismo pelo qual estas células são dirigidas para as cristas gonodais, porém foram estudadas algumas moléculas que se expressam durante sua migração e que poderiam desempenhar um papel importante na diferenciação deste tipo celular. A fosfatase alcalina é uma enzima que tem sido usada como marcador de CGP para determinar a sua origem e migração. Num estudo recente, foi inserido um marcador fluorescente que se exprime unicamente nas células germinativas primordiais de embriões transgênicos, e utilizando este marcador e a fosfatase alcalina determinou-se a origem e o padrão de migração destas células. O primeiro sinal de diferenciação das células germinativas primordiais é a expressão de fosfatase alcalina, e esta apareceu pela primeira vez na parte mais posterior da linha primitiva. No sétimo dia de desenvolvimento no embrião do camundongo, o endoderma visceral (AF+) é substituído pelo endoderma definitivo (AF-) originado na parte anterior da linha primitiva. O fator de transcrição Oct-4 é expresso nas CGP de ambos os sexos, pelo que acredita-se estar envolvido na mantença a totipotêncialidade das células. O receptor tirosina quinase, cujo ligante é o fator de Steel, é outra das moléculas que expressam as CGP. Tem sido demonstrado que este receptor possui um papel muito importante na sobrevivência deste tipo celular. Existem outros fatores que promovem a sobrevivência e/ou proliferação de CGP in vitro. Em experiências realizadas com o fator de transformação beta I (TGFβ-I), observou-se que este tem um efeito negativo sobre a proliferação das CGP. Outra atividade que tem sido postulada a este fator é o de um agente quimioatraente que possivelmente possa direcionar a migração destas células para a gônada. a) Um formado pelas células germinativas primordiais (precursoras dos gametas masculinos ou femininos), rodeadas de células somáticas das quais posteriormente se derivarão as células de Sertoli no macho e as células da granulosa na fêmea. b) O tecido que formará o estroma da gônada: tecido conjuntivo, vasos sanguíneos e as células intersticiais com atividade esteroidogênica (células de Leydig no testículo e a teca interna do ovário). As células somáticas do primórdio gonodal originam-se do mesoderma. Inicialmente são de três tipos: mesenquimáticas, mesoteliais e endoteliais. As células mesenquimáticas e mesoteliais iniciam grande atividade proliferativa ao chegar as CGP. Observa-se então uma condensação de células de origem mesotelial e mesenquimatoso que forma um agregado compacto denominado "blastema gonodal". A partir deste primórdio embrionário, diferenciam-se dois tecidos gonodais: os cordões sexuais e o estroma. Os cordões sexuais são arranjos epiteliais que se encontram delimitados por uma folha basal, e dentro deles encontramos as CGP. Por sua vez, no estroma encontram-se células do tipo mesenquimático e vasos sanguíneos. Neste momento, as gônadas são indiferenciadas e bipotencialmente sexuais, sendo impossível diferenciar, morfologicamente, uma gônada masculina de uma feminina, mas no caso dos machos genéticos já existe uma diferenciação da gônada a nível molecular. Nesta fase já se encontram presentes as estruturas das quais se desenvolvem os dutos mesonéfricos ou de Wolff precursores do aparelho genital masculino e os dutos paramesonéfricos ou de Müller que darão origem ao aparelho reprodutor feminino. Há uma série de fatores envolvidos no desenvolvimento precoce da gônada, entre os quais o fator esteroidogênico I (SFI: Steroidogenic fator l), que é um membro da subfamília de receptores nucleares, receptores órfãos. Este fator de transcrição tem um local de ligação ao DNA composto por dois dedos-de-Zinc. O SFI foi identificado como um ativador de genes envolvidos na biossíntese de esteroides em diferentes células. O SFI está presente durante o desenvolvimento embrionário em regiões associadas com funções endócrinas como gônadas, adrenais, pituitárias e hipotálamos. Os animais homozigotos para o gene SFI defeituoso, necessitam de gônadas e adrenais e têm a função gonadotrófica alterada. Os ratos sem SFI carecem de gonadotrofos e têm um desenvolvimento anormal do núcleo ventro-medial do hipotálamo; em particular as gônadas deixam de se desenvolver entre os dias 11 a 15 e degeneram-se por apoptose. No entanto, a crista genital forma-se e é colonizada pelas células germinativas, o que indica que estas continuam a receber o sinal adequado para a sua migração. Portanto, o SFI não está envolvido no desenvolvimento precoce da gônada e do sistema urogenital, mas parece estar envolvido na manutenção do crescimento das células somáticas presentes na gônada indiferenciada. O gene associado ao tumor de Wilms (WTI: Wilm's tumor Associated) está envolvido no desenvolvimento da gônada e do rim. Durante o desenvolvimento embrionário, WTI se expressa em todo o mesoderma intermediário e posteriormente na gônada indiferenciada, bem como no rim em formação. WTI regula o sinal indutivo do mesênquima para o epitélio celômico dos mesonefros. Se este for o caso, então WTI é responsável pelo crescimento da crista genital ao dirigir a entrada do epitélio celômico. Dado que estas células darão origem às células de Sertoli, a carência de WTI pode causar o desenvolvimento de embriões XY como fêmeas simplesmente porque não se formam as células de Sertoli. Em geral, todos os genes importantes na diferenciação do mesoderma intermediário e do sistema urogenital intervêm no desenvolvimento da gônada precoce. 1.4 DIFERENCIAÇÃO GONODAL O desenvolvimento das gônadas e ductos genitais descritos até o momento, é o mesmo para ambos os sexos. Igualmente, os genes descritos, que estão envolvidos no desenvolvimento das gônadas, ductos genitais e migração das células germinativas, afetam igualmente os embriões com genótipo XX ou XY. A gônada primitiva consiste anatomicamente de uma medula (interna) e uma crosta (externa), e de acordo com o local onde ocorre a colonização das células germinativas, diferenciara em testículo ou um ovário, respectivamente. Nos mamíferos, a primeira manifestação estrutural de diferenciação sexual é detectada na gônada dos machos, onde as células germinativas estão localizadas na medula. A diferenciação do testículo inicia-se quando os cordões sexuais se separam do epitélio celômico como consequência dos arranjos produzidos por uma invasão do mesênquima e vasos sanguíneos que provoca a compactação dos cordões, agora denominados cordões testiculares. As células que rodeiam os cordões se achatam e formam as células mioides, que são responsáveis pela formação das membranas basais. As células do epitélio interno, ou seja, as células de Sertoli, têm duas funções principais: o suporte das CGP e a síntese da hormona antimulleriana, responsável pela regressão dos ductos de Müller e secretada durante o período de diferenciação sexual. As células do estroma que rodeiam os cordões testiculares diferenciam-se para formar vários tipos de células: células mioides, fibroblastos, endotélio e células de Leydig, que são as mais importantes pela sua atividade endócrina. Posteriormente, os cordões testiculares dão origem aos túbulos seminíferos, que contêm o epitélio que produzirá os espermatozoides ao chegar à puberdade. Na fêmea, durante os estágios iniciais de diferenciação gonodal, não se observam mudanças em relação à gônada indiferenciada, só pode-se observar um certo crescimento devido à proliferação de células somáticas e germinativas. As células germinativas iniciam um período de proliferação, que termina com o início da meiose. Iniciada a meiose, dá-se o processo de foliculogênese; neste momento os cordões epiteliais se fragmentam, de tal maneira que cada ovócito fica rodeado de células epiteliais cobertas por uma folha basal fina (figura 1). Para que a gônada primitiva se desenvolva em testículo é indispensável a presença do cromossoma Y, independentemente do número de cromossomas X que contenha o genoma de um indivíduo. O gene determinante do testículo encontra-se localizado no cromossoma Y, denominado sry em ratos e SRY em humanos. O gene sry se expressa durante o desenvolvimento embrionário na crista genital de embriões de camundongos. A expressão é detectável no dia 10,5, pouco depois do aparecimento das cristas genitais, atinge o seu máximo durante o dia 11,5 e mantém-se até pouco depois de ocorrerem os primeiros sinais morfológicos de diferenciação testicular no dia 12,5. Este padrão de expressão é compatível com a teoria de que sry atua induzindo a ativação dos genes (figura 2) que conduzem ao desenvolvimento testicular, sem que exista a necessidade da expressão contínua de sry para manter a diferenciação do testículo após o dia 12,5. Como mencionado anteriormente, a gônada primitiva é composta por vários tipos de células. No entanto, as células germinativas primordiais não são o local de expressão do sry, já que os embriões que necessitam de células germinativas mantêm a expressão de sry e desenvolvem o sexo gonodal normalmente. As células somáticas na gônada em desenvolvimento incluem também as células de suporte. Sabe-se que é nestas células que o sry é expresso para que se diferenciem em células de Sertoli, e a expressão transitória de sry indica que deve ativar a outros genes para a manutenção das células de Sertoli. Uma vez diferenciadas as células de Sertoli, elas se encarregarão da diferenciação do resto das células na gônada. -/- Figura 1: Representação da diferenciação dos órgãos genitais internos. Adaptado de BRONSON, 1989. Figura 2: Cascada de genes envolvidos na diferenciação sexual, adaptado de KOOPMAN, 1999. O fator sry é necessário para a diferenciação do testículo. Embora não se conheçam os genes que provavelmente regulam esse gene, estudos realizados em camundongos demonstram que este gene parece coordenar-se com certos genes autossômicos. Entre estes genes autossômicos, o sox9, que é produzido pelas células de Sertoli uma vez que são estimuladas por sry, de modo que sox9 é um dos genes relacionados estruturalmente com sry. O Sox9 funciona como um fator de transcrição, mas não se sabe se a proteína tem qualquer outra função estrutural; este gene exprime-se abundantemente nos condrócitos e está relacionado com defeitos do aparelho ósseo chamados displasia campomélica. Curiosamente, os pacientes XY com esta condição sofrem frequentemente de reversão do sexo. O Sox9 é um dos poucos genes, além do SRY, do qual as mutações demonstraram interferir com a determinação sexual masculina. No entanto, apenas 75% dos pacientes com anomalias esqueléticas de tipo displasia campomélica têm reversão sexual e não foram encontrados casos de reversão sexual devido a um defeito de Sox9 que não seja acompanhado de defeitos esqueléticos. Isso indica que o Sox9 é apenas um membro da rede de genes que são ativados para determinar a diferenciação sexual, enquanto a rota que rege a condrogênese é mais sensível a perturbações deste. O momento em que se detecta a expressão do gene Sox9 (11dpc em ratos) coincide com a máxima expressão de sry, o que poderia indicar a possibilidade de que sry regule positivamente a Sox9. De fato, na região do promotor de Sox9 há um local de união ao que potencialmente se pode unir o sry. A expressão de Sox9 durante a diferenciação sexual sugere um papel abaixo de sry na diferenciação das células de Sertoli. O cromossoma X também é importante na diferenciação gonodal. O gene DAX-I foi isolado do lócus DSS (Dosage sensitive sex reversal) do cromossoma X. DAX-I é parte da cascata de determinação sexual, mas não é necessário para a formação do testículo. DAX-I é um membro dos receptores nucleares conhecidos como receptores órfãos. Este gene demonstrou ser um poderoso repressor da transcrição de SFI e de vários genes. Os padrões de expressão de DAX-I são complementares daqueles de SFI, ambos expressos nas cristas genitais. Em resumo, dada a evidência exposta, desenvolveu-se a hipótese de que DAX-I é um antagonista de sry; esse antagonismo é dependente dos níveis relativos de DAX-I e sry e de um limiar que varia de espécie para espécie. A DAX-I foi classificada como o gene antitestículo. Na fêmea (cariótipo XX) é importante que ocorra a inativação de um dos cromossomas sexuais X para que se mantenha o equilíbrio genético ao igualar o conteúdo de DNA dos cromossomas. Esse cromossoma inativado constitui o chamado corpúsculo de Barr. No entanto, para que a meiose se realize, é necessário dos dois cromossomas X ativos nos ovócitos para assegurar a diferenciação ovárica e a fertilidade. 1.5 DIFERENCIAÇÃO DOS DUCTOS SEXUAIS O embrião possui, além das gônadas indiferenciadas, dois sistemas de ductos: os de potencialidade masculina denominam-se ductos de Wolff ou mesonéfricos, e os de potencialidade feminina se chamam ductos de Müller ou paramesonéfricos (figura 1). Se a diferenciação gonodal levou à formação de um testículo, a partir do ducto mesonéfrico ou de Wolff se desenvolverão os ductos eferentes, o epidídimo, os ductos deferentes e as vesículas seminais. As hormonas importantes no desenvolvimento do aparelho genital masculino são a testosterona, produzida pelas células de Leydig, e sua forma 5α reduzida, a 5α di-hidrotestosterona. Acredita-se que a testosterona é responsável pela virilização dos ductos de Wolff, e a di-hidrotestosterona dos órgãos genitais externos. No macho, os canais de Müller atrofiam-se devido à ação de uma hormona fetal de origem testicular denominada hormona inibidora das estruturas de Müller (HIM) ou hormona antimulleriana. Este processo começa assim que os cordões espermáticos se formam e se diferenciam as células de Sertoli. A existência de HIM foi proposta baseada em estudos realizados em bezerras freemartin, devido à existência de uma hormona responsável pela atresia dos ductos de Müller que na fêmea dá origem ao útero e aos ovidutos. Essa hormona provoca a involução do aparelho genital do bovino nas gestações gemelares nas quais os produtos de diferente sexo têm comunicação sanguínea por ter ocorrido a anastomose dos vasos de ambas as placentas (figura 3). A HIM é uma glicoproteína pertencente à subfamília de TGFβ, é expressa pelas células que darão origem às células de Sertoli e é um dos primeiros marcadores de diferenciação nestas células. A HIM é secretada na vida adulta pelas células de Sertoli no testículo e por células da granulosa no ovário. No rato a HIM é expressa-se no 12° dia em um teste padrão que segue muito de perto o aumento na expressão de sry. No macho, esta secreção de HIM continua durante a vida fetal e adulta, contudo os níveis de HIM declinam na puberdade devido a um aumento na secreção de testosterona. Vários fatores intervêm na regulação do gene de HIM, incluindo os acima descritos SFI e Sox9. O gene HIM contém segmentos de DNA que são conservados em várias espécies de vertebrados. Existe um nexo de ligação para SFI, que ativa a transcrição de HIM. A mutação no local de ligação de SFI resulta em reversão do sexo em indivíduos XY incluindo genitais femininos normais, presença de um útero formado enfatizando a importância de SFI na determinação sexual e na expressão de HIM. Embora SFI seja um bom candidato como regulador de HIM, é expresso em outras células, como as de Leydig e adrenais, que não expressam HIM. Em contrapartida, Sox9 é expresso unicamente nas células de Sertoli que são as produtoras de HIM. O gene HIM também tem um nexo de ligação para Sox9. Além disso, Sox9 pode atuar sinergicamente com SFI para promover a secreção de HIM. Ao contrário destes dois fatores de transcrição, DAX-I antagoniza a ação de Sox9 e provavelmente SFI sobre o promotor de HIM. Assim, para que as células de Sertoli secretem HIM, a transcrição de DAX-I deve diminuir. Figura 3: Representação da diferenciação dos órgãos genitais externos. Adaptado de BRONSON, 1989. Os ductos de Wolff tornam-se o sistema de ejaculação do macho. A porção mais próxima dos testículos dá origem ao epidídimo, a parte central ao ducto deferente e a porção mais distal às vesículas seminais. A próstata e a parte membranosa da uretra do macho desenvolvem-se a partir da porção pélvica do seio urogenital. A virilização e diferenciação dos ductos de Wolff dependem da produção de testosterona pelo testículo. Quanto aos órgãos genitais externos do macho, o tubérculo genital é ampliado e as dobras uretrais se fundem para formar a uretra peniana. A fusão das dobras uretrais aproxima os tubérculos genitais para formar o escroto (figura 4). Figura 4: Diferenciação do aparelho genital da fêmea e do macho. Adaptado de KOOPMAN, 1989. A diferenciação dos órgãos genitais da fêmea ocorre de forma passiva, já que a ausência de testículos e por isso da hormona inibidora dos ductos de Müller (HIM), assim como dos andrógenos virilizantes, favorece o desenvolvimento dos ductos de Müller, enquanto os de Wolff sofrem atrofia. A porção cefálica dos ductos de Müller dá origem aos ovidutos, que na sua terminação caudal se fundem com o útero. O contato dos ductos de Müller com o seio urogenital induz uma intensa proliferação celular que resulta na formação da área uterovaginal localizado entre o seio urogenital e os ductos de Müller. As células do prato uterovaginal proliferam e aumentam a distância entre as duas estruturas criando o espaço que formará a vagina quando o prato é canalizado e forma um lúmen. Em contraste com o que ocorre no macho, na fêmea a maior parte do seio urogenital se mantém exposta na superfície da abertura onde desembocam a vagina e a uretra. O tubérculo urogenital da fêmea tem um crescimento limitado e forma o clitóris. A sequência de passos da diferenciação sexual do aparelho genital é resumida na tabela 1. Tabela 1: Destino em desenvolvimento dos rudimentos sexuais dos fetos macho e fêmea dos mamíferos -/- Rudimento sexual Macho Fêmea Gônada Testículo Ovário Ductos de Müller (Paramesonéfricos) Vestígios Útero, parte da vagina, ovidutos Ductos de Wolff (Mesonéfricos) Ductos eferentes deferentes, epidídimo, vesículas seminais Vestígios Seio urogenital Uretra, próstata, glândulas bulbouretrais Parte da vagina, uretra, vestíbulo, glândulas vestibulares Tubérculo genital Pênis Clitóris Pregas vestibulares Escroto Lábios vulvares Fonte: HAFEZ, 2004. 1.6 DIFERENCIAÇÃO SEXUAL DO HIPOTÁLAMO Os processos de diferenciação sexual não se limitam apenas às células somáticas do organismo do feto, mas incluem também os centros nervosos superiores do cérebro. Assim, da mesma maneira que a gônada e os ductos sexuais se desenvolvem para o tipo feminino ou masculino, propôs-se que o cérebro pode ser "masculinizado" ou permanecer "Feminizado". A diferenciação do hipotálamo vai depender do ambiente esteroidal do neonato e ocorre na fase perinatal. Estes eventos serão de grande transcendência na vida reprodutiva do indivíduo. Tanto a fêmea como o macho nascem com a capacidade de secreção de gonadotropinas de acordo com um padrão cíclico; contudo, no macho, a exposição do hipotálamo à ação dos andrógenos testiculares durante os primeiros dias da vida extrauterina provoca a masculinização, com o qual o hipotálamo do macho é programado para que a secreção de gonadotropinas se realize a um ritmo relativamente constante por parte da hipófise (secreção tônica). Na fêmea, tanto a secreção tônica como a cíclica se conservam. No entanto, observou-se que a injeção de testosterona ou o transplante de testículo na rata fêmea durante os primeiros dias de vida, suprime a sua futura atividade estral (secreção cíclica). Por outro lado, se os ovários forem transplantados para o rato macho normal castrado na idade adulta, o animal não desenvolve qualquer atividade cíclica, mas se os machos transplantados forem castrados ao nascer, o ovário é capaz de efetuar mudanças cíclicas e ovulações. Isto foi demonstrado em roedores, mas não em animais domésticos ou na espécie humana. Portanto, o padrão de secreção de gonadotropinas, seja cíclico ou tônico, não depende da hipófise, mas do hipotálamo e sua correta diferenciação. 1.7 CONCLUSÕES A maioria dos conhecimentos no campo da biologia do desenvolvimento e, muito especificamente, dos processos de diferenciação sexual têm sido originados de estudos relacionados com desordens congênitas, que na sua maioria devem-se a defeitos de genes específicos. A análise detalhada destas desordens permitiu entender alguns mecanismos endócrinos, moleculares e genéticos envolvidos na diferenciação sexual. A identificação do gene sry como determinante do testículo foi uma contribuição crucial e abriu as portas à compreensão dos mecanismos moleculares e celulares relacionados com o desenvolvimento do testículo. Se este gene não estiver presente, é criado um programa genético alternativo para levar a cabo a diferenciação gonodal para o ovário. Finalmente, devemos ter presente que é necessária uma correlação entre mudanças morfológicas e expressão de genes durante o desenvolvimento para entender os mecanismos relacionados com a diferenciação. -/- Apoio -/- Realização -/- REFERÊNCIAS BIBLIOGRÁFICAS ANDERSON, Robert et al. The onset of germ cell migration in the mouse embryo. Mechanisms of development, v. 91, n. 1-2, p. 61-68, 2000. AUSTIN, Colin Russell; SHORT, R. V. Reproduction in Mammals: Volume 1, Germ Cells and Fertilization. Londres: Cambridge University Press, 1972. BRONSON, Franklin H. Mammalian reproductive biology. Chicago: University of Chicago Press, 1989. BUEHR, Mia. The primordial germ cells of mammals: some current perspectives. Experimental cell research, v. 232, n. 2, p. 194-207, 1997. BYSKOV, Anne G. Differentiation of mammalian embryonic gonad. Physiological reviews, v. 66, n. 1, p. 71-117, 1986. CAPEL, Blanche et al. Migration of mesonephric cells into the mammalian gonad depends on Sry. Mechanisms of development, v. 84, n. 1-2, p. 127-131, 1999. CAPEL, Blanche. The battle of the sexes. Mechanisms of development, v. 92, n. 1, p. 89-103, 2000. DERIVAUX, Jules; BARNABÉ, Renato Campanarut. Reprodução dos animais domésticos. Zaragoza: Acribia, 1980. DOMENICE, Sorahia et al. Aspectos moleculares da determinação e diferenciação sexual. Arquivos Brasileiros de Endocrinologia & Metabologia, v. 46, n. 4, p. 433-443, 2002. DONAHOE, Patricia K. et al. Mullerian inhibiting substance activity in bovine fetal, newborn and prepubertal testes. Biology of reproduction, v. 16, n. 2, p. 238-243, 1977. HAFEZ, Elsayed Saad Eldin; HAFEZ, B. Reprodução animal. São Paulo: Manole, 2004. HANLEY, Neil A. et al. Steroidogenic factor 1 (SF-1) is essential for ovarian development and function. Molecular and cellular endocrinology, v. 163, n. 1-2, p. 27-32, 2000. HIORT, Olaf; PAUL-MARTIN, H. The molecular basis of male sexual differentiation. European journal of endocrinology, v. 142, n. 2, p. 101-110, 2000. HOLY, Lubos; MARTÍNEZ JÚSTIZ, G. Colab. Biología de la reproducción bovina. Havana: Revolucionária, 1975. JOSSO, Nathalie et al. The role of anti-Müllerian hormone in gonadal development. Molecular and cellular endocrinology, v. 145, n. 1-2, p. 3-7, 1998. JOST, Alfred et al. Studies on sex differentiation in mammals. In: Proceedings of the 1972 Laurentian Hormone Conference. Londres: Academic Press, 1973. p. 1-41. KNOBIL, Ernst. Knobil and Neill's physiology of reproduction. EUA: Gulf Professional Publishing, 2006. KOFMAN ALFARO, S.; MERCHANT LARIOS, H.; PEREZ PALACIOS, G. Diferenciacion sexual. I. Bases biologicas del dimorfismo sexual. Rev. invest. clín, p. 349-59, 1982. KOOPMAN, Peter. Sry and Sox9: mammalian testis-determining genes. Cellular and Molecular Life Sciences CMLS, v. 55, n. 6-7, p. 839-856, 1999. MCDONALD, L. E. Veterinary endocrinology. Lea & Febiger, Philadelphia, Pa, 1969. MEIZEL, S.; JOHNSON, M. H. Development in mammals. MH Johnson, Ed, v. 3, p. 1-64, 1978. MELLO, Maricilda Palandi de; ASSUMPÇÃO, Juliana de G.; HACKEL, Christine. Genes envolvidos na determinação e diferenciação do sexo. Arquivos Brasileiros de Endocrinologia & Metabologia, v. 49, n. 1, p. 14-25, 2005. -/- REFERÊNCIAS BIBLIOGRÁFICAS MERCHANT-LARIOS, H. Ovarian differentiation. The Vertebrate Ovary, p. 47-81, 1978. MIES FILHO, Antonio. Reprodução dos animais. Porto Alegre: Sulina, 1987. NEF, Serge; PARADA, Luis F. Hormones in male sexual development. Genes & Development, v. 14, n. 24, p. 3075-3086, 2000. PARKER, Keith L.; SCHEDL, Andreas; SCHIMMER, Bernard P. Gene interactions in gonadal development. Annual review of physiology, v. 61, n. 1, p. 417-433, 1999. SWAIN, Amanda; LOVELL-BADGE, Robin. Mammalian sex determination: a molecular drama. Genes & development, v. 13, n. 7, p. 755-767, 1999. WILHELM, Dagmar; PALMER, Stephen; KOOPMAN, Peter. Sex determination and gonadal development in mammals. Physiological reviews, v. 87, n. 1, p. 1-28, 2007. WILSON, Jean D.; GRIFFIN, James E.; GEORGE, Fredrick W. Sexual differentiation: early hormone synthesis and action. Biology of reproduction, v. 22, n. 1, p. 9-17, 1980. -/- Emanuel Isaque Cordeiro da Silva Belo Jardim, 07 de Maio de 2020. (shrink)

Can new technology enhance purpose-driven, democratic dialogue in groups, governments, and societies? Online Deliberation: Design, Research, and Practice is the first book that attempts to sample the full range of work on online deliberation, forging new connections between academic research, technology designers, and practitioners. Since some of the most exciting innovations have occurred outside of traditional institutions, and those involved have often worked in relative isolation from each other, work in this growing field has often failed to reflect the full (...) set of perspectives on online deliberation. This volume is aimed at those working at the crossroads of information/communication technology and social science, and documents early findings in, and perspectives on, this new field by many of its pioneers. -/- CONTENTS: -/- Introduction: The Blossoming Field of Online Deliberation (Todd Davies, pp. 1-19) -/- Part I - Prospects for Online Civic Engagement -/- Chapter 1: Virtual Public Consultation: Prospects for Internet Deliberative Democracy (James S. Fishkin, pp. 23-35) -/- Chapter 2: Citizens Deliberating Online: Theory and Some Evidence (Vincent Price, pp. 37-58) -/- Chapter 3: Can Online Deliberation Improve Politics? Scientific Foundations for Success (Arthur Lupia, pp. 59-69) -/- Chapter 4: Deliberative Democracy, Online Discussion, and Project PICOLA (Public Informed Citizen Online Assembly) (Robert Cavalier with Miso Kim and Zachary Sam Zaiss, pp. 71-79) -/- Part II - Online Dialogue in the Wild -/- Chapter 5: Friends, Foes, and Fringe: Norms and Structure in Political Discussion Networks (John Kelly, Danyel Fisher, and Marc Smith, pp. 83-93) -/- Chapter 6: Searching the Net for Differences of Opinion (Warren Sack, John Kelly, and Michael Dale, pp. 95-104) -/- Chapter 7: Happy Accidents: Deliberation and Online Exposure to Opposing Views (Azi Lev-On and Bernard Manin, pp. 105-122) -/- Chapter 8: Rethinking Local Conversations on the Web (Sameer Ahuja, Manuel Pérez-Quiñones, and Andrea Kavanaugh, pp. 123-129) -/- Part III - Online Public Consultation -/- Chapter 9: Deliberation in E-Rulemaking? The Problem of Mass Participation (David Schlosberg, Steve Zavestoski, and Stuart Shulman, pp. 133-148) -/- Chapter 10: Turning GOLD into EPG: Lessons from Low-Tech Democratic Experimentalism for Electronic Rulemaking and Other Ventures in Cyberdemocracy (Peter M. Shane, pp. 149-162) -/- Chapter 11: Baudrillard and the Virtual Cow: Simulation Games and Citizen Participation (Hélène Michel and Dominique Kreziak, pp. 163-166) -/- Chapter 12: Using Web-Based Group Support Systems to Enhance Procedural Fairness in Administrative Decision Making in South Africa (Hossana Twinomurinzi and Jackie Phahlamohlaka, pp. 167-169) -/- Chapter 13: Citizen Participation Is Critical: An Example from Sweden (Tomas Ohlin, pp. 171-173) -/- Part IV - Online Deliberation in Organizations -/- Chapter 14: Online Deliberation in the Government of Canada: Organizing the Back Office (Elisabeth Richard, pp. 177-191) -/- Chapter 15: Political Action and Organization Building: An Internet-Based Engagement Model (Mark Cooper, pp. 193-202) -/- Chapter 16: Wiki Collaboration Within Political Parties: Benefits and Challenges (Kate Raynes-Goldie and David Fono, pp. 203-205) -/- Chapter 17: Debian’s Democracy (Gunnar Ristroph, pp. 207-211) -/- Chapter 18: Software Support for Face-to-Face Parliamentary Procedure (Dana Dahlstrom and Bayle Shanks, pp. 213-220) -/- Part V - Online Facilitation -/- Chapter 19: Deliberation on the Net: Lessons from a Field Experiment (June Woong Rhee and Eun-mee Kim, pp. 223-232) -/- Chapter 20: The Role of the Moderator: Problems and Possibilities for Government-Run Online Discussion Forums (Scott Wright, pp. 233-242) -/- Chapter 21: Silencing the Clatter: Removing Anonymity from a Corporate Online Community (Gilly Leshed, pp. 243-251) -/- Chapter 22: Facilitation and Inclusive Deliberation (Matthias Trénel, pp. 253-257) -/- Chapter 23: Rethinking the ‘Informed’ Participant: Precautions and Recommendations for the Design of Online Deliberation (Kevin S. Ramsey and Matthew W. Wilson, pp. 259-267) -/- Chapter 24: PerlNomic: Rule Making and Enforcement in Digital Shared Spaces (Mark E. Phair and Adam Bliss, pp. 269-271) -/- Part VI - Design of Deliberation Tools -/- Chapter 25: An Online Environment for Democratic Deliberation: Motivations, Principles, and Design (Todd Davies, Brendan O’Connor, Alex Cochran, Jonathan J. Effrat, Andrew Parker, Benjamin Newman, and Aaron Tam, pp. 275-292) -/- Chapter 26: Online Civic Deliberation with E-Liberate (Douglas Schuler, pp. 293-302) -/- Chapter 27: Parliament: A Module for Parliamentary Procedure Software (Bayle Shanks and Dana Dahlstrom, pp. 303-307) -/- Chapter 28: Decision Structure: A New Approach to Three Problems in Deliberation (Raymond J. Pingree, pp. 309-316) -/- Chapter 29: Design Requirements of Argument Mapping Software for Teaching Deliberation (Matthew W. Easterday, Jordan S. Kanarek, and Maralee Harrell, pp. 317-323) -/- Chapter 30: Email-Embedded Voting with eVote/Clerk (Marilyn Davis, pp. 325-327) -/- Epilogue: Understanding Diversity in the Field of Online Deliberation (Seeta Peña Gangadharan, pp. 329-358). -/- For individual chapter downloads, go to odbook.stanford.edu. (shrink)

to appear in Lambert, E. and J. Schwenkler (eds.) Transformative Experience (OUP) -/- L. A. Paul (2014, 2015) argues that the possibility of epistemically transformative experiences poses serious and novel problems for the orthodox theory of rational choice, namely, expected utility theory — I call her argument the Utility Ignorance Objection. In a pair of earlier papers, I responded to Paul’s challenge (Pettigrew 2015, 2016), and a number of other philosophers have responded in similar ways (Dougherty, et al. 2015, Harman (...) 2015) — I call our argument the Fine-Graining Response. Paul has her own reply to this response, which we might call the Authenticity Reply. But Sarah Moss has recently offered an alternative reply to the Fine-Graining Response on Paul’s behalf (Moss 2017) — we’ll call it the No Knowledge Reply. This appeals to the knowledge norm of action, together with Moss’ novel and intriguing account of probabilistic knowledge. In this paper, I consider Moss’ reply and argue that it fails. I argue first that it fails as a reply made on Paul’s behalf, since it forces us to abandon many of the features of Paul’s challenge that make it distinctive and with which Paul herself is particularly concerned. Then I argue that it fails as a reply independent of its fidelity to Paul’s intentions. (shrink)

O renascimento do pragmatismo foi acompanhado por uma série de filósofas feministas que se esforçaram para resgatar do esquecimento as pensadoras que fizeram parte do movimento pragmatista clássico do final do século XIX e primeira metade do século XX. O presente trabalho visa introduzir aos leitores de língua portuguesa esse trabalho a partir de uma breve exposição das pensadoras Jane Addams, Mary Parker Follet, Charlotte Perkins Gilman, Mary Whiton Calkins e Ella Flagg Young.

In their article, “Immigrant legalization: A Dilemma Between Justice and The Rule of Law,” Sarah Song and Irene Bloemraad address rule of law objections to policies that would regularize the status of undocumented immigrants in the United States. On their view, justice requires that liberal democratic states (i.e., states that are committed to individual liberty and universal equality) provide pathways for undocumented immigrants to regularize their status. We do not disagree with Song and Bloemraad’s account: rule of law and (...) regularization policies are not inconsistent, and in fact regularization supports rule of law, when properly understood. Our view is that there needs to be a deeper investigation into the motivations of “rule of law” objections considered in Song and Bloemraad’s account. We argue that the real purpose of these objections is not necessarily to serve as an alternative to the justice-based claims of undocumented immigrants, but as a way to undermine them. On our account, these rule of law objections accomplish this undermining task through the mechanisms of dog whistling, discrediting and distorting, and ostracizing. (shrink)

A parcialidade epistêmica na amizade (PE) é a tese segundo a qual ser um bom amigo de alguém envolve tratar essa pessoa de forma diferente, em um sentido epistêmico. Sarah Stroud (2006) e Simon Keller (2004) defenderam essa tese e argumentaram que ela está em tensão direta com demandas de racionalidade epistêmica. A posição deles é que quando nossos amigos estão envolvidos em algum assunto ao qual temos que dar nossa avaliação (sobre os fatos, suas ações ou seu caráter), (...) tendemos a dar à questão um tratamento epistêmico diferencial, não reservado a não-amigos. Neste artigo, quero tratar de duas possíveis formas de responder à PE. Primeiro, quero discutir a rejeição de Sandy Goldberg (2018, 2020) a essa tese e à tensão que ela supostamente cria com as exigências da racionalidade epistêmica. Em sua proposta, Goldberg defende o comportamento epistêmico diferencial que a PE pressupõe, mas também argumenta que tal comportamento não configura um tipo de PE, e que tampouco está em tensão com as exigências da racionalidade epistêmica. Irei sugerir que a posição de Goldberg não capta uma distinção importante entre nossas atitudes epistêmicas diante do testemunho de um amigo e diante de relatos de terceiros sobre um amigo. Particularmente, o que eu argumentarei é que o caminho que leva da valorização da amizade às razões epistêmicas em apoio aos resultados doxásticos diferenciais quando nossos amigos estão envolvidos é, na melhor das hipóteses, frágil, já que envolve o que eu vejo como um movimento não autorizado de nosso desejo de preservar uma amizade para uma reação doxástica diferencial quando alguém testemunha negativamente sobre nossos amigos. Em segundo lugar, defenderei também que não devemos aceitar a prescrição da PE tão rapidamente. Argumentarei que, ao avaliar injustamente as credenciais epistêmicas de nossos amigos – algo que parece estar acontecendo em alguns casos de parcialidade epistêmica, podemos estar contribuindo para degradar as condições de trocas epistêmicas justas em uma comunidade. Se esse for o caso, teremos uma razão pragmática para rejeitar a PE. Na primeira seção do artigo, apresentarei a tese da parcialidade epistêmica na amizade, focalizando principalmente na forma como Stroud a articula. Depois disso, na seção II, tratarei da rejeição da PE por Goldberg e apresentarei uma crítica à sua posição. Na terceira e última seção, defenderei o que vejo como uma preocupação importante se aceitarmos a PE e oferecerei uma razão pragmática para questioná-la. (shrink)

For the past half-century, both jurisprudence and epistemology have been haunted by questions about why individual evidence (i.e., evidence which picks out a specific individual) can sufficiently justify a guilty or liable verdict while bare statistical evidence (i.e., statistical evidence which does not pick out a specific individual) does not sufficiently justify such a verdict. This thesis examines three popular justifications for such a disparity in verdicts – Judith Jarvis Thomson’s causal account, Enoch et al.’s sensitivity account, and Sarah (...) Moss’ knowledge-first account, before critiquing each in turn. After such an analysis, the thesis then defends the claim that legal verdicts require the factfinder (e.g., the judge or jury) to have a justified de re belief (i.e., a belief about a specific object – namely the defendant), and that this doxastic requirement justifies the disparity in rulings, as it is epistemically insufficient to justify a de re belief based on bare statistical evidence alone. A brief account of how these beliefs are formed and spread is also given. After making such a distinction, the thesis then formalizes the burdens of proof of the preponderance of the evidence and beyond a reasonable doubt using the de re/de dicto distinction. Finally, the thesis pre-empts possible objections, namely by providing an account of DNA evidence as individual evidence and giving an account of how false convictions can occur on the de re view of legal proof. (shrink)

In this paper, I argue that content externalism and privileged access are compatible, but that one can, in a sense, have privileged access to the world. The supposedly absurd conclusion should be embraced.

The practice of medicine frequently involves the unconsented restriction of liberty. The reasons for unilateral liberty restrictions are typically that being confined, strapped down, or sedated are necessary to prevent the person from harming themselves or others. In this paper, we target the ethics of chemical restraints, which are medications that are used to intentionally restrict the mental states associated with the unwanted behaviors, and are typically not specifically indicated for the condition for which the patient is being treated. Specifically, (...) we aim to identify the conditions under which chemical restraints are ethically permissible. It is wrong to assume that what is morally true of physical restraints is also true of chemical restraints. Our aim is thus to identify the conditions under which chemical restraints are permissible while distinguishing these conditions from those of the application of physical restraints. (shrink)

A probability distribution is regular if no possible event is assigned probability zero. While some hold that probabilities should always be regular, three counter-arguments have been posed based on examples where, if regularity holds, then perfectly similar events must have different probabilities. Howson (2017) and Benci et al. (2016) have raised technical objections to these symmetry arguments, but we see here that their objections fail. Howson says that Williamson’s (2007) “isomorphic” events are not in fact isomorphic, but Howson is speaking (...) of set-theoretic representations of events in a probability model. While those sets are not isomorphic, Williamson’s physical events are, in the relevant sense. Benci et al. claim that all three arguments rest on a conflation of different models, but they do not. They are founded on the premise that similar events should have the same probability in the same model, or in one case, on the assumption that a single rotation-invariant distribution is possible. Having failed to refute the symmetry arguments on such technical grounds, one could deny their implicit premises, which is a heavy cost, or adopt varying degrees of instrumentalism or pluralism about regularity, but that would not serve the project of accurately modelling chances. (shrink)

Moral bioenhancement is the potential practice of manipulating individuals’ moral behaviors by biological means in order to help resolve pressing moral issues such as climate change and terrorism. This practice has obvious ethical implications, and these implications have been and continue to be discussed in the bioethics literature. What have not been discussed are the epistemological implications of moral bioenhancement. This article details some of these implications of engaging in moral bioenhancement. The argument begins by making the distinction between moral (...) bioenhancement that manipulates the contents of mental states and that which manipulates other, non-representational states. Either way, I argue, the enhanced moral psychology will fail to conform to epistemic norms, and the only way to resolve this failure and allow the moral bioenhancement to be effective in addressing the targeted moral issues is to make the moral bioenhancement covert. (shrink)

Sob o título "Immanent Frames. Postsecular Cinema between Malick and von Trier", o livro editado por John Caruana e Mark Cauchi inclui um conjunto significativo de artigos sobre cinema “pós-secular”, de autores prestigiados, nomeadamente os próprios editores, mas também Robert Sinnerbrink, Catherine Wheatley, Sarah Cooper e William Rotham, entre outros. O livro está estruturado em 13 capítulos, distribuídos por três partes – Parte I: “The Poles of Postsecular Cinema: Malick and Von Trier”; Parte II: “The Spectrum of Postsecular Cinema: (...) Beyond Malick and Von Trier”; e Parte III: “Conversation on Cinema: Luc Dardenne and Jean-Luc Nancy”, esta última constituída por duas entrevistas, respectivamente com o cineasta e o filósofo. (shrink)

Despite the lack of evidence for their effectiveness, the use of physical restraints for patients is widespread. The best ethical justification for restraining patients is that it prevents them from harming themselves. We argue that even if the empirical evidence supported their effectiveness in achieving this aim, their use would nevertheless be unethical, so long as well known exceptions to informed consent fail to apply. Specifically, we argue that ethically justifiable restraint use demands certain necessary and sufficient conditions. These conditions (...) are that the physician obtain informed consent for their application, that their application be medically appropriate, and that restraints be the least liberty-restricting way of achieving the intended benefit. It is a further question whether their application is ever medically appropriate, given the dearth of evidence for their effectiveness. (shrink)

Some theorists argue that moral bioenhancement ought to be compulsory. I take this argument one step further, arguing that if moral bioenhancement ought to be compulsory, then its administration ought to be covert rather than overt. This is to say that it is morally preferable for compulsory moral bioenhancement to be administered without the recipients knowing that they are receiving the enhancement. My argument for this is that if moral bioenhancement ought to be compulsory, then its administration is a matter (...) of public health, and for this reason should be governed by public health ethics. I argue that the covert administration of a compulsory moral bioenhancement program better conforms to public health ethics than does an overt compulsory program. In particular, a covert compulsory program promotes values such as liberty, utility, equality, and autonomy better than an overt program does. Thus, a covert compulsory moral bioenhancement program is morally preferable to an overt moral bioenhancement program. (shrink)

Recent work has defended “Euclidean” theories of set size, in which Cantor’s Principle (two sets have equally many elements if and only if there is a one-to-one correspondence between them) is abandoned in favor of the Part-Whole Principle (if A is a proper subset of B then A is smaller than B). It has also been suggested that Gödel’s argument for the unique correctness of Cantor’s Principle is inadequate. Here we see from simple examples, not that Euclidean theories of set (...) size are wrong, but that they must be either very weak and narrow or largely arbitrary and misleading. (shrink)

There is recent empirical evidence that personal identity is constituted by one’s moral traits. If true, this poses a problem for those who advocate for moral enhancement, or the manipulation of a person’s moral traits through pharmaceutical or other biological means. Specifically, if moral enhancement manipulates a person’s moral traits, and those moral traits constitute personal identity, then it is possible that moral enhancement could alter a person’s identity. I go a step further and argue that under the right conditions, (...) moral enhancement can constitute murder. I then argue that these conditions are not remote. (shrink)

We present a novel approach to defining the mathematical constant π through the infinite den- sification of a sweeping net, which approximates a circle as the net becomes infinitely dense. By developing and enhancing notation related to sweeping nets and saddle maps, we establish a rigor- ous framework for expressing π in terms of the densification process using reverse integration. This method, inspired by the concept that numbers ”come from infinity,” leverages a reverse integral approach to model the transition from (...) infinite densification to the finite circle. Our work not only offers a new perspective on the geometric interpretation of π but also provides insights into reverse integration techniques and their applications in mathematical analysis. (shrink)

This paper explores the mathematical details behind the geometric transformation of folding a circle into a cone. It includes detailed theo- rems, proofs, and Python implementations for visualization, providing a thorough analysis of the transformation process.

There is no uniquely standard concept of an effectively decidable set of real numbers or real n-tuples. Here we consider three notions: decidability up to measure zero [M.W. Parker, Undecidability in Rn: Riddled basins, the KAM tori, and the stability of the solar system, Phil. Sci. 70(2) (2003) 359–382], which we abbreviate d.m.z.; recursive approximability [or r.a.; K.-I. Ko, Complexity Theory of Real Functions, Birkhäuser, Boston, 1991]; and decidability ignoring boundaries [d.i.b.; W.C. Myrvold, The decision problem for entanglement, in: (...) R.S. Cohen et al. (Eds.), Potentiality, Entanglement, and Passion-at-a-Distance: Quantum Mechanical Studies fo Abner Shimony, Vol. 2, Kluwer Academic Publishers, Great Britain, 1997, pp. 177–190]. Unlike some others in the literature, these notions apply not only to certain nice sets, but to general sets in Rn and other appropriate spaces. We consider some motivations for these concepts and the logical relations between them. It has been argued that d.m.z. is especially appropriate for physical applications, and on Rn with the standard measure, it is strictly stronger than r.a. [M.W. Parker, Undecidability in Rn: Riddled basins, the KAM tori, and the stability of the solar system, Phil. Sci. 70(2) (2003) 359–382]. Here we show that this is the only implication that holds among our three decidabilities in that setting. Under arbitrary measures, even this implication fails. Yet for intervals of non-zero length, and more generally, convex sets of non-zero measure, the three concepts are equivalent. (shrink)

Epistemic burdens – the nature and extent of our ignorance (that and how) with respect to various courses of action – serve to determine our incentive structures. Courses of action that seem to bear impossibly heavy epistemic burdens are typically not counted as options in an actor’s menu, while courses of action that seem to bear comparatively heavy epistemic burdens are systematically discounted in an actor’s menu relative to options that appear less epistemically burdensome. That ignorance serves to determine what (...) counts as an option means that epistemic considerations are logically prior to moral, prudential, and economic considerations: in order to have moral, prudential, or economic obligations, one must have options, and epistemic burdens serve to determine our options. One cannot have obligations without doing some epistemic work. We defend this claim on introspective grounds. We also consider how epistemic burdens distort surrogate decision-making. The unique epistemology of surrogate cases makes the priority of the epistemic readily apparent. We then argue that anyone who accepts a principle similar to ought implies can is committed to the logical priority of the epistemic. We also consider and reject several possible counterarguments. -/- . (shrink)

Contemporary scholarship is divided over whether Anselm maintains a version of Eudaemonism. The debate centers on the question of whether the will for justice only moderates the will for happiness or, instead, provides a distinct end for which to act. Because of two key passages, various scholars hold that Anselm maintained elements of medieval Eudaemonism. In this article, I argue that Anselm separates morality from happiness, and I provide a sketch of his alternative view. First, I argue against some recent (...) perspectives that Anselm maintained Eudaemonism. To do so, I provide a non-Eudaemonist reading of the two key passages and show how Eudaemonist readings are lacking in different respects. Second, I examine what this argument means for Anselm’s understanding of happiness and moral obligation. While there are some Eudaemonist themes in Anselm’s thinking, he flatly denies and revises aspects of the system. (shrink)

As the science and technology of the brain and mind develop, so do the ways in which brains and minds may be surveilled and manipulated. Some cognitive libertarians worry that these developments undermine cognitive liberty, or “freedom of thought.” I argue that protecting an individual’s cognitive liberty undermines others’ ability to use their own cognitive liberty. Given that the threatening devices and processes are not relevantly different from ordinary and frequent intrusions upon one’s brain and mind, strong protections of cognitive (...) liberty may proscribe neurotechnological intrusions, but also ordinary intrusions. Thus, the cognitive libertarian position “hog-ties” others’ use of their own liberties. This problem for the cognitive libertarian is the same problem that ordinary libertarianism faces in protecting individual rights to property and person. But the libertarian strategies for resolving the problem don’t work for the cognitive libertarian. I conclude that the right to mental privacy is weaker than what cognitive libertarians want it to be. (shrink)

Conceptual engineering is to be explained by appeal to the externalist distinction between concepts and conceptions. If concepts are determined by non-conceptual relations to objective properties rather than by associated conceptions (whether individual or communal), then topic preservation through semantic change will be possible. The requisite level of objectivity is guaranteed by the possibility of collective error and does not depend on a stronger level of objectivity, such as mind-independence or independence from linguistic or social practice more generally. This means (...) that the requisite level of objectivity is exhibited not only by natural kinds, but also by a wide range of philosophical kinds, social kinds and artefactual kinds. The alternative externalist accounts of conceptual engineering offered by Herman Cappelen and Derek Ball fall back into a kind of descriptivism which is antithetical to externalism and fails to recognise this basic level of objectivity. (shrink)

Default positions, predetermined starting points that aid in complex decision-making, are common in clinical medicine. In this article, we identify and critically examine common default positions in clinical ethics practice. Whether default positions ought to be held is an important normative question, but here we are primarily interested in the descriptive, rather than normative, properties of default positions. We argue that default positions in clinical ethics function to protect and promote important values in medicine—respect for persons, utility, and justice. Further, (...) default positions in clinical ethics may also guard against harm. Where default positions exist, there are epistemic burdens to overturn them. The person wishing to reject the default position, rather than the person endorsing it, bears this burden. The person who bears the burden of meeting the epistemic requirements must provide evidence proportional to the degree of harm the default position protects against. Default positions that protect against significant harm impose significant epistemic requirements to overturn. This asymmetry not only makes medical decision-making more economical but also serves to promote and protect certain values. The identification and analysis of common and recognizable default positions can help to identify other default positions and the conditions under which their associated epistemic requirements are met. The article concludes with considerations of potential problems with the use of default positions in clinical ethics. (shrink)

Some have suggested that certain classical physical systems have undecidable long-term behavior, without specifying an appropriate notion of decidability over the reals. We introduce such a notion, decidability in (or d- ) for any measure , which is particularly appropriate for physics and in some ways more intuitive than Ko's (1991) recursive approximability (r.a.). For Lebesgue measure , d- implies r.a. Sets with positive -measure that are sufficiently "riddled" with holes are never d- but are often r.a. This explicates Sommerer (...) and Ott's (1996) claim of uncomputable behavior in a system with riddled basins of attraction. Furthermore, it clarifies speculations that the stability of the solar system (and similar systems) may be undecidable, for the invariant tori established by KAM theory form sets that are not d-. (shrink)

Newton published his deduction of universal gravity in Principia (first ed., 1687). To establish the universality (the particle-to-particle nature) of gravity, Newton must establish the additivity of mass. I call ‘additivity’ the property a body's quantity of matter has just in case, if gravitational force is proportional to that quantity, the force can be taken to be the sum of forces proportional to each particle's quantity of matter. Newton's argument for additivity is obscure. I analyze and assess manuscript versions of (...) Newton's initial argument within his initial deduction, dating from early 1685. Newton's strategy depends on distinguishing two quantities of matter, which I call ‘active’ and ‘passive’, by how they are measured. These measurement procedures frame conditions on the additivity of each quantity so measured. While Newton has direct evidence for the additivity of passive quantity of matter, he does not for that of the active quantity. Instead, he tries to infer the latter from the former via conceptual analyses of the third law of motion grounded largely on analogies to magnetic attractions. The conditions needed to establish passive additivity frustrate Newton's attempted inference to active additivity. (shrink)

In biomedical ethics, there is widespread acceptance of moral realism, the view that moral claims express a proposition and that at least some of these propositions are true. Biomedical ethics is also in the business of attributing moral obligations, such as “S should do X.” The problem, as we argue, is that against the background of moral realism, most of these attributions are erroneous or inaccurate. The typical obligation attribution issued by a biomedical ethicist fails to truly capture the person's (...) actual obligations. We offer a novel argument for rife error in obligation attribution. The argument starts with the idea of an epistemic burden. Epistemic burdens are all of those epistemic obstacles one must surmount in order to achieve some aim. Epistemic burdens shape decision-making such that given two otherwise equal options, a person will choose the option that has the lesser of epistemic burdens. Epistemic burdens determine one's potential obligations and, conversely, their non-obligations. The problem for biomedical ethics is that ethicists have little to no access to others' epistemic burdens. Given this lack of access and the fact that epistemic burdens determine potential obligations, biomedical ethicists often can only attribute accurate obligations out of luck. This suggests that the practice of attributing obligations in biomedical ethics is rife with error. To resolve this widespread error, we argue that this practice should be abolished from the discourse of biomedical ethics. (shrink)