Throughout the biological and biomedical sciences there is a growing need for, prescriptive ‘minimum information’ (MI) checklists specifying the key information to include when reporting experimental results are beginning to find favor with experimentalists, analysts, publishers and funders alike. Such checklists aim to ensure that methods, data, analyses and results are described to a level sufficient to support the unambiguous interpretation, sophisticated search, reanalysis and experimental corroboration and reuse of data sets, facilitating the extraction of maximum value from data sets (...) them. However, such ‘minimum information’ MI checklists are usually developed independently by groups working within representatives of particular biologically- or technologically-delineated domains. Consequently, an overview of the full range of checklists can be difficult to establish without intensive searching, and even tracking thetheir individual evolution of single checklists may be a non-trivial exercise. Checklists are also inevitably partially redundant when measured one against another, and where they overlap is far from straightforward. Furthermore, conflicts in scope and arbitrary decisions on wording and sub-structuring make integration difficult. This presents inhibit their use in combination. Overall, these issues present significant difficulties for the users of checklists, especially those in areas such as systems biology, who routinely combine information from multiple biological domains and technology platforms. To address all of the above, we present MIBBI (Minimum Information for Biological and Biomedical Investigations); a web-based communal resource for such checklists, designed to act as a ‘one-stop shop’ for those exploring the range of extant checklist projects, and to foster collaborative, integrative development and ultimately promote gradual integration of checklists. (shrink)

The value of health states is often understood to depend on their impact on the goodness of people's lives. As such, prominent health states metrics are grounded in particular conceptions of wellbeing – e.g. hedonism or preference satisfaction. In this paper, I consider how liberals committed to the public justification requirement – the requirement that public officials choose laws and policies that are justifiable to their citizens – should evaluate health states. Since the public justification requirement prohibits public officials from (...) appealing to controversial conceptions of the good life, liberals committed to this principle face a significant puzzle. (shrink)

Hume discusses the distinction of reason to explain how we distinguish things inseparable, and so identical, e.g., the color and figure of a white globe. He says we note the respect in which the globe is similar to a white cube and dissimilar to a black sphere, and the respect in which it is dissimilar to the first and similar to the second. Unfortunately, Hume takes these differing respects of resemblance to be identical with the white globe itself. Contradiction results, (...) undermining his theory of abstraction. The way out is apparently to admit an intrinsic complexity in even simple things. (shrink)

Bjorn T. Ramberg’s book focuses on Davidson’s work in the philosophy of language, published between 1984 and the appearance of the book. Recent papers provide the focus for an overview of Davidson’s philosophy of language and its relations to broader debates and influences. Still, the reader is warned: the author “cannot claim” that the book “is in every detail a faithful representation or development of Davidson’s own current theory.” Instead, what we have is a “reconstruction” of Davidson on language and (...) meaning, an account “Davidsonian in spirit and in all its fundamental features.”1 The result is a projection of Davidson’s views, or important aspects of them, in a particular direction: Davidson and in- terpretation in process. The following critical discussion of main issues in Ramberg’s book should not dis- tract potential readers from this useful and thoughtful overview of Davidson on interpretation and meaning. (shrink)

The book is an “introductory” reconstruction of Davidson on interpretation —a claim to be taken with a grain of salt. Writing introductory books has become an idol of the tribe. This is a concise book and reflects much study. It has many virtues along with some flaws. Ramberg assembles themes and puzzles from Davidson into a more or less coherent viewpoint. A special virtue is the innovative treatment of incommensurability and of the relation of Davidson’s work to hermeneutic themes. The (...) weakness comes in a certain unevenness. While generally convincing and well written, the book has low points which may leave the reader confused or unconvinced. Davidson is the hero in this book, and our hero is sometimes over idealized. (shrink)

Bu çalışmada, bir yandan bilgiye yol açması bağlamında deneyimin inanca kaynak oluşturması, öte yandan insan edimlerine yol açması bağlamında inancın deneyimlenmesine olanak oluşturması nedeniyle inanç-deneyim ilişkisi irdelenecektir. İnanç-deneyim ilişkisinin olanaklılığı ve bu ilişkinin kuşkulu doğası, Davidson ve Wittgenstein gibi iki önde gelen çözümleyici filozofun konuyla ilgili açıklamaları dikkate alınarak araştırılmaktadır.Yazının ana savını şu temel fikir oluşturmaktadır: Sanılanın aksine, ne deneyimler inanç için sağlam ve kesin bir temel oluştururlar ne de deneyimler bilinmek için inançlara gereksinim duyarlar. In this paper, the relationship (...) between belief and experience will be investigated because on the one hand, experience creates a source for beliefs which leads knowledge and on the other hand it makes the experience possible, which leads human actions. Considering the analysis of two prominent analytic philosophers Davidson and Wittgenstein, the relationship of belief and experience, and the questionable nature of this relationship will be studied. The basic claim of this paper consists of the following primary idea: Contrary to what is believed, neither experiences form a firm and certain basis for beliefs, nor experiences are in need of beliefs to be known. (shrink)

Donald Davidson established causalism, i.e. the view that reasons are causes and that action explanation is causal explanation, as the dominant view within contemporary action theory. According to his “master argument”, we must distinguish between reasons the agent merely has and reasons she has and which actually explain what she did, and the only, or at any rate the best, way to make the distinction is by saying that the reasons for which an agent acts are causes of her (...) action. “Davidson's challenge” to non‐causalists is to come up with an alternative, more convincing, way of drawing the distinction. In this paper, I argue that G.E.M. Anscombe and G.H. von Wright offer such an alternative. Moreover, I argue that Davidson's own account of interpretation makes no use of his causalist claim. (shrink)

This book is a general defence of Donald Davidson's and G.E.M. Anscombe's 'unifying' approach to the individuation of actions and other events against objections raised by Alvin I. Goldman and others. It is argued that, ironically, Goldman's rival 'multiplying' account is itself vulnerable to these objections, whereas Davidson's account survives them. Although claims that the unifier-multiplier dispute is not really substantive are shown to be unfounded, some room for limited agreement over the ontological status of events is indicated. Davidson's (...) causal criterion of event identity is then defended against charges of triviality or inadequacy. It is concluded that Davidson's criterion is not primarily a criterion for arriving at particular judgments of individuation, but a metaphysical standard for the correctness of such judgments, however arrived at. Contents: Unifiers vs. Multipliers - Davidson's individuation of events - Goldman's act generation - causal, 'by'-relational, and temporal problems - ontology and event constituents - Davidson's causal criterion. This book is unique in providing a detailed survey and analysis of the recent unifier-multiplier dispute, and will be of interest to all researchers in action theory, as well as those working more broadly in metaphysics, philosophy of language, and philosophy of mind. (shrink)

Did Donald Davidson agree with G.E.M. Anscombe that action requires a distinctive form of agential awareness? The answer is No, at least according to the standard interpretation of Davidson’s account of action. A careful study of Davidson’s early writings, however, reveals a much more subtle conception of the role of agential belief in action. While the role of the general belief in Davidson’s theory is familiar and has been much discussed, virtually no attention has been paid to the singular (...) belief. This essay makes a start on remedying this neglect. I begin, in section 1, by examining Davidson’s claim that for a desire or belief to rationalize and cause an action it must have a suitable generality. It must, he says, be ‘logically independent’ of the action itself. While he was clear about this requirement in the case of the desire that forms part of a person’s primary reason, I show in section 2 that his early treatment of belief confuses general and singular beliefs. This confusion reflects his failure clearly to distinguish the two roles belief can play in his account of action: as rationalizing cause and as agential awareness. Somewhat surprisingly, though, after he carefully drew the distinction and announced that intentional action requires practical knowledge, he pretty much ignored it. This may explain why some have assumed that Davidson parted ways with Anscombe on this. But a careful study of their writings shows that in fact they held remarkably similar views on the nature and need for practical knowledge. (shrink)

Fictional and non-fictional texts rely on the same language to express their meaning; yet many philosophers in the analytic tradition would say, with reason, that fictional texts literally make no truth claims, or more modestly that the rhetorical and literary devices to which fiction and non-fiction writers alike have recourse are unconnected to truth or have no propositional content. These related views are associated with a doctrine in the philosophy of language, most notably advanced by the late Donald Davidson, (...) which holds that we understand the semantic structure of a language by applying to it a theory of truth, which involves discovering the truth conditions of its sentences. This approach to semantic theory raises several seemingly intractable problems, such as the problem of stating the meaning of non-declarative sentences, e.g. questions and imperatives. The chief aim of this paper will be to try to dispel these problems by suggesting an adjustment in Davidson’s account of the relation of truth to meaning, one which will also allow us to picture such troublesome linguistic items as metaphor within a semantic theory, and to expand the range of objects which can be brought into a general theory of meaning. (shrink)

The article by MacKay and Saylor (2020) claims that the principle of fair subject selection yields conflicting imperatives (e.g. in the case of pregnant women) and should be understood as “a bundle of four distinct sub-principles” (i.e. fair inclusion, burden sharing, opportunity, distribution of third-party risks), each having conflicting normative recommendations (MacKay and Saylor 2020). The authors also offer guidance as to how we should navigate between subprinciples that may conflict with each other. The problem is a crucial (...) one since fair subject selection is one of the principles regulating clinical research that produces generalizable knowledge with the potential of improving people’s health. Therefore, there may be cases where the way in which participants are selected directly influences the generalizability (or its lack) of the clinically relevant knowledge and its value (if any) to different groups. In my commentary article, written from the philosophical perspective, I notice a number of interrelated problems which I believe have not been discussed thoroughly in the target article: (1) the precise way in which health care priority setting should influence the content of health research priority setting and fair inclusion principles; (2) the distinction between group and individual benefits and burdens from clinical research; (3) the reference class problem in medical research. (shrink)

There are arguments for determinism. Admittedly, this is opposed by the fact of everyday experience of autonomy. In the following, it is argued for the compatibility of determinism and autonomy. Taking up considerations of Donald MacKay, a fatalistic attitude can be refuted as false. Repeatedly, attempts have been made to defend the possibility of autonomy with reference to quantum physical indeterminacy. But its statistical randomness clearly misses the meaning of autonomy. What is decisive, on the other hand, is (...) the possibility of knowledge, which opens up opportunities for planning, freedom of choice and ultimately 'self-choice'. Results of neurobiological research, especially Benjamin Libet's and more recently John-Dylan Haynes', seem to refute this: Actions are unconsciously initiated before conscious decision. But, as Libet has also shown, consciousness always has the possibility of a veto – and thus also of knowledge-driven action control. Ultimately, the idea of possible self-choice can thus become the determining condition. Only such a form of rational self-determination establishes a spiritual identity and at the same time represents the maximum of autonomy possible for human beings. (shrink)

Edited proceedings of an interdisciplinary symposium on consciousness held at the University of Cambridge in January 1978. Includes a foreword by Freeman Dyson. Chapter authors: G. Vesey, R.L. Gregory, H.C. Longuet-Higgins, N.K. Humphrey, H.B. Barlow, D.M. MacKay, B.D. Josephson, M. Roth, V.S. Ramachandran, S. Padfield, and (editorial summary only) E. Noakes. A scanned pdf is available from this web site (philpapers.org), while alternative versions more suitable for copying text are available from https://www.repository.cam.ac.uk/handle/1810/245189. -/- Page numbering convention for the pdf (...) version viewed in a pdf viewer is as follows: 'go to page n' accesses the pair of scanned pages 2n and 2n+1. Applicable licence: CC Attribution-NonCommercial-ShareAlike 2.0. (shrink)

This chapter will evaluate humor used with the specific intent to reveal glaring epistemic errors that lead to injustice; flaws in reasoning so transparent that straightforward logic, argument, and evidence seem ineffectual against them, and in some cases, just silly to think such tools would be needed. Laughter seems to be one of the only sane responses. In particular, I will assess how humor can combat conspiracy theories, propaganda, lies, and bullshit. The last one I view in Harry Frankfurt's sense (...) of a complete lack of concern for truth or reality, which I think sums up former President Donald Trump's epic lack of curiosity which has a trickle-down effect on his ardent followers. The sort of conspiracy theories I will focus on are an intermingling of propaganda, well defined and analyzed by Jason Stanley in his work How Propaganda Works, and the "new conspiracism", outlined by Muirhead and Rosenblum in A Lot of People are Saying: The New Conspiracism and The Assault on Democracy. There are perils with this potency of pugilistic comedy. It is easy to punch up, humorously fume at the foibles and fantastical blunders of a world leader who seriously considers ingesting bleach to combat the plague, who also, without irony, regales us of his capacious mnemonic prowess in recalling the following words on a cognitive test: "Person. Woman. Man. Camera. TV." The self-proclaimed "stable genius" aced it. But when Trumpism and QAnon e.g., spreads among many who are impoverished and disempowered, the very people to whom Trump and others in his powerful orbit have incessantly lied, it becomes less clear how to wield truth-and justice-seeking wit. Are consciousness-raising comedians seeking to uncover and undermine obvious and dangerous falsehoods punching in the morally correct direction, and how can we tell? (shrink)

RÉSUMÉL'interprétation de la philosophie pratique de Donald Davidson proposée par Robert Myers représente correctement maints aspects fondamentaux de sa pensée. Myers soutient à juste titre que Davidson évite les incohérences entre la position internaliste, l'objectivité éthique et le modèle croyance-désir en modifiant des éléments centraux de ce modèle, et que l'alternative proposée par Davidson rend légitime l'extension des arguments de l'interprétation et de la triangulation dans la sphère pratique. Cependant, Myers s’égare à une bifurcation cruciale de la route interprétative. (...) Davidson suit G.E.M. Anscombe sur une voie différente, une voie qui considère les désirs individuels comme constitués en partie par des jugements évaluatifs. (shrink)

Agency is a power, but what is it a power to do? The tradition presents us with three main answers: (1) that agency is a power to affect one’s own will, consequent upon which act further events ensue, beginning with the movement of a part of one's body; (2) that agency is a power to affect one’s own body, consequent upon which act further events ensue, beginning with the movement of an object that one touches; and (3) that agency is (...) a power to affect that material upon which one brings one's action to bear---e.g. the apple one is peeling (with a knife in one's hand). These three answers correspond to three increasingly expansive conceptions of the province of human agency. I refer to them, respectively, as volitionalism, corporealism and materialism. Only the first two are seriously considered in contemporary action theory. Favoring the third, and hoping to sharpen the conflict between the third and the first, I criticize the second. Corporealism has been a popular position—arguably, the default position in the philosophy of action—since Donald Davidson’s classic paper “Agency” (1971). Although it seems to occupy a sensible middle ground between volitionalism and materialism, corporealism is, I argue, indefensible: it shares the vulnerabilities of both its two rivals, without possessing the strengths of either. Nevertheless, reflection on corporealism lights the road to materialism, which, in the end, is the only possible alternative to volitionalism. (shrink)

The problem of act individuation is a debate about the identity conditions of human acts. The fundamental question about act individuation is: how do we distinguish between actions? Three views of act individuation have dominated the literature. First, Donald Davidson and G.E.M. Anscombe have argued that a number of different descriptions refer to a single act. Second, Alvin Goldman and Jaegwon Kim have argued that each description designates a distinct act. Finally, Irving Thalberg and Judith Jarvis Thomson have averred (...) that some acts are sequences of causally related events, which include both a primitive bodily action and some of its effects. All of these accounts have assumed that a simple invariantist account of act individuation captures how ordinary people distinguish between acts. For my dissertation, I devised an experiment to test the action theorists' assumptions. My data show that people's intuitions seem to depend on the valence of the consequences of the action under consideration. So, an invariantist account is not possible. In light of the empirical results, I argue that if we seek a folk account of act individuation, then that account should be able to explain the variability that seems to be present in people's intuitions about different cases. (shrink)

“Political epistemology” has recently emerged as an area of analytic epistemology. While it may not be an entirely new area, and its precise boundaries are up for negotiation, recent political events in the UK (e.g. Brexit) and the US (e.g. the election of Donald Trump) played a key role in its rise to prominence within contemporary analytic epistemology. Further, political epistemology is an inter-disciplinary field, drawing on relevant work in political science, political psychology, and science communication that is often (...) equally focused on the UK and US. Political epistemology is therefore parochial, though it is the kind of parochialism that is not always conscious of itself as parochial. In this talk I adopt a critical stance towards parochialism in political epistemology. But my aim is not just to point out the mistakes that can result from a parochial concern with political events in one’s own country. I suggest that we can view political epistemology as interested in certain fundamental problems and tensions, which political epistemologists may then seek to identify and address within the political context in which they are working. (shrink)

Translation in Greek of "A Geneticist's Roadmap to Sanity" (2019) by G.B. Côté. Μεταφράστηκε και στα Γαλλικά από τους Gilbert B. Côté και Roger Lapalme και προστέθηκε η βιβλιογραφία στις 28 του Απρίλη 2020: Pour comprendre le monde et revenir à la raison. La théorie du tout d'un généticien. Η ώθηση για τη συγγραφή ήταν η ανήθικη προεδρία του Donald J. Trump. Σε αυτό το κείμενο, θέλω να εξερευνήσω τα θεμέλια της ύπαρξής μας. Θα θίξω σύντομα την ενσυνείδηση, την (...) ελεύθερη βούληση, τη θρησκεία, την ηθική, τα βάσανα της ζωής , το πρόβλημα της δυαδικότητας του νου και του σώματος, την αχρονικότητα, τα πολλαπλά σύμπαντα και το ανθρώπινο πεπρωμένο. Για να διευκολύνω αυτήν την παρουσίαση, θα πρέπει πρώτα να δείξω ότι ο μαθηματικός πλατωνισμός είναι μια λογική αναγκαιότητα για την ύπαρξη οποιουδήποτε σύμπαντος, και θα εισαγάγω τους αφηρημένους, κβαντικούς και υλικούς τρόπους ύπαρξης (στη φιλοσοφία) που αντιστοιχούν στην πληροφόρηση, την ενέργεια και τη μάζα (στη φυσική). Το κείμενο αυτό αποτελεί μια σύνοψη της προσωπικής μου θεωρίας των πάντων. (shrink)

The vertiginous rise of right-wing populism, especially in its “nationalist, xenophobic and conservative form”, and some “racist, anti-Semitic, homophobic and sexist” drifts associated with this phenomenon – whether real or perceived as such – make the mainstream media play a double role. On the one hand, the mainstream media reflect the struggle for political hegemony between different vested interests; on the other hand, they engage in the fight against right-wing populism blasting both right-wing populist candidates and their voters or supporters. (...) Many mainstream journalists ask citizens to realize a “sanitary cordon”, a “wall” or a “republican front” to block far-right populism and preserve liberal democracy. Moreover, they urge people to be wary of all attempts to “dediabolize” or “normalize” some tokens of right-wing populism. The main idea of this article is that right-wing populism is more harmless than is generally believed and, if excessive, negative media coverage doesn’t baffle but feed it. Populism is essentially a latent side effect of liberal democracy. Populism rises and becomes obtrusive only if a significant part of society perceives a regime of illiberal majoritarianism instead of one of liberal democracy. Right-wing populists are chiefly frustrated “ci-devants” who feel dispossessed of their past, identity, properties, qualities, privileges or titles. Inasmuch as the causes of collective frustration are many and varied (e.g. the real or just perceived corruption of the elites, the “system”, the deep state, the relocation of jobs, immigration, national sovereignty, national identity, communitarianism, radical Islamism, the status of some traditional institutions, some chapters of official history, etc.), there will always be right-wing populists, whether they are self-declared or covert. By adopting David G. Hackett’s thesis that the media are “agents of hegemony”, we applied the critical analysis of discourse to a set of 346 media articles in order to reveal the discursive sources of power, domination, inequality and partiality. The articles appeared in The New York Times and Le Monde during the period 2016-2017, at the time when the presidential elections took place in the United States and France. The articles were selected according to the occurrence of the keywords “Donald Trump” – “populism” and “Marine Le Pen” – “populisme” within the titles. The analysis of these articles reveals a divisive discursive structure that correspond to a real political cleavage in society. It is true that populism presents a “Manichean outlook”, in which there are only friends and foes” and no compromise is possible. It is also true that mainstream media reinforce this Manichean perspective on society and make populists feel marginalized and politically disempowered. The mainstream media may appease right-wing populism if they treat its followers as legitimate and equal political actors. For this, they have to give up the narrative structures that underscore insurmountable divergences and irreconcilable interests. In a liberal democracy, mass media should chiefly play the role of mediator. They may not aim to defeat or re-educate certain categories of citizens just because they advocate “wrong” political solutions. (shrink)

According to a well-known view in the philosophy of mind, intentional attitudes by their very nature satisfy requirements of rationality (e.g. Davidson 1980; Dennett 1987; Millar 2004). This view (which I shall call Constitutivism) features prominently as the ‘principle of minimal rationality’ in de Sousa’s monograph The Rationality of Emotion (1987). By explicating this principle in terms of the notion of the formal object of an attitude, de Sousa articulates an interesting and original version of Constitutivism, which differs in important (...) respects from other extant versions. In this paper, I explore this version of Constitutivism against the background of recent developments in the theory of rationality and make explicit its ramifications for the long-standing dispute over whether the mind is essentially normative. My focus will be on how to conceive of the form of the rationality requirements that attitudes as such must satisfy according to this principle. I argue that, although de Sousa seems officially to endorse a structuralist conception of rationality, according to which these requirements are requirements of coherence, his considerations on formal objects suggest that they are more aptly conceived in terms of a reasons-responsive conception of rationality. I further argue that which of these two readings we choose makes a significant difference to the prospect of vindicating the essential normativity of mind by invoking the principle of minimal rationality. (shrink)

INTRODUÇÃO O ovo da galinha consiste em uma célula reprodutiva bastante comparável às encontrada nos mamíferos. Todavia, no caso da galinha, essa célula reprodutiva localiza- se na superfície da gema, sendo preenchida por albumens, membranas de casca, casca e cutícula. O ovário é responsável pela formação da gema; as porções restantes do ovo originam-se no canal do oviduto. • OVÁRIO No momento do desenvolvimento precoce do embrião, existem dois ovários e dois ovidutos, entretanto o conjunto ovário-oviduto direito atrofia-se, deixando apenas (...) o ovário e o oviduto esquerdo funcional para a realização dos processos embrionários e de formação do ovo (feto). Antes da produção de óvulos, o ovário consiste em uma massa inerte de pequenos folículos que contém os óvulos. Alguns óvulos possuem estatura suficiente para serem vistos visualmente; outros requerem ampliação para serem detectados. A galinha possui inúmeros folículos presentes no ovário, que são capazes de suprir toda a produção de gemas da vida da ave. FORMAÇÃO DA GEMA A gema (figura 1) não é a verdadeira célula reprodutiva, mas como uma fonte de material alimentar a partir do qual a célula blastoderma e seu embrião resultante irão se sustentar durante o desenvolvimento. Quando uma franga atinge a maturidade sexual, o ovário e o oviduto sofrem algumas alterações. Cerca de 11 dias antes da fêmea colocar seu primeiro ovo, uma sequência de alterações hormonais ocorrem em seu organismo. O hormônio FSH (folículo estimulante) produzido pela glândula pituitária (hipófise) anterior faz com que os folículos ovarianos aumentem de tamanho, mas para que isso aconteça a fêmea deve ser exposta à luz, já que é o segundo fator relevante depois da nutrição adequada para a formação do ovo, uma vez que através do olho os estímulos da luz que entram no olho atingem as células nervosas até a hipófise que libera o FSH. Em suma, o ovário ativado começa a gerar hormônios como o estrogênio, progesterona e testosterona (esteroides sexuais). Os níveis plasmáticos mais elevados de estrogênio iniciam o desenvolvimento do osso medular, bem como estimula a produção de proteína albumina e a formação de lipídios (gordura) pelo fígado, além de aumentar o tamanho do oviduto, o que permite a produção de proteínas de albumina, membranas da casca, carbonato de cálcio para a formação da casca, e cutícula. A primeira gema (óvulo) que começa a amadurecer capta as grandes quantidades do material produzido pelo fígado e transportado pelo sistema circulatório diretamente para o ovário em desenvolvimento. Um ou dois dias depois da primeira, a segunda gema começa a se desenvolver, e assim por diante, até que no momento em que é posto o primeiro ovo, cerca de cinco a dez gemas já estão no processo de crescimento. É necessário em torno de 10 dias para que uma gema cresça e siga o caminho para se transformar num ovo posto. Depósitos de material de gema são lentos no início e possuem coloração clara. Eventualmente, o óvulo atinge um diâmetro de 6 mm, valor que cresce a uma taxa muito expressiva diária de até 4 mm. Um número maior de gemas encontram- se em desenvolvimento ao mesmo tempo em matrizes (galinhas reprodutoras) do que em poedeiras, no entanto a matriz não possui a capacidade de produzir uma taxa grande de ovos completos. A coloração presente na gema é xantofila, um pigmento carotenoides derivado da dieta do animal. O pigmento é transferido primeiro para a corrente sanguínea em função do processo de digestão e absorção, em seguida, rapidamente para a gema, bem como para outras partes do corpo como as penas. Consequentemente, em função da dieta, um teor mais elevado de xantofilas é depositado na gema durante as horas em que a galinha está comendo. Isso dá origem a depósitos de camadas escuras e claras no material da gema, dependendo do pigmento dietético disponível. Cerca de 7 a 11 anéis concêntricos são encontrados em cada gema. A formação de gemas é uniforme e a espessura total de depósitos de coloração clara e escura durante 24 horas é de cerca de 1,5 a 2,0 mm. A gema de ovo é composta basicamente de gorduras (lipídios) e proteínas, que combinam-se para a formação das lipoproteínas, das quais 60% do peso da gema é de lipoproteínas de baixa densidade (LDL), e são conhecidas por serem sintetizado pelo fígado através da ação do estrogênio. Na galinha poedeira, o LDL é removido do plasma sanguíneo como partículas intactas para a deposição do mesmo diretamente nos óvulos em desenvolvimento. Fatores que influenciam o crescimento da gema As gemas variam de tamanho entre as aves individuais de um aviário da mesma idade e são, geralmente, associados com as diferenças no peso corporal. O tamanho da gema não está associado a taxa de postura da ave, mas provavelmente com o tempo necessário para que os óvulos atinjam a maturidade e se desprendam. As gemas de uma galinha aumentam de tamanho ao longo do ciclo de produção. Além disso, o primeiro ovo posto em uma ninhada geralmente conterá uma gema maior do que os restantes. Os ovos colocados durante o final do dia são cerca de 0,5 gramas mais leves para cada hora adicional do dia; isso também está associado com gemas menores. A inclusão de gordura e proteína na dieta também demonstram um aumento significativo no tamanho da gema em desenvolvimento. Localização do disco germinativo O material da gema é colocado adjacente ao disco germinal (figura 1) que permanece na superfície da massa da gema globular. Uma vez que o ovo é posto, a gema gira para que o disco germinal permaneça na extremidade do ovo. OVULAÇÃO Quando a franga entra na maturidade, os óvulos são liberados do ovário para que possam entrar no canal do oviduto por um processo conhecido como ovulação. Cada óvulo encontra-se pendurado no ovário por uma haste estreita que contém as artérias que fornecem o sangue para a gema em desenvolvimento. As artérias sofrem diversas ramificações nas membranas superficiais da gema e o folículo têm um aspecto altamente vascular (figura 2), exceto pelo estigma, uma faixa estreita no entorno da gema que é quase desprovido de vasos sanguíneos. Figura 2: ovário com os folículos pequenos e prontos para se desprenderem. Fonte: IPA. Quando um óvulo está maduro, o hormônio progesterona, produzido pelo ovário, estimula o hipotálamo para causar a liberação do hormônio luteinizante (LH) da hipófise anterior que, por sua vez, faz com que o folículo maduro se rompa no local do estigma liberando o óvulo do ovário. A gema é então cercada apenas pela membrana vitelina (membrana da gema). Atraso da primeira ovulação A maturidade sexual, visualizada através da primeira ovulação da ave, pode ser acelerada ou retardada. Restringir a alimentação ou diminuir a duração do dia durante o período de crescimento da franga são os dois procedimentos principais para a agilizar o processo na galinha. O que inicia a ovulação? Não se sabe ao certo os parâmetros que definem a hora da primeira ovulação da ave, porém tanto o sistema nervoso quanto as secreções hormonais são de essencial importância na manifestação da mesma. A segunda ovulação é regulada mediante a oviposição (postura) do primeiro ovo cerca de 15 a 40 minutos após o primeiro ovo passar pelo canal da cloaca. As ovulações posteriores ocorrem com a mesma frequência em função dos ovos subsequentes serem postos. Ovos postos em ninhadas As galinhas põem ovos em dias sucessivos conhecidos como ninhadas, do qual nenhum é posto por um ou mais dias. O corrimento do ciclo da ninhada pode várias de 2 dias a mais de 200 antes de um dia é perdido, mas a maioria das poedeiras comerciais pode produzir mais de 50 ovos sucessivos, sem uma pausa durante as fases iniciais de produção no primeiro ciclo da ninhada. O comprimento da ninhada é bastante consistente nos indivíduos; as poedeiras com taxas de produção menores possuem um ciclo mais curto, enquanto que as grandes produtoras possuem ciclos mais longos. Uma vez que o comprimir do ciclo ninhada é estabelecido, a galinha não irá ovular por um ou mais dias e, em seguida, irá produzir outra ninhada. As poedeiras menos produtivas possuem um período de descanso mais longo entre as ninhadas do que as boas produtoras. Tempo necessário para produzir um ovo O tempo necessário para que um ovo atravesse o oviduto varia de acordo com os indivíduos. A maioria das galinhas põe ovos sucessivos com intervalos de tempo entre 23 a 26 horas. Se o tempo for maior que 24 horas, cada ovo será posto no final do dia. Os ovos postos à tarde passaram mais horas no oviduto do que os postos pela manhã. Eventualmente, os ovos são colocados tão tarde que o ritmo é quebrado e uma ovulação é pulada. Teoricamente, alguns autores dizem que o tempo ideal para uma boa formação de um ovo é de 25 horas. O óvulo se desprende do ovário entrando no canal do oviduto, permanece por 15 minutos no infundíbulo que é a primeira região do oviduto, em seguida o óvulo vai para o magno a segunda região do oviduto e permanece nessa região entre 2 a 3 horas. Em seguida, vai para o istmo, ficando nessa região entre 1 a 1,5 horas. Por último, vai para o útero permanecendo nessa região entre 18 a 20 horas. Por fim, vai para a vagina onde recebe um óleo, indo para a cloaca onde é posto. Tempo de ovulação As galinhas que produzem ninhadas mais longas colocam seu primeiro ovo no início do dia, uma ou duas horas após o nascer do Sol ou as luzes artificiais são ligadas. A ovulação da próxima gema acontece rapidamente após o primeiro ovo ser posto, com apenas um pequeno intervalo de tempo. As poedeiras com comprimentos mais curtos da ninhada colocam seu primeiro ovo mais tarde do dia, a ovulação da gema seguinte é mais lenta, e a defasagem de tempo para a postura é maior. A maioria das ovulações ocorre durante as primeiras horas da manhã, já que não é natural que a ovulação ocorra em meados do final da tarde. Produção de ovos no início da postura Durante a primeira semana de postura, a ovulação é bastante irregular, uma vez que o mecanismo hormonal da galinha não está em equilíbrio. Na maioria das vezes, apenas dois a quatro ovos são produzidos na primeira ninhada. Entretanto, na segunda ou terceira semana, a ovulação irá progredindo gradativamente em sua taxa de pico até cair lentamente a cada semana durante o restante do ciclo de postura. Luz e ovulação A luz, seja natural ou artificial, possui um efeito direto sobre a glândula pituitária, estimulando-a a segregar uma quantidade maior do hormônio FSH que, por sua vez, ativa a região ovariana. A duração e a intensidade da luz são fatores importantes no processo de planejamento de uma granja, bem como durante a fase de postura. O procedimento para iluminar corretamente um galpão de galinhas poedeiras não é uma tarefa fácil e será discutido trabalhos posteriores. Nidificação como indicação de ovulação Na maioria das vezes, a galinha procura um ninho cerca de 24 horas após a ovulação, levando aos pesquisadores a teorizar que a nidificação pode ser usada como um fator de indicação da ovulação. Evidentemente, a presença de um ovo totalmente formado na cloaca não tem nada a ver com o desejo da galinha de procurar um ninho. Por exemplo, algumas galinhas irão ovular, todavia por causa de um imprevisto, o óvulo não chega ao oviduto, essas mesmas galinhas ainda irão procurar um ninho no dia seguinte. Ovulação dupla Normalmente, apenas uma gema é ovulada por dia, entretanto, ocasionalmente duas gemas podem ser liberadas e, em raras ocasiões até três gemas podem ser liberadas. Se duas gemas serão ovuladas ao mesmo tempo, normalmente apenas uma entra no canal do oviduto, mas se ambas são apanhadas simultaneamente pelo oviduto, resultará em um ovo de gema dupla (figura 3). Cerca de dois terços dos ovos de gema dupla são resultantes de ovulações dentro de 3 horas de um para o outro. Se houver uma grande diferença de tempo de ovulação, dois ovos poderão ser produzidos no mesmo dia, porém na maioria das vezes o segundo ovo possui casca mole ou apenas é revestido por uma membrana (figura 4). Geralmente, os ovos de gema dupla são mais comuns durante a primeira parte do período de produção do ovo causados por um ovário hiperativo e, frequentemente, são associados com frangos de corte do que com galinhas poedeiras. A incidência é um traço herdado, uma vez que algumas aves mais velhas produzem um percentual maior de ovos com gema dupla do que outras, sendo assim, a característica pode ser hereditária. As aves criadas na estação da Primavera e no Verão também produzem um número maior de ovos de gema dupla do que as galinhas criadas no Outono e no Inverno. Figura 3: ovo de gema dupla. Fonte: IPA. Figura 4: ovo com casca mole. Fonte: IFPE. CASCA DE OVOS DEFEITUOSAS Quando o intervalo normal de 23 a 26 horas entre as ovulações é quebrado, mais ovos são produzidos com casca defeituosas (figuras 4 e 5), incluindo aqueles com textura de lixa, bandas brancas, salpicos de cálcio e depósitos de calcário. A ocorrência é maior em ovos de matrizes do que em poedeiras. Cerca de 5 a 7% dos ovos produzidos por uma matriz poderá apresentar alguma forma de deformações na casca. Esses defeitos estão associados principalmente com a idade do lote e com as raças mais propensas ao problema do que outras. Figura 5: deformações na casca do ovo. Fonte: internet. TAMANHO DA GEMA AFETA O TAMANHO DO OVO O tamanho do ovo normal está associado mais com o tamanho da gema do que com qualquer outros fator relevante, embora as variações nas secreções de albumina no oviduto possam ter alguma influência. A relação gema-albumina muda ao longo do ciclo de postura. Os ovos que são produzidos no início do período de postura possuem gemas que representam em torno de 25% do peso total do ovo, enquanto que as gemas compõem cerca de 30% do peso do ovo quando as galinhas estão perto do final do período de postura. Em outras palavras, à medida em que o tamanho do ovo aumenta, o peso da gema aumenta mais rapidamente do que o peso do albúmen. Em lotes de frangas, quando o tamanho do ovo é pequeno, o aumento de proteína na dieta pode aumentar o peso total até 3,5 g/cada. MANCHAS DE SANGUE E DE CARNE Muitas vezes, quando o saco vitelino se rompe ao longo do estigma, pequenos vasos sanguíneos perto da área da ruptura são quebrados, formando um coágulo de sangue ligado à gema. A frequência de hemorragias pode estar relacionada com uma série de fatores, como a genética, alimentação, idade da galinha etc. As manchas de sangue são de duas a três vezes mais comuns em galinhas que produzem ovos de casca marrom do que em galinhas poedeiras de casca branca. Qualquer tecido deslocado do saco folicular ou do oviduto poderá ser incluído ao ovo em desenvolvimento à medida que passa pelo oviduto. Esses pedaços de tecido escurecem com a idade e são conhecidos como manchas de carne. Muitas manchas de sangue escurecem também, e muitas vezes são classificadas de forma incorreta como manchas de carne. Este problema é especialmente prevalente em ovos de casca marrom, onde 15% ou mais dos ovos podem ser afetados, em comparação com menos de 1% em ovos de casca branca. Figura 6: ovo com mancha de carne e com mancha de sangue. Fonte: internet. • PARTES DO OVIDUTO O oviduto é um tubo lindo através do qual a gema passa e onde os componentes restantes do ovo como a clara e a casca são incorporados. Normalmente, o oviduto é relativamente pequeno em diâmetro, mas com a aproximação da primeira ovulação seutamanho e espessura se expandem de forma significativa para que possa favorecer a passagem e o desenvolvimento do ovo. Os segmentos do oviduto e sua finalidade serão resumidos no texto abaixo e ilustrados na figura 7 e 8. INFUNDÍBULO A porção superior do oviduto que possui uma formato de funil é denominada infundíbulo. Quando encontra-se funcional, seu comprimento é de aproximadamente 9 cm. Normalmente é inerte, exceto quando ocorre a ovulação, seu objetivo é captar a gema ou óvulo que se desprende do ovário para que a mesma entre no oviduto, por isso a forma de funil. Após a ovulação, a gema entra na bolsa ovariana ou na cavidade do corpo, a partir da qual é capturada pelo infundíbulo. A gema permanece nessa secção por apenas um curto período de cerca de 15 minutos, depois é forçada ao longo do oviduto através das várias contrações ou movimentos peristálticos. Mau funcionamento do infundíbulo Para que o infundíbulo seja completamente funcional, ele deve capturar todas as gemas que se desprendem do ovário e caiu na cavidade do corpo. No entanto, verificou- se que uma média de 4% das gemas não são atraídas para o segmento, porém permanecem na cavidade do corpo onde são reabsorvidas dentro de um dia. A porcentagem de gemas retidas varia entre as várias linhagens de galinhas, algumas podem reter até 10% de suas gemas na cavidade corporal. As matrizes são as mais afetadas do que as poedeiras. Camadas internas Às vezes, o infundíbulo perde a sua capacidade de captação de uma alta proporção de gemas, e acabam acumulando-se na cavidade do corpo mais rápido do que possam ser reabsorvidas. Tal problema é definido por “camadas internas”, embora o termo não defina de forma clara a condição. O abdômen em tais camadas torna-se distendido, e a galinha fica em uma posição ereta. MAGNO O magno é a porção secretória de albúmen do oviduto, possui cerca de 33 cm de comprimento nas poedeiras em média. Demora aproximadamente cerca de 2 a 3 horas para passagem do ovo em desenvolvimento passar pelo magno. Albúmen O albúmen em um ovo é composto por quatro camadas, sendo elas: Chalaza ou calaza 2,7% Líquido branco exterior 16,8% Densidade branca 57,3% Branco fino exterior 23,2% Fonte: BELL. Enquanto todos os quatro são produzidos no magno, o branco fino exterior não é concluído até que a água seja adicionada no útero. Chalaza ou calaza Ao quebrar um ovo, percebe-se duas partes torcidas conhecidas como calaza, estendendo-se de polos opostos da gema através do albúmen. L albúmen calcífero é produzido quando a gema entra pela primeira vez no magno, mas a torção para formação dos dois calazas acontece mais tardiamente, como o ovo gira na extremidade inferior do oviduto. Torcidas em direções opostas, a calaza tende a manter a gema no centro do ovo depois que ele é posto. Líquido interior branco À medida que o ovo em desenvolvimento passa pelo magno, apenas um tipo de albúmen é produzido, porém a adição de água juntamente com a rotação do ovo dão origem a várias outras camadas, uma delas e a expressiva é o líquido interno de coloração branca. Densidade branca O branco denso constitui a maior parte do ovo. Contém muco que tente a mantê- lo juntos. A quantidade de branco espesso gerada no magno é grande, mas a degradação da mucina e a adição de água, já que o ovo move-se através do oviduto, tendem a reduzir a quantidade desse líquido denso e grosso, aumentando a quantidade do branco fino. No momento em que o ovo é posto, ele possui cerca de um terço do seu conteúdo original de clara, porém o restante ainda compreende mais da metade do albúmen no ovo. Deterioração da qualidade dos ovos Após a postura dos ovos, há uma mudança constante no conteúdo interno do ovo. A clara é a primeira que começa a perder gradualmente a sua composição viscosa e o seu volume diminui, enquanto que o branco fino fica mais aguado e sua quantidade aumenta. Essas condições são afetadas pela temperatura de retenção, umidade relativa, tempo e certas doenças. A quantidade crescente de branco fino é um dos melhores indicadores das condições de idade (frescura) dos ovos. ISTMO Depois da passagem pelo magno, o ovo em desenvolvimento é forçado para o istmo, uma secção relativamente curta de aproximadamente 10 cm de comprimento, onde permanece entre 1 a 1,5 horas (média geral de 75 minutos). Aqui, as membranas da casca interna e externa são formadas de modo a representar a dona final do ovo. O conteúdo presente nesse momento não é suficiente para preencher completamente as membranas da casca, e o ovo assemelha-se a um saco parcialmente preenchido. As membranas da casca são um material parecido com um papel composto de fibras proteicas. A membrana interna estabelece-se primeiro, seguida pela membrana externa, que é três vezes mais grossa que a membrana interna. As duas membranas são mantidas juntas até que o ovo seja posto; em seguida, na extremidade do ovo, as duas membranas se separam para formar a célula de ar, essencial para a respiração do feto no caso de ovos de matrizes. Em uma pequena porcentagem dos ovos, a célula de ar se formará na extremidade pequena ou nas laterais. Importância da célula ou câmara de ar Quando o ovo é posto pela primeira vez não há célula de ar. Ela é estabelecida através da redução de temperatura e aumenta de diâmetro para cerca de 1,8 cm conforme a perda de água do ovo por evaporação. À medida em que o ovo envelhece, a umidade ou presença d água dentro do mesmo evapora através dos poros presentes na casca e a câmara de ar aumenta em diâmetro e profundidade. O tamanho da célula de ar pode ser afetado por várias condições de armazenamento. A alta temperatura circundante e/ou a baixa umidade aumentam o tamanho da câmara de ar. O tamanho da célula, conforme determinado pela ovoscopia, é usado em programas de classificação de julgamento da idade do ovo. As células de ar maiores são prerrogativas de pior qualidade interior. Membranas da casca atuam como barreiras As membranas da casca atuam como uma barreira à penetração de organismos microscópios tais como as bactérias que podem afetar diretamente a qualidade do mesmo para consumo ou o embrião em desenvolvimento. Os ovos postos por frangas possuem membranas de casca mais espessas do que os ovos postos por galinhas mais velhas, o que se determina que conforme a idade da ave, as membranas protetoras vão ficando mais finas o que pode levar a penetração de microrganismos que afetam a qualidade do ovo. ÚTERO (GLÂNDULA DA CASCA) O útero é o penúltimo caminho do ovo em desenvolvimento, possui cerca de 10 a 12 cm de comprimento nas galinhas poedeiras. O ovo em desenvolvimento normalmente permanece no útero de 18 a 20 horas, muito mais do que em qualquer outra seção do oviduto. Exterior fino branco depositado após as membranas da casca Quando o ovo entra pela primeira vez no útero, a água e os sais minerais são depositados através das membranas da casca pelo processo de osmose de dentro para fora das membranas da casca de forma gradativa e aderindo para liquefazer alguns dos albumens finos que formam a quarta camada, o branco fino exterior. A casca A calcificação da casca do ovo começa antes do mesmo entrar no útero. Pequenas quantidades de Ca aparecem na membrana externa da casca pouco antes do ovo deixar o istmo. Esses são os locais de iniciação para a deposição de cálcio no útero. A quantidade de Ca provavelmente herdada desempenha um papel primordial na deposição de Ca mais tarde no ovo. Eles desaparecem pouco tempo depois que o ovo entra na glândula da casca ou útero. A primeira camada da casca é depositada sobre os locais de iniciação (istmo) que forma a casca interna, uma camada composta de cristais de calcita que é um material com característica esponjosa. Essa camada é seguida pela adição da camada externa, que é composta por uma camada de cristais de calcita que são os calcários, camada que possui cerca de duas vezes mais espessura que a superfície interna da casca. Quanto mais longas forem as colunas de calcita, mais forte será a casca. A casca do ovo quando completa, é composta quase inteiramente de carbonato de cálcio (CaCO3), com pequenas quantidades de sódio, potássio e magnésio. Figura 9: carbonato e fórmula do cálcio presente no útero e istmo. Fonte: internet. Fontes de cálcio para a casca de ovo Existem apenas duas fontes de cálcio para a produção da casca, a alimentação e os ossos que atuam como locais de armazenamento de cálcio no corpo. Normalmente, a maioria do Ca para a formação dos ovos vem diretamente da ração que a ave come, com alguns derivados do osso medular que serve como reservatório de Ca. O reservatório é particularmente importante à noite, quando a ave não está comendo e a casca do ovo está em processo de desenvolvimento. Formação do carbonato de cálcio O carbonato de cálcio (figura 9) é formado quando os íons de Ca presentes no sangue e os íons carbonatos do sangue e da glândula da casca ou útero se combinam no útero. Qualquer fator que reduza o fornecimento de qualquer um desses íons interfere com a formação de CaCO3 e o desenvolvimento da casca do ovo, muitas vezes resultando em baixa qualidade da casca, que será discutida em outros trabalhos. Acredita-se que as altas temperaturas ambientais também podem contribuir para este problema, uma vez que as cascas de ovos são mais finas durante o tempo quente. Qualidade da casca Muitos fatores podem causar uma deterioração na qualidade da casca do ovo, e a influência desse má qualidade pode não ser em função do fornecimento inadequado de íons de cálcio ou carbonato. A qualidade da casca é, geralmente, definida como a capacidade da casca de suportar o choque, sua aparência geral e suavidade. A resistência da casca pode ser medida mediante várias técnicas, incluindo a resistência à quebra, gravidade específica, deformações e espessura da mesma. Vários fatores podem reduzir a qualidade da casca, por exemplo: 1. A qualidade é reduzida à medida que a ave envelhece e continua a postura, uma vez que a galinha não pode produzir de forma eficiente a quantidade adequada de carbonato de cálcio para cobrir os ovos maiores produzidos durante a última parte do ciclo de postura, mesmo com o Ca presente na ração de consumo. 2. Aumento das temperaturas ambientais. 3. Ovos postos de manhã possuem uma qualidade da casca inferior à dos ovos postos pela tarde. 4. Estresse experimentado pelas aves que receberam chuva ou que foram, de alguma forma, submetidas à água. 5. Praticamente todos os ovos deformados e os ovos submetidos a controles corporais são postos entre às 6 e 8 horas da manhã, complemento do item 3. 6. Certas doenças como a bronquite infecciosa e a doença de Newcastle. 7. Determinados antibióticos ou outros fármacos. Necessidades de cálcio durante a produção A demanda da poedeira por Cá é extremamente alta. As aves poedeiras requerem mais Ca para a produção de ovos para consumo do que as matrizes reprodutoras que produzem pintainhos. Uma galinha de 2 kg produzindo 250 ovos de 56,7 gramas em média por ano requer cerca de 560 gramas de Ca. Uma vez que essa quantidade é 25 vezes maior que a quantidade de Ca presente no esqueleto da ave, é evidente que a necessidade alimentar de Ca seja grande. A maioria das rações de postura contém de 3 a 4% de Ca para atender as necessidades e permitir as ineficiências de absorção do Ca para o corpo e sim para o ovo. Figura 10: estrutura do ovo e da casca. Fonte: Adaptação da internet. Poros da casca do ovo As duas camadas da casca do ovo interna e externa possuem pequenas aberturas chamadas poros. Em um ovo pode haver até 8000 poros. Através dessas pequenas aberturas, o ar consegue passar para o ovo e fornece oxigênio para o embrião em desenvolvimento. Além disso, o dióxido de carbono e a umidade são removidos do ovo passando por esses mesmos poros. No ovo recém-posto, os poros presentes são quase completamente fechados, porém à medida que o ovo envelhece ou é lavado, o número de poros abertos aumenta. Cor da casca A casca do ovo é predominantemente branca ou marrons. No entanto, uma raça sul-americana, a Araucana, produz ovos de casca verde ou azul. Os pigmentos produzidos no útero no momento em que a casca é produzida são os responsáveis pela coloração. O tom de coloração é bastante consistente de acordo com cada ave, com a intensidade da cor sendo uma derivação da composição genética do indivíduo. Algumas linhagens de aves põem ovos com cascas castanhas mais escuras, enquanto que outras podem variar até ao branco. O pigmento marrom nas cascas de ovos é a porfirina, uniformemente distribuída por toda a casca. A cutícula A cutícula é colocada na parte externa da casca no útero e representa a última das camadas de formação dos ovos. É composta principalmente de material orgânico. Contém uma alta porcentagem de água e atua como lubrificante natural durante o processo de postura. Todavia, uma vez que o ovo é posto, o material da cutícula seca rapidamente, selando os poros da casca o que ajuda a evitar uma troca rápida de ar e umidade entre o interior do ovo e o ambiente externo, além de vedar a passagem de bactérias e outros microrganismos que podem afetar a qualidade ou o embrião. Vários processos de limpeza da casca (lavagem e desinfecção) reduzem a eficácia da cutícula. Para evitar esse problema, os processadores de ovos comumente aplicam um revestimento de óleo mineral na superfície da casca durante o processamento. Tal óleo ajuda a diminuir a perda de umidade e mantém a qualidade interna do ovo. REFERÊNCIAS BIBLIOGRÁFICAS ALBINO, L. F. T. et al. Galinhas poedeiras: Criação e alimentação. Viçosa: Aprenda Fácil, 2014. Anotações de aulas. Disciplina: Avicultura. Prof. Me. Cléber Rondinelli Gomes de Freitas. IFPE Campus Belo Jardim, 2017. BELL, Donald D. Formation of the egg. In: Commercial chicken meat and egg production. Springer, Boston, MA, 2002. p. 59-69. COTTA, Tadeu. Galinha: produção de ovos. Viçosa: Aprenda Fácil Editora, 2002. COTTA, T. Reprodução da galinha e produção de ovos. Lavras: UFLA-Faepe, p. 81- 92, 1997. DE MORAES, Ismar Araujo. Fisiologia da reprodução das aves domésticas. Fisiovet, 2006. FLORIANO, Luciane Sperandio. Anatomia e fisiologia das aves domésticas. Ururaí: rede E-tec, 2018. GRAU, C. R. Egg formation. In: Seabird energetics. Springer, Boston, MA, 1984. p. 33- 57. LANA, Geraldo Roberto Quintão. Avicultura. Recife: Livraria e Editora Rural Ltda, 2000 PERRINS, C. M. Eggs, egg formation and the timing of breeding. Ibis, v. 138, n. 1, p. 2- 15, 1996. STURKIE, Paul D. Fisiología aviar. Zaragoza: Acribia, 1967. (shrink)

Bertrand Russell, in the second of his 1914 Lowell lectures, Our Knowledge of the External World, asserted famously that ‘every philosophical problem, when it is subjected to the necessary analysis and purification, is found either to be not really philosophical at all, or else to be, in the sense in which we are using the word, logical’ (Russell 1993, p. 42). He went on to characterize that portion of logic that concerned the study of forms of propositions, or, as he (...) called them, ‘logical forms’. This portion of logic he called ‘philosophical logic’. Russell asserted that ... some kind of knowledge of logical forms, though with most people it is not explicit, is involved in all understanding of discourse. It is the business of philosophical logic to extract this knowledge from its concrete integuments, and to render it explicit and pure. (p. 53) Perhaps no one still endorses quite this grand a view of the role of logic and the investigation of logical form in philosophy. But talk of logical form retains a central role in analytic philosophy. Given its widespread use in philosophy and linguistics, it is rather surprising that the concept of logical form has not received more attention by philosophers than it has. The concern of this paper is to say something about what talk of logical form comes to, in a tradition that stretches back to (and arguably beyond) Russell’s use of that expression. This will not be exactly Russell’s conception. For we do not endorse Russell’s view that propositions are the bearers of logical form, or that appeal to propositions adds anything to our understanding of what talk of logical form comes to. But we will be concerned to provide an account responsive to the interests expressed by Russell in the above quotations, though one clarified of extraneous elements, and expressed precisely. For this purpose, it is important to note that the concern expressed by Russell in the above passages, as the surrounding text makes clear, is a concern not just with logic conceived narrowly as the study of logical terms, but with propositional form more generally, which includes, e.g., such features as those that correspond to the number of argument places in a propositional function, and the categories of objects which propositional.... (shrink)

This chapter develops an account of epistemic nihilism—roughly, the rejection of truth’s intrinsic or instrumental value in favor of statements that reject or obscure truth to secure an advantage for the speaker—by examining three instances of such nihilism: lying, bullshit, and trolling. It further argues that epistemic nihilism, exacerbated by changes in the media landscape, can pose a significant threat to liberal democratic institutions and ideals by undermining the democratic ideal of good faith engagement on a level playing field, while (...) also encouraging undemocratic actions (e.g., terrorism) among interlocutors who take the nihilist’s claims seriously. Finally, this chapter argues that in extreme cases, we are justified in denying epistemic nihilists a platform from which to speak by drawing a parallel with vexatious litigant laws that deny individuals the right to petition courts for redress on the grounds that abuse of that right results in significant harm to both individuals and the legal system itself. (shrink)

The federal system for allocating donated livers in the United States is often criticized for allowing geographic disparities in access to livers. Critics argue that such disparities are unfair on the grounds that where one lives is morally arbitrary and so should not influence one's access to donated livers. They argue instead that livers should be allocated in accordance with the equal opportunity principle, according to which US residents who are equally sick should have the same opportunity to receive a (...) liver, regardless of where they live. In this paper, we examine a central premise of the argument for the equal opportunity principle, namely, that geographic location is a morally arbitrary basis for allocating livers. We raise some serious doubts regarding the truth of this premise, arguing that under certain conditions, factors closely associated with geographic location are relevant to the allocation of livers, and so that candidates' geographic location is sometimes a morally non-arbitrary basis for allocating livers. Geographic location is morally non-arbitrary, we suggest, since by taking it into account, the UNOS may better fulfill its central goals of facilitating the effective and efficient placement of organs for transplantation and increasing organ donation. (shrink)

In this article, I ask whether a principle analogous to the principle of clinical equipoise should govern the design and conduct of RCTs evaluating the effectiveness of policy interventions. I answer this question affirmatively, and introduce and defend the principle of policy equipoise. According to this principle, all arms of a policy RCT must be, at minimum, in a state of equipoise with the best proven policy that is also morally and practically attainable and sustainable. For all arms of a (...) policy RCT, policy experts must either reasonably disagree about whether the trial arms are more effective than this policy, or know that they are. (shrink)

Australia, Canada, and New Zealand currently apply health requirements to prospective immigrants, denying residency to those with health conditions that are likely to impose an “excessive demand” on their publicly funded health and social service programs. In this paper, I investigate the charge that such policies are wrongfully discriminatory against persons with disabilities. I first provide a freedom-based account of the wrongness of discrimination according to which discrimination is wrong when and because it involves disadvantaging people in the exercise of (...) their freedom on the basis of morally arbitrary features of their identity. Discrimination is permissible, I suggest, when it is necessary to advance a valuable exercise of the discriminating agent’s freedom. I then apply this account to the case of social cost health requirements. Against critics of these requirements, I argue that it is sometimes permissible for states to discriminate against prospective immigrants with disabilities. States may do so, I suggest, when such discriminatory treatment is necessary to prevent an increase in rates of mortality and/or morbidity amongst citizens. Alongside critics of social cost health requirements however, I argue that existing policies are likely a form of wrongful discrimination insofar as they are too broad to satisfy this standard. (shrink)

Although the principle of fair subject selection is a widely recognized requirement of ethical clinical research, it often yields conflicting imperatives, thus raising major ethical dilemmas regarding participant selection. In this paper, we diagnose the source of this problem, arguing that the principle of fair subject selection is best understood as a bundle of four distinct sub-principles, each with normative force and each yielding distinct imperatives: (1) fair inclusion; (2) fair burden sharing; (3) fair opportunity; and (4) fair distribution of (...) third-party risks. We first map out these distinct sub-principles, and then identify the ways in which they yield conflicting imperatives for the design of inclusion and exclusion criteria, and the recruitment of participants. We then offer guidance for how decision makers should navigate these conflicting imperatives to ensure that participants are selected fairly. (shrink)

Journal of Political Philosophy, EarlyView.

The duty to rescue is a highly plausible and powerful ethical principle. It requires agents to assist others in extreme need in cases where doing so does not conflict with some weighty moral aim; requires little personal sacrifice; and is likely to significantly benefit the recipients.1 As a general obligation, it binds all persons simply qua persons, and it is owed to all persons simply qua persons. Clinical investigators working in low-income countries frequently encounter sick or destitute people to whom (...) they might possess a duty to rescue. Investigators may often ask themselves, what can I do, what should I do, to help? Such investigators often help people in the future by carrying out their... (shrink)

Many high-income countries have skill-selective immigration policies, favoring prospective immigrants who are highly skilled. I investigate whether it is permissible for high-income countries to adopt such policies. Adopting what Joseph Carens calls a " realistic approach " to the ethics of immigration, I argue first that it is in principle permissible for high-income countries to take skill as a consideration in favor of selecting one prospective immigrant rather than another. I argue second that high-income countries must ensure that their skill-selective (...) immigration policies do not contribute to the non-fulfillment of their duty to aid residents of low-and middle-income countries. (shrink)

Social scientists and research ethicists have begun, somewhat belatedly, to confront and address the ethical challenges raised by public policy experiments. In doing so however, they have not fully availed themselves of the large and sophisticated literature on the ethics of clinical research which has developed over the past 40 years. While clinical and public policy research are different, I argue that the clinical research ethics literature yields valuable insights for discussions of the ethics of policy experiments. Focusing on seven (...) ethical issues which have received a good deal of attention in public and scholarly discussions of the ethics of policy experiments, I make use of the history of reflection on the ethics of clinical research to provide guidance to researchers planning and conducting policy experiments. (shrink)

In this case discussion, Barnhill and Devine collect and present a significant amount of recent research on the various reasons why people struggle to succeed in weight loss programmes. Specifically, the authors focus on what they call ‘behavioural weight loss interventions’, which are ‘research, clinical or public health efforts to promote individual healthy eating and physical activity behaviours’. As defined, this is a very broad category of interventions and presumably includes all kinds of dieting and weight loss programmes or promotion (...) efforts short of private or independently chosen programmes. The authors argue, in a nutshell, that these clinical, research, and public health interventions have low efficacy, and while they may have some health or other benefits, the balance of evidence presented shows that they harm people in multiple ways. (shrink)

Governments are increasingly using randomized controlled trials (RCTs) to evaluate policy interventions. RCTs are often understood to provide the highest quality evidence regarding the causal efficacy of an intervention. While randomization plays an essential epistemic role in the context of policy RCTs however, it also plays an important distributive role. By randomly assigning participants to either the intervention or control arm of an RCT, people are subject to different policies and so, often, to different types and levels of benefits. In (...) this paper, I identify one necessary condition as well as a set of sufficient conditions for the permissible use of random assignment by government agencies. I argue first that random assignment is permissible only if it is consistent with governments’ duty to realize morally important outcomes. I argue second that random assignment is permissible in cases where investigators are in a state of genuine equipoise regarding all arms of the experiment and the policy to which people have a claim of justice. Finally, I defend a set of conditions under which random assignment is permissible in cases where one or more arms of a policy RCT are reasonably expected to be either superior or inferior to this policy. (shrink)

There is more than one way to say that composition is identity. Yi has distinguished the Weak Composition thesis from the Strong Composition thesis and attributed the former to David Lewis while noting that Lewis associates something like the latter with me. Weak Composition is the thesis that the relation between the parts collectively and their whole is closely analogous to identity. Strong Composition is the thesis that the relation between the parts collectively and their whole is identity. Yi is (...) right that Strong Composition does not fully reflect my view. We must recognize further what, borrowing Lewis's characterization, could be called the "stronger, and stranger" Composition thesis, or what I'll call the Stronger Composition thesis for short. On Strong Composition, it is only collectively that the parts are identical with the whole. On Stronger Composition, they are individually identical with it as well. I will explain and motivate this thesis. (shrink)

According to the norm of policy equipoise, it is permissible to randomly assign participants to two or more interventions in a public policy randomized controlled trial (RCT) when there is meaningful uncertainty among the relevant expert community regarding which intervention is superior. While this norm is gaining traction in the research ethics literature, the idea of interventional superiority remains unclear. Is one intervention superior to another if it is reasonably expected to realize one outcome of interest more effectively, even though (...) there is uncertainty regarding other outcomes of interest? Or must an intervention be reasonably expected to realize all outcomes of interest more effectively? I address this question in this paper. My aim is to develop and defend an account of interventional superiority for policy RCTs that are authorized, funded, or conducted by government institutions. I defend the greatest value view, according to which one intervention is superior to another if and only if it is reasonably expected to more effectively realize a set of outcomes with greater value. (shrink)

In this article, we suggest that the evidence regarding the social determinants of health calls for a deep re‐thinking of our understanding of distributive justice. Focusing on John Rawls's theory of distributive justice in particular, we argue that a full reckoning with the social determinants of health requires a re‐working of Rawls's principles of justice. We argue first that the social bases of health – a Rawlsian conception of the social determinants of health – should be considered a social primary (...) good. We argue second that including the social bases of health as a social primary good would lead the parties to the original position to choose an additional principle of justice and assign it lexical priority over Rawls's second principle. According to this principle, inequalities in people's share of the social bases of health are to be arranged so as to improve the health status of those least advantaged on the social health gradient. -/- . (shrink)

A principal rationale for public policy is to address market failures. Pareto efficiency is therefore a highly common and relatively non-controversial evaluative criterion for many policy analyses and is discussed at length in policy analysis texts. This makes sense, for Pareto improvements involve making at least one person better off without making anyone worse off. Who could object to that? But does efficiency deserve the prominence it enjoys in public policy? Is one policy option better than another, at least in (...) one respect, simply because it is more Pareto efficient? Or, is efficiency valuable for some other reason? In this chapter, I discuss Pareto efficiency as an evaluative criterion and argue that it is a stand-in for a more foundational criterion: wellbeing. I begin with an overview of Pareto efficiency, discuss the various ways in which it is operationalized to evaluate policy options, and argue that it is valuable insofar as more efficient states of affairs promise more wellbeing than less efficient states of affairs. I then raise questions regarding whether the conception of wellbeing presupposed by Pareto efficiency – preference satisfaction – is a defensible conception of wellbeing. I go on to introduce three alternative conceptions of wellbeing which have been proposed and defended by both philosophers and policy scholars, namely, hedonism, objective goods views, and the capability approach, and suggest ways in which each can be operationalized as an evaluative criterion. I close by discussing four ‘theory-free’ approaches to thinking about the impact of policies on the quality of people’s lives. Such approaches reject the idea that there is one single theory of wellbeing that should be used to evaluate policy options, and instead develop ways to evaluate the impact of policies on people’s lives that are not grounded in a specific theory. (shrink)

Government agencies and nonprofit organizations have increasingly turned to randomized controlled trials (RCTs) to evaluate public policy interventions. Random assignment is widely understood to be fair when there is equipoise; however, some scholars and practitioners argue that random assignment is also permissible when an intervention is reasonably expected to be superior to other trial arms. For example, some argue that random assignment to such an intervention is fair when the intervention is scarce, for it is sometimes fair to use a (...) lottery to allocate scarce goods. We investigate the permissibility of randomization in public policy RCTs when there is no equipoise, identifying two sets of conditions under which it is fair to allocate access to a superior intervention via random assignment. We also reject oft-made claims that alternative study designs, including stepped-wedge designs and uneven randomization, offer fair ways to allocate beneficial interventions. (shrink)

Governments often aim to improve children’s wellbeing by targeting the decision-making of their parents. In this paper, I explore this phenomenon, providing an ethical evaluation of the ways in which governments target parental decision-making in the context of anti-poverty policies. I first introduce and motivate the concept of parent-targeted paternalism to categorize such policies. I then investigate whether parent-targeted paternalism is ever pro tanto wrong, arguing that it is when directed at parents who meet a threshold of parental competency. I (...) next explore the factors that affect the degree of pro tanto wrongness of paternalistic anti-poverty policies targeting parents, and provide an account of the conditions under which such policies are on balance permissible, and when they are not. Finally, I illustrate the plausibility and usefulness of my framework by considering a case. (shrink)

The concept of metaphor as primarily a vehicle for conveying ideas, even if unusual ones, seems to me as wrong as the parent idea that a metaphor has a special meaning. I agree with the view that metaphors cannot be paraphrased, but I think this is not because metaphors say something too novel for literal expression but because there is nothing there to paraphrase. Paraphrase, whether possible or not, inappropriate to what is said: we try, in paraphrase, to say it (...) another way. But if I am right, a metaphor doesn't say anything beyond its literal meaning. This is not, of course, to deny that a metaphor has a point, nor that that point can be brought out by using further words.... My disagreement is with the explanation of how metaphor works its wonders. To anticipate: I depend on the distinction between what words mean and what they are used to do. I think metaphor belongs exclusively to the domain of use. It is something brought off by the imaginative employment of words and sentences and depends entirely on the ordinary meanings of those words and hence on the ordinary meanings of the sentences they comprise. Donald Davidson is University Professor of philosophy at the University of Chicago. He is the author of many important essays, including "Actions, Reasons and Causes," "Causal Relations," and "Truth and Meaning," coauthor of Decision-Making: An Experimental Approach, and coeditor of Words and Objections, Semantics of Natural Language, and The Logic of Grammar. (shrink)

Policy analyses begin with a systematic overview of the policy problem they address. This includes a comprehensive discussion of the nature and context of the problem, and the institutional and behavioral factors responsible for its emergence. Problem statements must also explain why the status quo is bad or undesirable, why it is something that governments, rather than private actors, should address, and establish that the relevant government institutions have the legitimacy to intervene. In this chapter, I provide an overview of (...) the principal types of policy problems that it is morally appropriate for governments to address. Each type denotes a class of states of affairs that (1) are bad, undesirable, or unjust, (2) the government is particularly well-suited to address, and (3) arise from spheres of action over which the relevant government institutions have the right to intervene. I begin with a discussion of collective action problems, that is, states of affairs in which action by rational and self-interested private actors is collectively self-defeating. I then argue for two additional types of policy problems. First, since the goal of government action is the construction of a just legal order, not merely an efficient one, states of affairs which are unjust constitute an additional type of policy problem. Relatedly, second, whereas analyses of collective action problems typically presuppose the existence of effective government institutions which can address them, such institutions may be deficient and/or unjust. A third type of policy problem is therefore deficient government institutions. -/- . (shrink)

Governments are increasingly making use of field experiments to evaluate policy interventions in the spheres of education, public health and welfare. However, the research ethics literature is largely focused on the clinical context, leaving investigators, institutional review boards and government agencies with few resources to draw on to address the ethical questions they face regarding such experiments. In this article, we aim to help address this problem, investigating the conditions under which informed consent is required for ethical policy research conducted (...) or authorized by government. We argue that investigators need not secure participants' informed consent when conducting government policy experiments if: the government institution conducting or authorizing the experiment possesses a right to rule over the spheres of policy targeted by the research; and data collection does not involve the violation of participants' autonomy rights. (shrink)

Soda taxes are controversial. While proponents point to their potential health benefits and the public projects that could be funded with their revenue, critics argue that they are paternalistic and regressive. In this paper, we explore the prospects for designing a just soda tax, one that appropriately balances the often-competing ethical considerations of promoting social welfare, respecting people’s autonomy and ensuring distributive fairness. We argue that policymakers have several paths forward for designing a just soda tax, but that the considerations (...) relevant to ethical policy design are more complicated than is sometimes acknowledged. (shrink)

The paper has two complementary objectives. First, it sustains an analysis of the concept of ‘coloniality’ that accounts for the epistemic imbalance in the modern world, demonstrating precisely how Africa is adversely affected, having been caught up in the throes of coloniality and its epistemic implications. Second – and complementarily – the paper attempts to bring this very concept of ‘coloniality’ into the discourse on Africa’s emigration crisis, arguing that Africa’s emigration crisis is traceable, inter alia, to the epistemic imbalance (...) in the very structure of modernity. This imbalance results from the stifling of Africa’s epistemic resources under Western epistemic hegemony. Epistemic coloniality, of course interacting with some material factors, creates a sufficient condition for emigration. It is further theorized that the apparent lack of epistemic will on the part of Africans to mobilize some surviving epistemic resources to address some problems on their own is also a function of coloniality. (shrink)

The field of public policy is dominated by the social sciences. Schools and departments of public policy and public administration are largely populated by economists, political scientists, and sociologists, and the vast majority of work in prestigious public policy journals employs empirical methods. This is unsurprising, in one respect, for collecting data, predicting and identifying the causal impacts of policies, and understanding political institutions and processes are massive, important tasks that require the tools of the social sciences. It is surprising, (...) in another respect however, since much policy scholarship and analysis aspires to offer recommendations to policymakers, and recommendations necessarily involve evaluative judgments, for example, that the status quo is deficient and that a certain course of action will make things better. To defend such judgments, policy scholars and analysts cannot appeal to the social sciences alone for these judgments concern the realm of values, not facts. Instead, careful ethical reflection and analysis is required. This need for ethical reflection in public policy is particularly evident in the practice of policy analysis, a principal analytic tool of the field. Policy analyses involve the identification of policy problems, the specification of criteria for evaluating possible solutions, and the recommendation that a policy option offers the best balance of trade offs. This identification of bads, the specification of goods policies should realize, and the weighing of these goods with the judgment that policymakers should or ought to pursue this course of action or that, are all deeply ethical activities. Ethical reflection and analysis is thus a constituent feature of policy analysis, and like the amassing of evidence and projection of outcomes, this reflection and analysis may be performed well or badly. The overall aim of this book is to provide students, scholars, and practitioners of public policy with guidance regarding the ethical dimensions of policy analysis. My aim in this chapter is to set the stage, providing an overview of these dimensions. After providing a brief overview of the practice of policy analysis, I identify the steps of an analysis where analysts must make ethical judgments in order to move forward, and fully articulate the ethical questions they must confront and take a position on. (shrink)

An essay on the compatibility of Jewish and Muslim aspirations for the Land that argues that a vision of peaceful coexistence to provide a spur to the settling of grievances, but that this vision must respect the deeply felt aspirations of both communities, including in particular those underpinned by religious lore. Existing formulations of the aims of each community are blatantly inconsistent; it is time to attempt to characterise the just and religiously authentic goals of each community in ways that (...) are compatible. I argue that there religious and personal dimensions of the conflict that have been displaced by less deep-seated political goals, but which can be addressed more readily. I outline a tiered constitutional settlement that could address legitimate aspirations by avoiding the anathema of partition. (shrink)

There is a familiar problem in moral theories that recognize positive obligations to help others related to the practical room these obligations leave for ordinary life, and the risk that open-ended obligations to help others will consume our lives and resources. Responding to this problem, Kantians have tended to emphasize the idea of limits on positive obligations but are typically unsatisfactorily vague about the nature and extent of these limits. I argue here that aspects of Kant’s discussion of duties of (...) virtue owed to ourselves suggest a useful metric we can use in discussing these limits and that generalizing this account and combining it with elements of Barbara Herman’s view, offers us an attractive model of moral deliberation with the resources we need to engage the critic’s challenge properly. (shrink)

In this chapter, we provide an overview of the ethical considerations relevant to the use of nudges in organ donation policy. We do not defend a position on the permissibility of nudging in this context, but instead aim to clearly outline the strongest arguments on the different sides of this issue that have been presented in the English-language scholarly bioethics literature. We also highlight the questions that are in need of further investigation. In part 1, we briefly discuss nudging before (...) considering proposals to use nudges to increase the number of registered organ donors, including opt-out donor registration systems and the use of “nudge statements.” In part 2, we discuss the use of nudges to influence the decision-making of family members in circumstances where they have a veto over the donation of their loved one’s organs. (shrink)