Cetaceans show high cognitive abilities and strong social bonds. Their primary sensory modality to communicate and sense the environment is acoustics. Research on their echolocation and social vocalizations typically uses visual and tactile systems adapted from research on primates or birds. Such research would benefit from a purely acoustic communication system to better match their natural capabilities. We argue that a full duplex system, in which signals can flow in both directions simultaneously is essential for communication research. We designed and (...) implemented a full duplex system to acoustically interact with cetaceans in the wild, featuring digital echo-suppression. We pilot tested the system in Arctic Norway and achieved an echo suppression of 18 dB. We discuss the limiting factors and how to improve the echo suppression further. The system enabled vocal interaction with the underwater acoustic scene by allowing experimenters to listen while producing sounds. We describe our motivations, then present our pilot deployment and give examples of initial explorative attempts to vocally interact with wild orcas and humpback whales. (shrink)

Esta investigación se emprende motivada por la necesidad de desentrañar la progresión delos modelos de aprendizaje, los cuales se han ido adaptando para responder a las demandas de lasociedad en su dinámica constante de fluctuación y transformaciones. El objetivo de este trabajo es examinar de forma sistemática la evolución de los modelos de aprendizaje, destacando los cambios paradigmáticos que han favorecido la transición de enfoques de aprendizaje tradicionales hacia propuestas más innovadoras y transdisciplinarias. Para lograrlo, se lleva a cabo un (...) análisis bibliográfico apoyado en el método hermenéutico para la interpretación contextual de la literatura y los discursos, a fin de desentrañar las complejidades inherentes en la evolución de los modelos de aprendizaje. Los resultados resaltan la influencia limitante del paradigma de la simplicidad en laformación educativa tradicional y la necesidad de un giro hacia la dialogicidad y la colaboración eintegración disciplinaria para avanzar hacia la complejidad. Se concluye argumentando a favor de la adopción del paradigma de la complejidad, abogando por una epistemología transdisciplinariay un enfoque de aprendizaje interestructurante, que permitan el desarrollo humano integral.El reconocimiento de la complejidad humana en la enseñanza y el aprendizaje exige una transformación radical de la educación hacia prácticas más holísticas y transformadoras, esenciales para construir una sociedad equitativa y justa. (shrink)

Rational agents face choices, even when taking seriously the possibility of determinism. Rational agents also follow the advice of Causal Decision Theory (CDT). Although many take these claims to be well-motivated, there is growing pressure to reject one of them, as CDT seems to go badly wrong in some deterministic cases. We argue that deterministic cases do not undermine a counterfactual model of rational deliberation, which is characteristic of CDT. Rather, they force us to distinguish between counterfactuals that are relevant (...) and ones that are irrelevant for the purposes of deliberation. We incorporate this distinction into decision theory to develop ‘Selective Causal Decision Theory’, which delivers the correct recommendations in deterministic cases while respecting the key motivations behind CDT. (shrink)

The aim of Dimitris Vardoulakis’s paper, ‘Toward a Critique of the Ineffectual: Heidegger’s Reading of Aristotle and the Construction of an Action without Ends’, is to provide the foundation for a critique of aimless action by tracing its genesis to Heidegger’s putative misinterpretation of Aristotelian phronēsis (practical wisdom) in the 1920s. Inasmuch as ‘the ineffectual’—the name Vardoulakis gives to action devoid of ends—plays a crucial role in post-Heideggerian continental philosophy, he thereby seeks to diagnose and to provide an aetiology of (...) an illness afflicting contemporary thought. In my response, I will first argue that, while Vardoulakis is right to identify an emphasis on the ineffectual in Heidegger, he is mistaken about its origin. Heidegger does not strip phronēsis of instrumentality, nor does he mistranslate Nichomachean Ethics 1139a31–32. Second, I trace an alternative source for the ineffectual, which is not simply a negative alternative to technological machination but stems from a positive experience of what Meister Eckhart, and Heidegger in his wake, called life without why. Finally, I look at a couple of texts, including one discussed by Vardoulakis, in which even the later Heidegger is not entirely dismissive of calculative instrumentality but instead assigns the latter to a secondary, restricted site of competence. (shrink)

This paper is about intentional identity, the phenomenon of intentional attitudes having a common focus. I present an argument against an approach to explaining intentional identity, defended by Nathan Salmon, Terence Parsons and others, that involves positing exotic objects. For example, those who adopt this sort of view say that when two astronomers had beliefs about Vulcan, their attitudes had a common focus because there is an exotic object that both of their beliefs were about. I argue that countenancing these (...) exotic objects does not help us explain intentional identity. (shrink)

Near the end of 'Naming the Colours', Lewis (1997) makes an interesting claim about the relationship between linguistic and mental content; we are typically unable to read the content of a belief off the content of a sentence used to express that belief or vice versa. I call this view autonomism. I motivate and defend autonomism and discuss its importance in the philosophy of mind and language. In a nutshell, I argue that the different theoretical roles that mental and linguistic (...) content play suggest these kinds of content should be understood as sensitive to different things. (shrink)

There are two families of influential and stubborn puzzles that many theories of aboutness (intentionality) face: underdetermination puzzles and puzzles concerning representations that appear to be about things that do not exist. I propose an approach that elegantly avoids both kinds of puzzle. The central idea is to explain aboutness (the relation supposed to stand between thoughts and terms and their objects) in terms of relations of co-aboutness (the relation of being about the same thing that stands between the thoughts (...) and terms themselves). (shrink)

La presente reflexión tiene por objetivo central aportar, desde la teoría científico-filosófica sobre el cuerpo humano construida por Pedro Laín Entralgo, una propuesta antropológica que posibilite el diálogo con el transhumanismo tecnocientífico. A nivel metodológico, el texto se ha estructurado en dos momentos. En el primero, se hace una revisión de la situación (sitius) del cuerpo de cara al transhumanismo info, para luego, en un segundo momento, aportar (locus), desde la obra lainiana, una concepción antropológica integral. Se espera que, al (...) pensar la materia desde un dinamismo estructural que hace de la realidad corpórea una unidad psico-orgánica capaz de decir “yo” (persona), se pueda establecer un cuestionamiento profundo a la concepción antropológica propuesta por el transhumanismo info, para la cual, el cuerpo orgánico es materia inútil de la que es necesario liberarse para superar los límites de la biología. (shrink)

In transplant medicine, the use of normothermic regional perfusion (NRP) in donation after circulatory determination of death raises ethical difficulties. NRP is objectionable because it restores the donor's circulation, thus invalidating a death declaration based on the permanent cessation of circulation. NRP's defenders respond with arguments that are tortuous and factually inaccurate and depend on introducing extraneous concepts into the law. However, results comparable to NRP's—more and higher‐quality organs and more efficient allocation—can be achieved by removing organs from deceased donors (...) and using normothermic machine perfusion (NMP) to support the organs outside the body, without jeopardizing confidence in transplantation's legal and ethical foundations. Given the controversy that NRP generates and the convoluted justifications made for it, we recommend a prudential approach we call “ethical parsimony,” which holds that, in the choice between competing means of achieving a result, the ethically simpler one is to be preferred. This approach makes clear that policy‐makers should favor NMP over NRP. (shrink)

Internalism about a person's good is roughly the view that in order for something to intrinsically enhance a person's well-being, that person must be capable of caring about that thing. I argue in this paper that internalism about a person's good should not be believed. Though many philosophers accept the view, Connie Rosati provides the most comprehensive case in favor of it. Her defense of the view consists mainly in offering five independent arguments to think that at least some form (...) of internalism about one's good is true. But I argue that, on closer inspection, not one of these arguments succeeds. The problems don't end there, however. While Rosati offers good reasons to think that what she calls 'two-tier internalism' would be the best way to formulate the intuition behind internalism about one's good, I argue that two-tier internalism is actually false. In particular, the problem is that no substantive theory of well-being is consistent with two-tier internalism. Accordingly, there is reason to think that even the best version of internalism about one's good is in fact false. Thus, I conclude, the prospects for internalism about a person's good do not look promising. (shrink)

I propose an approach to liar and Curry paradoxes inspired by the work of Roger Swyneshed in his treatise on insolubles (1330-1335). The keystone of the account is the idea that liar sentences and their ilk are false (and only false) and that the so-called ''capture'' direction of the T-schema should be restricted. The proposed account retains what I take to be the attractive features of Swyneshed's approach without leading to some worrying consequences Swyneshed accepts. The approach and the resulting (...) logic (called ''Swynish Logic'') are non-classical, but are consistent and compatible with many elements of the classical picture including modus ponens, modus tollens, and double-negation elimination and introduction. It is also compatible with bivalence and contravalence. My approach to these paradoxes is also immune to an important kind of revenge challenge that plagues some of its rivals. (shrink)

The problem of the many seems to problematize the platitude that we can think about particular things in the world. How is it that, given how very many cat-like candidates there are, we often manage to think and talk about a particular cat? I argue that this challenge stems from an under-examined assumption about the relationship between metaphysics and intentionality. I explore and develop a way of characterizing what it is to think and talk about the world, according to which (...) an abundant ontology poses no obstacle to our ability to think and talk about particular things. (shrink)

This paper considers contractarianism as a method of justification. The analysis accepts the key tenets of contractarianism: expected utility maximization, unanimity as the criteria of acceptance, and social-scientific uncertainty of modelled agents. In addition to these three features, however, the analysis introduces a fourth feature: a criteria of rational belief formation, viz. Bayesian belief updating. Using a formal model, this paper identifies a decisive objection to contractarian justification. Insofar as contractarian projects approximate the Agreement Model, therefore, they fail to justify (...) their conclusions. Insofar as they fail to approximate the Agreement Model, they must explain which modelling assumption they reject. (shrink)

According to Hobbes, individuals care about their relative standing in a way that shapes their social interactions. To model this aspect of Hobbesian psychology, this paper supposes that agents have social preferences, that is, preferences about their comparative resource holdings. Introducing uncertainty regarding the social preferences of others unleashes a process of trust-unravelling, ultimately leading to Hobbes’s ‘state of war’. This Trust-unravelling Model incorporates important features of Hobbes’s argument that past models ignore.

Almaatouq et al. propose a novel integrative approach to experiments. We provide three examples of how unaddressed measurement issues threaten the feasibility of the approach and its promise of promoting commensurability and knowledge integration.

Twilight Zone and Philosophy attempts to bring the insights and paradoxes of Rod Serling's project to contemporary audiences through a variety of philosophical perspectives"--Publisher.

In his recently published Donner le temps II, Derrida raises, but does not develop, the possibility that Heidegger's notion of Gelassenheit (‘releasement’, ‘letting-be’) might escape the economic confines of exchange, debt, and repayment and therefore qualify as a pure gift. In this paper, I explore this possibility, explaining that Gelassenheit would have to be understood, first, not primarily as a human comportment but at the level of being itself, second, beyond appropriation, and third, as ‘without why’. If Heidegger's focus on (...) appropriation in ‘Time and Being’ remains entangled in the economy of exchange (as Derrida insinuates in the final session of Donner le temps II), Heidegger's anarchic treatment of ‘letting’ ( laisser, Lassen) in the final session of his 1969 seminar in Le Thor opens instead onto a ‘pure giving’ ( pur donner, reines Geben). (shrink)

Reflecting current debates on ‘organizational virtues’ as going beyond the capitalocentrist bias of contemporary economies and to see diversity as ‘ethical responsibility,’ this article explores ‘ethical organizing’ at the intersection of alternative organizations and diversity. Our interest in a diversity-oriented analysis of alternative organizations stems from the assumption that those which question taken-for-granted notions of existing economies and follow alternative values of autonomy, solidarity, and responsibility might also be likely to challenge existing diversity relations and, thus, potentially open up new (...) avenues for ethical organizing. Discussing our findings in terms of Lewis and Simpson’s (in)visibility vortex, our study shows that even though organizations position themselves discursively as ‘alternative,’ this positioning is not related to diversity issues. We conclude that a shift is needed to fully constitute ethical organizing, namely the establishment of a strong connection between alternative organizations’ virtues with, e.g., the feminist, anti-racist, queer, and disability rights movements. (shrink)

This article introduces the main conceptual and normative questions about willful ignorance. The first section asks what willful ignorance is, while the second section asks why—and how much—it merits moral or legal condemnation. My approach is to critically examine the criminal law's view of willful ignorance. Doing so not only reveals the range of positions one might take about the phenomenon but also sheds light on foundational questions about the nature of culpability and the relation between law and morality.

This article analyses the parallels between the pre-Qin Daoist notion of heng 恒 as a constancy that is nevertheless ceaselessly in motion, and Karl Barth’s concept of Beständigkeit as God’s constancy throughout infinite transformation. Underlying both concepts is an understanding of the ultimate origin (whether dao 道 or the Christian God) as irreducibly temporal in nature. Stemming from this conviction, both systems of thought ultimately identify the continuous change of the ultimate origin with the flow of time in the universe. (...) The commonalities found between these two traditions provide fresh resources to advance the study of both. On the one hand, Barth’s deliberate juxtaposition of contrary statements to illustrate the union of permanence and transience in Beständigkeit challenges the frequent assumption that similar juxtapositions in the pre-Qin texts comprise careless inconsistency or outright incoherence. By extension, Barth’s metaphysical underpinning of this juxtaposition offers a compelling framework to explicate the Daoist notion of heng. On the other hand, the pre-Qin texts’ confluence of permanence and freedom in the principle of ziran 自然 offers a new lens through which to read and hence redeem Barth’s oft-critiqued attempt to combine the irrevocability and ongoing freedom of God’s decision of election. (shrink)

John Rawls argues that it is possible to describe a suitably defined initial situation from which to form reliable judgements about justice. In this initial situation, rational persons are deprived of information that is . It is rational, Rawls argues, for persons choosing principles of justice from this standpoint to be guided by the maximin rule. Critics, however, argue that (i) the maximin rule is not the appropriate decision rule for Rawls's choice position; (ii) the maximin argument relies upon an (...) imprecise account of the satisfactory minimum to be secured under the maximin rule; or that (iii) Rawls relies upon unrealistic assumptions about diminishing marginal value. These critics, I will suggest, argue from a number of assumptions that are confused or false. The satisfactory minimum that choosers in the original position seek to achieve is not a minimum level of primary goods, nor is the satisfactory minimum sought under the maximin rule supplied by the difference principle. I will argue that the maximin argument is more robust than has generally been recognized and that this argument performs a number of important functions in clarifying the nature and implications of Rawls's argument for justice as fairness. (shrink)

Evaluating other people's moral character is a crucial social cognitive task. However, the cognitive processes by which people seek out, prioritize, and integrate multiple pieces of character‐relevant information have not been studied empirically. The first aim of this research was to examine which character traits are considered most important when forming an impression of a person's overall moral character. The second aim was to understand how differing levels of trait expression affect overall character judgments. Four preregistered studies and one supplemental (...) study (total N = 720), using five different measures of importance and sampling undergraduates, online workers, and community members, found that our participants placed the most importance on the traits honest, helpful, compassionate, loyal, and responsible. Also, when integrating the information that they have learned, our participants seemed to engage in a simple averaging process in which all available, relevant information is combined in a linear fashion to form an overall evaluation of moral character. This research provides new insights into the cognitive processes by which evaluations of moral character are formed. (shrink)

In this study, the author develops an original reading of the Fifth Cartesian Meditation. This text, far from giving rise to a “transcendental solipsism”, as classical commentators claim, leads to a constitution of intersubjectivity on various levels . In its center, a “phenomenological construction” operates, i.e. a methodological piece that masters the genetic approach of intersubjectivity. Closely following the “almost mathematical” rigour of this crucial text of Husserl’s phenomenology, the author equally tackles the issue of the constitution of the experience (...) of the other and the truly intersubjective structure of transcendental subjectivity. The article concludes with the metaphysical results of the analysis of the experience of the other. (shrink)

This article aims at a new interpretation of paragraph §1 of Fichte’s main work of 1794/95, the Grundlage der gesammten Wissenschaftslehre. This well-known text of the early Jena period explicitly introduces a number of thought motifs that will prove to be valuable for the later versions of the Wissenschaftslehre – including the second version of 1804 – and these motifs will furthermore illuminate the significance of the first principle for Fichte’s entire Wissenschaftslehre.

Some intentional attitudes (beliefs, fears, desires, etc.) have a common focus in spite of there being no object at that focus. For example, two beliefs may be about the same witch even when there are no witches, different astronomers had beliefs directed at Vulcan, even though there is no such planet. This relation of having a common focus, whether or not there is an actual concrete object at that focus, is called intentional identity. In the first part of this thesis (...) I develop a new theory of intentional identity, the triangulation theory, and argue that it has significant advantages over the extant theories of intentional identity in the literature. Empty attitudes (attitudes that are not, prima facie, about anything that exists) will serve as useful cases for testing theories of intentional identity. -/- In the second part, I put the theory developed in the first part to work. I use triangulation theoretic tools to shed light on other debates about intentional attitudes. Some issues to which intentional identity are relevant are the debate about the content of intentional attitudes, the issue of whether or not we need to appeal to external constraints on the content of intentional attitudes, how we should understand the agreement and disagreement of attitudes, how we should construe communication and how we ought to solve Kripke’s puzzle about belief. The second part of this thesis also motivates a broadly internalist and individualistic approach to the con-tent of intentional attitudes; it turns out that if we take a closer look at the narrowly construed psychological states of agents we find materials that allow us to make sense of phenomena usually associated with externalist constraints on the content of attitudes (such as causal constraints and eligibility constraints) in a new way. (shrink)

Taken together, Sections 145 and 63 of the Mental Health Act 1983 provide for treatment without consent of physical illness ancillary to the mental disorder with which a patient presents. On a daily basis, clinicians make both the decision that the Act’s authority can be applied to their patient’s case, and that it should be applied. But in the unusual circumstances where there is uncertainty as to the applicability of the MHA to the ancillary treatment of physical illness, the assistance (...) of a court may be sought. In so doing, the law may justify compulsion but never prescribes it; the clinician is presented with authority that he or she could use but is left to decide whether it should be employed. This paper explores how the clinical question is set before the court, and whether the distinction between symptom, manifestation and consequence is sufficiently understood. This has important consequences in the context of self-neglect and its close cousin self-harm: the question whether the relevant ailment was attributable to or exacerbated by neglect or self- inflicted harm will determine whether compulsion under the MHA is applicable; and furthermore, whether or not compulsion is clinically acceptable. No data are available. Not applicable. (shrink)

RESUMEN La presente reflexión tiene como punto de partida la noción de antropotécnica desarrollada por el filósofo Peter Sloterdijk. El autor asume que los humanos somos seres ejercitantes en tanto día a día ejecutamos una serie de rutinas diarias que nos permiten modelar nuestra existencia. En dicho proceso nos encontramos con instituciones sociales que orientan tales ejercicios antropotécnicos. A partir de una caracterización exhaustiva del planteamiento de Sloterdijk, proponemos la noción de antropotécnica negativa, como envés de la antropotécnica, para referirnos (...) a una comprensión alternativa de las ejercitaciones contraindicadas que se realizan en oposición a valores legitimados e idealizados cutralmente sobre cómo modelar la existencia. Concluimos que la antropotécnica negativa puede ser un recurso analítico para aproximarnos a la mala ejercitación como fenómeno histórico y a la potencia existencial de algunas vidas que se expresan privilegiadamente como negatividad, abyección o marginalidad. ABSTRACT This analysis uses the notion of anthropotechnics developed by the philosopher Peter Sloterdijk as its starting point. The author assumes that humans are exercising beings in that day by day we carry out a series of diary routines that allow us to shape our existence. Within this process, we encounter social institutions that guide those anthropotechnics exercises. From an exhaustive characterization of Sloterdijk's approach, we propose the notion of negative anthropotechnics (as the inverse of anthropotechnics) to refer to an alternative understanding of the counterindicated exercises that are performed in opposition to legitimized and idealized values of how to shape existence. We conclude that negative anthropotechnics can be an analytical resource to approach malpractice as a historical phenomenon and to the existential potency of some lives that are expressed as privileged negativity, abjection, or marginality. (shrink)

We define mereologically invariant composition as the relation between a whole object and its parts when the object retains the same parts during a time interval. We argue that mereologically invariant composition is identity between a whole and its parts taken collectively. Our reason is that parts and wholes are equivalent measurements of a portion of reality at different scales in the precise sense employed by measurement theory. The purpose of these scales is the numerical representation of primitive relations between (...) quantities of being. To show this, we prove representation and uniqueness theorems for composition. Thus, mereologically invariant composition is trans-scalar identity. (shrink)

In this article, I explore how Schopenhauer's theory of aesthetic experience—independently of his theory of arts—accommodates the possibility of contemplation. The standard reading of his aesthetics is that contemplation becomes possible because of a certain “surplus” of intellect and facilitating external occasions. I argue, however, that the “essential imperfections” of intellect and Schopenhauer's overall metaphysics are inconsistent with the very idea of will‐less cognition and, hence, of a free intellect. An alternative explanation of contemplation better fits with Schopenhauer's philosophy overall (...) by stating that it is driven by the will itself. I analyze two approaches to elaborating such a theory. First, the “metaphysical” account, according to which the will as thing‐in‐itself brings forth the (surplus of) intellect needed for contemplation as a means of self‐cognition. Second, the “physiological” account, which presupposes a quasi‐evolutionary process that has aesthetic cognition as a byproduct of intellect. The two accounts complement each other and in tandem better explain the possibility of contemplation than postulating a will‐less intellect. (shrink)

The American Journal of Bioethics, Volume 11, Issue 11, Page 22-23, November 2011.

Die Metaphysik ist seit dem 21. Jahrhundert erneut in den Fokus der Aufmerksamkeit geruckt. Alexander Schnell entwickelt eine Position, die sich von neueren "realistischen" Ansatzen unterscheidet. In den systematischen Ausarbeitungen der klassischen deutschen Philosophie verstanden sich die Deutschen Idealisten zugleich als die grossten Realisten. In der aktuellen Diskussion hingegen scheint jeder idealistische Standpunkt kompromittiert zu sein, da er auf einem uberholten Subjektivismus beruhe. Der hier verteidigte transzendentale Idealismus verfolgt eine Perspektive, in der die Frage nach dem "Sein" diesseits der (...) hypostasierten Subjekt-Objekt-Beziehung gestellt wird. Diese Abhandlung uber die phanomenologische Metaphysik fugt sich somit in eine zeitgenossische Debatte ein, die sowohl philosophische (insbesondere dank des "neuen Realismus") als auch anthropologische (in Bezug auf den Status des "Relationismus") Relevanz hat. (shrink)

English summary: In this work, Alexander Schnell expounds the role played by the formation and conferral of sense in our understanding of reality and matters of fact. Starting from the phenomenological standpoint of consciousness analysis, he tries to show how the power of imagination in particular serves as a formative function for reality. Picking up on important phenomenological concepts--such as sense, the grounding of knowledge, the unconscious, reality, truth, time, space, the human, subjectivity, transcendence--the author deals with these anew. (...) The volume thereby also contributes to the reinvigorated realism-idealism debate of recent years in which phenomenology - more than a hundred years after its inception - has yet again been awarded a key role. German description: Alexander Schnell macht in diesem Band die Rolle der Sinnbildung und Sinnstiftung in unserem Verstandnis von Realitat und faktischem Geschehnis deutlich. Vom phanomenologischen Standpunkt der Bewusstseinsanalyse ausgehend, zeigt er auf, dass hierbei der Einbildungskraft eine wirklichkeitsbildende Funktion zukommt. Hierzu nimmt er einige bedeutsame Begriffe der Phanomenologie - Sinn, Erkenntnisbegrundung, Unbewusstes, Realitat, Wahrheit, Zeit, Raum, Mensch, Subjektivitat, Transzendenz - wieder auf und behandelt sie neu. Zugleich tragt dieser Band zur Realismus-Idealismus-Debatte bei, die in den letzten Jahren dank des Neuen Realismus neu entfacht und in welcher der Phanomenologie uber ein Jahrhundert nach ihrer Grundung wieder eine bedeutsame Rolle zugestanden wurde. (shrink)

George Bealer has provided an elaborate defense of the practice of appealing to intuition in philosophy. In the present paper, I argue that his defense fails. First, I argue that Bealer’s theory of determinate concept possession, even if true, would not establish the “autonomy” of philosophy. That is, even if he is correct about what determinate concept possession consists in, it would not follow that it is possible to answer the central questions of philosophy by critical reflection on our intuitions. (...) Furthermore, I argue that Bealer’s account of determinate concept possession in fact faces serious problems. Accordingly, I conclude that Bealer does not succeed in vindicating the appeal to intuition in philosophy. (shrink)

We prove the following Main Theorem: $ZF + AD + V = L(R) \Rightarrow DC$ . As a corollary we have that $\operatorname{Con}(ZF + AD) \Rightarrow \operatorname{Con}(ZF + AD + DC)$ . Combined with the result of Woodin that $\operatorname{Con}(ZF + AD) \Rightarrow \operatorname{Con}(ZF + AD + \neg AC^\omega)$ it follows that DC (as well as AC ω ) is independent relative to ZF + AD. It is finally shown (jointly with H. Woodin) that ZF + AD + ¬ DC (...) R , where DC R is DC restricted to reals, implies the consistency of ZF + AD + DC, in fact implies R # (i.e. the sharp of L(R)) exists. (shrink)

Let the chain antichain principle (CAC) be the statement that each partial order on $\mathbb{N}$ possesses an infinite chain or an infinite antichain. Chong, Slaman, and Yang recently proved using forcing over nonstandard models of arithmetic that CAC is $\Pi^1_1$-conservative over $\text{RCA}_0+\Pi^0_1\text{-CP}$ and so in particular that CAC does not imply $\Sigma^0_2$-induction. We provide here a different purely syntactical and constructive proof of the statement that CAC (even together with WKL) does not imply $\Sigma^0_2$-induction. In detail we show using a (...) refinement of Howard's ordinal analysis of bar recursion that $\text{WKL}_0^\omega+\text{CAC}$ is $\Pi^0_2$-conservative over PRA and that one can extract primitive recursive realizers for such statements. Moreover, our proof is finitary in the sense of Hilbert's program. CAC implies that every sequence of $\mathbb{R}$ has a monotone subsequence. This Bolzano-Weierstraß}-like principle is commonly used in proofs. Our result makes it possible to extract primitive recursive terms from such proofs. We also discuss the Erdős-Moser principle, which—taken together with CAC—is equivalent to $\text{RT}^2_2$. (shrink)