Nozick’s contribution to the epistemology of the last half of the twentieth century includes addressing the question of whether knowledge is closed under known implication. I argue that the question of closure provides a serious obstacle to Nozickian approaches to epistemology.

Would the Ontological Argument Greater Than Which None Can Be Conceived proue the existence of God? Might an ontological argument prove the actuality of the world (as Robert Nozick once suggested)? Should you believe that you’re actual, even if you’re not? And what happens if we attempt to answer these questions, having adopted Nozick’s mature view of the function of argument?

Is there a plausible argument for external world skepticism? Robert Nozick’s well-known discussion focuses upon arguments which utilize the Sensitivity Requirement and the Closure Principle. Nozick claims, correctly, that no such argument succeeds. But he gets almost all the details wrong. The Sensitivity Requirement and the Closure Principle are compatible; the Sensitivity Requirement is incorrect; and even if true, the Closure Principle is structurally incapable of generating a plausible and valid global skeptical argument. It is therefore a mistake to take the Closure Principle as central in discussions of skepticism. The paper concludes by examining the prospects for a plausible skeptical argument.

If the point of argument is to produce conviction, an argument tor a foregone conclusion is pointless. I maintain, however, that an argument makes a variety of cognitive contributions, even when its conclusion is already believed. It exhibits warrant. It affords reasons that we can impart to others. It identifies bases tor agreement among parties who otherwise disagree. It underwrites confidence, by showing how vulnerable warrant is under changes in background assumptions. Multiple arguments for the same conclusion show how our beliefs hang together.

Many theories of personal identity allow for the metaphysical possibility of fission. In 1981 Nozick proposed a theory of personal identity called ‘the closest continuer view’ (CCV) that denies fission in the case of persons but allows fisson in the case of human beings. CCV may thus appear to reduce ‘person’ to a nonmetaphysical, practical notion. Against this I argue that CCV is an externalist metaphysical theory that purports to solve a problem that is insurmountable within the confines of an internalist metaphysics of personal identity.

I begin with a rather unpromising dispute that Nozick once had with Ian Hacking in the pages of the London Review of Books, in which both vied with one another in their enthusiasm to repudiate the thesis that some human people or peoples are closer than others to animality. I shall attempt to show that one can build, on the basis of Nozick’s discussion of rationality, a defense of the view that the capacity tor language places human rationality out of reach of a comparison with animals. The difference rests, paradoxically, on the human capacity tor irratianality. Irrationality depends on the capacity tor language, which allows the detachment of explicit thoughts from their underlying dynamic implementation; these, in turn, condition the essential disputability of principles of rationality. That is what places every human potentially -- if not actually -- on the other side of an unbridgeable gulf that separates us from other animals.

This essay deals critically with Nietzsche’s anthropological typology of the “free spirit par excellence”, “we spirits”, persons endowed with positive as against negative power patterns, and the ideal of the Übermensch. The conclusions are twofold. The first is that actually it was not Nietzsche’s ideal of the Overman that was the pinnacle of his anthropological philosophy, but the even more ideal type of the “free spirit par excellence”. The second conclusion is that it is impossible to envisage a society consisting of such “free spirits”. This thesis is highlighted by contrasting the society of Übermenchen, who, according to Nietzsche, might live in society and even need it as a sine qua non for their cultivation, with free spirits par excellence, who are by definition free from any social ethos, and hence impossible within its framework. However, I argue that, on Nietzsche’s terms, the ideal of the Übermench is also not viable in society. Hence this essay points to an inherent flaw ofNietzsche’s existential philosophy -- thenon-viability of its most sublime ideals.

Theoreticity is closely connected in the (mainstream) philosophy of science to the idea of non-observability. A closer analysis of measurement, however, may give us a deeper perspective into this connection. This was done by Kyburg in his Theory and Measurement, where he argued that theory is much more pervasive then usually thought of -- even the simplest forms of measurement essentially invoke non-observables. In my article I advance Kyburg’s ideas and try to show that theoreticity implicitly invoked by Kyburg’s pervasive theory may be cast in terms of what I call “non-vagueness principle”. Further, I argue that this principle can provide for a natural demarcation between mature science and other more rudimentary forms of science.

The aim of this paper is to identify some of the motivations that can be found for taking a realist position concerning mathematical entities and to examine these motivations in the light of a case study in contemporary mathematics. The motivations that are found are as follows: (some) mathematicians are realists, mathematical statements are true, and finally, mathematical statements have a special certainty. These claims are compared with a result in algebraic topology stating that a certain sequence, the so-called Mayer-Vietoris sequence, has different properties when placed in different categories. The conclusion is that the before mentioned motivations should be modified and it is suggested that they could also be explained by a position claiming that mathematical entities are introduced by mathematicians.

According to the received view, the regularity “All F’s are G” is a real law of nature only if it supports a counterfactual conditional “If x were an F (but actually it is not), it would be a G”. Popper suggested a different approach -- universal generalisations differ from accidental generalisations in the structure of their terms. Terms in accidental generalisations are closed, extensional and terms in laws of nature are open, strictly universal, intensional. But Popper failed to develop this point and used a mistaken and unnatural interpretation of counterfactual assumptions in order to defend the view that both laws of nature and accidental generalisations support counterfactuals. The idea that terms in laws of nature stand for intensions was developed twenty-five years later in the so called DTA theory, which explains laws of nature as relations between properties.

This essay provides a critical discussion of Philip Pettit’s book A Theory of Freedom: From the Psychology to the Politics of Agency (Oxford: Oxford University Press, 2001). It evaluates the general prospeets of a ‘global theory of freedom’ of the kind advocated by Pettit, i.e. one that seeks explicitly to link a metaphysical theory of free agency to a distinct conception of political liberty. Pettit’s in many ways innovative views concerning ongoing debates in metaphysics and political theory (e.g. compatibilism, republicanism, etc.) are also examined in detail. While recognising the legitimacy and originality of this intellectual endeavour, the paper concludes that, however full of important insights, Pettit’s account fails to realise the desired “reflective equilibrium” between a theory of free agency and that of political liberty.

Two ways of characterizing natural kinds are currently popular: the Kripke-Putnam appeal to microstructure and Boyd’s appeal to causal homeostasis. I argue that these conceptions are more divergent than is often acknowledged, that they give no credence to essentialism, and that they are both faulty. In their place, I sketch an alternative view of natural kinds, which I call “bare projectibilism”. This conception avoids the appeal to explanation common to microstructuralism and the causal homeostasis view, but is still compatible with scientific realism.

A discussion of views first presented by this author and Edward Zalta in 1995 in the paper “Naturalized Platonism vs. Platonized Naturalism”. That paper presents an application of Zalta’s “object theory” to the ontology of mathematics, and claims that there is a plenitude of abstract objects, all the creatures of distinct mathematical theories. After a summary of the position, two questions concerning the view are singled out for discussion: just how many mathematical objects there are by our account, and the nature of the properties we use to characterize abstract objects. The difference between the authors in more recent developments of the view are also discussed.

Three fundamental forms of semiotic process (reference, addressing, and intentionality) are presented and their relations to language explained. After that, the fundamental inference forms (formal deduction, induction, and abduction) are presented and their connections with semiosis shown. Finally, we show some important differences between semiosis and inference, and propose to see information processing as a dynamical attractor of inference.

In this paper, I discuss the general features of what I call ‘the semantics of message and attachment’. According to this theory, utterances of declarative sentences may be semantically associated with a plurality of information contents. I explain how this suggestion may provide a promising tool for the analysis of a variety of phenomena in the semantics for natural languages, such as complex demonstratives, dangling adverbs, or appositive clauses. I then focus on certain structural aspects of the theory, in particular pertaining to the demands it imposes on the lexicon, and on the role it plays with respect to the truth-conditions for an utterance. In this last respect, I also discuss the logical outcomes of the theory, and I compare what I call a ‘content-containment’ approach to validity with a more traditional, truth-conditional understanding.

This essay on the social history of logic discusses arguments in the programmatic writings of Carnap/Neurath, but especially in the widely read book by Lillian Lieber, Mits, Wits and Logic (1947), where Mits is the man in the street and Wits the woman in the street. It was seriously argued that the intense study of formal logic would create a more rational frame of mind and have many beneficial effects upon the social and political life. This arose from the conviction that most metaphysical conundrums, religious and political problems and even fanaticism had their root in the irrationality of ordinary discourse, which had to be replaced by the more logical “ideal language” of Principia Mathematica. The enthusiastic promotion of formal logic occurred at a time when it was widely thought that minds could be “made over”, “reprogrammed” by proper intervention. J.B. Watson, (who claimed that he taught the American woman to smoke) wrote that “[S]ome day we shall have hospitals devoted to helping us change our personality, because we can change the personality as easily as we can change the shape or our nose... I wish I could picture for you what a rich and wonderful individual we should make of every healthy child”. Thesecond part of the essay deals, not with the history of logic as a formal science, but with the social role it was thought to play from Francis Bacon on, during the Enlightenment, in Kant and in the 19th century.

Many philosophers argue that Bayesian epistemology cannot help us with the traditional Humean problem of induction. I argue that this view is partially but not wholly correct. It is true that Bayesianism does not solve Hume’s problem, in the way that the classical and logical theories of probability aimed to do. However I argue that in one important respect, Hume’s sceptical challenge cannot simply be transposed to a probabilistic context, where beliefs come in degrees, rather than being a yes/no matter.

Scott Atran has argued that scientific thinking about living things necessarily emerges out of a common-sense structure of ideas which reflects the ways in which humans are constitutionally disposed to think about ‘manifestly perceivable empirical fact’. He maintains that the uniformity in folk-biological taxonomy under diverse socio-cultural learning conditions established by recent ethnobiological research undermines the predominant view that folk classifications of living things are a function of local interests and culture, and he further maintains that such uniformity must be grounded in species-specific and domain-specific cognitive capacities. I consider certain philosophically controversial lessons that Atran wishes to draw from these claims, concerning (a) philosophical theories of natural kinds, and (b) the ‘reality’ of folk-biological kinds and the relation between such kinds and the kinds posited by biological science. I argue that, even if we grant the ethnobiological evidence to which he appeals, such evidencedoes not bear upon the philosophical issues in the ways that he proposes.