We investigate axiomatizations of Kripke's theory of truth based on the Strong Kleene evaluation scheme for treating sentences lacking a truth value. Feferman's axiomatization KF formulated in classical logic is an indirect approach, because it is not sound with respect to Kripke's semantics in the straightforward sense: only the sentences that can be proved to be true in KF are valid in Kripke's partial models. Reinhardt proposed to focus just on the sentences that can be proved to be true in (...) KF and conjectured that the detour through classical logic in KF is dispensable. We refute Reinhardt's Conjecture, and provide a direct axiomatization PKF of Kripke's theory in partial logic. We argue that any natural axiomatization of Kripke's theory in Strong Kleene logic has the same proof-theoretic strength as PKF, namely the strength of the system RA< ωω ramified analysis or a system of Tarskian ramified truth up to ωω. Thus any such axiomatization is much weaker than Feferman's axiomatization KF in classical logic, which is equivalent to the system RA<ε₀ of ramified analysis up to ε₀. (shrink)

I consider three aspects in which machine learning and philosophy of science can illuminate each other: methodology, inductive simplicity and theoretical terms. I examine the relations between the two subjects and conclude by claiming these relations to be very close.

Quine's reasons for recommending naturalist epistemology are: (1) knowledge, Mind and meaning are part of the world they have to do with, (2) since the cartesian quest for certainty and reductionism of carnap's 'aufbau' type have failed, Rational reconstruction has no more any advantage over psychology, (3) since phenomenalist validation of science is no longer our concern, It is not circular to appeal to psychology. Against this it is argued that (a) no definite methodological policy can be based on (1) (...) alone; (b) certainty and phenomenalist reduction are not the only purposes of rational reconstruction; (c) it would be circular to appeal to psychology in developing a theory of rational method of acquiring knowledge: (d) logic and psychology of science are complementary not mutually exclusive. (shrink)

Natural modalities are often analysed from an abstract point of view where they are associated with putative laws of nature. However, the way possibilities are represented in physics is more complex. Lagrangian mechanics, for instance, involves two different layers of modalities: kinematical and dynamical possibilities. This paper examines the status of these two layers, both in the classical and quantum case. The quantum case is particularly problematic: we identify four possible interpretive options. The upshot is that a close inspection of (...) the way possibilities are represented in physics could lead to new ways of thinking about natural modalities. (shrink)

In this paper, I develop a "safety result" for applied mathematics. I show that whenever a theory in natural science entails some non-mathematical conclusion via an application of mathematics, there is a counterpart theory that carries no commitment to mathematical objects, entails the same conclusion, and the claims of which are true if the claims of the original theory are "correct": roughly, true given the assumption that mathematical objects exist. The framework used for proving the safety result has some advantages (...) over existing nominalistic accounts of applied mathematics. It also provides a nominalistic account of pure mathematics. (shrink)

Scientific realism is the view that the aim of science is to produce true or approximately true theories about nature. It is a view which not only is shared by many philosophers but also by scientists themselves. Regarding Kuhn’s rejection of scientific progress, Steven Weinberg once declared: “All this is wormwood to scientists like myself, who think the task of science is to bring us closer and closer to objective truth.” But such a realist view on scientific theories is not (...) without problems. The paper discusses some arguments for and against the ontological commitments that scientific theories may entail. The upshot is that scientific realism according to which the semantic content of theories should be understood literally is not sustainable. Instead, it is argued that only realism with respect to entities can be reasonably and practically maintained. Finally, the paper discusses structural realism which presents itself as a modern alternative to scientific realism which may meet both the optimistic no-miracle argument and the pessimistic meta-induction argument. My conclusion is that such a position is neither attractive nor defendable. (shrink)

I offer an explicit account of the underdetermination thesis as well as of the many challenges it poses to scientific realism; a way to answer to these challenges is explored and outlined, by shifting attention to the content of theories. I argue that, even if we have solid grounds (as I contend we do) to support that some varieties of the underdetermination thesis are true, scientific realism can still offer an adequate picture of the aims and achievements of science.

Carl Hempel introduced what he called "Craig's theorem" into the philosophy of science in a famous discussion of the "problem of theoretical terms." Beginning with Hempel's use of 'Craig's theorem," I shall bring out some of the key differences between Hempel's treatment of the "problem of theoretical terms" and Carnap's in order to illuminate the peculiar function of Wissenschaftslogik in Carnap's mature philosophy. Carnap's treatment, in particular, is fundamentally antimetaphysical—he aims to use the tools of mathematical logic to dissolve rather (...) solve traditional philosophical problems—and it is precisely this point that is missed by his logically-minded contemporaries such as Hempel and Quine. (shrink)

Richard Cytowic has done considerable service to the scientific study of synesthesia, conducting important research and publishing two recent books on the subject. The study of synesthesia raises interesting questions about scientific method, both because of the negative reception it received initially--often being viewed as tainted by a reliance upon introspective reports--and because of the connections Cytowic has found between synesthetic perception and the limbic system, thereby possibly undermining some of the claims to objectivity in perception and scientific method. I (...) dispute some of the more extreme methodological conclusions Cytowic draws from his work and reinforce others by reference to different arguments current within the philosophy of science. (shrink)

Work on how to axiomatize the subtheories of a first-order theory in which only a proper subset of their extra-logical vocabulary is being used led to a theorem on recursive axiomatizability and to an interpolation theorem for first-order logic. There were some fortuitous events and several logicians played a helpful role.

Consistency of choice is a fundamental and recurring theme in decision theory, social choice theory, behavioral economics, and psychological sciences. The purpose of this paper is to study the consistency of choice independent of the particular decision model at hand. Consistency is viewed as an inherently logical concept that is fundamentally void of connotation and is thus disentangled from traditional rationality or consistency conditions imposed on decision models. The proposed formalization of consistency takes two forms: internal consistency, which refers to (...) the property that a choice model does not generate contradictory statements; and semantic consistency, which refers to the idea that a theory’s predictions are valid with respect to some observed data. In addressing semantic consistency, the relationship between theory and data is analyzed in terms of so-called duality mappings, which allow a passage between the two universes in a way that consistency is preserved. The formalization of consistency concepts relies on adapting the revealed preference theory to the context-dependent setting. The paper concludes by discussing the implications of the proposed framework and how it relates to classical revealed preference theory and other formalizations of the relationship between the theory and reality of choice. (shrink)

On the basis of a wide range of historical examples various features of axioms are discussed in relation to their use in mathematical practice. A very general framework for this discussion is provided, and it is argued that axioms can play many roles in mathematics and that viewing them as self-evident truths does not do justice to the ways in which mathematicians employ axioms. Possible origins of axioms and criteria for choosing axioms are also examined. The distinctions introduced aim at (...) clarifying discussions in philosophy of mathematics and contributing towards a more refined view of mathematical practice. (shrink)

This paper seeks to evaluate the potential of the Newman objection to function as an immanent critique of Carnap's use of the Ramsey method of regimenting scientific theories. Stress is laid on the distinctive way in which ramseyfications are used by Carnap to formulate the analytic/synthetic distinction for the theoretical language and on the difference between the ontological and the epistemic readings of the Newman objection. While the former reading of the Newman objection is rejected as trading on an assumption (...) that Carnap did not share, the latter is accepted as critical. It is argued to turn on overlooking that the Ramsey sentence constitutes an idealization concerning which our normal expectations of what theories are like are bound to be frustrated. This idealisation need not reflect Carnap's considered view but can be regarded as adopted solely for the project of semantic explication. The distinctions drawn in the course of the argument also help to motivate Carnap's abstention from the discourse of realism and its denial. (shrink)