In his paper “Explaining Deductive Inference” Prawitz states what he calls «a fundamental problem of logic and the philosophy of logic»: the problem of explaining «Why do certain inferences have the epistemic power to confer evidence on the conclusion when applied to premisses for which there is evidence already?». In this paper I suggest a way of articulating, and partly modifying, the intuitionistic answer to this problem in such a way as to both answer Prawitz’s problem and satisfy a requirement (...) I argue to be crucial for any epistemic theory of the meaning of the logical constants: the requirement that evidence is epistemically transparent. (shrink)

In section 1 we argue that the adoption of a tenseless notion of truth entails a realistic view of propositions and provability. This view, in turn, opens the way to the intelligibility of theclassical meaning of the logical constants, and consequently is incompatible with the antirealism of orthodox intuitionism. In section 2 we show how what we call the potential intuitionistic meaning of the logical constants can be defined, on the one hand, by means of the notion of atemporal provability (...) and, on the other, by means of the operator K of epistemic logic. Intuitionistic logic, as reconstructed within this perspective, turns out to be a part of epistemic logic, so that it loses its traditional foundational role, antithetic to that of classical logic. In section 3 we uphold the view that certain consequences of the adoption of atemporal notion of truth, despite their apparent oddity, are quite acceptable from an antirealist point of view. (shrink)

I will be concerned with the following question: are there compelling arguments for postulating a distinction between the truth of a statement and the recognition of its truth, when truth is conceived along the lines of a suitable generalization of the intuitionistic idea that it should be characterized as the existence of a proof? I will argue that the distinction is not necessary within the conceptual framework of intuitionism by replying to two arguments to the contrary, one based on the (...) paradox of inference, the other on considerations concerning the content of a statement. (shrink)

Suppose we want to take seriously the neoverificationist idea that an intuitionistic theory of meaning can be generalized in such a way as to be applicable not only to mathematical but also to empirical sentences. The paper explores some consequences of this attitude and takes some steps towards the realization of this program. The general idea is to develop a meaning theory, and consequently a formal semantics, based on the idea that knowing the meaning of a sentence is tantamount to (...) having a criterion for establishing what is a justification for it. Section 1 motivates a requirement of epistemic transparency imposed onto justifications conceived as mental states. In Section 2, the formal notion of justification for an atomic formula is defined, in terms of the notion of cognitive state. In Section 3, the definition is extended to logically complex formulas. In Section 4, the notion of truth-ground is introduced and is used to give a definition of logical validity. (shrink)

Suppose we are prepared to conceive the meaning of a sentence as a classification criterion which enables us to establish whether something is or is not a justification to believe that sentence. Which properties of the intuitive notion of justification are, from this point of view, essential for believing a sentence? And how might a theoretical notion of justification for a sentence be defined? In Sections 2-5 some properties are suggested as essential, in particular Intentionality (a justification is always a (...) justification for a sentence), Defeasibility (a justification for a sentence A can cease to be a justification for A as new information is received), and Epistemic transparency (a justification for A is not a justification for A unless it is recognized as such by an idealized knowing subject). In Section 6 a sketch of definition is proposed, according to which a justification for a sentence A is a cognitive state in which the subject has at his disposal a certain amount of information, and the hypothesis that A is the best explanation of that information. Section 7 shows how the notion defined escapes a crucial objection to defeasible justifications recently stated by P. Casalegno. (shrink)

The articles of this volume address only some aspects of Nozick's philosophy: his conception of argument, knowledge, rationality, and identity. In examining Nozick's approach to these topics, one has to take issue, ultimately, with his peculiar conception of philosophy whose manifesto appears at the outset of Philosophical Explanations and is echoed in the introduction to philosophical method of Invariances . To transform philosophy into a science or build an impeccable deductive system was not Nozick's dream. He thought of philosophy as (...) aiming at explanation rather than proof. The goal in pursuing philosophy is not to establish one view, but to elaborate theories that can make us understand some phenomena better. (shrink)

This volume develops a theory of meaning and a semantics for both mathematical and empirical sentences inspired to Chomsky’s internalism, namely to a view of semantics as the study of the relations of language not with external reality but with internal, or mental, reality. In the first part a theoretical notion of justification for a sentence A is defined, by induction on the complexity of A; intuitively, justifications are conceived as cognitive states of a particular kind. The main source of (...) inspiration for this part is Heyting’s explanation of the intuitionistic meaning of logical constants. In the second part the theory is applied to the solution of several foundational problems in the theory of meaning and epistemology, such as Frege’s puzzle, Mates’ puzzle about synonymy, the paradox of analysis, Kripke’s puzzle about belief, the de re/de dicto distinction, the specific/non-specific distinction, Gettier’s problems, the paradox of knowability, and the characterization of truth. On a more general philosophical level, throughout the book the author develops a tight critique of the neo-verificationism of Dummett, Prawitz and Martin-Löf, and defends a mentalist interpretation of intuitionism. (shrink)