Peter Pagin

If proofs are nothing more than truth makers, then there is no force in the standard argument against classical logic (there is no guarantee that there is either a proof forA or a proof fornot A). The standard intuitionistic conception of a mathematical proof is stronger: there are epistemic constraints on proofs. But the idea that proofs must be recognizable as such by us, with our actual capacities, is incompatible with the standard intuitionistic explanations of the meanings of the logical constants. Proofs are to be recognizable in principle, not necessarily in practice, as shown in section 1. Section 2 considers unknowable propositions of the kind involved in Fitch''s paradox:p and it will never be known thatp. It is argued that the intuitionist faces a dilemma: give up strongly entrenched common sense intuitions about such unknowable propositions, or give up verificationism. The third section considers one attempt to save intuitionism while partly giving up verificationism: keep the idea that a proposition is true iff there is a proof (verification) of it, and reject the idea that proofs must be recognizable in principle. It is argued that this move will have the effect that some standard reasons against classical semantics will be effective also against intuitionism. This is the case with Dummett''s meaning theoretical argument. At the same time the basic reason for regarding proofs as more than mere truth makers is lost.

Suppose we have an idea of what counts as communication, more precisely as a communicative event. Then we have the further task of dividing communicative events into successful and unsuccessful. Part of this task is to find a basis for this evaluation, i.e. appropriate properties of speaker and hearer. It is argued that success should be evaluated in terms of a relation between thought contents of speaker and hearer. This view is labelled ‘classical’, since it is justifiably attributable to both Locke and Frege (section 2). Most of the paper is devoted to discussing competing contemporary views, such as behaviorist/pragmatist views (section 4), requirements of knowledge (section 5), of reliability (section 6) and that success should be defined in terms of public language semantics rather than in terms of thought content (section 7).

An assertion is a speech act in which something is claimed to hold, e.g. that there are infinitely many prime numbers, or, with respect to some time t, that there is a traffic congestion on Brooklyn Bridge at t, or, of some person x with respect to some time t, that x has a tooth ache at t. The concept of assertion has often occupied a central place in the philosophy of language, since it is often thought that making assertions is the use of language most crucial to linguistic meaning, and since assertions are the natural expressions of cognitive attitudes, and hence of importance for theories of knowledge and belief.

This is the second part of a two-part article on compositionality, i.e. the principle that the meaning of a complex expression is determined by the meanings of its parts and the way they are put together. In the first, Pagin and Westerståhl (2010), we provide a general historical background, a formal framework, definitions, and a survey of variants of compositionality. It will be referred to as Part I. Here we discuss arguments for and against the claim that natural languages have a compositional semantics. We also discuss some problem cases, including belief reports, quotation, idioms, and ambiguity.