Online research in philosophy

I present an argument that negation is a problem for proof-theoretic semantics: it's meaning cannot be defined by rules of inference, and that's particularly problematic for Dummett's and Prawitz' Justification of Deduction. I won the Jacobsen Essay Price of the University of London for this essay a few years ago.

The focus of this paper are the meaning-theoretical arguments against classical logic that Dummett bases on consideration about the meanings of negation. Using Dummettian principles, I shall outline three such arguments, of increasing strength, and show that they are unsuccessful by giving responses to each argument on behalf of the classical logician. What is crucial is that in responding to these arguments a classicist need not challenge any of the basic assumptions of Dummett's outlook on the theory of meaning. In (...) particular, I shall grant Dummett his general bias towards verificationism or justificationism, encapsulated in the slogan `meaning is use'. The second general assumption I see no need to question is Dummett's particular breed of molecularism. Some of Dummett's assumptions will have to be given up, if classical logic is to be vindicated in his meaning-theoretical framework. A major result of this paper will be that the meaning of negation cannot be defined by rules of inference in the Dummettian framework. (shrink)

The fundamental assumption of Dummett’s and Prawitz’ proof-theoretic justification of deduction is that ‘if we have a valid argument for a complex statement, we can construct a valid argument for it which finishes with an application of one of the introduction rules governing its principal operator’. I argue that the assumption is flawed in this general version, but should be restricted, not to apply to arguments in general, but only to proofs. I also argue that Dummett’s and Prawitz’ project of (...) providing a logical basis for metaphysics only relies on the restricted assumption. (shrink)

Ph.D. thesis submitted for Philosophy (KCL) on 24 July 2007. Supervisors: Keith Hossack, Mark Sainsbury and Wilfried Meyer-Viol.

In this paper, I'll present a general way of "reading off" introduction/elimination rules from elimination/introduction rules, and define notions of harmony and stability on the basis of it.