Upcoming Events

Hartry Field (NYU): "What Is Logical Validity?"
Friday, April 27, 2012 4:00 PM    Harbour Centre:  7000 Earl & Jennie Lohn Policy Room

I'll begin with a very brief argument that it can’t be the role of model theory or proof theory to explain the concept of validity; I may or may not have time to explain the main philosophical roles that proof theory and model theory do serve. But the main body of the talk will be concerned with two views of how the concept of validity (at least, the one employed in classical logic and in those non-classical logics that are genuine rivals to it) is to be explained.

One explanation is in terms of necessary truth-preservation; I'll argue that while this account works excellently within a wide range of cases, it fails very badly outside of that range, and that the problem in that broader range can’t be solved by shifting to the preservation of a related property such as determinate truth.

The other explanation is in terms of the conceptual role of validity, focused in particular on the role of validity in governing what we accept and reject; I've proposed something like this before, but the version offered here is much more fully developed.

Views of this sort raise some delicate questions about the normativity of logic, and its objectivity; I'll discuss such questions in terms of an analogy between validity and objective chance.