Bob Hale教授・Conrad Asmus博士講演会

2012/11/26 Bob Hale教授・Conrad Asmus博士講演会

Bob Hale教授 (University of Sheffield)
Conrad Asmus博士 (RCIS)
Contingent beings (Bob Hale)
Cross term restrictions in theories of logical consequence (Conrad Asmus)

Contingent beings
(Bob Hale)
This discusses some problems confronting an essence-based account of
necessity and possibility arising from the assumption that many things which
exist might not have existed, and that there might have existed things other
than those which actually exist. This includes some discussion of a view of
Kit Fine’s about necessity and non-existence and a puzzling argument he uses
to motivate it, which infers from plausible premises?\?eAristotle is
necessarily a man?f and ?eAristotle might not have existed?f?\the seemingly
unpalatable conclusion ?eAristotle might have been a man but not existed?f.

Cross term restrictions in theories of logical consequence
(Conrad Asmus)
In The Concept of Logical Consequence, John Etchemendy argues against
interpretational theories of consequence. An interpretational theory of
consequence deems A to be a consequence of B if and only if, for every
interpretation of the non-logical vocabulary in A and B, if B is true, so is
A. Only the interpretation of non-logical vocabulary is allowed to vary;
other than this, the way that the world is must remain constant. Etchemendy
demonstrates that any interpretational theory of consequence for classical
logic (where the domains of quantification vary) relies on cross term
restrictions. A cross term restriction is a restriction on the variation of
interpretations between logical categories. This is an unwarranted
restriction on all possible interpretations and is, according to Etchemendy,
unmotivated in the interpretational context. I will show that there are
standard free logics that do motivate some cross term restriction. I will
then discuss observations from Dummett’s Frege: philosophy of language that
provide different ways of motivating cross term restrictions in the non-free
logic cases. If any of these motivations are acceptable, then classical
logic can be recaptured. Finally, I will discuss the importance of this
discussion for noninterpretational theories.