[Alta-Logic] Logic Miniconference This Weekend (Belnap, Segerberg, Antonelli)

[Richard Zach]

Logic Miniconference Abstracts

All Talks in 1243 Social Sciences, University of Calgary
Relevant papers may be found by following the links below

Nuel Belnap - Pittsburgh
Friday, March 27, 4 pm

"Truth Values, Neither-True-Nor-False, and Supervaluations"

My oral remarks are based on an essay to appear in Studia Logica.  (The
essay evidently has more sections that I can adequately treat in the
time allotted.)  The first section defends reliance on truth values
against those who, on nominalistic grounds, would uniformly substitute a
truth predicate. I rehearse with great brevity some practical, Carnapian
advantages of working with truth values in logic.  In the second
section, after introducing the key idea of "auxiliary parameters," I
look at several cases in which logics involve, as part of their
semantics, an extra auxiliary parameter to which truth is relativized, a
parameter that caters to special kinds of sentences.  In many cases,
this facility is said to produce truth values for sentences that on the
face of it seem neither true nor false.  Often enough, in this situation
appeal is made to the method of supervaluations, which operate by
"quantifying out" auxiliary parameters, and thereby produce something
like a truth value. Logics of this kind exhibit striking differences.  I
first consider the role that Tarski gives to supervaluation in first
order logic, and then, after an interlude that asks whether
neither-true-nor-false is itself a truth value. I consider sentences
with non-denoting terms, vague sentences, ambiguous sentences,
paradoxical sentences, and future-tensed sentences in indeterministic
tense logic, I conclude my survey with a look at alethic modal logic
considered as a cousin, and finish with a little "advice to
supervaluationists," advice that is largely negative.  The case for
supervaluations as a road to truth is strong only when the auxiliary
parameter that is "quantified out" is in fact irrelevant to the
sentences of interest--as in Tarski's definition of 'truth' for
classical logic.  In all other cases, the best policy when reporting the
results of supervaluation is to use only explicit phrases such as
"settled true" or "determinately true," never dropping the
qualification.  

http://www.phil.ucalgary.ca/philosophy/node/410


Krister Segerberg - Uppsala/Calgary
Saturday, March 28, 10 am

Three Deontic Paradoxes

I am trying to develop a dynamic deontic logic, the outlines of which I
will sketch. To motivate this attempt, and also to assess its merits, I
will consider three classic paradoxes:  those due to Chisholm,
Ross, and Forrester.


Aldo Antonelli - California at Davis
Saturday, March 28, 2 pm

Free Quantification and Logical Invariance

In order to present the problem of providing a natural and well-behaved
semantics for (positive) free logic, a number of approaches are
considered, some old, some new -- all of which are found wanting in some
respect or other. We then shift our perspective in order to tackle the
problem from the standpoint of the theory of generalized quantifiers,
with accompanying emphasis on permutation invariance as a characteristic
feature of  logical notions. This will finally result in a natural and
well-motivated semantic theory for positive free logic -- which,
however, also leads to questioning the logical nature of free
quantification.

http://www.phil.ucalgary.ca/philosophy/node/493