Graham Priest
Universities of Melbourne,
St Andrews, and the Graduate Center,
CUNY
REVISING LOGIC
The paper asks (i) whether logic can be revised; (ii) whether this
can be done rationally; and (iii) if so, how. The answers to the questions
depend on what exactly one means by ‘logic’. One must distinguish
between (a) logica docens (our theory of logic); logica utens (the logic
we use), and (c) logica ens (validity itself).
With regard to (a), the answer to questions (1) and (ii) are clearly
‘yes’, because this has happened in the history of Western philosophy.
The paper sketches a model for an answer to (iii).
With regard to (b), the paper argues that the answers to (i) and (ii)
are also ‘yes’, and answers (iii) by arguing that the rational practice is the
one determined by the most rational theory, as discussed in connection
with (a).
The answers with regard to (c), are the hardest, and depend on how
one understands what validity itself is. Whilst the paper does not try to
answer this question, it discusses how various answers to that question
will affect questions (i), (ii), and (iii).