[FOM] Tennant on relevant logic
A.P. Hazen
a.hazen at philosophy.unimelb.edu.au
Sat Mar 4 01:10:55 EST 2006
I have an awful feeling that two different things are being
discussed without distinguishing between them. Could Professor
Tennant say something about the relation between his "Classical
Relevant Logic" (and his real favorite, "Intuitionistic Relevant
Logic") and the systems studied in the tradition starting with
Ackermann, Anderson and Belnap?
Tennant's systems amount to classical or intuitionistic logic with
certain restrictions on the sorts of proofs allowed. In particular,
they have the same logical vocabulary as Classical (resp.
Intuitionistic) logic. What the other tradition calls relevant (or
relevance) logics extend classical logic by the addition of
non-classical connectives (the implication connective, and sometimes
"fusion" and "fission", which are analogous to Girard's
multiplicatives). They also do NOT involve a restriction to cut-free
proofs.
Since the stronger relevant logics contain classical logic, I
suspect Tennant's theorem (classical consequences of consistent
axioms are relevant consequences of them) may well apply to them as
well. I am less confident (but basically ignorant) of whether it
would apply to the weaker relevance logics of interest to
(dialetheic and other) fans of non-trivial inconsistent "naive" set
theory. (Cut-free formulations are known for many relevance logics,
but the metatheory of these systems is very difficult!)
---
Allen Hazen
Philosophy Department
University of Melbourne
More information about the FOM
mailing list