This
is a series of periodic online talks delivered by early career
researchers working in proof-theoretic semantics or akin fields,
organised by the PTS-Network.
https://ksu.zoom.us/j/98878047069?pwd=1cbukpC7U6BBHTLIRAMDQY5kTlLh2Y.1Meeting ID: 988 7804 7069Passcode: pts
On
February 25, 5pm (UTC+0): Mariela Rubin (University of Buenos Aires)
will present her work with the title "A substructural route to Gibbard's collapse result".
Here is the abstract:
"In
1980, Gibbard proved that when one extends classical logic logic with a
symbol meant to model the indicative conditional that validates the
equivalence known as Import-Export, that is supraclassical, —that is, if
φ classically implies ψ, then 'if φ then ψ' is a theorem of the
extended logic— and if one assumes that the indicative conditional is at
least as strong as the material conditional, then both collapse into
the material. Later on, Fitelson showed that it is not necessary to
assume classical logic, rather intuitionistic logic suffices for the
collapse to happen. These results are usually stated in terms of a
dilemma: either one accepts that the indicative conditional is something
in between the intuitionistic and the material conditional or one
endorses a semantics for indicative conditionals that invalidates
Import-Export or Supraclassicality.
In this work, I will show
that the collapse can happen in even weaker logics, in particular in
many non-contractive and non-monotonic logics. I will also show that it
is not necessary to assume anything about the rest of the language (in
particular about conjunctions), yet there are some structural
assumptions needed to derive the collapse. As a consequence of this
result, several non-monotonic conditionals will also collapse to the
indicative. I will show it three times. First without assuming anything
about the non-conditional fragment of the language. Then I will prove it
twice with two different sets of more conservative assumptions.
Following
Belnap's famous arguments about tonk (1962), I will reflect on how the
consequence relation influences the meaning of the connectives one is
defining and I will argue that if one thinks the meaning of a
conditional in terms of the rules it validates, then some of these
conditionals are good candidates to model indicatives."
Please make sure you convert the time correctly to your time zone!