Grice, "⥽ and ⊃"

In "Introduction to Logical theory", Strawson wrote:


"⊃ and 'if'"

--- He was criticising Grice.

Grice took the challenge. He dedicated his William James Logic, on Logic and Conversation, to Strawson. Notably to Strawson's mis-account of 'if':

Grice started his lectures with a recognition of his own mistakes in "Causal theory of perception", but adds:

"A bigger mistake," however, "is made by Strawson".

Grice goes on to quote verbatim from Strawson:

Grice writes, on p. 9 of his book, when Strawson is first cited:

"Again, Strawson maintained that, while 'if p, then q' entails 'p ) q', the reverse entailment does not hold; and he characterised a primary or standard use of "if ... then" as follows."

Then Grice quotes from Strawson, Intr. Log. Theory, III, pt. 2:

"each hypothetical statement made by this
use of 'if' is acceptable (true, reasonable)
if the antecedent statement, if made or accepted,
would be in the circumstances be a good ground or
reason for accepting the consequent statement; and
the making of the hypothetical statement carries
this [IMPLICATION] either of uncertainty about, or
of disbelief in, the fulfilllment of both antecdent
and consequent."

Grice, who played bridge, went on to provide a few examples where Strawson's commentary does not apply. In this, Grice is being Megarian.

Oddly, when I was browsing the Journal of Philosophy, I came across an essay by J. F. Thomson (he was an Oxford exile in MIT). He had written on "In defense of material implication", as Grice would. The thing was written by Thomson in 1966. And Grice cites Thomson in Reply to Richards in 1986. Spirits with affinity.

----

When Grandy/Warner were compiling their festschrift for Grice, they contacted Sir Peter. Rather than write something new, he said, "Publish this". It was ") and if" and it provoked some new literature on an old topic -- but always fascinating.

So what we should consider is if

"if p, q"

is best represented, as Grice thinks, as

p ⊃ q

or as some other theorists propose (Strawson is never clear):

p ⥽ q

Or not.