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David J. Chalmers, Alan Hájek, Ramsey + Moore = God, Analysis, Volume 67, Issue 2, April 2007, Pages 170–172, https://doi.org/10.1093/analys/67.2.170
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Extract
Frank Ramsey (1931) wrote:
If two people are arguing ‘if p will q?’ and are both in doubt as to p, they are adding p hypothetically to their stock of knowledge and arguing on that basis about q. . . . We can say that they are fixing their degrees of belief in q given p.
Let us take the first sentence the way it is often taken, as proposing the following test for the acceptability of an indicative conditional:
‘if p then q’ is acceptable to a subject S iff, were S to accept pand consider q, Swould accept q.
Now consider an indicative conditional of the form
Suppose that you accept p and consider ‘I believe p’. To accept p while rejecting ‘I believe p’ is tantamount to accepting the Moore-paradoxical sentence ‘p and I do not believe p’, and so is irrational. To accept p while suspending judgment about ‘I believe p’ is irrational for similar reasons. So rationality requires that if you accept p and consider ‘I believe p’, you accept ‘I believe p’.
