From the one man’s modus ponens is another
man’s modus tollens department, here’s a passage on time travel from Ned
Markosian’s entry on time
in the Stanford Encyclopaedia of Philosophy.

And for another
thing, as I mentioned at the beginning of this section, we often think about
time travel stories; but it is very plausible to think that a story cannot
depict things that are downright impossible. For example, it is natural to
think that there could not be a story in which two plus two are five, or in
which there is a sphere that both is and is not red all over. (This seems
especially true if the story is told pictorially, as in the case of a movie.)
Hence, if time travel is impossible, then we should not even be able to
consider any story in which time travel occurs. And yet we do so all the time!
One task facing the philosopher who claims that time travel is impossible,
then, is to explain the existence of a huge number of well-known stories that
appear to be specifically about time travel.

Hmm. I seem to remember drawing exactly the
opposite conclusion from this. It was sort of a crucial point in my imaginative
resistance paper that since we can represent impossible time travel
situations in fictions, fictional representability did not entail possibility.
(This argument was lifted in its entirety from some almost parenthetical
remarks in Tamar Gendler’s paper on imaginative resistance.) So who’s drawing
the right inferences here?

Well, I think I am. (No? Really?!) Ned’s
looking for an argument that time travel is possible. But this argument
overgeneralises, for if it worked it would be an argument that many kinds of
time travel are possible, including changing the past Back to the Future style
time travel that most everyone agrees is impossible. Since we can represent
that kind of time travel, the fact that we can also represent the more seamless
kinds of time travel where the past and future all ‘fit together’ hardly shows
that that kind of time travel is possible.