Logic vs Evidence

[Chas]

I am trying to think of an example, but don't immediately think that arguments that are both sound and valid can contradict reality. Mostly, because reality is the arbiter of the truthfulness of premises.

I agree. So the answer would seem to force us to examine validity, logic itself. X strictly implies Y, for example. I don't know formal logic well enough to make that examination. :-)

Logic to me is semantic. A definitional truth.

All mammals breast feed.
Humans breast feed.
Humans are mammals.

I forget the axiom involved, but something to the effect of A is A.

Your syllogism is, in fact, incorrect.

An equivalent syllogism:
All prime numbers greater than two are odd.
Nine is an odd number.
Nine is a prime number.