Logic vs Evidence

[dyresand]

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.

sun goes up
sun goes down
reality
we revolve around the sun giving the illusion that the sun is moving up and down.