Here's a good paradox that destroys post-modernism:

According to post-modernism, there is an infinite amount of interpretations to everything. All interpretations are equally valid.

In order for this to be true, there needs to be a finite amount of interpretations (just one) of what's true. (Paradox 1)

Also, the claim that there is a finite amount of interpretations and that these are NOT equally valid, must be valid as well. (Paradox 2)

Post-modernism destroys itself.