I'd like to challenge the validity of the "Ad Hominem" fallacy - it seems to rest on a certain metaphysics. At the very least, this metaphysics should be argued, not assumed, in my view. The separation of a person from his/her ideas strikes me as certainly not obvious. Isn't this the reason why we urge people not to discuss religion and politics with each other? Because their views, expressive of their very identities, can offend us?