Artful Dodger: Actually, sir, you are correct! As far as it goes, that is....

Calling your debating opponent "irrational" or calling him "whacky" is roughly the same. And calling his argument "irrational" or "whacky" is also roughly the same.

The difference, the crucial one, is that applying these terms to your opponent does not logically strengthen your argument, as it does not bear on the evidence presumably culled to support it. It is therefore a diversionary tactic.

If I say that a man who says 4+4 = 5 is making an irrational statement, my position is borne out by the evidence. If I say HE is irrational, that may or may be so but it is not germain to the topic at hand and that in itself, true or not, cannot be construed as evidence that 4+4 does not equal 5.

My point is that you, in my opinion, do not use these terms in a matter conducive to healthy debate or with an aim to establishing the truth of any assertion you make, based on evidence you present. You rather use it out of anger and/or more precisely for purposes of intimidation, to in fact lessen the substantial quality of the debate, to make it harder for others to pick up the threads....and to let others know they can expect the same treatment should they disagree with you. This is, for example, what your hero O'Reilly makes a living at. And it is the first defense of most who vehemently support the official 9/11 conspiracy theory. :o)