However, as we now find out, the "argument against it" is in error. It does deliver good information. See Sheik Mohammed, Khalid (KSM) for details.
But is waterboarding "torture"? After all, we routinely exposed our own troops to it as part of their training exercises. Would we torture our own personnel, do you think?
Indeed, are any of the interrogation techniques practiced at Gitmo really "torture"? Moving the thermostat up and down, sleep-deprivation, solitary, etc., are all "uncomfortable", to be sure. But are they, in your mind, "torture"?
Yes, I think waterboarding is torture, but so long as it provides information and is used on a combatant, I have no problem with it; nor, of course, when it is used for the purpose of training.
Regarding milder forms of discomfort, I don’t know. It is, I suppose, a matter of degree.