Why the ends do not justify the means

I don't know how this happened, but somehow, the rightness/wrongness of torture has actually become an issue for debate in this country.
I don't think anybody's trying to claim that torture is moral. It's more of an "ends justify the means" argument. Presumably, it's okay to torture somebody if it will prevent another 9/11.
This argument would only make sense if torture were the best way to gain information. Which it isn't. For example, remember that information about the al qa'ida link to Iraq? Turns out that the operative just said that so that they would stop torturing him.

Edit: Sorry! Mad props to the Angry Arab for the story.