US intelligence services have traditionally said that torture doesn't yield reliable "confessions" and information -- i.e., it doesn't work.
But in any case, the reason we shouldn't torture is because torture is for regimes like North Vietnam - the animals who caged our military men and treated them inhumanely. The military of the United States - the military founded by Washington, and led by the likes of Grant, Pershing, MacArthur, Eisenhower -- does not torture. McCain is against torture, I hope and believe, because it is wrong and it would dishonor this nation and our noble military.
Have you actually read about how the United States tortures jihadists? From the look of your posts, the clear answer is a resounding NO.
But other freepers have so we can enlighten you. The forms of "torture" that we've used include sleep deprivation, playing music loudly, etc. The absolute WORST torture I've seen mentioned anywhere is light punching in the stomach.
And at least you've dropped the claims that torture doesn't work because McCain in his autobiography admits that it worked on him.