The torture bill that just passed is one of the most reprehensible actions Congress has ever taken. There is so much wrong with it at every level. I'll just cover a few highlights of why torture is such a terrible thing, with assistance from this surprisingly intelligent Something Awful thread.
Bush & Co. argue that nobody can define precisely the boundaries of humane treatment, so there's no point in such guidelines, but does anyone doubt that ripping off people's nipples with pliers is torture? Somehow we have a firm enough definition to know that. They misleadingly say that since there is some grey area, it's all grey area. They also claim that what they're doing "isn't that bad." If that was true, why would they do it? It's a waste of energy and time to try things that don't work, not to mention just plain mean. If is effective, then it really is that bad. What would make you reveal information that could result in the capture and death of friends and relatives? Just because what they're doing sounds mild does not mean it actually is mild. It's likely that the methods they have disclosed were chosen particularly because they sound less innocuous than pliers and hot irons while still being cruel and devastatingly effective.
It's also not just about any particular method in isolation, but the totality of circumstances. There's a huge difference between reading a description of waterboarding or even having it demonstrated on you once in a safe, controlled environment, and having it inflicted on you over and over again by people who wouldn't mind if you died in a gulag from which you have no chance of escape. Certainly that provides a motivation for telling the truth.
But then, how do the torturers know you're telling the truth? If they have enough information to know what is fact and what is fiction, then the torture is pointless in all but the most extreme and contrived cases. If they don't have enough information to distinguish, they could stop before they get the real truth or continue long after. What if their corroborating information is wrong, and the victim is telling a truth that disagrees with it? The goal of torture is to break the victim, but once the victim is broken, their attachment to their cause severed, and their will made subservient to the torturers, it's ludicrous to think they could have any attachment to the truth. Torture doesn't work any better than slower, less cruel methods. More effective and less cruel methods focus on psychological manipulation that builds trust and makes the subject want to help you. And no, "make the pain stop!" is not the same thing as wanting to help you. That is the key practical issue with torture. It provides you with little that is useful while destroying something of great value.
What torture does is turn a human into a savage beast. When a torture victim is "broken," you reduce them to a sub-rational animal state of helpless terror, where the world reduces to a simple binary choice: say this and the pain continues, or say that and the pain stops. Whether there is any truth in it back from when you were still a rational human being is immaterial. Whether the interrogators promised to keep you from suffering permanent injury or dying is irrelevant. Even if you even remember what you were before or what promises you heard, you're not likely to believe it or be able to think rationally when your world has shrunk to hold only agony. That is the fundamental immorality of torture, that its effect, indeed, its goal, is to take a human being and reduce him to a cowering, fearful, pathetic animal.
The effect isn't to make you tell the truth, but to make you do whatever it takes to make it stop. There is effectively no difference between breaking your will to keep secrets and just plain breaking you and turning you into the torturer's eager slave. As a means of obtaining information, torture is almost always ineffective in comparison to the gentler methods, and you can never know until after the fact whether it was the rare case where it was more effective. As a means of obtaining reliable information, it's useless.
That doesn't mean that torture is useless in general, though. It's great for getting people to say what you want and to confess to whatever you want them to. That's why Stalin and Pol Pot and an endless list of murderous sadists liked it so much; they weren't after information or justice but instead wanted a confession to justify their actions, no matter how valid or true the confession might be. It's also effective as an intimidation tactic aimed at anyone who might cross you. In theory, that's not us, but bills like this recent one and the apparent inability of our government to listen to people with experience in these matters tells me that we're not so much better after all. Among a host of tragedies, that is a final one.
Using torture robs us of the most essential weapon we have in our battles against Al Qaeda and the like: the moral high ground. America has made plenty of mistakes, but we've always been distinguished from other nations in that our defining essence is based on principle rather than geography, ethnicity, or other accidents of history. What makes Al Qaeda and the Iraqi insurgency and the Chechens and all of those terrorists so very wrong isn't what they want, but how they're willing to hurt and kill innocents to achieve those ends. We bind ourselves with limitations because we understand that is what separates right causes from wrong ones, not the goals. What is fundamentally American is that a nation ought to be founded on freedom and justice. Torture ought to be beneath us, because we should be both too smart and too good to do it. And yet, here we are.