One of the better explanations I've read -- and free of the histrionics that'd be there if I were writing it -- of why our pro-torture policies are a bad idea.

Why not apply game theory to the question?  Tyler Cowen posits this scenario:

Let us say that you have been captured and threatened with torture.  You are, for whatever reason, entirely willing to betray the information you hold.  Your primary goal is to avoid pain, and perhaps you positively want to squeal.  How should you present what you know?  I see a few options:

1. Break down immediately, beg for mercy, humiliate yourself, and spill the beans.  (If you talk right away, will they torture you anyway?  And since no further good information can be offered why should they stop?)

2. Go in acting tough, really tough.  At the first sign of serious pain, start crying and switch to strategy #1.

3. Wait until they apply their "best shot" torture, and then talk.  They will feel they have done their job and stop.

4. First offer (or make up) compromising information to show your disloyalty to the cause your torturers are fighting.  Your confession will then be more credible.

5. Say you don't know anything, try to fight the torture, but break down when you can't stand it any more.  You can't fool them, so the best you can do is to actually "go through the wringer."  You are stuck in the pooling equilibrium, and trying to deviate only makes you worse off.

Which of these is the most credible signal that you have told all you know?  Can you do any better than number five?  And how does your best answer depend upon the hypothesized motives of the torturers?  Is there anything you can say to the U.S. to avoid being sent out for rendition?  I do't see any simple answer here, the question is which behavior your torturers will interpret as an unlikely tactic from a truly determined trickster.

Sebastian Holsclaw picks apart the torture argument with what has always been one of my main points in this discussion:

Now suppose that you don't actually have any information, because you have been mistakenly picked up.  How are you going to convey that to the torturers?  You can't tell them you don't know anything at the beginning--they won't believe you and will continue torturing you.  You can't tell them anything useful because you don't know anything useful.  So you are being tortured and you don't know anything.  Is it probable that you will start making stuff up in the hopes that your torturers will think they got something eventually.  I suspect it is probable. 

So if you are not a terrorist and you get picked up by those who torture, you will probably get tortured even more than many real terrorists because you can't break and give verifiably useful information. 

Conservatives don't believe in the infallibility of government agencies and all indications are that the intelligence agencies are more fallible than many.  So why would we set up a situation where innocents are likely to be tortured more than the guilty, and which is likely to produce vast amounts of faulty information?  Doesn't seem wise.  It also doesn't seem right. 

I think that torture is reprehensible and a moral outrage.  But putting that perspective aside, one of the most salient reasons to oppose torture is that we don't know if it works.  Right-wingers will come up with scary scenarios to frighten you into thinking that it's a good idea -- "what if you just captured a guy that knew where an atomic bomb was?  In Manhattan?  In a baby carriage?  With a copy of the Ten Commandments?" -- but the thing is, you never know that the guy does in fact know where the bomb is, or how to defuse it.  You don't think innocent people are ever arrested?  Don't we, in this country and as a society,  value the protections of civil liberties over the possibility of a guilty person going free?

Again:  Aside from the utter moral bankruptcy that the use of torture implies, there's no way we can know if or when it can ever be effective.  And we can never know if the person being tortured even has possession of the information being sought.  And we can never know when to stop.

(And, as a former interrogator points out, even if you spill the beans, that's no guarantee that they won't torture you anyway.)