Let me suggest a few reasons why I think that last question is the wrong one.
First, torture DID work. It forced false agreement with war lies, helping to launch a long-desired illegal war. And it persuaded many Americans that some very scary and very foreign people were out to get them, people so scary that they had to be tortured in order to talk with them, people whose every false utterance, aimed at stopping the pain, instead generated color-coded horror warnings.
Second, torture has boosted recruitment for anti-U.S. organizations tremendously, horribly damaged the United States' image, stripped U.S. diplomats of the power to address human rights abuses abroad, as well as stripping U.S. citizens of a clear moral right to protest being tortured, and set an example that has spread far and wide. Torture has brutalized participants and witnesses, and we are all witnesses, and it has destroyed lives both through torture to the point of death and through torture to the point of unbearable life.
Fourth, if torture had produced life-saving information, we would have long since heard that fact shouted from every television studio. In fact, we did hear such claims made. They just all turned out to be fictional. In the latest claim of this sort, torture supposedly produced information on the planned bombing of a building in Los Angeles, and this information was transported back in time to the moment at which investigators had already discovered that proposal and laughed heartily at the then-debunked claim that a serious plot had ever developed. The fact that Dick Cheney is pushing this nonsense on us is not actually a compelling reason to believe it unquestioningly.
Fifth, if torture ever produced life-saving information it would be through sheer luck and not intention. Nobody tortures with that intention, because expert interrogators believe other methods are more effective than torture. And if that lucky day ever came, there would be no basis on which to surmise that other methods would not have been at least as effective as the torture was. So, even if a real ticking time bomb situation could be created, there would be no reason to believe torture to be the best tool. And if you could magically design a situation in which, by definition, torture was the ethical choice, you still would not have created a situation in which ignoring the crime of torture would do less damage than pardoning the torturers.
But so must the debate over whether torture must be abolished. Torture is illegal. Our laws must be enforced. Torture's recent prominent use by the United States came about in an attempt to promote a far worse crime than torture, the crime of aggressive war. We should not be asking ourselves whether torture was an acceptable means toward that end. We should be asking ourselves how we can best rid the world of wars of aggression.