Generally the people saying it doesn't work all claim that a person will say anything under duress. While this is true, interrogation is generally not done in a complete vacuum.

The interrogator will know things that can help determine whether the target is lying or not. If he confirms things you know but he doesn't know you know, you're probably on the right track. It's never like in the movies where they just ask, "Who's in charge?" and ratchet up the torture until the guy answers. That would have near zero intel value.

We also talk about torture as a binary. There is really a whole range from mild discomfort to extreme pain, injury and threat of death. There is a whole range of activities to debate whether they are torture. Is threat alone torture? Some have committed suicide while facing legal threats alone. Others shrug off mere threats as just talk -- demonstrative torture could make those threats real to some and thus work.

On the flip side, the consensus (30 years ago anyway) was that if you're captured, you're going to give up everything when faced with torture, so go ahead and do so, just try to hold on for 24 hours before you do.

If a reasonably person has to ask is this torture its probably torture.

What is a reasonably person?

That ought to have been reasonable thanks.

A common ethical standard.