This is something I have also struggled with and I have come to this: no, it's not ok under any circumstances.

People for it generally argue for a fictitious situation that is black and white. Kill one, save a thousand. In theory that sounds great.

To believe something in theory and implement it in practice can seem be opposite at times.

Assuming that situation is black and white. What information is getting discovered? Is it, where's Osama bin Ladin? ISIS HQ? Let's say that information is discovered. The west goes in and kills the one to save a thousand. What's the fallout?

First, you make the terrorist a martyr. In Islam, this is just like a catholic sainthood/canonizing. Then, their role will/can just be replaced. Think of the mythical hydra here. Not exactly a 1 for 2, but definitely a possibility. Lastly, these groups will not be disuaded or thwarted by a single instance. There would need to be a missive amount of high level people that would be torture-able.

Many of them have done bad things according to western ideals. But most importantly it's what torture does to the torturer.

Again, the administration of torture affects the torture more; bc it only takes a small series of bad events for the torturer (or the people group they represent) to become the new terrorist(s).

Final note, the world is never black and white. My second favorite Samuel Clemens quote is "Truth is stranger than fiction, but it is because Fiction is obliged to stick to possibilities; Truth isn't." Nearly any society that seeks to guide people to some sort of utopia never truest actualizes. Instead, it produces a dystopian nightmare.

Once you become a minority, then you are an outsider. Outsiders can been seen as threats. Therefore, as a minority you can become a threat.