[What follows was is an excerpt from an anonymous screed written in a world parallel to our own in the Third Galaxy. Its relevance to our own world, where torture is unacceptable, is therefore of course only theoretical]
Torture is abusing people one has under ones total control. All other definitions are bullshit serving other, usually hidden agendas.
Torture is evil, wicked, a slippery slope leading to the black hole of a bottomless hell.
By all that is holy and sacred, by all that is mundane and profane:
Take this silver bullet and shoot the beast in it's heart of cold stone, shattering it to a thousand slivers and grind it to dust.
Take this ashen stake a drive it into the void where a soul should have been.
Like all lies of the devil, torture does not even deliver what is supposed to be its "justification", that is the gathering of reliable intelligence. This has been attested to again and again in the present as well as the distant past. Upon closer examination, all claims of positive results turn out to be exaggerations of trivia and outright lies.
Torture "works" -- but only in the short term -- when it is used to terrorize and thus "pacify" a population or a subset of a population by randomly incarcerating many individuals and torturing them all.
Thus it was that the French "won" the Battle of Algiers -- but lost Algeria. Thus it was that Operation Phoenix "pacified" the villages of South Vietnam -- but lost the war. Furthermore, torture used in this way leads inevitably to extrajudicial execution -- the execrable phrase is "pump and dump".
Authoritarian and regimes resort to torture because it is an anodyne for the fears of tyrants and dictators, but there is a parallel used to justify torture to open, democratic societies: "the ticking time-bomb scenario..."
Like the piece of candy the pederast offers to a little child, the "ticking bomb" is just a come on, a trick to lure the innocent to a place where obscenities occur.
The other trick is to redefine torture, to sugarcoat the ugliness as if were a distasteful medicine needed to "cure" a greater evil.
The fact is that torture is an evil in itself. The fact is that good ends cannot be achieved through wicked deeds -- the means always justify, that is, determine, the ends.