Since we seem unable to define torture, perhaps we should start at a more fundamental level.
Let's start by imagining we're all fundamentally good people (even the sociapath) and it's our life experience (psychology) that steers us away from being good; is that our fault?
Does it deserve punishment? All you can do to another is deprive them of something but in doing so, you damage yourself; to condemn other's only condemns our soul.
I'm reminded of The pearl.