Why are apparently good people tempted to commit evil acts, asks novelist AL Kennedy.I spend a lot of time in hotels. They offer many temptations and although, like most people, I believe I'm more than averagely honest, nevertheless temptation does prove, on occasion, tempting. Well, it would.These days, mini-bars are often left both warm and aggressively empty to circumvent thefts, but since I have no interest in any mini-bar's contents I feel this bespeaks a hurtful lack of trust. And I wouldn't - unlike some acquaintances - steal a towel, no matter how snowy, or unscrew a light fitting and take it home.But in a hotel corridor, if someone has happened to leave a room service trolley unattended and the biscuits in my room are horrible and there are all these packs of Bourbon creams just lying there and they are for guests and I am a guest and I would even bring the bloody fruit Shrewsburys that were in my room back (and I'd point out they're not fruit Shrewsbury, they've got some currants, they're mummified and sparse fruit corpse Shrewsburys) and I would possibly swap the Shrewsburys for the Bourbon creams which would be fair, but I know that, yes, my biscuit appropriation is still technically stealing… And I have helped myself to Bourbon creams, which is to say, stolen them. Once or twice.I did wrong. Because I was unobserved. No one was watching me.And I'm not alone in behaving badly when I know I'm unobserved. When psychologists test how people behave with and without oversight, it becomes depressingly clear that if we think nobody's looking, we don't even remotely always let our conscience be our guide. And this means we do bad things, sometimes extremely bad things. And our doing of bad things and how preventable this is has fascinated me all my life.We inhabit an age when the complaint, "Why do bad things happen to good people?" is often voiced. It's a question I find slightly pointless, because perceived goodness is no defence against physics. How could it be? And because sometimes other apparently good people are making the bad things happen.After World War II showed our species just how many hells on earth it could create, a whole generation of researchers devoted themselves to what I find a much more vital question. "Why do apparently good and normal people do abnormal and appalling things ?" Interestingly, those post-war researchers - psychologists, sociologists, anthropologists - found answers to that question.They found reliable, repeatable results which offer a map we could follow to better places, a guide we could offer to children everywhere, as necessary as instructions on how to cross roads safely - how to be human safely, how not to behave like a sociopath.