it's not necessarily the case that people who watch executions are psychotic. they feel strongly about the "integrity" of the judgment (about which they are easily convinced, as most humans are, about anything); they want the satisfaction of seeing it carried out.. 

one would imagine that after the shock of watching your first, sympathy and disgust would prevent you from seeing the next. what actually happens, i think, is an enormous feat of self-conviction; an attempt to force the act into the existing paradigm

such is the way your ambivalence drains, becomes certainty and hardens into stone