“The very idea of penalizing based on propensities is nauseating. To accuse a person of some possible future behavior is to negate the very foundation of justice: that one must have done something before we can hold him accountable for it. After all, thinking bad things is not illegal, doing them is. It is a fundamental tenet of our society that individual responsibility is tied to individual choice of action. [...] Were perfect predictions possible, they would deny human volition, our ability to live our lives freely. Also, ironically, by depriving us of choice they would exculpate us from any responsibility.”