Our philosophy professor should spend some time studying behavioural psychology.
People are not as rational and self managing as they like to think (cue the self deception and confirmation bias).
Some are sociopathic by nature, and my observation is that "It's not that they don't know that they are harming others, it's that they don't care."
Good people think that if the psychos 'knew' what they were doing then they would control themselves.
Wrong, wrong, and stupidly wrong.