I am of the philosophy that nearly everyone feels what they are doing is right or necessary at the moment they are doing it. Every man is the hero of his own book. It is just that sometimes their perceptions are so warped that they end up causing harm. Some perform horrible acts out of vengence or redirected agression, feeling that they are merely repaying a wrong done in the past to an individual or group. A fanatic believes he is directed by god's mandate. A rapist may excuse himself 'cause the whore deserved it'. A thief may feel that he deserves or needs the wealth more than those who already have so much. Some excuse their acts simply through the belief that the action felt right; how could something that feels so good possibly be wrong. The list is as long as the human race.