At his young age, the focus needs to be on the behavior. That is, regardless of his sense of how he thinks things should be, he's expected to conform to a ceratin code of conduct that does not include physical aggression. So the preferred intervention should focus on stopping the aggressive behavior, not on changing his view of the world around him. The quickest way to stop aggression is to establish an absoulte, unalterable rule against it, and placing him in time out immediately upon the occurrence of any aggressive behavior. If you examine the behavior management approach detailed in Lynn Clark's SOS Help for Parents, you'll find the protocol that will end your son's aggressive behavior. You are correct, of course, in thinking that it will be helpful to your son to display more flexibility and adaptability, but that will come with time and experience. More quickly, he needs to stop hurting people.