Conscience is what prevents one from lying and also, therefore, from lying to oneself. Consequently, if a given person has no conscience, he has no conscience to prevent him from lying to himself, and he is therefore limitless able to rationalize his circumstances to himself. Whence the psychopath's apparent indifference to the consequences for himself of his own actions. It isn't that he doesn't care what happens to him: he very much cares. It is that he is willing to deceive himself about the likely consequences for himself of his actions, since he has no conscience to prevent him from engaging in deception.