Egoism is usually considered in two forms. Psychological egoism is the view that people are always motivated by self-interest. Ethical egoism is the view that whether or not people are like this, they ought to be like this; usually this is advanced in the form that rational behaviour requires attempting to maximize self-interest. Psychological egoism is usually thought to depend upon confusions, such as reasoning from ‘all my actions need a motive which is mine’ (true) to ‘a state of myself is the object of all my motives’ (false, or at any rate not proven). Critics such as Joseph Butler also emphasize that without other objects of desire a life spent absorbed in one's own pleasure cannot well get off the ground (see hedonism, paradox of). We need something independent to spark the pleasure. Ethical egoism is often argued to be self-defeating, in that a society of egoists do worse for themselves than a society of altruists (see prisoners' dilemma). Another fundamental objection is that it is inconsistent with the nature of trust and friendship that each party should be motivated solely by self-interest. Yet the ethical egoist gives no reason why these goods should be given up in favour of an egoistic conception of rational behaviour. See also altruism, friendship.