It is often alleged that altruism is inconsistent with economic rationality, which assumes that people behave selfishly. Certainly, much economic analysis is concerned with how individuals behave, and homo economicus (economic man) is usually assumed to act in his or her self-interest. However, self-interest does not necessarily mean selfish. Some economic models in the field of behavioural economics assume that self-interested individuals behave altruistically because they get some benefit, or utility, from doing so. For instance, it may make them feel better about themselves, or be a useful insurance policy against social unrest, say. Some economic models go further and relax the traditional assumption of fully rational behaviour by simply assuming that people sometimes behave altruistically, even if this may be against their self-interest. Either way, there is much economic literature about charity, international aid, public spending and redistributive taxation.