Philosophers such as Hobbes argued that a government must force people to give to each other because, in a "state of nature," we would not do so. Hobbes (1651/1996) argued that outside of society, people's interests are fundamentally opposed. If two people desire the same thing, which they usually do, they become enemies and desire to destroy each other. Thus, outside of society, people are in a perpetual state of war. He claims that "men have no pleasure, (but on the contrary a great deale of griefe [sic]) in keeping company, where there is no power able to over-awe them all" (p. 88). If true, this entails that people take no pleasure in behaving altruistically towards each other. Indeed, he said that the only factors that checks this perpetual war are fear of death and desire for comfortable living - certainly not good will towards others as a value in itself. Since life in a state of nature is "solitary, poore [sic], nasty, brutish, and short" (p. 89), Hobbes concluded that we must have a government to force us to behave altruistically towards each other. Of course, a conclusion is only as sound as the premises from which it is derived, so we must question how sound Hobbes's premises are. What evidence did Hobbes provide to sustain the claim that there can be no altruism in a state of nature? The only empirical observation he provides is of the "brutish" (p. 89) Native Americans, whom we now know to have been, ironically, quite altruistic towards each other [REF?].

Thus, in order to determine whether people would, in general, behave altruistically towards each other in the absence of laws, we must again ask what the source of altruism is. We may now integrate question (2) with question (1): Is the source of altruism the norms and laws of society, or is it our genetic heritage? Knowing the answer to this question will help us answer questions (1) and (2).

II. Clarification and Identification of Key Concepts

Before we can look for the source of altruism, we must know precisely what we are looking for. There are two things we can look for, each of which is appropriate to focus on in different contexts: altruistic behavior and the psychological mechanism that mediates this behavior. Before we can proceed with our search, we must define the former and identify the latter.