their covenant... [C]ovenants without the sword are but words... And Jean-Jacques Rousseau in The Social Contract: [The social contract] can arise only where several persons come together: but, as the force and liberty of each man are the chief instruments of his self-preservation, how can he pledge them without harming his own interests, and neglecting the care he owes himself? In order then that the social contract may not be an empty formula, it tacitly includes the undertaking, which alone can give force to the rest, that whoever refuses to obey the general will shall be compelled to do so by the whole body. This means nothing less than that he will be forced to be free... Even Herman Melville, in Moby-Dick, has the cannibal harpooner Queequeg explain why he has saved the life of someone who had been jeering him as so: "It's a mutual, joint-stock world, in all meridians. We cannibals must help these Christians." The original role of government is to provide the coercive power to enforce the social contract (and in commercial societies, contracts and covenants generally). Where government does not exist or cannot reach it is often deemed the role of religion to promote prosocial and moral behavior, but this tends to depend on threats of hell-fire (what Hobbes called "the terror of some power"); such inducements seem more mystical than rational, and philosophers have been hard-pressed to explain why self-interest should yield to morality, why there should be any duty to be "good". Yet, cooperation and even altruism and morality are prevalent even in the absence of coercion, and even though it seems that a properly self-regarding individual should reject all such social strictures and limitations. As early as 1890, the Russian naturalist Petr Kropotkin observed that the species that survived were the ones where individuals cooperated, and that "mutual aid" (cooperation) was found at all levels of existence. By the 1960s biologists and zoologists were noting many instances in the real "jungle" where real animals and even microbes (see microbial cooperation) – presumably unfettered by conscience and not corrupted by altruistic liberals – were cooperating. Darwin's theory of natural selection is a profoundly powerful explanation of how evolution works; its undoubted success strongly suggests an inherently antagonistic relationship between unrelated individuals. Yet cooperation is prevalent, seems beneficial, and even seems to be essential to human society. Explaining this seeming contradiction, and accommodating cooperation,