The philosopher Michael Ruse has argued that "morality is a collective illusion foisted upon us by our genes." If that's true, why have our genes played such a trick on us? One possible answer can be found in the work of another philosopher Richard Joyce, who has argued that this "illusion" — the belief in objective morality — evolved to provide a bulwark against weakness of the human will. So a claim like "stealing is morally wrong" is not true, because such beliefs have an evolutionary basis but no metaphysical basis. But let's assume we want to avoid the consequences of weakness of will that would cause us to act imprudently. In that case, Joyce makes an ingenious proposal: moral fictionalism.

Following a fictionalist account of morality, would mean that we would accept moral statements like "stealing is wrong" while not believing they are true. As a result, we would act as if it were true that "stealing is wrong," but when pushed to give our answer to the theoretical, philosophical question of whether "stealing is wrong," we would say no. The appeal of moral fictionalism is clear. It is supposed to help us overcome weakness of will and even take away the anxiety of choice, making decisions easier.

That is William Irwin writing in the Stone, the NY Times's forum for contemporary philosopher.The full article is worth reading.