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1.5 Moral Anti-realism and Motivation
Drawing on his attack on reason's role in judging behavior, Hume argued that immoral behavior is not immoral by being against reason. He first claims that moral beliefs are intrinsically motivating – if you believe killing is wrong, you will be ipso facto motivated not to kill and to criticize killing and so on (moral internalism). He then reminds us that reason alone can motivate nothing – reason discovers matters of fact and logic, and it depends on our desires and preferences whether apprehension of those truths will motivate us. Consequently, reason alone cannot yield moral beliefs. Hume proposed that morality ultimately rests upon sentiment, with reason only paving the way for our sensitive judgments by analysis of the moral matter in question. This argument against founding morality on reason is now one in the stable of moral anti-realist arguments; Humean philosopher John Mackie argued that, for moral facts to be real facts about the world and, at the same time, intrinsically motivating, they would have to be very weird facts. So we have every reason to disbelieve in them.
For relevant contemporary work, see J. L. Mackie's Ethics: Inventing Right and Wrong, Mackie's Hume's Moral Theory, David Brink 's Moral Realism and the Foundation of Ethics, and Michael Smith's The Moral Problem.
1.6 Free Will versus Indeterminism
Just about everyone has noticed the apparent conflict between free will and determinism – if your actions were determined to happen billions of years ago, then how can they be up to you? But Hume noted another conflict, one that turned the problem of free will into a full-fledged dilemma: free will is incompatible with indeterminism. Imagine that your actions are not determined by what events came before. Then your actions are, it seems, completely random. Moreover, and most importantly for Hume, they are not determined by your character – your desires, your preferences, your values, etc. How can we hold someone responsible for an action that did not result from his character? How can we hold someone responsible for an action that randomly occurred? Free will seems to require determinism, because otherwise, the agent and the action wouldn't be connected in the way required of freely chosen actions. So now, nearly everyone believes in free will, free will seems inconsistent with determinism, and free will seems to require determinism. Hume's view is that human behavior, like everything else, is caused, and therefore holding people responsible for their actions should focus on rewarding them or punishing them in such a way that they will try to do what is morally desirable and will try to avoid doing what is morally reprehensible. (See also Compatibilism.)
For a relevant contemporary work, see Daniel C. Dennett's Freedom Evolves.
1.7 The Is-ought Problem
Hume noted that many writers talk about what ought to be on the basis of statements about what is. But there seems to be a big difference between descriptive statements (what is) and prescriptive statements (what ought to be). Hume calls for writers to be on their guard against changing the subject like that, not without giving an explanation of how the ought-statements are supposed to follow from the is-statements. But how exactly can you derive an 'ought' from an 'is'? That question, prompted by Hume's small paragraph, has become one of the central questions of ethical theory, and Hume is usually assigned the position that such a derivation is impossible. (Others interpret Hume as saying not that one cannot go from a factual statement to an ethical statement, but that one cannot do so without going through human nature, that is, without paying attention to human sentiments.) G. E. Moore defended a similar position with his "open question argument," intended to refute any identification of moral properties with natural properties—the so-called " naturalistic fallacy." Now any ethical theorist who wishes to give morality an objective grounding in more down-to-earth features of the world is fighting an uphill battle.
It was probably Hume who, along with his fellow members of the Scottish Enlightenment, first advanced the idea that the explanation of moral principles is to be sought in the utility they tend to promote. Hume's role is not to be overstated, of course; it was his countryman Francis Hutcheson who coined the utilitarian slogan "greatest happiness for the greatest numbers." But it was from reading Hume's Treatise that Jeremy Bentham first felt the force of a utilitarian system: he "felt as if scales had fallen from [his] eyes." Nevertheless, Hume's proto-utilitarianism is a peculiar one from our perspective. He doesn't think that the aggregation of cardinal units of utility provides a formula for arriving at moral truth. On the contrary, Hume was a moral sentimentalist and, as such, thought that moral principles could not be intellectually justified. Some principles simply appeal to us and others don't; and the reason why utilitarian moral principles do appeal to us is that they promote our interests and those of our fellows, with whom we sympathize. Humans are hard-wired to approve of things that help society – public utility. Hume used this insight to explain how we evaluate a wide array of phenomena, ranging from social institutions and government policies to character traits and talents.
