Natural Law Theory Unnatural Acts Many people are apparently willing to judge certain actions or practices to be immoral because those actions or practices are (or are said to be) unnatural. See, e.g., arguments that have been offered against homosexuality, bestiality, genetic engineering, etc. For natural law theory this idea that morality can be identified with nature becomes a fundamental principle 1
Natural Law (NL) Theory The general idea of NL has been discussed by scholars in a number of different traditions Perhaps the best-developed certainly the best-known version in the Western tradition is due to Aristotle (384-22 BCE); later influentially developed and expanded upon by St. Thomas Aquinas (1225-74 CE) The Teleological View of Nature I 1. Aristotle: Everything in nature has a purpose; (nearly) everything fits into an orderly hierarchy of means/ends relationships. (The human species happens to be toward the top of that hierarchy) [anthropocentricism] Aquinas: Nature s purposes = God s intentions The natural (i.e., God-given) inclinations of human beings indicate which ends are intrinsically valuable; morality is ultimately grounded in facts about human nature. 2
The Teleological View of Nature II 2. I.e., laws of nature are not simply (descriptive) generalizations about how things happen to be, but are fundamentally specifications of how things ought to be. Aristotle: We live in a well-ordered world; things are mostly as they ought to be. When they appear not to be, we can explain natural evils either as accidents or necessities, but such things are consistent with NL. Aquinas: Yes, but natural evil is not caused by God it is enabled by the absence of good in His creation. (Cf. part of God s plan ). Moral evil, by contrast, is a matter of choice and is possible because of human beings sinfulness. The Teleological View of Nature III 3. The laws of nature are (must be) ultimately rational. So, when it comes to moral decision-making, we ought (only) to do whatever is consistent with NL. (Accord with NL = the right-making property ) Aristotle: Ultimately, this is simply a matter of behaving like a properly developed member of our biological species. It s fundamentally a scientific issue. Aquinas: Yes. We can know everything we need to know about morality via reason ( natural revelation ), but some things can be known only by divine revelation 3
NL: Aquinas Account NLT: An action is right if and only if (and because) in performing the action one does not directly violate any of the basic (intrinsic) values. According to Aquinas, there are four basic intrinsic goods: Human life Human procreation (including parenting) Human knowledge Human sociability (friendship, society, politics) So, e.g., killing a human being is (normally) morally wrong; use of contraception is morally wrong; interfering with knowledge by lying is (normally) morally wrong in each case because doing so damages a basic natural value. But how can we know when we have directly violated an intrinsic value? After all, a single action may affect different values differently 4
Doctrine of Double Effect DDE: An action that would bring about at least one evil effect and at least one good effect is morally permissible if (and only if) the following conditions are satisfied: Intrinsic permissibility (the act is at least morally neutral) Necessity (the good effect can only be brought about the action that will lead to the bad effect) Nonintentionality (the bad effect is not intended) Proportionality (the bad effect is not out of proportion to the good effect) NL Theory: Implications & Criticisms I. NL Theory violates Hume s Law (one cannot validly derive an ought conclusion from is premises only): More specifically: Saying that we are naturally disposed to do X does not entail that we ought to do X. It is logically irrelevant. (Consider, for added flavour: selfishness, rape, wars of conquest, non-procreative sex ) II. Moreover, even if NL theory were correct, it doesn t necessarily entail any moral requirement for religious belief! Believers and non-believers are in the same boat /w/r/t nature. 5
Coda: Arguments from Nature Consider the following general argument form: 1. X is unnatural. 2. Anything unnatural is wrong. 3. Therefore, X is wrong. Values of X might include homosexuality, rights for women, abortion, degenerate art... Can arguments of this form ever be sound? 1. X is unnatural. 2. Anything unnatural is wrong. 3. Therefore, X is wrong. For an argument to be sound a) all of its premises must be true and b) its argument form must be valid (i.e., the conclusion must follow from the premises such that the truth of the premises guarantees the truth of the conclusion). One special form of unsound reasoning: begging the question (petitio principii) the conclusion is already assumed in the premises. Note: Technically a valid argument, but unsound, circular. More precisely, tautological no actual proof is provided 6