Natural Law Theory
The Euthyphro Argument has been around long enough for those who think that morality is a matter of religion to come up with an intriguing alternative to DCT. Natural Law Theory (NLT) assumes that the world was created in such a way that it and everything in it has a proper purpose. This is the Teleological World View. We students of Newton, Kepler, and Galileo are not terribly impressed by the Teleological World View. But suppose everything did have a proper purpose. Then it is fairly easy to derive an ethical theory.
The Principle of NLT
An action X is morally right iff X is consistent with all relevant proper purposes in a world of proper purpose.
The Standard of Clarity
Are there any unintelligible concepts? Well, what is a proper purpose? As with the concept of a culture, the concept of a proper purpose is deeply problematic.
Can we determine the implications for action from this statement of the theory? Presumably we can, but only if we first know what the proper purposes are.
The Standard of Coherence
Are there any contradictions? It seems plausible to argue that the proper purpose of sex contradicts the proper purpose of contraception under the Catholic Church's interpretation of NLT. However, I think there is a straightforward answer to these kinds of contradictions. Contraception is an artificial device, whereas sex is natural. Hence the contradiction is not genuine.
On the other hand, NLT clearly fails Coherence because it assumes the Teleological World View. To put it bluntly, the Teleological World View is false. All of our advances in science have been made by rejecting the Teleological World View.
The Standard of Reflective Equilibrium
Consider the following arguments:
| The Masturbation Argument | |||
| 1 | If NLT is true, then (under the Catholic Church's interpretation) masturbation is morally wrong. | ||
| 2 | It is not the case that masturbation is morally wrong. | ||
| ∴ | 3 | NLT is not true (under the Catholic Church's interpretation). | 1&2 |
| The Contraception Argument | |||
| 1 | If NLT is true, then (under the Catholic Church's interpretation) the use of contraceptives is morally wrong. | ||
| 2 | It is not the case that the use of contraceptives is morally wrong. | ||
| ∴ | 3 | NLT is not true (under the Catholic Church's interpretation). | 1&2 |
| The Homosexuality Argument | |||
| 1 | If NLT is true, then (under the Catholic Church's interpretation) homosexuality is morally wrong. | ||
| 2 | It is not the case that homosexuality is morally wrong. | ||
| ∴ | 3 | NLT is not true (under the Catholic Church's interpretation. | 1&2 |
It's a simple matter to generate these kinds of arguments. But since many Catholics would no doubt object to the second premise in each case, we can only say that NLT arguably fails the Standard of Reflective Equilibrium.