4.4: Summary of Aquinas’s Natural Law Theory

For Aquinas everything has a function (a telos) and the good thing(s) to do are those acts that fulfil that function. Some things such as acorns, and eyes, just do that naturally. However, humans are free and hence need guidance to find the right path. That right path is found through reasoning and generates the “internal” Natural Law. By following the Natural Law we participate in God’s purpose for us in the Eternal Law.

However, the primary precepts that derive from the Natural Law are quite general, such as, pursue good and shun evil. So we need to create secondary precepts which can actually guide our day-to-day behaviour. But we are fallible so sometimes we get these secondary precepts wrong, sometimes we get them right. When they are wrong they only reflect our apparent goods. When they are right they reflect our real goods.

Finally, however good we are because we are finite and sinful, we can only get so far with rational reflection. We need some revealed guidance and this comes in the form of Divine Law. So to return to the Euthyphro dilemma. God’s commands through the Divine Law are ways of illuminating what is in fact morally acceptable and not what determines what is morally acceptable. Aquinas rejects the Divine Command Theory.