Divine command theory

The Divine command theory (hereafter: DCT) is a theory of ethics. It states that the difference between right and wrong is simply that the former is that which has been commanded by God (or the gods), while the latter is that which has been prohibited by God.

Plato's Euthyphro

The DCT was challenged by Plato in his dialogue, Euthyphro[?]. In this dialogue, Socrates asks essentially this question:

Is an act good because God commands it, or does he command it because it is good?

The question is such that either answer seems to lead to the rejection of the DCT. Firstly, if an act is good solely because God commands it, then that would mean that if murder, rape or theft were divinely commanded, they would be good. This seems to be absurd, although on some occasions it has indeed been seriously proposed.

This may provoke a reply to the effect that God would never command such things, because God would never command what was wrong. However, this argument cannot be made if the DCT is to be maintained - under the DCT, if God commanded something, it would not be wrong.

Secondly, if God commands an act because it is good, this again undermines the DCT, as it means that the act was good independently of God's commanding it, and therefore being commanded by God is not the only reason the act is good. Rather, whatever reason God had for commanding it is the ultimate reason that it is good.

This line of attack on the DCT is well-enough known that it is referred to as the Euthyphro dilemma. Plato is generally believed to have refuted the DCT outright. However, it should be noted that certain other theories that link morality to God are more subtle and are not straightforwardly refuted in this manner.