I just debated a very incompetent opponent on debate.org over whether the moral argument for god is sound. I hit him with the very well known Euthyphro Dilemma to see if he could handle it—and apparently he couldn't because he almost completely ignored it.
Now when making the Euthyphro, you absolutely must preempt the most common response that theists are going to use—that god is good. If you cover that before they make it, as I have below, then you leave your opponent no room to get out of it, and they're logically backed into a corner.
So the following passage from my debate below is how to do that properly, in case any theist pulls the moral debate on you:
One counter argument to the moral argument is called the Euthyphro Dilemma. It was posed by Socrates 2,400 years ago. It asks, “Is something moral because God commands it, or does God command it because it is moral?”
The person who believes objective morality is founded in God here has two options. If something is moral because God commands it, then morality is arbitrarily decided by God. God could command that we murder our children or own slaves and it would be good – merely because God said so. The actual commands would be meaningless and we’d have no way to gauge whether something is morally good or not except on whether it was commanded by God. This would be a “might makes right” ideology.
In the other option, God is merely a messenger who alerts us to what is right or wrong independently to whether God exists or not. Morality is not decided by God, God is simply the enforcer of what is naturally right or wrong.
Neither option is particularly appealing to the theist. The first option makes morality simply dependent on God’s opinion at any given time. He could command that murder and rape are good, then change his mind and command that they are wrong. The second option turns God merely into a messenger, who one might say is redundant, and at best can only serve as a medium by which natural truths are known. The ontological foundation of [good] would exist independently of him.
Now the Euthyphro Dilemma has been around for over 2000 years and theists have had plenty of time to respond to it. One common objection is to say that God is good – he is the absolute standard by which good is measured and founded. But is this a successful refutation of the dilemma?
If God is the standard of goodness, by what means can we know this to be true? So we can ask, why is God good? The theist might say God is good because he is intrinsically loving, compassionate and fair. But then all we have to do is reformulate the Euthyphro Dilemma accordingly: Is God good because he is loving, compassionate and fair, or is being loving, compassionate and fair good because God is good? If you pick the former, then the attributes God has that make him good exist independently of God and are merely descriptive terms applied to God, if you pick the latter then how can we possibly know that being loving, compassionate and fair is good? It can’t simply be good because God is good, because then the word “good” is meaningless.
There has to be a reason why we call something good. So what characteristic comes first – God’s goodness, or his being loving, compassionate and fair? The theist is in a squirm here. He cannot simply define God as being “good” without justification. Goodness has to be justified descriptively. But if those descriptions are warranted, then they imply goodness for epistemological reasons that are verifiable due to their intentions and effects. And thus the source of goodness would exist independently of God.
If you want additional counter arguments against the notion that god is good, you can either read the rest of my debate on debate.org, or you can check out section 1.2 of my lengthy post "Objective Morality Without God."