Last time, we considered the concept of objective moral values. Let's look at two slightly more technical issues that come up when discussing the moral argument. If you're already comfortable with the argument, or don't care for the technical details, you can move past this.
Ontology and epistemology
Dr. Craig brings up the distinction between ontology and epistemology as part of his reply to a question about the moral argument: QA #199: Objections to the Moral Arugment.
When talking about morality, we must distinguish between ontology and epistemology. Ontology is all about realism -- what actually is. Epistemology is about knowledge -- what we know. So put more simply, we should distinguish between objective morality existing, and us knowing about it. We should distinguish between whether objective morality exists, and how we know about it.
Which of the two is involved in the moral argument? Ontology.
We're not saying that God is the only way you can know morality. You don't have to believe in God to recognize moral truths. What we're saying, instead, is that morality cannot be without God to ground it.
The Euthyphro dilemma
Dr. Kreeft briefly considers the Euthyphro dilemma in his Addendum on Religion and Morality to Argument #15 in Twenty Arguments for the Existence of God. Dr. Craig also engages with it; for example, he answers a question about the dilemma in Q&A #44.
In the Euthyphro, Plato asks Euthyphro "Is a thing pious because the gods will it, or do the gods will it because it is pious?" We might ask, along the same line, "is something good because God says it is good, or does God say it's good because it already is?" Which comes first: the thing's goodness, or God's declaration?
Plato refuted the first option. We must reject the second option, as well, for as Dr. Kreeft writes: "...it makes God conform to a law higher than himself,
a law that overarches God and humanity alike." Nothing is greater than God.
If we reject both options - and if we're right in doing so - then there must be at least one more option. We must be able to "split the horns of the dilemma" by presenting a third possibility. In this case, we can say that things are good because they reflect something of God's nature. That goodness is not something God declares; it is something that God is.
You can listen to Dr. Craig cover the Euthyphro dilemma very efficiently in What is the Euthyphro Dilemma?. If you have more time, he teaches an entire lesson on the dilemma in the video The Euthyphro Dilemma.
Next, we'll finish up arguments for God and move on to the next step in building up to the Catholic faith from the ground up.