The short answer is, no, only if you try to justify that truth by referring back to God’s nature. Here is the long answer. It is possible to blend Hume’s is-ought distinction in Ethics with Plato’s justified-true-belief theory of knowledge. A catchy name for it is the Ought-Is-Belief theory of knowledge, moral or otherwise.
Simply put, whatever sort of beliefs one is talking about, including moral beliefs, they must be ‘both’ justified by reasons (a justified belief OUGHT to be believed) ‘and’ correspondent to reality (a true belief IS true). Just because one has good reasons for one’s belief does not mean it is true. And even if one believes something that is true, one may have horrible reasons for believing it (bit of a tangent: Gettier was wrong in assuming falsehoods count towards justification) (Gettier is answered elsewhere). All of this is true about any belief one holds, moral or otherwise. In order for one’s belief to be knowledge, it must satisfy those two conditions: 1: It must be backed by good reasons (justified/ought). 2: It must correspond to reality (true/is). These conditions are very different from each other. Both are required separately. So, satisfying both conditions is not Hume’s problem—it is when one condition takes the place of the other that one commits Hume’s is-ought fallacy, or its reverse (ought-is).
Hume obviously only drew this distinction when he was discussing moral knowledge, not any other kind of knowledge, and Plato grappled with Euthyphro’s (false) dilemma (it, skeptics, anti-realists and Gettier are all answered elsewhere).
If one understands the blending of Hume and Plato (Ought-Is-Belief) and one is not a Christian, one may not be comfortable with it, because one’s moral theory doesn’t correspond to, or describe, anything in reality, knowing of no always-good person who never has and never will violate one’s moral theory. That discomfort, though understandable, is not a valid reason to reject the is-ought distinction.
If one is a theist who still rejects Hume’s is-ought distinction because one thinks it means the Good cannot correspond to God, then one is misunderstanding what Hume really meant by his distinction, and there is still some work to do in communicating the blending properly.
What would violate Hume’s is-ought, and Plato’s justified-true, is if one attempted to justify moral truth by referring to something that is: “You ought to do this, because God exists” or “…because it is a command of God.” It would also violate Hume’s is-ought, and Plato’s justified-true, in reverse if you turned it around and said, “This moral belief is justified, therefore God exists.” You ‘can’ say, “This justified moral belief is not true unless God exists”—but it would not follow that, therefore, God exists. Still, it does not violate the Ought-Is-Belief theory to ground moral truth in God’s nature: “This moral belief is true only if it corresponds to God.” Something is only true if it corresponds to something in reality. If there is nothing to which it corresponds, it is impossible for it to be true. So, again, the short answer is no—grounding moral truth in God’s nature does not violate Hume’s is-ought. And, for that matter, it does not violate Plato’s justified-true.
A version of this post appeared originally on Ichthus77.