In “Question of the Week #222: Why Is God the Foundation of Moral Values?” you said, “these qualities are good because they are found in God’s nature.” Doesn’t that commit the is-ought fallacy? I was wondering if I could get some feedback on a resolution to this I’ve been chewing on for years (since roughly 2007). There are two issues here. 1) Whether or not there ‘is’ moral truth, and to what it might correspond (metaphysical/ontological), 2) What we truly ‘ought’ to do, and how we justify that (epistemological/justification). God’s nature grounds the first option (“is”), but can not ground the second (“ought”) (Hume’s is-ought fallacy). And if we have justification for the second (“ought”), that does not necessarily mean we’ve satisfied the first (“is”) (antirealism/postmodernism) (reverse is-ought). So–we must have both, independently–Plato’s “Justified-True-Belief” requirement for knowledge (including moral knowledge) (I answer Gettier elsewhere if you’d like to examine that and offer feedback see the first link below). The Euthyphro Dilemma and Hume’s is-ought fallacy are basically saying the same thing, and apply to moral knowledge as much as they apply to other knowledge: a (moral) belief is not true because it is justified, and it isn’t justified because it is true. So the good cannot be justified by its corresponding to God’s nature, for that commits the is-ought fallacy and does not escape the Euthyphro Dilemma. Instead, we must use reasons to show that the good is justified. Still, reasons alone do not show that there is a ‘real’ good–there must exist a being to which it may correspond (God). No God, no ‘true/correspondent’ good. No plants, no ‘true/correspondent’ formula for photosynthesis. So–how do we use reasons to show that the good is justified? We consider the questions that all the theories on-offer are considering, we rule out any inconsistent theories, and we see the theory/answer with which we are left (I believe that is where plausibility can then come in). I believe that most-plausible theory is the Golden Rule (self=Other) as demonstrated by Christ in switching perspectives with us on the cross. I discuss the common questions and inconsistencies of other theories, et cetera, elsewhere and would love for you to offer feedback on my thinking if you would like to examine the link below (2) which is a bit of a nutshell-version (still pretty rough). I hope you are doing well and I’ll end this here. Oh, also, I have other questions in the third link below.
William Lane Craig: Take a look at QoW #165 for my take on this, Maryann.