There has been a lot of discussion about what grounds morality following the debate between Sam Harris and William Lane Craig on whether God is the only possible ground for morality. Many will argue this is the case, and I think it’s even the reason C.S. Lewis switched teams. So, let’s consider the problem of grounding morality.
It seems to me that certain theories only manage to compound problems when it comes to explaining morality. For example, a Divine Command theorist rests morality on two questionable assumptions – the existence of God and the existence of divine commands. Even if God exists, it is not clear that it would provide commands. And, of course, you have the very uncertain epistemological issue of how to determine what those commands actually are. Most moral theories have such issues of epistemology, but I would say this one is especially tricky.
You could also ground morality in some kind of Platonic form. Maybe morality just exists in some sense, like logic and abstract objects do (at least according to platonists). Again, you are basing morality on something which may not even exist.
Or perhaps morality is grounded in something like well-being, happiness, virtue, etc. Again, there is a lot of vagueness surrounding what these terms even pick out in the actual world.
Can these approaches really be the best solution given our available evidence? These all seem to have problems that could keep them from ever even getting off the ground. With questions of moral ontology, it seems much better to begin with things we already know exist. For example, say you are a city planner and you have to decide where a park should be located. You have one person telling you there is an open field near their house while another person is telling you about a novel they read which takes place in said town. In the novel, a beautiful meadow on a hillside is described and it sounds like the perfect place for the new park. Now, the planner has a decision. Should he use the field or go searching for a possibly fictional meadow? I think many would choose the field.
So, why not ground morality in something more concrete – something we know exists and that we can use to weigh decisions? That is why I tend toward theories that ground morality in something like reason or desire (The leading candidates for me as moral theories are Rawls-style Contractarianism and Desirism). They are not without their own issues to solve, but we can avoid many of the problems with the traditional approaches. And, if nothing else, at least we know they are real!
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