The Open Question: Can Morality be Naturalized?
Abstract
Ethics feels special—but is it beyond nature? Moore’s famous Open Question Argument challenges naturalism by insisting that moral concepts can’t be captured by natural facts, sparking a debate that still shapes philosophy today.
The Puzzle
When we talk about morality, we often assume it’s about more than just biology, psychology, or social custom. But can moral truths—claims about what’s good, right, or just—be reduced to facts about the natural world? This is the problem G.E. Moore took aim at in his 1903 Principia Ethica, with what became known as the Open Question Argument (OQA).
At first glance, Moore’s idea is simple: no matter what natural property we try to equate with “good” (say, pleasure, survival, or social harmony), it will always remain an open question whether that thing is truly good. If “good” just meant “pleasurable,” then asking “But is pleasure good?” would be as redundant as asking “Is a bachelor an unmarried man?” But it isn’t redundant—it’s meaningful. This suggests that ethical concepts can’t be reduced to natural ones.
From Hume to Moore: The Fact–Value Gap
Moore’s argument builds on David Hume’s earlier warning: you can’t logically derive an “ought” from an “is.” Knowing a fact about the world (“tax evasion is illegal”) doesn’t by itself tell you what you should do (“you ought to pay taxes”). This “fact–value gap” haunts naturalists, who want to ground morality in descriptive truths.
Moore radicalizes this worry. Instead of just pointing out the gap, he insists that any attempt to define ethical terms with natural ones is guilty of the naturalistic fallacy. Ethics, for Moore, has its own sui generis status.
Why Critics Push Back
Moore’s OQA was groundbreaking, but it hasn’t aged smoothly. Two major objections stand out:
The Non-Analytical Naturalist Response
Philosophers like Frege showed that some identities can be both true and informative: “water is H₂O” isn’t a tautology, even though both terms pick out the same thing. Likewise, “good” might be identical to “pleasure” or “desire satisfaction,” even if the concepts feel different. Moore’s argument, critics say, leans too heavily on semantics and ignores how science often uncovers non-obvious truths.The Supervenience Objection
Another challenge points out that moral properties seem to depend on natural ones. Imagine a world identical to ours in every natural detail but where Hitler’s actions weren’t morally wrong. Inconceivable, right? That suggests moral facts supervene on natural facts—they can’t float free in their own metaphysical realm, as Moore envisioned.
Where Does This Leave Us?
Moore’s Open Question Argument is valuable for highlighting the strange, irreducible flavor of ethical concepts. It forces us to notice that calling something “good” isn’t the same as describing its natural features. But on its own, the OQA doesn’t prove that morality exists beyond the natural world—it mostly shows that simple definitions fail.
Modern ethicists often treat Moore as an important starting point, not the final word. His challenge keeps naturalists honest, even if responses like non-analytical naturalism or supervenience theory blunt its force.
For me, reflecting on Moore feels like confronting philosophy’s recurring tension: the desire for crisp definitions versus the messy reality of human values. Just as with Nozick’s libertarian blueprint, what looks neat in theory often falters under pressure. Moore wanted to safeguard morality’s specialness, but in doing so, he may have overplayed his hand.
In the end, the Open Question Argument doesn’t close the case against naturalism—it leaves us with a sharper, harder question: how do we explain the authority of moral facts without either flattening them into nature or banishing them into mystery?
