P1. Some moral propositions are objectively true. For example, it is objectively wrong to torture an innocent person purely for entertainment, regardless of whether a society approves of it. P2. If objective moral obligations exist, they cannot ultimately be grounded merely in subjective preferences, social conventions, evolutionary instincts, or material facts, because those things can describe what people believe or how people behave without establishing what people objectively ought to do. P3. Objective moral obligations require an objective normative foundation that exists independently of human opinion. P4. A purely naturalistic description of reality consists of physical facts and processes, but physical facts by themselves do not logically entail moral obligations. “Humans evolved to dislike suffering” does not entail “therefore humans objectively ought not inflict pointless suffering.” P5. Therefore, if objective moral obligations exist, reality contains something beyond merely subjective human preferences and descriptive physical facts that grounds those obligations. P6. A personal moral ground—an ultimate mind whose nature grounds objective moral value and obligation—provides such a foundation more adequately than impersonal matter or abstract propositions. C. Therefore, the existence of objective moral obligations provides evidence for a transcendent moral foundation, and ultimately for God. I am not arguing that atheists cannot recognize morality, behave morally, or know moral truths. The question is what makes those truths objectively true in the first place. Atheism can describe our moral psychology, but the deeper question is what makes an objective “ought” exist independently of human minds.

Your response doesn't actually address my argument. I did not appeal to fine-tuning, cosmic complexity, miracles, unanswered science, or “we don't know, therefore God.” Those are completely different arguments. My argument is a metaethical argument about the grounding of objective moral obligations. The relevant question is: Are there genuinely objective, mind-independent moral truths? If yes, what makes them objectively true? Saying “science explains disease” doesn't answer that question. Medicine can explain why a treatment works; it cannot by itself establish why torturing an innocent person for fun is objectively wrong rather than merely socially condemned or evolutionarily disadvantageous. In fact, this is an established issue in academic metaethics. The Stanford Encyclopedia of Philosophy distinguishes moral realism—the view that objective, stance-independent moral facts exist—from anti-realism, and discusses the serious philosophical dispute over whether natural facts can adequately ground moral facts. � Stanford Encyclopedia of Philosophy +1 You also haven't shown that evolution solves the problem. Evolution can explain why humans developed certain moral instincts, but explaining the origin of a belief does not automatically establish that the belief is objectively true. Evolutionary debunking arguments are themselves an active philosophical debate. � Stanford Encyclopedia of Philosophy So let's keep the arguments separate. If you reject objective morality, defend moral anti-realism: tell me why “torturing an innocent person purely for entertainment is objectively wrong” is false. If you accept objective morality, then explain what grounds that objective normativity independently of human minds. You haven't refuted my argument yet—you've responded to an argument I didn't make.

You're conflating two completely different questions: what causes humans to make moral judgments and what makes a moral judgment objectively true. If stimulating or damaging someone's brain changes their moral judgment, that shows that our beliefs about morality depend partly on brain states. It does not follow that the moral facts themselves are brain-dependent. If I damage someone's visual cortex and they stop seeing red, I haven't shown that redness itself is nothing more than a brain state. I've shown that our access to or perception of something depends on our brains. This distinction is standard in moral realism: moral realism holds that moral facts can make our judgments true or false, rather than our judgments making the facts true. � OUP Academic +1 Your second objection is more important: perhaps objective moral facts exist without God. But notice what you've actually offered: “perhaps.” That's a possible alternative, not a refutation of the theistic explanation. In fact, philosophers explicitly defend both sides of this dispute. There are non-theistic moral realists such as Erik Wielenberg who argue that objective, non-natural moral facts can exist without God. � But that position therefore has to explain what these irreducible normative facts are and why they exist. Simply saying “brute moral facts” doesn't explain their existence; it stops the explanatory question. OUP Academic Conversely, the theistic account provides a unified grounding: objective moral obligations ultimately derive from the necessary nature of a perfectly good personal reality rather than from human conventions or arbitrary physical states. Philosophers have developed detailed versions of this theistic grounding argument as well. � OUP Academic So we're now at the actual disagreement: Are objective moral truths real, and if they are, what ultimately grounds their objective normativity? Brain manipulation explains moral psychology. It does not answer that metaphysical question. You have shown that humans can be mistaken about morality. You have not shown that there is no objective morality, nor have you shown that objective morality can exist without an adequate metaphysical ground.

The brain-tumor example still doesn't establish what you need it to establish. You are showing that our capacity to make moral judgments is physically dependent on the brain. I agree. But that is an epistemological/psychological claim, not a claim about what makes moral propositions objectively true. If a brain tumor causes someone to believe that torturing children is acceptable, that doesn't make torture objectively acceptable. It demonstrates that someone's belief about morality can be mistaken and causally altered. The distinction between moral judgment as a psychological phenomenon and morality in the normative sense is explicitly recognized in the philosophical literature. � Stanford Encyclopedia of Philosophy +1 Here's the crucial analogy: damaging someone's visual cortex can change their perception of color, but that doesn't establish that the wavelengths of light themselves are created by their brain. Likewise, altering someone's moral psychology doesn't establish that objective moral truth is created by their brain. Your second objection—that objective moral facts could exist as abstract, brute facts—is logically possible. But “could exist” is not the same as “therefore they do exist.” You have proposed a competing metaphysical explanation; you haven't demonstrated it. And notice what you're conceding: objective moral truths exist independently of human opinion. That's already moral realism. Contemporary metaethics recognizes naturalist, non-naturalist, and supernaturalist attempts to explain such stance-independent facts. � Stanford Encyclopedia of Philosophy +1 So the actual dispute is now much narrower: What best grounds objective normativity? If you say “brute moral facts,” you've stopped the explanation at morality without giving a reason why such irreducible normative facts exist. If you say “natural facts,” you need to explain how purely descriptive facts generate genuine obligation. If you say “abstract moral truths,” you still need to explain why these truths have normative authority over rational agents. The theistic proposal isn't “we don't know, therefore God.” It's an explanatory hypothesis: objective moral obligation is ultimately grounded in the necessary nature of a perfectly good personal reality. So your brain-tumor example doesn't defeat objective morality, and “maybe brute moral facts exist” doesn't refute the theistic grounding argument. You've established that our moral cognition has physical mechanisms; you have not established that objective moral normativity itself is reducible to those mechanisms.

Your objection now shifts from whether objective moral facts exist to how we know they exist. Those are different questions. You say we can independently verify redness with instruments but cannot put a “brute normative fact” under a microscope. But that's an argument from epistemology to ontology: “we cannot scientifically measure X” does not entail “X does not exist.” Moral realism explicitly holds that moral facts, if they exist, need not be reducible to ordinary empirical facts, and contemporary metaethics treats moral epistemology as a separate philosophical problem. � Stanford Encyclopedia of Philosophy +1 More importantly, your brain-damage argument still only establishes that our moral cognition is physically mediated. It doesn't establish that moral truth itself is physically generated. A malfunctioning calculator can produce a wrong answer, but the fact that the calculator is physical doesn't make mathematical truth subjective. Likewise, a damaged brain can produce a false moral judgment without making morality itself brain-dependent. And I agree with one thing: the existence of objective moral facts does not deductively entail God by itself. That's why I'm presenting this as an inference to the best explanation. There are competing accounts. Erik Wielenberg, for example, explicitly defends a godless moral realism, so I'm not pretending atheistic moral realism is logically impossible. � OUP Academic But now we can actually compare explanations. The theistic account grounds objective obligation in a necessary, perfectly good personal reality; prominent philosophers have explicitly defended this kind of grounding account. � The alternative you have offered is essentially that objective normative facts are simply brute, mind-independent features of reality. OUP Academic +1 That's possible. But possibility isn't superiority. So the challenge remains: If objective moral obligations genuinely exist, what explains their objective and authoritative normativity? Brain chemistry explains our awareness of morality; it doesn't explain why there is an objective moral truth to be aware of. You haven't demonstrated that God is unnecessary. You've demonstrated only that moral knowledge is philosophically complicated—which moral realists already acknowledge. � Stanford Encyclopedia of Philosophy