What is William Lane Craig's moral argument for God's existence, and how do naturalistic moral realists respond to it?

William Lane Craig — the contemporary analytical Christian philosopher — formulated one of the most famous versions of the moral argument for God's existence in the 21st century. His argument is simple in structure, but the debate around it is complex and multifaceted, touching on fundamental issues in moral philosophy and metaethics.

Inadequate Responses to Avoid

From some believers, two common responses are insufficient:

"Atheists have no morals, therefore the argument is correct." This is a serious error. Craig himself emphasizes that atheists can be very moral in their behavior. His argument is not about moral behavior, but about the ontological foundation of morality. Confusing "knowledge of morality" with "foundation of morality" weakens the argument and turns it into personal attack rather than serious philosophy.

"Without God, everything is permitted (Dostoyevsky)." A hackneyed and misunderstood quote. First, Dostoyevsky put this phrase in the mouth of a fictional character (Ivan Karamazov), not as his personal philosophical position. Second, even if the phrase were true, it needs philosophical proof, not mere literary repetition. Craig offers a detailed philosophical argument, not a slogan.

From some naturalists, two responses are also insufficient:

"Evolution explains morality, end of discussion." This is reductionism. Evolution may explain the emergence of moral inclinations, but Craig asks about moral normativity. Why should I obey my evolutionary inclinations? Evolution also produced inclinations for rape and murder — does this make them morally correct? Confusing description with prescription is an old philosophical error (Hume's fallacy).

"Society determines morality." Naive relativism. If society is the standard, then no society can be morally criticized. Nazism was socially acceptable in 1930s Germany — does this mean it was morally correct? Most serious naturalist philosophers reject this absolute relativism.

Structure of Craig's Moral Argument

Craig formulates his argument in a simple logical syllogism with two premises:

First Premise: If God does not exist, then objective moral values and duties do not exist.

Second Premise: Objective moral values and duties do exist.

Conclusion: Therefore, God exists.

The syllogism is logically valid (modus tollens). The question is: are both premises true?

Craig's Defense of the First Premise

Craig distinguishes between three levels: moral epistemology (how we know what is right), moral motivation (why we act morally), and moral ontology (what is the foundation of morality). His argument concerns only the third level.

He says: in naturalism, humans are "merely evolved animals by chance." There is nothing ontologically special about humans that gives them particular value. Morality is merely an "evolutionary adaptation" useful for survival, like hands or eyes. But evolutionary adaptations are not objectively "right" or "wrong" — they are only "useful" or "useless" for survival.

In theism, however, humans are created in God's image and have inherent value. And God — absolute goodness — is the ontological standard for morality. Divine commands reflect God's good nature, thus becoming objective duties.

Craig's Defense of the Second Premise

Craig relies on direct moral intuition: we know that torturing children for pleasure is objectively wrong, not merely personal opinion or social agreement. This knowledge is clearer than any philosophical argument against it. Those who deny moral objectivity bear a massive burden of proof.

He adds: even atheist ethicists act as if morality is objective. They criticize injustice, defend human rights, condemn genocides. This behavior makes no sense if morality is merely personal taste.

Responses from Naturalistic Moral Realists

Naturalistic moral realists — such as David Brink, Michael Huemer, Erik Wielenberg, and Russ Shafer-Landau — accept the second premise (objective morality exists) but reject the first. Their main strategies:

First Strategy: Neo-Platonic Moral Realism.
Russ Shafer-Landau in "Moral Realism: A Defence" (2003) defends the existence of necessary moral facts, like mathematical facts. "Torture for pleasure is wrong" is a necessary truth like "2+2=4." It doesn't need God to be true, just as mathematics doesn't need God.

Craig's criticism: Mathematics describes abstract relations, while morality imposes duties on persons. How does an abstract truth impose a duty on a conscious being?

Second Strategy: Cornell Moral Naturalism.
David Brink and other "Cornell realists" see moral properties as complex natural properties. "Good" is not something mysterious, but a set of natural properties (like promoting welfare, justice, human flourishing). They can be discovered empirically like any scientific fact.

Craig's criticism: This turns morality into descriptive science. Why should I pursue welfare or justice? Nature doesn't impose "duties."

Third Strategy: Independent Moral Necessity.
Erik Wielenberg in "Value and Virtue in a Godless Universe" (2005) developed a middle position: some moral facts are necessary and eternal, but they are "instantiated" in natural beings. Pain is bad by necessity — not because God said so, but because of pain's very nature.

Craig's criticism: This assumes the universe has a fundamental "moral structure" without explanation. In theism, God explains this structure. In naturalism, it remains a mystery.

Fourth Strategy: The Reversed Euthyphro Dilemma.
Many naturalists turn the argument around: if morality depends on God's commands, is the good good because God commanded it (divine arbitrariness), or did God command it because it is good (good is independent of God)? Both options weaken Craig's argument.

Craig's response: A third option — the good is neither independent of God nor arbitrary, but is God's very nature. God is goodness itself.

Contemporary Developments in the Debate

From the theistic side: Robert Adams developed "Modified Divine Command Theory." Linda Zagzebski connects morality with divine virtue theory. J.P. Moreland integrates the moral argument with other arguments in a cumulative approach.

From the naturalistic side: Derek Parfit in "On What Matters" defended non-naturalistic moral realism. Sam Harris in "The Moral Landscape" attempted to establish scientific ethics (though many philosophers criticized him). Shelly Kagan in his famous Yale course defends objective morality without God.

Fundamental Weaknesses

In Craig's argument: the assumption that naturalism cannot establish moral objectivity. Many respected naturalist philosophers disagree. Also, the Euthyphro dilemma remains challenging even with his proposed solution.

In naturalist responses: difficulty explaining moral normativity ("why ought?") in a purely naturalistic framework. Also, the moral intuition they rely on may be inherited from religious culture.

From the Perspective of Rational Preference (rajḥān ʿaqlī)

The moral argument — like most arguments for God's existence — is not a decisive proof, but evidence within a cumulative system. Its strength depends on how convinced one is of moral objectivity and the difficulty of explaining it naturalistically. Its weakness lies in the possibility of naturalistic moral realism, despite its philosophical difficulties.

Where We Stand in This Debate Today

The debate is very active and ongoing. Surveys show that most professional philosophers (about 56%) lean toward naturalistic moral realism, while a significant minority defends theistic foundations for morality. The question remains philosophically open, with sophisticated arguments on both sides.