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The Argument from Morality

Objective morality as evidence for the existence of God

Like a lot of people I intuitively accepted the existence of ethical right and wrong but didn't think about how or why it exists. Many theists think that God is the correct explanation for the existence of objective morality. Objective morality is the idea that moral principles are valid, binding, and true independently of whether any of us think, feel, or believe them to be so. I’ll also refer to this belief as moral objectivism or ethical objectivism.

Although there are a number of different ways to argue the moral argument, the general idea (and my central claim here) is that if morality exists independently of what we human beings think, then this fact is evidence for the existence of God. Some philosophers even go so far as to say that if God did not exist, then objective morality would not exist. Why would anybody claim that? Wouldn’t we still feel that people committing genocide and rape is reprehensible even if there were no God? Of course we would. But if the immorality of such behaviors is to be an objective truth that is independent of what we think, then something besides us has to say people shouldn’t behave this way. That is to say there must be a foundation of morality that transcends human opinion, and many theists believe God is that foundation.

A Caveat

Note that the claim is not that an atheist cannot recognize the existence of moral values. An atheist could believe, however mistakenly, that God is not necessary for objective morality. Nor is the claim that belief in theism is necessary to live a moral life. An atheist could follow the rules of morality and still disagree, however mistakenly, on the metaphysical basis of those rules. Nonetheless, the moral argument does claim that God is the metaphysical basis for objective morality, and that to the very least objective morality constitutes evidence for the existence of God.

What Kind of Morality?

To get a better idea of morality we should distinguish between conditional and unconditional “oughts.” A conditional ought takes the form of something sufficiently like “If you want to do X, you ought to do Y” and says what conditions help accomplish a particular goal without saying whether one should aim for the goal in the first place, e.g. “If you want to poison your teacher to death, you should use a sufficiently strong toxin.” An unconditional ought says what ought to be period and is the sort of ought found in “You should not poison teachers to death” and “the worst possible misery and suffering for everyone for all eternity is a state of affairs that ought not to be,” and is thus goal-independent in a way that a conditional ought is not. Moral obligations are a type of unconditional “oughtness.” An unconditional ought is not to be confused with an “ought” that doesn’t rely on any circumstances whatsoever; e.g. one could believe the unconditional ought with respect to not killing applies in some circumstances but that this obligation does not exist in certain other situations (some self-defense cases perhaps).

Moral wrongness is a type of unconditional ought. An action is morally wrong for subject some person only if that person ought not to do it. The property of moral wrongness is universalizable in that applies equally to all relevantly similar situations, and the property is supremely authoritative, overriding any other “ought” (e.g. legal rules). If we think of “moral rightness” as the property of following some moral obligation, we get the same thing as “moral wrongness” but in the opposite direction. An action is morally right for some person only if that person ought to do it etc.

The type of morality being used here then is called normative morality (morality that has that sort of “ought” component to it). Another confusion one can make is descriptive morality, i.e. that which merely describes the codes of conduct we humans in fact use (as opposed to the codes of conducts humans really ought to follow, which is what normative morality is). The claim then is not that God is needed for descriptive morality to exist; rather, the moral argument aims to show that normative morality that is valid and binding independently of human opinion constitutes evidence for God.


For sake of clarity I’ll explicitly define several more terms before getting to the actual argument. By authority I mean being the source of some obligation. For example, many theists believe God has authority in the sense that he is the source of moral obligation. Morality is metaphysically necessary in the sense that its existence “couldn’t be otherwise.” If we let a possible world be a complete description of the way the world is or could be like, something like “kindness is a virtue” is metaphysically necessary in the sense that it holds in all possible worlds. Similarly, there is no possible world where “torturing infants just for fun” isn’t morally wrong. Moral ontology is the discipline that studies the foundations of morality (e.g. are moral properties like moral wrongness physical or nonphysical?). Thus an ontological explanation of morality is an explanation of how morality exists and what sort of reality it constitutes.

The Scientist Testing for Objective Morality

What it means for moral properties to be non-natural varies between writers, but we can borrow philosopher Robert Adam’s description that it means moral properties “cannot be stated entirely in the language of physics, chemistry, biology, and human or animal psychology.”[1] Either morality exists solely as part of the natural world (moral naturalism) or it exists to at least some degree as part of the non-natural realm (moral non-naturalism). One of these has to be true, because if morality exists neither as part of the natural realm nor as part of the non-natural realm, then it follows that morality does not exist as part of reality at all. If morality exists, some type of ontological explanation or other must be correct.

Objectively existing unconditional moral “ought” properties appear to be non-natural and nonphysical (in that they are outside the realm that physics, chemistry, biology etc. studies). To illustrate, imagine a moral nihilist who concedes that torturing puppies just for fun inflicts pain on the little mammals but he denies there is any moral dimension to such torture. The moral nihilist is also a brilliant scientist and has scientific equipment that he can use to detect every property within the fields of chemistry, physics, etc. What experiment could one have him do to empirically verify the existence of objective moral wrongness associated with the torture? If moral properties were purely natural properties, then our hypothetical moral nihilist should be able to empirically detect the objectively existing unconditional ought property of moral wrongness, but the existence of that unconditional ought property doesn’t seem to be the sort of thing that the moral nihilist could empirically test for (no matter how brilliant he is). Why not? One reason is that objectively existing unconditional “oughtness” cannot have any physical effect, unlike say the property of redness (which can be seen) or a physical organism’s intelligence (which can affect behavior and be empirically detected via cognitive tests). Barring the supernatural, the presence or absence of objectively existing unconditional “oughtness” would not affect the physical world at all. All things considered, it isn’t merely that we can’t think of an experiment for our hypothetical moral nihilist to empirically detect objective moral wrongness; upon reflection we see that the moral nihilist can’t empirically test for such objectively existing unconditional “oughtness,” because we see that such “oughtness” that exists independently of human belief and perception of it just isn’t the sort of thing that the moral nihilist could empirically test for. That sort of objective “oughtness” is too fundamentally different from the physical world to be empirically testable by the moral nihilist. Objective moral ought properties like moral wrongness appear to be nonphysical and non-natural.

One version of the moral argument is that moral properties like moral wrongness are objective and non-natural, yet these nonphysical moral properties are attached to actions in the physical world (e.g. a man stealing a television has the nonphysical property of moral wrongness). An ontological explanation is needed for that, and one could argue that theism is the best ontological explanation. For example, moral wrongness being one and the same property as that which God forbids explains why moral wrongness is objective (God’s authority is supreme) and non-natural.

Another version of the moral argument is what I’ll call “the argument from ontological simplicity.” If one has trouble wrapping their head around “non-natural,” one can substitute the claim of objective moral properties being non-natural with objective moral properties being nonphysical, and that will be close enough for our purposes (as the scenario of the scientist above illustrates, it does seem clear that objective moral properties are at least nonphysical).

The Basis of Morality

It’s an axiom of rationality that, all other relevant factors being equal, the simplest explanation is the best one. Given that moral properties are nonphysical and thus that morality exists as part of the nonphysical realm to at least some degree, it is interesting to note what would happen if we posited just one nonphysical entity and tried to find the simplest explanation for it grounding morality; let’s label that entity X. We would find that our posited nonphysical entity X that is the source of moral value and obligation has the following properties:

  1. Transcendence. As a nonphysical entity, X must be transcendent in the sense that it transcends the physical world.
  2. Authority. As the source of moral obligation, X has authority in that it imposes moral duties and grounds their “oughtness.” Two aspects of its authority are worth mentioning:
  3. Metaphysical necessity. X must exist in every possible world (and therefore have necessary existence) to ground morality in every possible world, because morality is metaphysically necessary. While multiple entities spread about in different possible worlds grounding morality is logically possible, if we’re looking for the simplest explanation it is preferable to posit just one grounding entity to explain morality’s metaphysical necessity.
  4. Eternality X must be eternal, since at no time and in no circumstances can metaphysically necessary entities fail to exist.

Notice what results. If we posit just one nonphysical entity to ground morality and tried to find the simplest explanation for that entity grounding morality, we wind up with an eternal, transcendent, metaphysically necessary entity that imposes moral duties upon us with supreme and universally binding authority. This, of course, sounds suspiciously like God.

Objections and Rejoinders
Objection: God being the basis of morality is vacuous and circular

The idea that goodness is whatever God commands makes moral goodness vacuous and circular, at least if we ascribe the property of “goodness” to God. God’s commands are supposed to be “good.” But we define “good” as “whatever God commands.” It’s circular. God’s commands are only “good” in that they conform to themselves.


First I’ll define some terms that represent three different branches of moral philosophy.

  1. Moral epistemology: how do we know what is moral?
  2. Moral semantics: what does “morality” mean?
  3. Moral ontology: what is the foundation for morality?

The last two are of interest here. The criticism that God being the basis of morality makes goodness circular conflates moral semantics with moral ontology. God is being offered as the foundation of morality, not the definition of it. What is the foundation for morality? God. What is the definition of morality? The definition of morality is not “God” or “whatever God commands.” Rather, the definition of morality is a different question with a different answer. One possible answer to the definition of morality (and the one used here) is “a set of principles describing how we ought to behave.” Morality is defined as a certain set of ought-statements, and the existence of God is merely the explanation of why those ought-statements exist.

Objection: the Euthyphro dilemma; and if God commands rape, then raping people would be ethical.

God being the basis of morality implies divine command theory. Divine command theory says something is morally good/bad because God commands it to be so. The Euthyphro (YOO-thiff-row) dilemma produces a fatal problem for it. In Plato’s Euthyphro, Socrates asked, “Do the gods love holiness because it is holy or is it holy because the gods love it?” Applying that principle in the case of ethics, this version of the Euthyphro dilemma becomes, “Is it good because God commands it, or does God command it because it is good?” If God commands it because it is good, then good is independent of God and God is not the basis of ethics. If it is good because God commands it, then ethics becomes arbitrary in the sense that God could command anything and it would become morally good. For instance, God could have commanded rape and rape would become ethical.


God’s nature

At first I thought this was a really good argument, but on closer examination it doesn’t quite work out, at least in part because divine command theory isn’t necessarily what we’re talking about when we say that God is the best explanation for objective ethics (though that may depend on how you define divine command theory).

One definition of divine command theory is that what is morally right and wrong flows solely from God’s commands, and that there is no deeper underlying foundation for morality. If we use this definition, divine command theory would indeed say that the God’s commands are good merely because God commanded them. However, the Euthyphro dilemma is a false dilemma because exists at least one other alternative: God’s commands are good not merely because God commanded them but because they reflect His perfectly good nature. Rather than the commands being arbitrary, those commands flow necessarily from that perfect nature. For instance, God necessarily commands us to love our neighbor because God is by nature loving. It is God’s nature that is the standard by which actions are judged as good, and God’s nature is the basis of morality (we could call this divine nature theory).

The general idea roughly resembles what Plato called “the Good.” Plato (c. 427-347 BCE) was a Greek philosopher who believed that physical things had models or archetypes called “Forms” from which they are generalized. For instance, a basketball takes after the Form of a sphere, and though a basketball may not be a perfect sphere, we have a conceptual idea of what a perfect sphere is. A sphere is an example of a Form from which we say “the basketball is spherical.” Similarly, Plato believed in “the Good,” the perfect archetypal nature of moral goodness. God is what Plato called “the Good,” in that God’s nature supplies the supreme moral standard. God’s commands reflect that perfectly moral nature.

Arbitrary morality

Still, some define divine command theory broadly enough to include God’s commands being rooted in His nature. And one could still argue that morality being based in God in any way would make ethics arbitrary in the sense that God could have commanded anything, even rape and torture, and it would become ethical. For instance, one could claim that God's nature is arbitrary in that it could have been anything, and therefore He could have commanded anything, even boiling babies. In any case, we can organize this sort of argument as follows:

  1. If God were the basis of morality, then it would be possible for God to command rape, and thus it would be possible for rape to be ethical.
  2. Rape cannot possibly be ethical.
  3. Therefore: God is not the basis of morality.

The argument is deductively valid (i.e. if the premises are true, then the conclusion must be true). But is the argument sound (i.e. valid with true premises) or does it contain a false premise? One key problem is this. Suppose the second premise is true: rape cannot possibly be ethical. But if rape cannot possibly be ethical, then it cannot be possible for the basis of morality (whatever that might be) to command rape. We would have to reason that the basis of morality has some type of immutable nature. But if we know the basis of morality cannot command rape, why think that if God were the basis of morality He could command it?

Perhaps because the type of possibility being referred to is logical possibility, and it is logically possible for God to command rape. Something is logically possible if and only if it does not violate the law of noncontradiction. This law says for any proposition p, it is impossible for both p and not p to be true; a statement about reality cannot be both true and false at the same time and in the same context. Examples of logically impossible claims include “hairless men have hair” and “bachelors are married.” Many false claims such as “The Earth is flat” and “I created a perpetual motion machine” are nonetheless logically possible because they are not self-contradictory. Thus the statement “God commands rape,” while perhaps false, is logically possible.

But then we must be consistent. If we are only saying it is logically possible for God to command rape, then the end of the first premise becomes “thus it is logically possible for rape to be ethical.” And the second premise must be “It is not logically possible for rape to be ethical” to arrive at “Therefore God is not the basis of morality.” In other words, we get the following:

  1. If God were the basis of morality, then it would be logically possible for God to command rape, and thus it would be logically possible for rape to be ethical.
  2. It is not logically possible for rape to be ethical.
  3. Therefore: God is not the basis of morality.

The first premise is true, but the second premise is false. It is logically possible for rape to be ethical, because the statement “rape is ethical,” while false, does not produce a self-contradiction. So having the type of possibility be logical possibility and pointing out “It is logically possible for God to command rape” will fail to produce the desired conclusion.

So what kind of impossibility are we referring to if we say “rape cannot possibly be ethical”? Perhaps it is metaphysical or ontological impossibility, such as “the number six created the universe,” where even if it is logically possible such a thing cannot happen in reality under any possible circumstances. Suppose it is in this sense that rape cannot possibly be ethical. Then it still must be true that the basis of morality cannot possibly command rape. So we go back to our original problem: if God were the basis of morality, why think it is possible for God to command rape?

Perhaps because it is possible for humans to make such a command, and if humans can do this then God can also. But this would be making an anthropomorphic assumption about God that isn’t necessarily true. God’s nature is not necessarily like that of humans, especially if God is the basis of morality. If rape cannot possibly be ethical then it follows that the basis of morality (whatever it is) has an immutable nature such that it cannot command rape, so why think it is impossible for God to have this nature? Especially if God is not as anthropomorphic as the argument would seem to assume? If certain virtues are unalterable, then wouldn’t it follow that if God were the basis of morality, these virtues embodied in the nature of God would also be immutable? If for instance telling the truth is an unchangeable virtue, then God cannot lie. Incidentally, the belief that God cannot lie goes at least as far back as early Christianity (it can be found in Hebrews 6:18 of the Christian Bible). Why think such views are necessarily false?

In the end, trying to justify both premises faces serious problems of justification. If rape cannot possibly be moral, then the basis of morality cannot command it. So how does one justify that “If God were the basis of morality, He could command rape?” Apparently, it cannot be done without making some assumptions about God that are not necessarily true. If the basis of morality requires some type of immutable nature, there seems to be no reason why God cannot have this characteristic.

Other Versions of the Moral Argument

There are other forms of the moral argument. At my blog I have a series on the moral argument that (among other things) discusses this version:

  1. If God does not exist, then objective morality does not exist.
  2. Objective morality does exist.
  3. Therefore, God exists.

Of course, for the above argument to be a good one, the first premise requires some justification. If you’re curious about that, see part 2 of the moral argument series on my blog (by the time you finish reading this web page, you can probably skip part 1 of the moral argument series).

[1] Adams, Robert M. The Virtue of Faith (New York: Oxford University Press, 1987), p. 145.