top of page

The Moral Argument

As I read about apologetics and philosophy in high school, I realized that one important element (perhaps the main element) of philosophical thought is questioning presuppositions. Very often, people operate on the surface or at the top level of their structures of belief. Once you begin to think critically about those beliefs, this process will move you down that structure until you're asking questions you've never asked about beliefs you've never questioned. This can be a difficult but incredibly rewarding process.

Because of this, I often found myself in philosophy classes in college asking that one question no one would think to ask. If we were discussing the situations in which it was acceptable to kill someone, I'd ask, "What's wrong with murder for any reason?" I didn't do it to be a contrarian, but instead to provoke my classmates to think more deeply about their presuppositions. This was the method of Socrates, who would ask a series of questions to reveal inconsistencies or presuppositions in the reasoning of his interlocutor.

The moral argument for the existence of God encourages people to do just that: to question their presuppositions. We tend to take for granted that some actions are good and others evil. But, in the words of one famous Christian philosopher, why think a thing like that? If we believe that some actions are good and others evil, then by what standard do we think this? The concept behind the moral argument is that God is the standard by which there is good and evil. Here is the video:

Fortunately for us, this argument is somewhat simpler than the ones before! You'll notice immediately, if you have followed the series on Natural Theology until now, that the first premise is a conditional (if/then) statement. What's different about this premise is that both the antecedent and consequent are negations. How can we understand this? First, let's write out the argument in English:

  1. If God does not exist, then objective moral values and duties do not exist.

  2. Objective moral values and duties do exist.

  3. Therefore, God exists.

Remember that, when we negate a proposition, we write "not-" in front of the letter meant to represent the proposition. For this argument, let's use G for "God exists" and O for "objective moral values and duties exist." Notice that the second premise affirms O, which essentially means that it negates the proposition not-O. This is called double negation and is another rule of inference. This one is simple and intuitive:

Double Negation

  1. not-not-p

  2. Therefore, p

In other words, by negating the negation of a proposition, you affirm that proposition. So here is the argument symbolized:

  1. not-G implies not-O

  2. O

  3. Therefore, G

Once we recognize that the negation of the negation of a proposition is the affirmation of that proposition, then we can recognize the logical structure of the moral argument. It is modus tollens. As a reminder, here is the form of modus tollens:

  1. p implies q

  2. not-q

  3. Therefore, not-p

Therefore, the argument is valid.

What about the premises? Are they true? Before I get into that, some clarification of these concepts is in order. The difference between moral values and moral duties can be confusing to some. The difference has to do with actions that are good or bad and actions that are right or wrong. There is plenty of overlap here. Murder is both bad and wrong. When we speak of moral value, however, we're considering the quality of the act; is that type of act a good thing or not? Duties, on the other hand, have to do with obligations. When we make claims about what one should or shouldn't do, then we're making claims about one's obligations. It is important to make this distinction because objective morality has to do with discovering what grounds both values and duties. Some claims concerning what grounds values may not ground duties. Our goal is to discover what, if anything, grounds both of these.

Along with this, the word "objective" needs to be defined. If a claim is true objectively, then it is true, whether or not anyone thinks that it is true. In other words, the truth of the claim is mind-independent, rather than subjective truths, which are grounded in the subject in question. Therefore, if some moral claims are true objectively, then they're true, whether or not anyone believes them to be true.

With this in mind, let's discuss the premises:

Premise 1

  • If God does not exist, then it seems impossible that there could be an objective standard for the truth of moral claims. Such a standard would have to transcend human beings, since human beings, if the standard, would choose arbitrarily. Therefore, without God, no objective standard would exist.

Premise 2

  • We tend to ascertain the existence of objective values and duties as a result of immediate moral experience. This is much like our experience of the external world, which gives us a belief that the external world exists immediately. Given that we have no reason to reject this belief, then it is rational to accept it. In epistemology, this is called a properly basic belief. In other words, we have every reason to accept premise 2 and no reason to reject it.

What are the strengths of this argument? At least three points come to my mind. First, unlike some of the other arguments that we have covered, the moral argument is very easy to understand without philosophical training. Not many concepts must be explained, and the logic of the argument is easier to grasp. In my experience, I find the moral argument to be the easiest to explain. All human beings are intimately acquainted with moral experience because moral experience is a fundamental part of what it means to be human. In explaining this argument to someone, it is easy to come up with examples from human experience to illustrate the premises of the argument.

Second, this argument, perhaps more than any other argument we've covered, speaks deeply to what it means to be human. As William Lane Craig has pointed out, every morning, we are forced to answer the question for ourselves, "How will I live?" The reality of objective moral values and duties confronts us daily in our own experience, as well as the experience of others. To deny this reality is both willfully ignorant and ultimately impossible. You, at least, matter to you, and you can't help but live that way.

Third, because of the second point, the moral argument tends to be very compelling and difficult to deny. William Lane Craig often tells a story that I have seen reflected in my own experience presenting this argument. When you initially present the argument to an atheist, say, you may find that he or she will reject one of the premises. Let's say that he or she rejects the first premise but affirms the second. So he or she denies the claim that if God does not exist, objective moral values and duties do not exist. You may then ask, "Well, if God doesn't exist, then what's the objective standard for morality?" Later in this discussion, this atheist comes to affirm the first premise but, realizing the conclusion that follows, then denies the second premise. You rightfully point out that to deny the reality of moral experience seems absurd, which moves the atheist to then affirm the second premise but deny the first premise. I call this phenomenon "premise-hopping," and it is unique to the moral argument and illustrates well how strong of an argument for God it is. Its two premises are very probable, and I often find that atheists will hop from denying one premise to the other in order to avoid the reality of God.

This should be instructive for Christians, since we see in this a confirmation of Scripture in Romans 1:18 when Paul teaches that unbelievers "suppress the truth in unrighteousness." Ultimately, only a humble and contrite heart is willing to surrender to God's holy authority, and no argument alone works. We must pray for the work of the Holy Spirit through arguments and be willing to speak the truth of the gospel plainly as we meet unbelievers where they are.

That's it for this week's post! If you have any comments or questions, feel free to leave a comment or send me an email or message. I hope that these arguments continue to interest and edify you. Next week, we'll discuss the ontological argument. This is my favorite argument for God's existence personally because it is so fascinating and has an interesting history. Stay tuned for that post!

If you find yourself continuing to come back to the blog, please consider subscribing to it, so that you will get notified of each new post. With a subscription, you can also comment below and start a discussion! Finally, if you have any questions or comments about the blog, then you can send me a message from the bottom of the homepage. I look forward to receiving messages from you. Thank you for reading!

18 views0 comments

Recent Posts

See All


bottom of page