An Abductive Moral Argument (Part 1, Introduction)

In a series of six blogs I intend to discuss the particular variant of the moral argument for God’s existence that I tend to favor. These entries will be brief, so for more details check out Good God: The Theistic Foundations of Morality and God and Cosmos: Moral Truth and Human Meaning, books I’ve written with Jerry Walls, or the more accessible forthcoming The Morals of the Story: Good News About a Good God I wrote with my wife. Or, if you can, come study with me in the Divinity School at Liberty University, where we spend many an hour explicating and scrutinizing such arguments.

Background & History

Moral apologetics fascinates me, as I’ve lived with the argument for twenty years. The more I look into it, the more interesting it becomes. Plenty of folks think the moral argument practically originated with C. S. Lewis, or perhaps Immanuel Kant. But actually there were precursors to Kant’s famous formulation, and plenty of folks after Kant, both before and subsequent to Lewis. In fact, a number of these thinkers gave Gifford lectures on the topic, a famous lecture series given at Scottish universities. A. E. Taylor, William Sorley, Hastings Rashdall, and plenty of others all gave their Gifford lectures on the moral argument. The history of moral apologetics is far richer than many realize; my co-author and I are wrapping up a book on this history.

The Moral Argument

Moral arguments come in all shapes and sizes, flavors and textures, and there’s nothing sacrosanct about any particular form. The one I’ll be offering here just happens to be my preference for a few reasons I’ll make clear as we go along. By “abductive” I’m referring to an “inference to the best explanation,” and the idea is fairly simple. Something needs an explanation, there are a variety of explanation candidates, and we use various criteria to choose which explanation is the best. We then tentatively infer to it as the likely true explanation. Among the criteria for narrowing down to the best explanation are explanatory scope and explanatory power. Explanatory scope pertains to how much of what needs explanation is explained; explanatory power is how well the explanations explain. Other criteria include degree of ad hoc-ness (the less the better), conformity with other beliefs, (the more the better), and the like. Notice, importantly, that an abductive argument is not a deductive argument; the conclusion doesn’t follow from the premises with anything like certainty.

When it comes to morality, what needs explanation? Simply saying “morality” is far too course-grained; we need to identify some of its central salient features. The way we did this in God and Cosmos was offering a four-fold moral argument encompassing four distinct features of morality. We called them (1) moral facts, (2) moral knowledge, (3) moral transformation, and (4) moral rationality. The next four blogs will be devoted to these four aspects of moral reality, each in turn. The sixth and last blog will pull the whole argument together. The moral facts refer to such moral phenomena as moral freedom, moral rights, moral obligations, and moral goodness—including such value questions as why human beings having the equality and inherent dignity they do.

When it comes to the rival explanation candidates, the most important distinction for present purposes is between secular ethics and religious ethics, but quite a bit more needs to be said to avoid ambiguity. Both religious ethical theories and secular ethical theories come in lots of different forms. So to narrow the field, I’ll focus on the type of theistic ethical theory I’m drawn to, and then some sample secular and naturalistic ethical theories currently on offer. In personal conversations, it’s often convenient to narrow the focus to the particular theories the interlocutors in question happen to hold. The only ultimate way to make the full abductive case is to consider the full range of options available, which is a big task. This is why Jerry and I are finishing our third book on the project, with yet more planned after that.

The Abductive Version

Before getting into the argument, let’s look at William Lane Craig’s version of the moral argument, which looks like this:

(1) If God does not exist, then objective moral values and duties don’t exist.
(2) Objective moral values and duties do exist.
(3) So, God exists.

This is a deductively valid argument, which is to say that the premises logically guarantee the conclusion—which is to say that, if the premises are true, then the conclusion will be true too. The conclusion follows in an airtight way from the evidence. But that still leaves open the question of whether the premises are true. Since the argument is valid, if the premises turn out to be true, then the argument is sound. A sound argument is a deductively valid argument with all true premises. And a salutary feature of a sound argument is that its conclusion is true.

Still, I have a few doubts about this version of the argument. My concern has to do with the first premise. What’s a world like in which God doesn’t exist? Is such a world even possible? Should we take a world like this one, assume God doesn’t exist, and go from there? If so, is it really the case if someone finds himself in a world as rich as ours that nothing can be said by way of objective morality? That seems unlikely to me, especially if God created this world and inhabited it with beings like us—eternal creatures made in the very image of God. The notion that such a fertile world as this would give us no fodder at all for generating moral theory strains credulity.

I happen to take an abductive route. C. Stephen Evans cashes his moral argument in terms of “natural signs.” Others might speak in terms of moral evidence being more likely on theism than atheism. There are different ways to do this, but I happen to offer an abductive argument. Notice a few features of my argument. It’s a distinctly less-than-deductive case, so one in which the premises don’t have as much work to do, and it centrally involves this notion of explanation. It also requires a fair bit of patience, because there are a lot of ethical theories on offer. It’s an ongoing and large research question and agenda. In the posts to follow you’ll get at least a flavor of how the argument goes.

Part 1  |  Part  2Part 3  |  Part 4  |  Part 5  |  Part 6

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Chan Arnett

Excellent article! Really looking forward to your other articles on this topic as I think all of the moral arguments in kffering have strengths and weaknesses. I’m learning that this abductive approach is very good, but as you say in the article, it can take a while to be effective at using since one would have to learn the ins and outs of many secular theories. However, I consider that to be just like anything else we learn to better and more effectively lead people to the truth. Keep up the good work Dr. Baggett, and you too Capturing Christianity!


It’s good to see people appealing to abductive arguments. I find it strange that even has be justified (and in particular, that it doesn’t lead to certainty like a deductive argument does) – because it’s such a natural way to reason for someone coming from the sciences: It’s not that there’s no other possible explanations, it’s that one explanation fits (explains more data, has simpler assumptions, ect) better than the others.

I’m looking forward to the rest of the articles.