Aquinas’s Argument from Degrees of Perfection for the Existence of God: Introduction

Over the course of the last eight months I’ve written around fourteen articles on the first three of Aquinas’s famous “Five Ways” or arguments for the existence of God. Those first three, collectively, are all categorized as Thomistic cosmological arguments, because of their similarities in structure, method, and end point. All three argue from some feature of the world to the existence of a Being of Pure Act, or Subsistent Being Itself, based on the impossibility of infinite regress in essentially ordered causal series. Their individual distinctiveness comes from their starting points: the First Way starts from motion, the Second starts from efficient causation in general, and the Third from generation and corruption of beings.

The Fourth and Fifth Ways, however, are markedly different from the first three, and are not considered cosmological arguments. The Fifth Way, as we shall see when we turn to it, is often classified as a type of “Teleological” argument (although it differs greatly from most modern formations of such), thus leaving the Fourth Way as the “odd man out”, a unique species of argumentation in its own right.

However, continuing our tradition of comparing Thomistic arguments to arguments that are more popular in contemporary circles as a way of introduction, we could venture to examine the Fourth Way, or Argument from Degrees of Perfection, alongside modern “moral” arguments, as they each deal, although in very different ways, with the grounding of concepts such as “goodness”. The moral argument, also known technically as the axiological argument, is one of the most popular contemporary arguments used in defending the existence of God, and is plausibly one of the most naturally “obvious” arguments in that it is often implicitly assumed/understood by people with otherwise no philosophical background. Interestingly, one general overview article on the moral argument lists the Fourth Way itself as one of the first instances thereof:

“Something that resembles a moral argument for God’s existence, or at least an argument from value, can be found in the fourth of Thomas Aquinas’s ‘Five Ways'” [1].

However, pushing a bit against this, I’d contend that most modern formulations of moral arguments do not trace their roots back to the Fourth Way, because of how radically different they are. More plausibly, we could point to Kant as the real first modern advocate of a type of a moral argument. Since then there have been various different formulations of the argument, culminating in a version that has become quite standard in contemporary philosophy of religion today. But before we look at that, I’d also like to point out that the moral argument is quite popular in apologetics circles, arguably due to its use in C. L. Lewis’s extremely well known Mere Christianity, which begins with a presentation of a moral argument to God’s existence. The first section therein, or “Book I”, is titled “Right and Wrong as a Clue to the Meaning of the Universe”, and it goes on to argue that there is a general “Law of [human] Nature” that governs moral knowledge, conscience, behavior, and ethics, and which must be objective by some ultimate absolute standard, or “Lawgiver” if you will, which is then identified as God, a “Mind behind the Universe” who has purposes and intents and prefers certain actions to others, which is what we call Right and Wrong [2].

In all honesty, I must admit that I have a sort of personal bias in favor of Lewis’s argument, for it was, many years ago, the very first argument for the existence of God I ever encountered, and was what began my interest in philosophy of the first place. However, it also must be admitted that Lewis’s argument is very simplistic, and I cannot commit myself to defending it, or any other of the moral arguments under consideration here. I think they’re interesting, and after more study I may come to agree with/support them, but until then, I offer them merely as a means of comparison.

Finally, the standard, contemporary version of the moral argument, as defended by philosophers such as William Lane Craig, often appears something like this:

  1. If God does not exist, objective moral values and duties do not exist
  2. Objective moral values and duties do exist
  3. Therefore, God exists [3]

This argument maintains that the only objective grounding for moral values and duties can be God, which is a metaethical claim about moral ontology. The argument is often defended in relation to the system of ethics known as Divine Command Theory, or Modified Divine Command Theory. On a basic level, the argument seeks to ask how we can account for the reality of moral features in our experience, and asserts that we cannot do so an an atheistic/naturalistic framework. Advocates of this argument love to appeal to Nietzsche: “Morality ‘has truth only if God is the truth–it stands or falls with faith in God'” [4].

However, contemporary philosophers also make distinctions between two general types or branches of moral argument, one ontological, the other epistemological. The argument above is the former. Renowned philosopher Richard Swinburne, however, is rather skeptical of such arguments, and prefers instead an argument from moral knowledge. He writes:

“It is crucial to distinguish two different arguments from morality. First there is the argument from the fact that there are moral truths and secondly there is the argument from human awareness of moral truths” [5].

And he concludes that “I cannot see any force in an argument to the existence of God from the existence of morality” [6] but that “the fact of moral awareness provides one more good [inductive] argument for the existence of God” [7].

In other words, some philosophers such as Swinburne do not think it possible to argue from the fact of the existence of moral truths to the existence of God as a cause/explanation of those moral truths; but that it might be possible to argue from our own knowledge/awareness of moral truths to the existence of God as cause/explanation of our knowledge of moral truths. This is an important difference, related in some respects to the force behind “arguments from reason”, such as Plantinga’s version, which essentially contends that on naturalism, the unguided evolutionary process of development of human consciousness gives us no reason to trust our cognitive abilities, whereas theism does.

As I’ve said before, I do not aim here to defend or critique any of these arguments. In the future, especially when I begin writing about ethics and morality more generally, I’d like to return to some of them. But for now, let’s see how they relate to the Fourth Way.

One possible concept that gives rise to ontological moral arguments is what has come to be known as the “naturalistic fallacy” or the “fact/value distinction” asserted famously by David Hume. Hume’s dictum was that it is impossible to derive an “ought” from an “is”. Craig and Moreland write:

“In general, a fact or factual belief involves a description about the way the world is . . . In contrast, a value or value belief involves the adherence to some moral proposition that prescribes what morally ought to be. An ‘ought’ statement makes a prescription” [8].

Philosopher Ed Feser summarizes: “Hume famously argued [that] conclusions about what ought to be done (which are statements about ‘value’) cannot be inferred from premises concerning what is the case (statements of ‘fact’) [9].

Needless to say, Aquinas, on the foundation of his Aristotelianism, would reject such a fact/value distinction as an accurate description of reality. He does, however, think that an argument for the existence of God can be made on the basis of “grades of perfection” of certain value-like qualities in beings. And this argument is his Fourth Way.

But why would he reject the fact/value distinction? Because his understanding of reality is entirely different (and, in my view, superior) to that of David Hume and the moderns. The moderns have what Feser refers to as a kind of “mechanistic-cum-nominalistic understanding of nature” [10]. Nominalistic in that it denies the real, intrinsic essences of things which could be abstracted and understood universally; mechanistic in that it denies the reality of final causation, or ends/goals/purposes towards which the essences of beings are intrinsically directed. As natural law theory argues, it’s very hard to account for moral “oughts” without appealing to some sense of teleology/final causation. But even more fundamentally, Aristotelians would suggest that there’s a certain level of “oughtness” built into the very nature of reality, right down to the molecules, atoms and subatomic particles, and that it is entirely objective.  Feser explains:

“From the traditional Thomistic point of view, however, there simply is no ‘fact/value distinction’ in the first place. More precisely, there is no such thing as a purely ‘factual’ description of reality utterly divorced from ‘value,’ for ‘value’ is built into the structure of the ‘facts’ from the get-go. A gap between ‘fact’ and ‘value’ could exist only given a mechanistic-cum-nominalistic understanding of nature of the sort commonly taken for granted by modern philosophers, on which the world is devoid of any objective essences or natural ends. No such gap, and thus no ‘fallacy’ of inferring normative conclusions from ‘purely factual’ premises, can exist given an Aristotelian-Thomistic essentialist and teleological conception of the world. ‘Value’ is a highly misleading term in any case, and subtly begs the question against critics of the ‘fact/value distinction’ by insinuating that morality is purely subjective, insofar as ‘value’ seems to presuppose someone doing the valuing. Aristotelians and Thomists (and other classical philosophers such as Platonists) tend to speak, not of ‘value’ but of ‘the good,’ which on their account is entirely objective” [11].

And it is this objective understanding of “the good” that the Fourth Way is based upon. But what exactly is “the good”? Answering that question is what we’ll turn to in the next post.

For now, to close this brief introduction, I’m going to stray from the pattern I’ve used in my previous series on the first three Ways. I’m going to conclude this post by writing in full the Fourth Way in Aquinas’s own words, straight from the Summa, without an commentary or explanation. I’ll spend the rest of the series explaining and defending the argument, but here I’d just like to let it stand on its own:

“The fourth way is taken from the gradation to be found in things. Among beings there are some more and some less good, true, noble, and the like. But more and less are predicated of different things, according as they resemble in their different ways something which is the maximum, as a thing is said to be hotter according as it more nearly resembles that which is hottest; so that there is something which is truest, something best, something noblest and, consequently, something which is uttermost being; for those things that are greatest in truth are greatest in being, as it is written in Metaph. ii. Now the maximum in any genus is the cause of all in that genus; as fire, which is the maximum heat, is the cause of all hot things. Therefore there must also be something which is to all beings the cause of their being, goodness, and every other perfection; and this we call God” [12].



[1]. Evans, C. Stephen, “Moral Arguments for the Existence of God”, The Stanford Encyclopedia of Philosophy (Winter 2016 Edition), Edward N. Zalta (ed.), forthcoming URL = <;.

[2]. See Lewis, C. S. Mere Christianity. 1952. New York: HarperCollins, 2011. Print. Chapters 1-5.

[3]. Craig, William Lane. Reasonable Faith: Christian Truth and Apologetics. 1984. 3rd. ed.,Wheaton: Crossway, 2008. Print, 172.

[4]. Nietzsche quote from Nietzsche, F. (1968) Twilight of the Idols and the Anti-Christ. New York. Penguin Books. 70. Full quote from Linville, Mark D. “The Moral Argument.” The Blackwell Companion to Natural Theology, edited by William Lane Craig and J. P. Moreland, Blackwell Publishing, 2012, 392.

[5]. Swinburne, Richard. The Existence of God. 2nd. ed., Oxford: Oxford University Press, 2004. Print, 212.

[6]. Ibid., 215.

[7]. Ibid., 218.

[8]. Moreland, J. P. and Craig, William Lane. Philosophical Foundations for a Christian Worldview. Downer’s Grove: InterVarsity Press, 2003. Print, 407.

[9]. Feser, Edward. Aquinas. London: Oneworld Publications, 2009. Print, 175.

[10]. Ibid.

[11]. Ibid.

[12]. Aquinas, Thomas. Summa Theologica. 1265-1274. Trans. Fathers of the English Dominican Province. Coyote Canyon Press, 2010. ebook. I, Q. 2, Art. 3.


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