Medieval Arguments for the Existence of God Part 4: Teleological Arguments

This is part 4 of a four-part series on the medieval arguments for the existence of God. Part 1 outlined the four types of arguments for God’s existence, part 2 covered ontological arguments, part 3 covered cosmological arguments, and this final part (part 4) will wrap up the series by covering teleological arguments. 

Teleological arguments are arguments for the existence of God—or for some intelligent creator or creators—based on the perceived evidence of deliberate design in the natural world. Teleological arguments were first proposed in ancient Greece and later developed by medieval theologians—particularly St. Thomas Aquinas—with various criticisms and counter-arguments offered up to the present day.

Considering the immensity of the topic—which touches on science, evolution, mathematics, probability, and more—this post could run the length of a book. My purpose, however, is not to cover all the relevant issues, arguments, and science, but to simply comment on what I believe to be the most critical points in determining whether or not the argument provides sufficient or legitimate grounds for belief in God today.

While there are different versions of the teleological argument, and key differences between Aquinas’s version and William Paley’s watchmaker analogy, we’re going to focus on Paley’s argument, and the related fine-tuning argument, as they have proven to be the most enduring and convincing (to some). 

William Paley’s watchmaker analogy

In discussing teleological arguments, a good place to start is with William Paley’s watchmaker analogy, as described in his book Natural Theology in 1802:

“In crossing a heath, suppose I pitched my foot against a stone, and were asked how the stone came to be there; I might possibly answer, that, for anything I knew to the contrary, it had lain there forever: nor would it perhaps be very easy to show the absurdity of this answer. But suppose I had found a watch upon the ground, and it should be inquired how the watch happened to be in that place; I should hardly think of the answer I had before given, that for anything I knew, the watch might have always been there. … There must have existed, at some time, and at some place or other, an artificer or artificers, who formed [the watch] for the purpose which we find it actually to answer; who comprehended its construction, and designed its use. … Every indication of contrivance, every manifestation of design, which existed in the watch, exists in the works of nature; with the difference, on the side of nature, of being greater or more, and that in a degree which exceeds all computation.”

All teleological arguments, including modern forms of Intelligent Design, ultimately rely on this basic intuition. Applied to the explanation of the complexity of life, the argument takes the following general form: 

  1. Biological organisms consist of several complex parts and functions that interact with each other in a way that suggests deliberate design.
  2. This complexity can be explained either by chance or by design.
  3. Chance is a highly unlikely explanation (as it is for the watch) for the complexity we find in biological organisms.
  4. Therefore, life was deliberately designed by an intelligent designer.

In Paley’s watchmaker analogy, the watch could have assembled itself by chance, but we understand the probability of this happening to be so low that we can rightfully infer the existence of an intelligent designer (a human agent). Likewise, since the complexity of life was unlikely to come about by chance—in the same way as the watch—we can rightfully infer the existence of an intelligent designer of even greater capacity than the human designer of the watch.

The standard objection to this argument is that, when it comes to explaining the complexity of life, Paley’s watchmaker analogy presents a false dilemma between chance and design, as seen in the second premise of the above argument. As Darwin’s theory of evolution would later show, Paley missed the third alternative: the step-by-step accumulation of progressive complexity through random mutations and (unconscious) natural selection. 

I won’t defend evolution in this post, as it is essentially incontrovertible and all but universally accepted by the scientific community. But I will say that this is not, as some suppose, the final objection to Paley’s argument. A more charitable interpretation of Paley’s argument does not look only to biological evolution, but rather to the total picture of facts that allows evolution to occur in the first place, in the manner that it does. 

Remember, it is a false dilemma to suggest that life evolved either by chance or by design. It evolved, rather, through a slow, cumulative process of variation (in genes) and selection (natural selection) where advantageous (and some neutral) traits persist in nature whereas disadvantageous traits are eliminated. 

We are confident in our explanation of the evolution of life because we avoid having to conclude that it did, in fact, arise by simple chance in a single step. Although life does not require a designer, we would be uncomfortable concluding that it arose entirely by chance without the guidance, albeit unconscious guidance, of natural selection. 

However, things get trickier when we begin to consider the laws of physics themselves, which are necessary for any life to begin evolving in the first place. Consider the following argument:

  1. Finely-tuned and invariable physical laws are necessary for the existence of life. 
  2. The laws of physics were either designed or came about by chance.
  3. It is highly unlikely that all of the finely-tuned physical constants came about by chance. 
  4. Therefore, the physical laws were designed by an intelligent designer.

As you recall, in terms of explaining the development of life itself, Paley presented a false dilemma between chance and design. Darwin showed a third way, namely, natural selection, that did not have to rely on chance alone. But the physical laws (e.g., the gravitational constant, strong nuclear force, etc.) did not and cannot evolve; instead, they remain fixed. If the physical laws did not evolve, then they must have either been designed or came about by simple chance in a single step.

Now imagine a hypothetical scenario. Imagine that science had confirmed that evolution was false, and that macroevolution cannot and did not occur. If the choice was again between chance and design—as it was for Paley before the discovery of evolution—which option, between chance or design, would you think to be more likely? In that case, and without a third option, reason would seem to compel you to believe in a designer. 

But if that’s the case, then what should we think about the laws of physics and the finely-tuned physical constants? The probability that the laws of physics are exactly what they need to be to support life, and that this happened randomly, is presumably even smaller than the spontaneously-generated watch. But if there is no third way of evolution in terms of explaining the laws of physics, then shouldn’t we conclude that a designer must have created them?

Indeed, as modern physicists have pointed out, the universe is undoubtedly finely-tuned. For example, as physicist Paul Davies pointed out, if the strong nuclear force were 2 percent stronger than it is, this would drastically alter the physics of stars, potentially precluding the existence of life (or at least life as we know it). 

Additionally, according to physicist Leonard Susskind, if the cosmological constant was a slightly larger value, or if there were a slightly larger amount of dark energy, space would expand too rapidly to be able to form galaxies. 

There are several other examples, but the point is that, taken together, all of the physical constants appear to be working together to create the conditions in which life can emerge.

This is the more difficult version of Paley’s argument, and of the teleological argument more generally, that we must confront. It is variously referred to as the “fine-tuning argument.” 

Objections to the fine-tuning argument

The fine-tuning argument, if we are honest, appears to be legitimate, at least on the surface. But before we all renounce our skepticism and conclude that there must be a designer, we should consider two key weaknesses in the argument. 

Winning the lottery

The odds of winning the Powerball lottery are very low, about 1 in 300 million. While it is always surprising to the person who wins, it is not surprising—considering the number of players and the rules of the game—that someone wins, and this can always be explained entirely by chance. The person who wins the lottery may attribute the victory to divine intervention—and wonder why it was her that won out of so many other people—or may even come to believe that the lottery was created just for her. But we understand this to be purely psychological, and does not in itself imply any intelligent intervention in the outcome. 

In the same way, a universe that contains self-reflective sentient life will be a universe in which those sentient beings reflect upon the conditions supportive of their existence. In other words, only in a universe capable of eventually supporting life will there be living beings capable of reflecting on the fact that the universe supports life. This is known as the anthropic principle. 

And this is a significant problem for the fine-tuning argument. To conclude that it is too improbable for the universe to have arisen by chance, we must be able to calculate accurate odds. But for us to calculate accurate odds, we must be confident in asserting that 1) we live in the only current universe, 2) that our universe is not part of some evolutionary process of past universes, and 3) that our universe is not cyclical. 

First, if there are multiple universes, each with different physical laws (some of which are unsupportive of life), then living in our particular life-sustaining universe is like the person who wins the Powerball lottery. Several prominent physicists, such as Brian Greene, Sean Caroll, Hugh Everett, Max Tegmark, David Deutsche, and Stephen Hawking are all proponents of some form of multiverse theory. 

Second, physicist Lee Smolin has proposed the possibility of cosmological natural selection, which suggests that the process of natural selection applies to the largest scales of the universe. According to this theory, black holes represent the creation of new universes on the other side—with different physical constants. 

And third, as Albert Einstein proposed, there is the possibility that our universe is cyclical—that it perpetually expands and contracts—creating different conditions in each cycle, some supportive of life and others not. 

The bottom line is that there is a sufficient amount of uncertainty regarding the fact that we live in the only universe and that our universe is not part of a larger process or “megaverse.” And so it is premature to think that we can even begin to calculate the odds of our universe being able to sustain life. 

Another line of argument calls into question the coherence of engaging in probability calculations on this topic at all. Say, for example, that you play a game with a million people. All one million contestants, including you, enter their name into a spreadsheet, after which the host randomly generates and assigns a number to all the names, sorts the names, and selects the top name with the highest number to win the game. If you win, you should be rightly surprised, considering the odds. The odds are low because there were a million possible outcomes, and you were only one outcome among them.

But let’s say you were the only person to play the game, and the only person to enter a name. Are you justified in being surprised that you were selected, when you are the only possible outcome? If the universe is all that exists and has ever existed, then it could have only turned out to be one way—the way it is—and probability doesn’t factor into the reasoning as to why it is like it is. To be surprised that you live in the only extant universe, one that supports your existence, is like being surprised that you won the game that only you were playing. The universe is what it is because it’s the only universe, and perhaps science will one day demonstrate why it’s the only possible way the universe can be. 

A final point is that the universe appears fine-tuned for life as it exists on planet earth. But we should not be so quick to conclude that a different form of life couldn’t arise under different conditions with different physical constants and laws. This could also change the probability calculation, if we deem that probability even applies.  

The ultimate Boeing 747 argument

Teleological arguments, remember, all rely on the intuition that complexity—whether in regard to complex life forms or to complex sets of physical constants—requires an explanation. That explanation can either be random chance or else the existence of design.

If you’ve read parts 2 and 3 of this series of posts, covering the ontological and cosmological arguments, you’ve probably noticed that I’ve used the same strategy in each; namely, using the logic of the arguments against themselves. This has turned out to be a reliable strategy that works just as well with design arguments. 

In his book The God Delusion, biologist Richard Dawkins compares the probability of life arising in a single step to that of a tornado sweeping through a junkyard to assemble a Boeing 747 airplane. Of course, life did not arise in a single step; it evolved in progressive steps through evolution by natural selection.  

But that is not the point: the main point of the argument is to demonstrate the self-defeating logic of teleological arguments. If the existence of complex life on earth is equivalent to the assembly of the junkyard Boeing 747, then God represents the “ultimate Boeing 747” that requires his own explanation. 

According to the watchmaker analogy, the human watchmaker was necessarily more complex than the watch, as the human agent must possess the knowledge and means necessary to construct the functioning watch. It would make little sense to conclude that the watch was more complex than the designer, because the designer must understand everything about the functioning of the watch to be able to actualize its existence.

Likewise, if God created man, then God must be more complex than man. To create a human requires a complete knowledge of the complex functioning of humans, and so if human anatomy, physiology, consciousness, and thought is complex and requires an explanation, then the God who created humans, having complete knowledge of humans, must necessarily be more complex and must also require the same explanation. 

And so the theist is faced with the same dilemma they are posing to others: namely, did God arise by chance or does He require his own designer? 

If the theist maintains that God arose by chance, then they might as well conclude that the universe arose by chance, because the universe is necessarily less complex than the entity that created it (because the creator must contain a complete understanding of its own creation).

The theist must therefore conclude that God requires his own designer, but this leads to an infinite regress. 


We’ll conclude this post with a quote from the Christian philosopher Alvin Plantinga, responding to Richard Dawkins’ “ultimate Boeing 747” argument, and the assertion that God must be more complex than His creation. In it, Plantinga unintentionally points out the main problem with all arguments for the existence of God. Plantinga wrote:

“So first, according to classical theology, God is simple, not complex. More remarkable, perhaps, is that according to Dawkins’s own definition of complexity, God is not complex. According to his definition (set out in The Blind Watchmaker), something is complex if it has parts that are “arranged in a way that is unlikely to have arisen by chance alone.” But of course God is a spirit, not a material object at all, and hence has no parts. A fortiori (as philosophers like to say) God doesn’t have parts arranged in ways unlikely to have arisen by chance. Therefore, given the definition of complexity Dawkins himself proposes, God is not complex.”

So Plantinga has, by fiat, declared God to be simple, immaterial, and immune from both empirical and rational investigation. How convenient. This is exactly what we saw with the cosmological argument. Theists insist that everything requires a cause, but then exempt God from this requirement because God “lives outside of time and space.” In the same way, theists insist that complexity requires a designer, but that God is not complex because God is immaterial and has no parts. (If God is immaterial and has no parts, what else might this suggest?)

I think you can see the pattern here. Ultimately, all arguments for God’s existence fail to be persuasive because the logic is self-contradictory, unless you define God in such a way as to remove him from all possible refutation. But you should ask yourself on what authority Plantinga, or anyone else, has the right to define God in this way. The arguments for God’s existence are supposed to demonstrate the existence of God, but if you’re going to define God as part of the argument, then you are already presupposing his existence, and thus simply arguing in a circle. 

Further reading

Since teleological arguments for God often present the false choice between chance and design as the only explanations for the complexity of life, it’s important to understand how evolution, as the “third way,” works, including the evidence we have for it. Here are my favorites:

It’s also important to understand the philosophical implications of evolution, covered by these two books:

For more information on the current state of cosmology, and the possibility of multiple or parallel universes, check out:

For a defense of the teleological position, along with other arguments for God’s existence, check out:

Finally, check out the classic counter-argument to the teleological argument by David Hume, as well as the entry on design arguments from the Stanford Encyclopedia of Philosophy:

2 thoughts on “Medieval Arguments for the Existence of God Part 4: Teleological Arguments

  1. We are enclosed by what our senses show and memory, imagination, thinking in the mind.
    There is no way; you can come out of this format. All one’s ideas about God, who created this Universe – arise as thinking, that is, within this format.
    Anything that comes before you, including stars, galaxies arise within this field. The field of senses and the field of memory, imagination, thinking is the Total Field.
    One can not find the Original as an object. As the investigation will always require a subject-object format.
    Object-the world is seen by the subject-the observer, mind. Now there is no observer of the observer. There is nothing behind the observation. ‘Why there is no observer’ or ‘there may be an observer’ are all expressions, thoughts arising in the mind. When this is clearly noticed, subject-object is seen as a singular, complete, self-sustained process.

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