Did the Stoics Get Their Theory of Beauty Wrong? – by Massimo Pigliucci

Discobolus at the National Roman Museum, Rome, photo by the Author

Massimo Pigliucci gave a version of this talk at Stoicon 2023. The video of his talk can be viewed here.

Stoicon, as you probably know, is the annual international conference gathering (online) people interested in Stoicism. This year’s theme was rather unusual: the relationship between Stoicism and beauty. Perhaps predictably, I played the part of the token skeptic, with a talk on “Did the Stoics get their theory of beauty wrong?” Spoiler alert: the answer, I think, is yes. But we can learn a lot from the mistake and even correct it.

Let’s begin with the basics. My dictionary gives me two definitions of beauty: (i) a combination of qualities, such as shape, color, or form, that pleases the aesthetic senses, especially the sight; (ii) a combination of qualities that pleases the intellect or moral sense.

So for instance, beauty of the first kind might be exemplified by Michelangelo’s Pietà, a lake landscape, a painting by Caravaggio, a colorful butterfly, or an orange Lamborghini (my favorite car). Beauty of the second kind could be instantiated by, say, an act of moral kindness, the equations of the general theory of relativity, Marcus Aurelius’s Meditations, or a goal scored by Lionel Messi.

Why do we care about this in the first place? Because our sense of beauty (formal, intellectual, moral) guides what we do, what we seek, and what we appreciate. So this isn’t just a discussion about the philosophy of aesthetics, it has a large pragmatic component.

As it turns out, the Stoics too had a definition of beauty. They understood beauty as summetria. Although the word is obviously related to our concept of symmetry, the notion is significantly more sophisticated. Something has summetria if it fulfills two conditions: (a) there is harmony of parts with each other; and (b) there is functional integration of parts within the whole.

Apparently, the idea of summetria originated with a sculptor, Polycleitus (5th century BCE), who wrote a book called Canon in which he used a statue as an example. A beautiful statue, according to Polycleitus, is characterized by a harmony of the various parts with each other, in the sense that the limbs, torso, head, and so on, have to be proportional in the right way for a human being. There also has to be a functional integration of the various parts into the whole, meaning that we get the unmistakable impression from looking at the statue that a person like that really could perform feats of athletics.

So far so good. However, the Stoics’ account of beauty as summetria is intimately linked to their notion of a rational, providential universe. This in turn is connected to their conception of the cosmos as a living organism endowed with the Logos (i.e., reason). This is what is often referred to as Stoic pantheism (or panentheism, depending on how one interprets Stoic doctrine). The cosmic logos is the ultimate source of the harmony among parts and of their functional integration, that is, of summetria.

I often encounter modern Stoics who are not convinced that what I just described was indeed the ancient stance. So here is a clear and unambiguous description of it, uttered by the character of Balbus, speaking for the Stoics, in Cicero’s On the Nature of the Gods:

“Thus we can assume that the universe must possess wisdom and that the element which holds together all that exists excels in perfect reason. From this we see that the universe is in fact God and that the vital force of the universe is held together by this divine nature.” (De Natura Deorum, 2.30)

I will claim in a moment that this picture of the universe is incorrect in the light of modern science. But since you may be shocked that a modern Stoic dares to claim that the ancients got something wrong, I will remind you of at least two other instances in which the Stoics were unquestionably mistaken.

One was the location of the famous ruling faculty, the hegemonikon mentioned repeatedly by Marcus Aurelius, the seat of Epictetus’s faculty of prohairesis, or volition. The Stoics thought it was situated in the heart, not an unreasonable conclusion, given the state of human anatomy at the time. And yet already Galen, Marcus Aurelius’s own physician and one of the most famous doctors of antiquity, made merciless fun of the Stoics for not having realized that obviously the hegemonikon is located in the brain.

A second instance concerns the Stoic belief in divination, that is, in the ability of some specially trained people to predict the future while looking at the entrails of animals or the flight of birds. Again, such belief wasn’t completely cuckoo, based as it was on the Stoic notion that everything is interconnected by a universal web of cause and effect. It stands to reason, then, that if we look at one part of the web (the entrails of a sacrificed animal) we might be able to infer the structure of another part of the web (the future). Nevertheless, Cicero, in On Divination, harshly criticized the Stoics for accepting the practice as valid, thus producing the first known treatise on what we today call pseudoscience.

Back to the cosmos understood as a living organism endowed with reason. As a scientist and philosopher of science living in the 21st century, I don’t see a way to rescue that particular Stoic conception. It simply doesn’t fit either with the notion of organism as it emerges from contemporary biology or with our understanding of both cosmology and fundamental physics. The universe just is not like that.

Worse, the Stoics’ reasons for their view of the cosmos were varied, but the principal one was what we nowadays call an argument from design. Like this:

“If there is anything in nature that the human mind and reason or human strength and power cannot achieve, it is certain that such a thing must have been created by something superior to man. Now, the heavenly bodies in their eternal order cannot have been created by man. Therefore, that which created them is superior to man. What would we call this creator other than God?” (Balbus, quoting or paraphrasing Chrysippus, on behalf of the Stoics, in Cicero’s De Natura Deorum, 2.16)

Once again, this was eminently reasonable at the time, and if I had been born a contemporary of Epictetus I would likely have accepted it. But such acceptance is no longer reasonable after the lethal double punch that arguments from design got from David Hume (1711-1776) and Charles Darwin (1809-1882). Hume raised serious doubt about the design argument on philosophical grounds, and Darwin gave us empirical evidence that the appearance of design is produced by an entirely natural and thoughtless process, which we call evolution by natural selection.

The Stoics themselves, by the way, would have been open to these proposed changes in their view of the world. Stoicism, after all, is a philosophy, not a religion, and Seneca wonderfully wrote:

“Shall I not follow in the footsteps of my predecessors? I shall indeed use the old road, but if I find one that makes a shorter cut and is smoother to travel, I shall open the new road. Men who have made these discoveries before us are not our masters, but our guides. Truth lies open for all; it has not yet been monopolized. And there is plenty of it left even for posterity to discover.” (Letter 33.11)

In my opinion, this is one of those times when, with all due respect to our teachers, we need to abandon the old path and chart a new one. We need, in other words, a new account of summetria.

Enter evolutionary aesthetics, the notion that our sense of beauty is the result of evolution by natural selection to enhance survival and reproduction. This is still a functional theory of beauty, but not at the cosmic level. What is beautiful to us may not be beautiful in the eyes of members of different species, because different things contribute to the survival and reproduction of individuals belonging to distinct biological lineages.

Let’s consider an example: according to Chrysippus, the third head of the original Athenian Stoa, the peacock was created by Zeus / Nature / the cosmic logos for the beauty of its tail. According to Darwin, by contrast, the peacock’s tail evolved in order to attract the female of the species, a process known as sexual selection. I hope the latter account strikes you as more in tune with the scientific worldview than the first one.

One of the other speakers at Stoicon, Aistė Čelkytė, wrote what I think is the book about the Stoic theory of beauty. There she states:

“The equivalence of ethical and aesthetic value implies that the good shares the properties of the beautiful, and the beautiful shares the properties of the good. … [For the Stoics] beauty is a property built into the world. … It is possible to draw an analogy between the Stoic use of aesthetic properties as special attributes of the good and the use of aesthetic properties by scientists as special attributes of especially apt scientific theories. … When a scientist is faced with two theories with equal truth value and she prefers the one which she considers to be, for instance, the more elegant, she makes the judgement based on the theoretical virtue.” (The Stoic Theory of Beauty, ch. 3)

Except that beauty is not a property built into the world. It is the result of the judgment of individual human (or other) beings. Without a beholder there would be no beauty. The universe just is, and it is us who impose value judgments on facts of the world. That, ironically, is a fundamental Stoic lesson, as when Epictetus reminds us that there is a crucial difference between external things and events on the one hand, and our judgments about them on the other hand (Enchiridion 5a).

Note that in the second part of the above quote Čelkytė writes, correctly, that scientists often use their aesthetic sense as a guide to theory evaluation, other things being equal. But that practice has, just as correctly, come under heavy fire of late. My friend Jim Baggott has written a whole book about how parts of modern physics have bid farewell to reality precisely because they increasingly rely on non-empirical criteria of theory evaluation. And theoretical physicist Sabine Hossenfelder has concluded that a number of modern physicists are lost in math because beauty leads them astray.

And it gets worse! Research in modern psychology has uncovered the so-called attractiveness halo effect, a phenomenon by which people tend to think that attractive individuals are ipso facto trustworthy, responsible, and morally good. Needless to say, there is absolutely no connection between physical attractiveness and character, and we make serious mistakes if we think there is.

So here is the take-home: the ancient Stoics thought of beauty as summetria, a concept that implies harmony among parts and functional relationships within the whole. They derived their aesthetic theory from their conception of a rational living cosmos. But the modern scientific worldview does not appear to be compatible with the Stoic notion of a living cosmos. Yet, modern science provides a reasonable alternative to explain summetria: evolutionary aesthetics. However, since there is no empirical link between physical and moral beauty, we need to be very careful when acting on the basis of our sense of aesthetics.

Massimo Pigliucci, Scholarch of the School for a New Stoicism, is an author, blogger, podcaster, as well as the K.D. Irani Professor of Philosophy at the City College of New York. His academic work is in evolutionary biology, philosophy of science, the nature of pseudoscience, and practical philosophy. Massimo publishes regular columns in Skeptical Inquirer and in Philosophy Now. He also curates the Figs in Winter newsletter of the School for a New Stoicism.