Aristotle Was Not Wrong about Everything

The ancient Greek philosopher Aristotle (lived 384 – 322 BCE) is widely portrayed in popular culture as an overconfident buffoon who made assertions based on no evidence whatsoever and who was wrong about nearly everything. It is often claimed that his errors and overconfidence held back the progress of science for two thousand years. This portrayal is wildly inaccurate and is rooted in a centuries-old tradition of hostile writers deliberately misrepresenting Aristotle’s works to make him look as stupid as possible.

It is undoubtedly true that Aristotle made quite a few mistakes, but he was wrong a lot less often than is usually claimed. Furthermore, Aristotle did, in fact, rely on empirical evidence. In fact, of all ancient Greek philosophers, Aristotle is by far one of the most empirical. When Aristotle did make a mistake, it was generally not because he didn’t care about evidence, but rather because the evidence available to him was incomplete or his interpretation of the evidence was faulty.

Finally, the claim that Aristotle held back the progress of science for two thousand years is demonstrably wrong and ridiculous. For one thing, for much of the two thousand years in question, Aristotle wasn’t even generally seen as the most authoritative philosopher in the parts of the world where his works were being regularly studied. Furthermore, even when Aristotle was seen as the most authoritative philosopher, his authority was still open to some degree of question.

That saying about Aristotle being “a philosopher, not a scientist”

Aristotle’s critics often reiterate that he was “a philosopher, not a scientist.” This saying, however, is very misleading. The ancient Greek word that is usually translated as “philosopher” is φιλόσοφος (philósophos), which literally means “lover of wisdom.” The ancient Greeks applied this word to basically anyone who devoted themself to the study of knowledge, including people who studied things that we now generally think of as being part of “science.” In other words, for the ancient Greeks, there was no distinction between a “scientist” and a “philosopher.”

Indeed, one thing that is actually remarkable about Aristotle is his unusually natural outlook. From what we can tell, Aristotle’s immediate philosophical predecessors Socrates and Plato weren’t particularly interested in observing the natural world; they were far more interested in talking about things that we think of as “philosophy” or even “sociology”—government, human societies, the nature of virtue, and so forth.

Aristotle’s father Nikomachos, on the other hand, was a medical doctor and Aristotle evidently inherited some of his father’s interests, because he tended to be far more interested in subjects that we generally think of as “science”—especially biology, physics, and astronomy.

Whatever Aristotle was, he was the closest thing to a scientist that existed in the Greek world at the time when he was alive and it’s not really a fair assessment for people to speak of him as though he was someone totally unqualified making comments about matters outside his realm of expertise.

ABOVE: The School of Athens, painted between 1509 and 1511 by the Italian Renaissance painter Raphael, showing an anachronistic gathering of various ancient philosophers, with Plato and Aristotle in the center

Aristotle on gravity

Now that we’ve talked about what Aristotle’s interests really were, let’s talk about some of the mistakes for which he is often criticized. Aristotle’s most famous error is about gravity. In this particular instance, Aristotle really was wrong, but his mistake has been widely misrepresented to make him look as stupid as possible, even though it was really quite an understandable mistake.

Aristotle writes in his treatise On the Heavens 308a–308b that, when two objects are dropped, one of the objects may be “exceeded by the other in the speed of its downward movement.” This is an empirically verifiable fact. If you drop an object that is extremely buoyant in air (like, for instance, a feather) and an object that is not very buoyant (like, for instance, a rock) from the same height at the same time, the object that is less buoyant will hit the ground before the object that is more buoyant.

Aristotle, however, made the mistake of assuming that the reason why one object falls faster than another object is because of weight. The much later Byzantine Greek scholar and commentator Ioannes Philoponos (lived c. 490 – c. 570 CE) demonstrated that this conclusion was inaccurate. He conducted an experiment in which he dropped two weights, one heavier than the other, from the same height at the same time and observed that they hit the ground at almost exactly the same time. Philoponos writes in his Commentary on Aristotle’s Physics: 682–4, as translated in A Source Book in Greek Science by Morris R. Cohen and I. E. Drabkin:

“But this is completely erroneous, and our view may be completely corroborated by actual observation more effectively than by any sort of verbal argument. For if you let fall from the same height two weights, one many times heavier than the other you will see that the ratio of the times required for the motion does not depend [solely] on the weights, but that the difference in time is very small. And so, if the difference in the weights is not inconsiderable, that is, if one is, let us say, double the other, there will be no difference, or else an imperceptible difference, in time…”

Nearly a thousand years later, the Italian astronomer Galileo Galilei (lived 1564 – 1642) read this passage from Ioannes Philoponos’s commentary and cited it as a clear example of Aristotle being wrong, claiming that Aristotle clearly hadn’t based his conclusions on actual observation. This is misrepresentative, because it’s pretty clear that Aristotle did have evidence; he just drew an inaccurate conclusion based on the evidence he had available.

Later writers have distorted the narrative even further by omitting the fact that Galileo was relying on Ioannes Philoponos’s work and claiming that Galileo discovered Aristotle’s mistake all on his own through his own experimentation, thereby misrepresenting the evidence to make it seem as though Aristotle’s mistakes went totally unquestioned throughout the entire Middle Ages.

The British historian Herbert Butterfield (lived 1900 – 1979) further distorts Aristotle’s theories to make them sound childish and superstitious, claiming in his 1949 book The Origins of Modern Science: 1300–1800, on page 6, that Aristotle argued “that the falling body moved more jubilantly every moment because it found itself nearer home.” This assertion is not, however, based on anything Aristotle himself actually wrote, but rather based entirely on what Butterfield imagined that Aristotle might have been thinking.

ABOVE: Portrait of the Italian astronomer and physicist Galileo Galilei, who relied on the work of the Byzantine scholar Ioannes Philoponos, but sadly always gets credited with Philoponos’s discoveries

Aristotle on the brain

Aristotle has also been frequently made fun of for the fact that he believed that the heart was the seat of consciousness and that the brain was just an organ to radiate heat from the heart. It is true that he believed this, but it is also true that he had some pretty good evidence-based reasons for doing so.

Aristotle describes his evidence for concluding that the brain is an organ to radiate heat in his Parts of Animals, book two, chapter seven. In particular, he cites his own dissections of invertebrate animals, noting that animals that do not have recognizable blood also do not have organs that are immediately recognizable as brains; whereas all animals that have recognizable blood also have recognizable brains.

He also cites evidence from dissections of vertebrate animals, noting that there are a few blood vessels leading to the brain, which are thick and designed to carry lots of blood at once, but there are many small, thin blood vessels leading throughout and away from the brain. Based on this, he deduces that the blood is meant to be dispersed to more easily radiate heat. Here are his own words, as translated by William Ogle:

“But as all influences require to be counterbalanced, so that they may be reduced to moderation and brought to the mean (for in the mean, and not in either extreme, lies the true and rational position), nature has contrived the brain as a counterpoise to the region of the heart with its contained heat, and has given it to animals to moderate the latter, combining in it the properties of earth and water.”

“For this reason it is, that every sanguineous animal has a brain; whereas no bloodless creature has such an organ, unless indeed it be, as the Poulp, by analogy. For where there is no blood, there in consequence there is but little heat. The brain, then, tempers the heat and seething of the heart.”

“In order, however, that it may not itself be absolutely without heat, but may have a moderate amount, branches run from both blood-vessels, that is to say from the great vessel and from what is called the aorta, and end in the membrane which surrounds the brain; while at the same time, in order to prevent any injury from the heat, these encompassing vessels, instead of being few and large, are numerous and small, and their blood scanty and clear, instead of being abundant and thick.”

“We can now understand why defluxions have their origin in the head, and occur whenever the parts about the brain have more than a due proportion of coldness. For when the nutriment steams upwards through the blood-vessels, its refuse portion is chilled by the influence of this region, and forms defluxions of phlegm and serum.”

Aristotle’s conclusion here is, of course, incorrect. The correlation Aristotle notices between animals having recognizable blood and having recognizable brains is not because the brain is needed to radiate heat from the blood, but rather because these are evolutionary developments that happened around the same time. Likewise, the reason why blood is dispersed throughout the brain is not because it is necessary to disperse the heat from the blood, but rather because blood carries vital nutrients like oxygen and it is necessary for every part of the brain to get enough blood.

Even though Aristotle is wrong here, though, he has perfectly justifiable reasons for making the conclusions that he does. The problem isn’t that he’s making stuff up without evidence, but rather that he is trying to figure out how organs work essentially from scratch, without access to any kind of modern medical knowledge. Honestly, it’s rather impressive that he’s able to figure out as much as he does. He realizes that the brain and the heart are both important, but he’s wrong about what exactly their purposes are.

ABOVE: Photograph from Wikimedia Commons of Cotylorhiza tuberculata, a kind of jellyfish found in the Aegean Sea. Jellyfish among the many species of invertebrates that have no brains.

Later, in book two, chapter ten, Aristotle responds to people in his own time who were arguing that the brain is the center of consciousness. These people have a few good arguments, such as that the main sensory organs (i.e., the eyes, ears, mouth, and nose) are all located in the head, close to the brain, and that the brain is an unusually complex organ. They also, however, seem to have believed that people would live longer if they had fleshier heads—an argument which Aristotle rightly dismisses as silly. Here is what he says:

“There are, indeed, some who hold that the life of man would be longer than it is, were his head more abundantly furnished with flesh; and they account for the absence of this substance by saying that it is intended to add to the perfection of sensation. For the brain they assert to be the organ of sensation; and sensation, they say, cannot penetrate to parts that are too thickly covered with flesh. But neither part of this statement is true.”

“On the contrary, were the region of the brain thickly covered with flesh, the very purpose for which animals are provided with a brain would be directly contravened. For the brain would itself be heated to excess and so unable to cool any other part; and, as to the other half of their statement, the brain cannot be the cause of any of the sensations, seeing that it is itself as utterly without feeling as any one of the excretions.”

“These writers see that certain of the senses are located in the head, and are unable to discern the reason for this; they see also that the brain is the most peculiar of all the animal organs; and out of these facts they form an argument, by which they link sensation and brain together. It has, however, already been clearly set forth in the treatise on Sensation, that it is the region of the heart that constitutes the sensory centre.”

It’s clear that, in the fourth century BCE when Aristotle was alive, the science on anatomy wasn’t in yet and there were legitimate arguments at the time in favor of both the brain and the heart as the seat of consciousness.

Ultimately, the Greek medical writer Galenos of Pergamon (lived 129 – c. 210 CE), who lived about five hundred years after Aristotle, correctly concluded that the brain is the center of consciousness. Consequently, his view became accepted orthodoxy among doctors throughout the Middle Ages and the Early Modern Period. Arguments for the heart as the center of consciousness occasionally resurfaced, but, in general, Galenos’s anatomy superseded Aristotle’s.

ABOVE: Photograph from Wikimedia Commons of a human brain

Aristotle and geocentrism

Aristotle has also been extensively criticized for supporting the geocentric model of the universe, which holds that all the heavenly bodies orbit around the earth. It’s true that this model ultimately turned out to be wrong and that the heliocentric model, which holds that the earth and the planets orbit around the sun, turned out to be correct. Nonetheless, I think it is entirely unfair to criticize Aristotle for supporting geocentrism. At the time when he was alive, the heliocentric model had not even been proposed as a hypothesis.

As I discuss in this article from December 2019, the first person known to have proposed a fully heliocentric model of the universe is the Greek astronomer Aristarchos of Samos (lived c. 310 – c. 230 BCE), who was not even born until over a decade after Aristotle’s death. Even then, Aristarchos only proposed heliocentrism as a hypothesis and he probably didn’t have any compelling evidence to support it.

Furthermore, the geocentric model actually did a remarkably good job of explaining the motions of the heavenly bodies as the Greeks in Aristotle’s time observed them. From an earthly perspective, it undeniably looks like the sun, the moon, the stars, and the planets orbit around the earth. It’s even possible to calculate and predict the motions of the heavenly bodies using a geocentric model with a high degree of accuracy.

ABOVE: Illustration from 1660 showing the Ptolemaic geocentric model of the universe, developed by the Greek astronomer Klaudios Ptolemaios (lived c. 100 – c. 170 CE)

Moreover, in ancient and medieval times, there was an extremely compelling scientific reason to believe that the earth was not moving. Ancient astronomers observed that, every year, the same stars and constellations rise and fall in the night sky like clockwork and, although their positions in the sky may change, they always appear in the same formations.

Astronomers expected that, if the earth were really moving, then the formations of the stars would change over time due to the phenomenon of stellar parallax. Since no one could observe any sign of stellar parallax, the most parsimonious conclusion seemed to be that it didn’t exist and that the earth was not moving.

In reality, stellar parallax does exist; the problem is that the stars are all so infinitely far away that the parallax is so extraordinarily minute that it is impossible to observe with the naked eye. Thus, it was only in the early nineteenth century—long after astronomers began making close, detailed observations of the heavenly bodies using telescopes—that astronomers were able to observe and document stellar parallax, definitively proving that the earth was indeed moving.

Unfortunately, telescopes did not exist at the time when Aristotle was alive and he did not have access to the information that was available to early modern astronomers. Calling Aristotle an incompetent hack for not knowing that the earth orbits around the sun is exactly as unfair as calling Isaac Newton an incompetent hack for not knowing about general relativity. Heliocentrism only seems intuitive to us because we are standing on the shoulders of giants. Aristotle didn’t have those shoulders to stand on.

ABOVE: Diagram from Wikimedia Commons illustrating the phenomenon of stellar parallax

It is especially unfair to blame Aristotle for not endorsing heliocentrism when you consider the fact that he was actually remarkably knowledgeable about astronomy for the time in which he lived. As I discuss in this article from February 2019, pretty much all the philosophers before Plato whose opinions are known thought that the earth was some shape other than a sphere. Plato is the earliest writer who is known to have explicitly described the earth as a sphere.

Aristotle, however, presents the earliest known empirical case for the sphericity of the earth in Book Two of his treatise On the Heavens. Here are his three main arguments:

• Gravity naturally pulls all matter in towards the center of the earth. This can only result in a planet that is roughly spherical.
• The earth always casts a circular shadow on the moon during a lunar eclipse. The only shape that always casts a circular shadow no matter what angle the light hits it from is a sphere.
• Whenever a person travels north or south, the stars that are visible change, indicating that the surface of the earth is curved.

It is really quite amazing that ancient Greek intellectuals were able to figure out that the earth is a sphere in the fourth century BCE, without access to any kind of satellite photographs. Aristotle probably did not come up with all the arguments he presents for the sphericity of the earth on his own; he probably learned at least some of them from Plato. Nonetheless, the fact that he knew these arguments is truly impressive.

ABOVE: Composite satellite image of the earth in 2012. Aristotle was able to present a compelling argument for the sphericity of the earth—without access to modern satellite technology.

Aristotle on the number of teeth women have

Occasionally, Aristotle does say things that were genuinely verifiably false even at the time when he was alive. Indeed, of all the things Aristotle wrote, the thing he is perhaps most often criticized for is his claim that males have more teeth than females. Aristotle writes in his History of Animals 509b (2.3.13):

“Ἔχουσι δὲ πλείους οἱ ἄρρενες τῶν θηλειῶν ὀδόντας καὶ ἐν ἀνθρώποις καὶ ἐπὶ προβάτων καὶ αἰγῶν καὶ ὑῶν· ἐπὶ δὲ τῶν ἄλλων οὐ τεθεώρηταί πω.”

This means, in my own translation:

“And the males have more teeth than the females in humans, in sheep, in goats, and in swine; and in the other species the observation has not been made yet.”

As most people already know, this claim is incorrect; men have exactly the same number of teeth as women.

Aristotle has been lambasted for reporting this false information. The British philosopher Bertrand Russell (lived 1872 – 1970) is particularly known for mocking Aristotle’s claim about women having fewer teeth than men. Russell writes in his book The Impact of Science on Society, originally published in 1952:

“Aristotle maintained that women have fewer teeth than men; although he was twice married, it never occurred to him to verify this statement by examining his wives’ mouths.”

The textbook Ancient Greece: A Political, Social, and Cultural History by Pomeroy et al. turns Russell’s comment about Aristotle and women’s teeth into a savage burn about Aristotle’s views on women:

“At times, Aristotle’s powers of observation deserted him when women were their subject. The twentieth-century philosopher Bertrand Russell quipped that Aristotle would not have claimed that women had fewer teeth than men if he had allowed his wife to open her mouth” (page 401 in the fourth edition).

Aristotle’s critics are certainly correct that he could have easily checked to verify whether women really had fewer teeth than men. Nonetheless, I think that much of this criticism is rather unfair. Aristotle was clearly relying on a report he had heard from someone else that he thought was based on observation. Aristotle evidently assumed that the report was correct and did not bother to verify it for himself.

Now, we might blame Aristotle for not bothering to personally verify the report, but, honestly, I don’t really blame him for not asking his wife to open her mouth so he could count how many teeth she had. After all, looking in someone else’s mouth and counting their teeth is really weird. I can only imagine how awkward that would be, both for Aristotle and for his wife.

Indeed, I seriously doubt that Bertrand Russell personally ever counted his own teeth and his wife’s teeth to make sure that the number was really the same. I strongly suspect Russell did exactly the same thing as Aristotle; he heard a report that men and women had the same number of teeth and he assumed that it was true without personally verifying it.

The only real difference between Aristotle and Bertrand Russell in this regard is that the report Russell heard happened to be correct and the report Aristotle heard happened to be wrong.

ABOVE: Photograph from Wikimedia Commons of some healthy human teeth

Some things Aristotle got right that he rarely gets credited for

Aristotle has been blamed for all kinds of mistakes, but he rarely gets credited for things that he actually got right—and, when it comes to matters of what we think of as science, he was actually right far more often than he was wrong. Notably, Peter Gainsford, a classicist from New Zealand, went through and fact-checked every single statement in Aristotle’s chapter on teeth in his History of Animals and found that the vast majority of statements he makes are actually correct.

Aristotle was serious about observing animals. He spent approximately two years on the Greek island of Lesbos observing the animal life there. He observed living marine animals, performed dissections on them, and, in some cases, probably even performed vivisections. He describes his observations in his treatises History of Animals, Parts of Animals, Generation of Animals, Movement of Animals, and Progression of Animals. In these works, he also lays out his own system of classification of animals into species.

As far as we know, Aristotle was the first person ever to conduct this kind of exhaustive zoological research. His observations were detailed and, in most cases, accurate. In some cases, modern researchers have been shocked at just how accurate his observations have been. In the nineteenth century, many biologists doubted the accuracy of his description of the hectocotyl arm of an octopus until it was discovered that he had actually been right all along. (I think it really tells us something about what Aristotle was like as a person that he apparently knew more about the reproductive organs of Aegean cephalopods than about the anatomy of a human woman’s mouth.)

In any case, Aristotle really laid the groundwork for later researchers. His student and successor as head of the Peripatetic school in Athens, Theophrastos of Eresos (lived c. 371 – c. 287 BCE), continued his teacher’s legacy by writing his own enquiry into the biology of plants, titled History of Plants—the earliest known inquiry of its kind.

ABOVE: Illustration from 1914 of Tremoctopus violaceus, showing its hectocotyl arm

A lot of people have heard about the instances in which Aristotle fell victim to false reports, but there are many other cases in which he actually refutes misconceptions that were popular among the Greeks at the time when he was alive.

In one particularly impressive example of this, in his History of Animals 498a, Aristotle refutes the popular misconception that elephants are incapable of bending their knees and are therefore forced to sleep standing up by pointing out that elephants can, in fact, bend their knees and that they have been observed sleeping on their sides. He writes, as translated by D’Arcy Wentworth Thompson:

“The elephant does not sleep standing, as some were wont to assert, but it bends its legs and settles down; only that in consequence of its weight it cannot bend its leg on both sides simultaneously, but falls into a recumbent position on one side or the other, and in this position it goes to sleep. And it bends its hind legs just as a man bends his legs.”

As anyone who has ever seen an elephant at a zoo can attest, Aristotle is right here again. He does make one tiny error in the fact that elephants can sleep standing up if they want to, but he is correct that they are not obliged to do so.

There were no elephants in Greece at the time when Aristotle was alive, but Aristotle gives so much detailed and accurate information about elephants’ anatomy (and not just in the passage quoted here) that it is generally believed he must have seen one in person, although it is unclear how he could have managed this.

ABOVE: Photograph from Flickr of an elephant sleeping on its side—exactly as described by Aristotle in his History of Animals

Aristotle’s supposed overconfidence

All around, it is really hard to deny that Aristotle was a really smart guy and that he did indeed help advance scientific knowledge. But what of the popular claim that he was overconfident, stubborn, and incapable of admitting he was wrong? Well, there isn’t really evidence that Aristotle himself was any of those things. There is no recorded instance in which anyone ever presented Aristotle with compelling evidence that he was wrong about something, so we can’t know how he would react.

The notion that Aristotle could never admit to being wrong even in the face of compelling evidence is mainly based on how some later Aristotelians from over a thousand years after Aristotle’s death elevated their master’s teachings to the status of dogma and refused to accept when he was mistaken.

Aristotle cannot really be personally blamed for any of this, though; he was long dead by the time all this was happening and we shouldn’t imagine that he had any control over his posthumous admirers. Indeed, if his dedication to observation is any indication, we should think that he would have embraced new observations and discoveries and modified his conclusions accordingly.

Aristotle holding back science for two thousand years?

It is often claimed that Aristotle’s philosophy was so wrong and dogmatic that it held back the entire fields of science, logic, and philosophy for two thousand years. Bertrand Russell notably claims this in his book A History of Western Philosophy, which was originally published in 1945, writing:

“Nonetheless, Aristotle’s logical writings show great ability, and would have been useful to mankind if they had appeared at a time when intellectual originality was still active. Unfortunately, they appeared at the very end of the creative period of Greek thought, and therefore came to be accepted as authoritative. By the time that logical originality revived, a reign of two thousand years had made Aristotle very difficult to dethrone. Throughout modern times, practically every advance in science, in logic, or in philosophy has had to be made in the teeth of the opposition from Aristotle’s disciples.”

This whole passage is patently absurd. First of all, Aristotle did not live “at the very end of the creative period of Greek thought” in any sense. Multiple massively influential schools of Greek philosophy developed after Aristotle’s death. For instance, the philosopher Pyrrhon of Elis (lived c. 360 – c. 270 BCE) founded the school of Pyrrhonic Skepticism, Zenon of Kition (lived c. 334 – c. 262 BCE) founded the school of Stoicism, and Epikouros of Samos (lived c. 341 – c. 270 BCE) founded the school of Epicureanism.

These schools of Greek philosophy that emerged during the Hellenistic Era have been derided and not taken seriously by western European scholars for over two hundred years at least. As I discuss in greater depth in this article I wrote about Stoicism in January 2020, the German philosopher Georg Wilhelm Friedrich Hegel (lived 1770 – 1831) dismissed all the Hellenistic philosophies as out-of-touch, saying that they served no purpose aside from “rendering the soul absolutely indifferent to everything which the real world had to offer.”

I think that this criticism is unfair, but, even if it were fair, it is hard to argue that these new philosophical schools were somehow not “creative” or “original.” They revised and synthesized ideas from older philosophical traditions and developed new ideas of their own.

ABOVE: Depictions of Zenon of Kition (left), Epikouros of Samos (middle), and Pyrrhon of Elis (right), who all founded major, highly influential schools of Greek philosophy after Aristotle’s death

The claim that there was no creativity in Greek thought after the time of Aristotle also ignores the radical transformations that established schools of Greek philosophy underwent in later eras. For instance, after Arkesilaos became the head of the Platonic Akademia in around the 260s BCE, the school actually became skeptical, evolving into a philosophy that, in many ways, more closely resembled Pyrrhonism than traditional Platonism.

Under the Roman Empire, Platonic philosophy emerged in new and different forms. The schools of Neopythagoreanism and Middle Platonism flourished from around the first century BCE until around the late second century CE. Then Neoplatonism emerged in the late second century CE, partly as a fusion of these two strains of thought, incorporating many entirely new ideas and interpretations of old ideas that would probably have baffled Plato himself.

Greco-Roman philosophy changed even more drastically during late antiquity as it adapted to the new Christian religious environment. Christianity fused with Neoplatonism, resulting in the fascinating syncretism evidenced in the writings of Origenes of Alexandria (lived c. 184 – c. 253 CE), Augustine of Hippo (lived 354 – 430 CE), and Pseudo-Dionysios the Areopagite (flourished c. fifth or sixth century CE), who applied ideas from Neoplatonism to Christian theology. After that, you enter the realm of medieval philosophy, which had many interesting innovations of its own.

You can’t just draw a line in the sand and say that, after that point, Greek creativity no longer existed. Although western philosophy has gone through some periods in which it has tended to be more conservative, philosophical creativity has never died out in the Greek world, or the western world in general. People have always been coming up with new ideas and reinterpreting old ones.

ABOVE: Imaginative illustration of Pseudo-Dionysios the Areopagite, made in 1584 by the French engraver André Thevet

The claim that Aristotle was seen as the sole, unquestionable authority on everything for two thousand straight years from his death until the Renaissance is also wildly false. For most of the “two thousand years” of which Bertrand Russell speaks, Aristotle was not even seen as the most authoritative philosopher in the parts of the world where his works were being studied. Instead, for much of that time, Aristotle was seen as second fiddle to Plato.

Plato was the preeminent philosopher of the Mediterranean world in late antiquity. Consequently, his ideas were massively influential on the Christian Church Fathers and on later Christian philosophy. The writings of Aristotle, meanwhile, actually disappeared from western Europe with the collapse of the western Roman Empire in the fifth and sixth centuries CE.

Aristotle’s works continued to be studied in the surviving Greek-speaking eastern portion of the Roman Empire, but, when the early eastern Romans studied Aristotle, they studied him from a mostly Neoplatonist perspective. They certainly respected Aristotle very much, but they were not afraid to criticize him. As I have already mentioned above, Ioannes Philoponos roundly excoriates Aristotle in his commentaries, outright rejecting entire segments of his philosophy.

Then, in early Islamic philosophy, this situation started to change. Aristotle’s writings were translated from Greek into Arabic. The Arabic philosopher Al-Kindi (lived c. 801 – 873 CE), the Iranian philosophers Al-Farabi (lived c. 872 – c. 951 CE) and Ibn Sina (lived c. 980 – 1037 CE), and the Andalusian philosopher Ibn Rushd (lived 1126 – 1198 CE) all studied Aristotle’s works extensively, commentating on them and elevating Aristotle to a level higher than Plato.

ABOVE: Illustration from an Arabic manuscript dated to around 1220 CE depicting Aristotle teaching one of his students

Latin translations of Aristotle’s writings started to trickle into western Europe in the late twelfth and early thirteenth centuries CE, along with Latin translations of the works of Arabic philosophers such as Ibn Rushd. The German philosopher Albertus Magnus (lived 1200 – 1280 CE) and the Italian philosopher Thomas Aquinas (lived 1225 – 1274 CE) sought to harmonize Aristotelian philosophy with Catholic theology.

It was only really after Thomas Aquinas that Aristotle finally became seen as the preeminent philosopher in western Europe, authoritative above all others. Even then, though, his works were not unquestionable dogma; they could be questioned and, indeed, they often were. Even Aquinas himself did not accept everything Aristotle had written as true.

In the fifteenth century, there was famously widespread scholarly conflict between Platonists and Aristotelians. The Greek Neoplatonist philosopher Georgios Gemistos Plethon (lived c. 1360 – c. 1454 CE) published a treatise titled De Differentiis denouncing Aristotle in favor of Plato. This triggered the Eastern Orthodox patriarch and Aristotelian philosopher Gennadios Scholarios (lived c. 1400 – c. 1473 CE) to write a response titled Defense of Aristotle. Plethon responded with a work titled Reply.

The controversy soon spilled over into Italy, with various Greek and Italian scholars publishing a whole flurry of treatises defending either Plato or Aristotle. This became a defining controversy of the Italian Renaissance. In the sixteenth and seventeenth centuries, criticism of Aristotelianism only intensified. As I mentioned earlier, Galileo Galileo attacked Aristotle vociferously and he was far from alone. By the eighteenth century, whatever Aristotelian consensus had once existed had broken down.

Thus, the only period in which Aristotelianism was really dominant in Europe was between approximately the late thirteenth century and the early eighteenth century at best. That’s only around five hundred years—not at all the “two thousand years” that Russell claims. And, again, even during this period, Aristotle’s writings were questioned, doubted, and interrogated.

They also weren’t seen as the ultimate authority for all subjects; scholars during the Renaissance regarded Galenos of Pergamon as the primary authority for matters of medicine and Klaudios Ptolemaios as the primary authority for matters of astronomy.

ABOVE: Portrait of the Greek Neoplatonist philosopher Georgios Gemistos Plethon, who thought Aristotle’s philosophy was bogus

Things you can really criticize Aristotle for

Make no mistake: I am not in any way saying that Aristotle cannot be fairly criticized. The unfortunate truth is that, despite his talents as a natural philosopher, Aristotle wrote some genuinely appalling things that can’t really be defended. Perhaps the most disgusting aspect of Aristotle is that he was one of the most ardent defenders of slavery in the ancient world. Many ancient philosophers owned enslaved people, but Aristotle is one of the very few authors who sought to provide a systematic justification for enslaving people.

In his treatise Politics, Aristotle mentions that there were certain people in the fourth century BCE when he was alive who were arguing that slavery was “contrary to nature.” He therefore attempts to respond to these people by arguing that slavery is completely natural because some people have a natural disposition for enslavement. He writes in his Politics 1254a, as translated by H. Rackham:

“Hence whereas the master is merely the slave’s master and does not belong to the slave, the slave is not merely the slave of the master but wholly belongs to the master. These considerations therefore make clear the nature of the slave and his essential quality: one who is a human being belonging by nature not to himself but to another is by nature a slave, and a person is a human being belonging to another if being a man he is an article of property, and an article of property is an instrument for action separable from its owner.”

“But we must next consider whether or not anyone exists who is by nature of this character, and whether it is advantageous and just for anyone to be a slave, or whether on the contrary all slavery is against nature. And it is not difficult either to discern the answer by theory or to learn it empirically. Authority and subordination are conditions not only inevitable but also expedient; in some cases things are marked out from the moment of birth to rule or to be ruled.”

From the very beginning of the Transatlantic slave trade, European supporters of slavery used this exact argument from Aristotle to justify the enslavement of people of African descent.

This does not mean that Aristotle is solely responsible for the horrors of American slavery, but it does mean that he has a very, very dark legacy. It’s very strange that critics of Aristotle seem to always attack him for supposedly holding back science for two thousand years—something he definitely did not do—rather than for justifying slavery—something he definitely did do.

ABOVE: The Slave Trade, painted in 1840 by the French painter François-Auguste Biard

Aristotle’s chauvinism and proto-racism

Unfortunately, Aristotle has contributed to the development of racism in more ways than one. In addition to arguing that some people are naturally dispositioned for enslavement, he also argued that people from different parts of the world have different innate good and bad qualities and that people of the Greek nation are naturally fit to rule over all other peoples because they have all the good qualities found in all the peoples throughout the world and none of the bad qualities. He writes in his Politics 1327b, as translated by H. Rackham:

“The nations inhabiting the cold places and those of Europe are full of spirit but somewhat deficient in intelligence and skill, so that they continue comparatively free, but lacking in political organization and capacity to rule their neighbors. The peoples of Asia on the other hand are intelligent and skillful in temperament, but lack spirit, so that they are in continuous subjection and slavery. But the Greek race participates in both characters, just as it occupies the middle position geographically, for it is both spirited and intelligent; hence it continues to be free and to have very good political institutions, and to be capable of ruling all mankind if it attains constitutional unity.”

In comments like these, it is easy to see the beginnings of modern racist ideology. The idea of Greek superiority predates Aristotle by centuries at least, but Aristotle is unusual for the way he seeks to justify his own ethnocentrism using the language of natural philosophy. In this way, he sets a precedent for later so-called “scientific racists.”

ABOVE: Tondo from an Attic red-figure kylix dated to c. 480 BC or thereabouts depicting a Greek hoplite fighting with a Persian warrior

Aristotle’s sexism

In addition to espousing chauvinistic and proto-racist views, Aristotle was also sexist. It’s true that male ancient Greek authors generally tended to be misogynistic and Aristotle is far from the most misogynistic Greek author whose writings have survived. Nevertheless, Aristotle is unusual for the way he sought to systematize and justify his own sexism using natural philosophy.

Aristotle firmly believed that women are supposed to be subservient to men in all things, and he tried to use his own observations of animal behavior to support his beliefs about human gender roles. For instance, he writes in his History of Animals 608b, as translated here by J. C. McKeown:

“Women are more compassionate than men, more easily moved to tears. But they are also more prone to envy, grumbling, criticizing, aggression, depression, pessimism, deceit, trickery, resentment. They are more wakeful than men, more hesitant, harder to rouse to action, and they need less food. Men are braver than women, and more ready to help others. Mollusks demonstrate this difference: when a female cuttlefish is struck by a trident, the male helps her, but if a male is struck, the female flees.”

I don’t know enough about mollusks to say whether what Aristotle says here is true, but what is significant is that, as far as I am aware, he is the very first author known to have tried to use empirical findings from biology to support the claim that men and women have inherently and insurmountably different minds and behavioral patterns. Present-day misogynists who insist that gender roles are biologically ordained are very much following a tradition that begins with Aristotle.

In this, Aristotle differs rather significantly from his teacher Plato. As I discuss in this article from September 2020, Plato was still pretty sexist. He believed that men were generally superior to women in all ways and he rather notoriously wrote that men who live cowardly lives will be reborn as women. Nonetheless, he argued that women should be educated just like men and he is even said to have allowed at least two women—the philosophers Lastheneia of Mantineia and Axiothea of Phleious—to study at his Akademia in Athens.

It’s no surprise that many later female Greek philosophers (such as Hypatia of Alexandria, Aidesia of Alexandria, and Theodora of Emesa) followed in the Platonic tradition; whereas I’m not aware of any ancient female philosophers in the Aristotelian tradition.

ABOVE: Photograph from Wikimedia Commons of an Attic red-figure pelike dated to between c. 470 and c. 460 BCE, depicting two Greek women doing laundry

Conclusion

There are certainly a lot of things that Aristotle deserves to be criticized for. If you want to criticize Aristotle, you can criticize him for his attempts to justify slavery, his proto-racism, his sexism, his elitism, or even his unbearably tedious writing—but don’t repeat that old lie about him supposedly holding back the progress of science for two thousand years because that one is just not true.