Teleology in Nature

Against the Explanations the Inquirers into Nature give


Unlike θεολογία ("theology"), for example, or other compound Greek words such as φυσιολογία, there is no ancient Greek word that transliterates as teleology.
Aristotle thinks that sensible substances have their specific behaviors (the behaviors common to members of the kind) for an end and that the end is the benefit the behavior brings.

This is part of the picture in the Timaeus, but Aristotle understands it a new way.

We can build to Aristotle's understanding by first considering a passage in the Phaedo where Socrates hopes for the kind of explanation Plato later gives in the Timaeus.

Socrates and Anaxagoras

"One day I heard a man reading from a book, as he said, by Anaxagoras, that it is intelligence (νοῦς) that arranges and is the cause (αἴτιος) all things. I was pleased with this cause, and it seemed to me to be somehow right that intelligence should be the cause of all things, and I thought that intelligence in ordering all things must order them and place each thing as it is best for it to be" (Phaedo 97b).

νοῦς is an Attic form of νόος. It means "mind." Sometimes νοῦς translated as "intellect" or "intelligence," where this is the power the mind possesses. This has its roots in the translation of νοῦς into Latin as intellectus.

"My glorious hope, my friend, was quickly snatched away from me. As I went on with my reading I saw that the man made no use of intelligence, and did not assign any real causes for the ordering of things, but mentioned as causes air and ether and water and many other absurdities. And it seemed to me it was very much as if one should say that Socrates does with intelligence whatever he does, and then in trying to tell the causes of everything I do, to say that the reason that I am sitting here is because my body consists of bones and sinews, because the bones are hard and are separated by joints, that the sinews are such as to contract and relax, that they surround the bones along with flesh and skin which hold them together, .... He would mention other such causes for my talking to you: sounds and air and hearing, and a thousand other such things, but he would neglect to mention the true causes, that, after the Athenians decided it was better to condemn me, for this reason it seemed best to me to sit here and more right to remain and endure whatever penalty they ordered" (Phaedo 98b).

Anaxagoras is the author of "books" (βίβλοι). Socrates, in the Apology, says that they can be bought cheaply (26a).

Socrates says that "I made all haste to get hold of the books and read them as quickly as possible" (Phaedoe 98b).

When Socrates says that "the man made no use of intelligence," he is making a joke Anaxagoras's expense. In addition, and more importantly, he is saying that Anaxagoras does not explain what happens when "intelligence" orders things. In the Timaeus, Plato tries to supply the explanation in terms of the divine maker.


"It is unnatural that either fire or earth or any other such element should cause existing things to be or become well and beautifully disposed; or indeed that those thinkers should hold such a view. Nor again was it satisfactory to commit so important a matter to accident and chance. Hence when someone said that there is mind in nature, just as in animals, and that this is the cause of all order and arrangement, he seemed like a sane man in contrast with the haphazard statements of his predecessors. We know Anaxagoras adopted this view" (Metaphysics I.3.984b)
In the Phaedo, in a story about his past interest in the inquiry into nature, Socrates says that when he was young he hoped to learn from Anaxagoras something he very much wanted to know. Anaxagoras talked about νοῦς ("mind"), and Socrates thought this would mean that Anaxagoras was going to explain that things are as they are because this way is best. He found, though, when he read on in the book, that Anaxagoras made no use of his νοῦς.

Socrates has the traditional thought that order is the result of the behavior of a mind or intellect. He expected that Anaxagoras would give such an explanation but to his surprise and disappointment found that Anaxagoras gave no "real causes for the ordering of things."

Socrates gives an analogy to show what Anaxagoras does in his explanations that Socrates takes to be so absurd. He says that it is as if Anaxagoras had said that Socrates has a mind but then makes it do no work in his explanations for why Socrates does what he does. Instead of mentioning the "true causes" to explain why Socrates is sitting in jail, Anaxagoras would blather on about Socrates' bones and sinews being situated in a certain way.

The "true causes," Socrates thinks, are what would figure in his doing "with intelligence whatever he does." For his sitting in jail, as he is doing in the Phaedo, he explains that he is doing this because after the Athenians convicted him, "it seemed best to [him] to sit here [in jail] and more right to remain and endure whatever ever penalty they ordered."

(After Socrates was convicted, he had to wait in jail for his execution until the ship of Theseus returned to Athens (Phaedo 57b). Crito, his friend from childhood, had visited him in this intervening time and offered to help him escape. Socrates declined (Crito 44b).)

Socrates, in doing "with intelligence whatever he does," is acting for something. He is acting for the sake of the good. He thinks that what is good and thus is beneficial is what is "right" and that this is to sit in jail to wait for the penalty the Athenians ordered.

In the Gorgias, as we have seen, Socrates advocates for this understanding of action.

  "Then when do you say it is better to do these things? Tell me where you draw the line.
  I would rather that you, Socrates, answered that.
  Well then I say, Polus, if you prefer to hear it from me, that it is better when these things are done rightly, and worse when wrongly" (Gorgias 470b).

  "Polus and I, if you, Callicles, recollect, decided that everything we do should be for the sake of what is good. Do you agree with us in this view—that the good is the end of all our actions, and it is for its sake that all other things should be done, and not it for theirs? Do you add your vote to ours, and make a third?
  I do.
  Then it is for the sake of what is good that we should do everything, including what is pleasant, not the good for the sake of the pleasant.
  Certainly.
  Now is it in every man's power to pick out which sort of pleasant things are good and which bad, or is professional skill required in each case?
  Professional skill, Socrates" (Gorgias 499e).

The "For Something" is in Nature

"It is absurd to think that nothing comes to be for the sake of something unless that which effects the change is observed to deliberate. In fact, even the art does not deliberate. And if the art of making ships were present in the wood, it would make the same way as in nature. So, if the for something is present in the thing produced by art, so it is in the thing produced by nature (Physics II.8.199b).


Aristotle thinks that an "accidental" (αὐτόματος) outcome is one that occurs concidentally and that "luck" (τύχη) is the special case of an accidental outcome that happens in connection with a choice someone makes. If, to use one Aristotle's examples, a man goes to market and happens to see someone who owes him money, we says that it was a matter of luck that he collected the debt.

"Among the products of thought, such as a house or a statue, some never are due to accident or necessity but always the for something; others, like health and security, may also be due to luck" (Posterior Analytics II.95a).

"It is clear, then, that when any causal agency coincidentally produces a significant result outside its aim, we attribute it to an accidental outcome; and in the special cases where such a result springs from deliberate action (though not aimed at it) on the part of someone capable of choice, we may say that it comes about by luck" (Physics II.VI.197b).
Aristotle also thinks the explanations the inquirers into nature give are inadequate, but he takes the argument further than Socrates. Aristotle thinks that these inquirers, with their explanations, eliminate what he describes as the "for something" (ἕνεκά του) in nature.

Aristotle wonders why we should believe that the for something is in nature rather than that nature works in the way the inquirers into nature suppose in their explanations.

We can see him doing this in the following passage from Book II of the Physics.

"The question arises why we should suppose nature acts for something and because it is better, but as Zeus rains not to make the corn grow but of necessity the rising vapor is condensed into water by the cold, and then must descend, and coincidentally, when this happens, the corn grows. If corn on the threshing floor is ruined, it does not rain for this, so that the corn is ruined. This is coincidental to the raining. What, then, is to stop the parts of nature from being like this--the front teeth of necessity growing sharp and suitable for biting, the back teeth broad and serviceable for chewing, not coming to be for this, but by coincidence? And similarly for the other parts in which the for something seems to be present. So that when things turned out just as they would had they come to be for something, but instead were suitably set together as an accidental outcome, they survived. Otherwise,

"Empedocles says that at the beginning of Love [one the two forces he thinks moves things in nature] there were born first, as it happened by chance, the parts of animals, like heads, hands, and feet, and that later these came together, that is, composites of cattle and human beings. And all the parts that were assembled with one another in such as way as to be capable of surviving became animals and continued to exist because they satisfied each other’s needs, the teeth cutting and chewing the food, the stomach digesting it, the liver turning it into blood. And a human head, coming together with a human body, ensures the survival of the whole, but with a cow’s body it is not adapted and is destroyed. For whatever did not come together according to an appropriate relation perished. In this same way everything happens now too" (Simplicius, Commentary on Aristotle’s Physics; D 152; DK B 31 61).

"These are Empedocles's words: Many grew double of face..., races of man-prowed cattle, while others sprang up inversely, creatures of cattle-headed men" (Aelian, On the Characteristics of Animals XVI.29, D 156; DK 31 B 61).

"At that time the earth tried to create many monsters with weird appearance and anatomy— androgynous, of neither one sex nor the other but somewhere in between; some footless, or handless; many even without mouths, or without eyes and blind; some with their limbs stuck together all along their body, and thus disabled from doing anything or going anywhere, from avoiding harm or obtaining anything they needed. These and other such monsters the earth created. But to no avail, since nature prohibited their development. They were unable to reach the goal of their maturity, to find sustenance, or to copulate. For we see that creatures need the concurrence of many things in order to be able to reproduce and to spread their progeny" (Lucretius, On the nature of things V.837).

Titus Lucretius Carus (first century BCE). On the nature of things is an exposition (in Latin) of Epicureanism.


"[I]t may be asked, how is it that varieties, which I have called incipient species, become ultimately converted into good and distinct species, which in most cases obviously differ from each other far more than do the varieties of the same species? ... [The answer is that this occurrence follows] inevitably from the struggle for life. Owing to this struggle for life, any variation, however slight and from whatever cause proceeding, if it be in any degree profitable to an individual of any species, in its infinitely complex relations to other organic beings and to external nature, will tend to the preservation of that individual, and will generally be inherited by its offspring. The offspring, also, will thus have a better chance of surviving, for, of the many individuals of any species which are periodically born, but a small number can survive. I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection, in order to mark its relation to man's power of selection" (Charles Darwin, On the Origin of the Species. III. Struggle for Existence, 61; published in 1859).
they perished and still perish, as Empedocles says of the man-headed calves" (Physics II.8.198b).

In the explanations in question, the "for something" is not present (just as "doing with intelligence" is not present in the explanation Socrates imagines Anaxagoras would give to explain why he is sitting in jail). Necessity, in these explanations, makes animals develop in the ways we see, and because the for something is not part of the process, it is a coincidence that this development benefits them. It is a coincidence that these animals use their front teeth for biting and that their front teeth come in sharp and thus are suited for biting.

The problem, Aristotle thinks. is that this not a coincidence. Coincidences are infrequent.

"This account or one like it might give us pause, but it is impossible for things to be this way. The things mentioned, and all things due to nature, come to be as they do always or for the most part, and such things are not the outcome of luck or an accidental outcome. We do not think it is luck or chance that there is a lot of rain in winter, but only if there is a lot in August; nor that there are heatwaves in August, but only if there is a heatwave in winter. If, then, things seem to be coincidental outcomes or for something, and the things we are discussing do not coincide as accidental outcomes, they must be for something. But all such things are due to nature, as the authors of the views under discussion themselves admit. The for something, then, is present in things that are and come to be by nature" (Physics II.8.198b).

Forward in the Physical Works

This shows to Aristotle's satisfaction that "nature acts for something and because it is better," but it does not show how. Sensible substances are forms in matter. They have their specific behaviors because their forms are the particular organizations of the matter they are.

Now we need to see the connection between these organizations and the benefit they bring to members of the species. Aristotle does not believe in natural selection. He does not think the organizations that endure are the ones where the individuals with these organizations have a greater chance of surviving and passing on their organization to their offspring.

Instead, in his explanation of the connection, Aristotle argues for the existence of a divine being he describes as the "first mover, which is unmovable" (πρῶτον κινοῦν ἀκίνητον).

This being is part of a perspective Aristotle shares with Socrates and Plato but not so much with us. Aristotle has the traditional thought that the explanation of order and regularity is in terms of intelligence, but he does not accept the divine maker in the Timaeus.

To understand this in Aristotle, it is helpful first to see a behavior in human beings he thinks benefits them. This behavior is the development of reason. Aristotle thinks that human beings naturally develop reason as they mature from children into adults, that they use reason for knowing and choosing, and that the reason they develop is suited for this use.

The soul in human beings, as Aristotle understands it, is the cause of this behavior. He argues in On the Soul, as we will see in the next lecture, that the soul is the form of living things. It is their nature and the "starting point of change and staying unchanged" in them.




Perseus Digital Library

Aristotle, Metaphysics.

Henry George Liddell, Robert Scott, A Greek-English Lexicon

αὐτόματος, automatos, adjective, "just happens, without cause"
ἕνεκα, heneka, preposition followed by the genitive case, "on account of, for the sake of, because of, for"
ἕνεκά του, heneka tou, "for something" (του is an indefinite singular pronoun in the genitive case)
συμβαίνω, symbainō, verb, "to come together, coincide"
συμβεβηκός, noun, nominalization of a perfect passive participle from of σῠμβαίνω, "accident, coincidence"
κατὰ συμβεβηκός, "by accident, coincidentally"
σύμπτωμα, symptōma, noun, "thing that has befallen"
τέλλω, verb, "to make arise, accomplish"
τέλος, noun, "fulfilment or completion"
τύχη, tychē, noun, "luck, fortune"

Charlton T. Lewis, Charles Short, A Latin Dictionary:
forma, noun, "form, contour, figure, shape"
species, noun, "the outward appearance, outside, exterior; shape, form, figure"

"This thing they call the ἰδέαν, a name already given it by Plato; we can correctly term it form (speciem)" (Cicero, Academica I.30).

Arizona State University Library. Loeb Classical Library:
Aristotle, Physics
Empedocles, Early Greek Philosophy, Volume V: Western Greek Thinkers, Part 2




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