36 - A Principled Stand: Aristotle's Epistemology

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Peter discusses Aristotle's Posterior Analytics, asking what demands we must meet in order to count as having knowledge. The bar turns out to be set surprisingly high.

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Further Reading

• P. Adamson, “Posterior Analytics II.19: a Dialogue with Plato?” in Aristotle and the Stoics Reading Plato, ed. V. Harte, MM McCabe, R.W. Sharples and A. Sheppard (London: 2010), 1-19.

• J. Barnes, Aristotle, Posterior Analytics (Oxford: 1996).

• M. Burnyeat, “Aristotle on Understanding Knowledge,” in E. Berti (ed.), Aristotle on Science: The Posterior Analytics (Padua: 1981), 97–139.

• M. Ferejohn, The Origins of Aristotelian Science (New Haven: 1980).

• M. Frede, “Aristotle’s Rationalism” in M. Frede and G. Striker (eds), Rationality in Greek Thought (Oxford: 1996).

Comments

Luke Cash on 23 February 2012

Aristotle's ideas about taxonomy and evolution

Aristotle's idea of persistent generalization seems to explain why he believed there was a static order in the animal kingdom. It could be said that his epistemics directly relate to his classification of the species according to type and binomial definition, right?

So, where was it that he wrote about what they coined "The Great Chain"? I'm interested to read that work.

In reply to by Luke Cash

Peter Adamson on 23 February 2012

The great chain

Hi Luke,

Yes, you're exactly right about the relation of his biology and epistemology, that's one reason I tried to emphasize the point about the universality of knowledge (according to him).

The "great chain of being" idea is to me most familiar as the title of a book by Arthur Lovejoy. The basic idea is that there is a hierarchy of types of beings with God at the top, down through angels (or whatever), humans, animals, plants, minerals, and perhaps elements or matter itself at the bottom. Aristotle anticipates that to some extent, but doesn't use the expression I don't think.

Cheerio,

Peter

Luke Cash on 23 February 2012

The first principle

How interesting it is that Aristotle himself seems to be the root for our idea of an axiom.

Charles B on 30 April 2012

Middle Term

Hi Peter thanks for your great podcasts! I am just wondering about the 'middle term'. In medicine, doctors are always trying to isolate and identify the causes of various diseases. So after experiment and trial and error they might find that the cause of disease X is Y, and so for example they found that the cause of TB was a particular kind of bacteria that spreads through the air (and not something in the water or something in the food etc). So could this be expressed as an Aristotelian or other kind of syllogism or is this just a different and non-syllogistic kind of cause?

Thank you

In reply to by Charles B

Peter Adamson on 30 April 2012

Medical example

Hi -- that's an excellent example I think, actually, because Aristotle wants the middle term to be a causal link between the extreme terms. So the syllogism would go like this:

All flu sufferers are affected by the flu virus

All who are affected by the flu virus get symptoms X Y and Z

Therefore all flu sufferers get symptoms X Y and Z

So the idea would be that we started by observing that people have these symptoms and we look for the explanatory cause, which turns out to be the virus. It would be important for Aristotle that the same virus is always the cause, because these links for him are supposed to be necessary (so it couldn't be that sometimes the flu has some other underlying cause).

Might be worth thinking about this in the context of the medical epistemology debate I covered in this other episode. Basically I think the Empiricists would claim that the middle term isn't helping you do anything in terms of treatment -- just recognizing the symptoms is enough -- whereas the Rationalists would claim that it is integral to medicine that we discover the underlying cause.

Thanks,

Peter

yunus on 28 May 2015

Science (knowledge) from Ilm?

Thank you Professor, again for this nice Episode! to keep it short here just my question: 

As you have linked the word "Science" from Latin sciencia from Knwoledge directly coming from the influence of Epistēmē, I wanted to ask if there is a possibility that we can also talk of an direct influence on this manner from Al Farbis Book: Ihsa' al-'Ulum (The Listing of the Sciences). Which is righfully tranlated as  "De scientiis" in Latin by Dominic Gundissalinus at around 1140. Where as in contrast, Boehtius and Hugh of St. Victor in his Book: "Didascalicon" (On the Studying of Reading) in the 1120's have a more Art like definition than Scientific Categories of these Principles. 

As always Thank you in advance!

Yunus Hueck 

In reply to by yunus

Peter Adamson on 28 May 2015

Science

Hi Yunus,

Definitely, yes. The Ihsa' was a major influence on late 12th and early to mid 13th century classifications of the sciences, I have been coming across lots of references to it in my reading on the 13th episodes which I'm writing at the moment. One should however bear in mind that the double meaning (science and knowledge) is also there in the Greek and so arguably this would have gotten into the Latin tradition no matter what via the translation of the Posterior Analytics.

Permapoesis on 24 July 2017

The problem of privilege

Oh boy, I have so enjoyed this series, until now. Aristotle exempflies the problem of privilege in western culture. From philosopher to consumer we are prone to generating the greatest of pollutions. Go out and plant some corn, Aristotle, catch some fish, spend time with loved ones, your poesis stagnates with your non-oxygenating blood. The lonely male in his garret has done so much harm in the world. You need to walk further than around your Lyceum, go out, get out, away with you.

In reply to by Permapoesis

TyborSeptim on 5 April 2019

"Aristotle fails to see that

"Aristotle fails to see that happiness must be found solely in virtue, not physical well-being or in external circumstances; he denies the effective care of providence for human affairs, and so denies the value of prayer and man's answerability hereafter for his actions; he denies that the world is created; he denies the immortality of the soul. Excellent as a guide to terrestrial facts, he is a weak and blind guide on transcendental realities." (Chadwick, Early Christian Thought and the Classical Tradition, 109)

BT on 26 August 2022

Aristotle

Once again, I'm really enjoying this podcast!  Unfortunately, I haven't actually read Aristotle's works, so I'm going solely based on the content of the podcast here, but since the historical development of both logic and scientific methodology are both interests of mine, I'd love to understand one aspect of his philosophical perspective a little bit better.  I gathered that one of Aristotle's criteria for a syllogism to be demonstrative is that it be "genuinely explanatory," and I'm wondering if you might be able to provide a quick summary (to whatever extent a "quick" one is possible) of how Aristotle understands or deals with correlation/causality distinctions in the statements that he considers to be "explanatory" when they occur in the "middle terms," as you put it, of syllogisms.  For example, when dealing with a syllogism like "Giraffes are land animals that eat leaves off tall trees.  All land animals that eat leaves off tall trees have long necks.  Therefore, giraffes have long necks," does Aristotle take care to address the kind of distinction between cause and (perfect) correlation that we would keep in mind when interpreting a syllogism like this one as not only logically true but demonstrative?  Is causality even really part of what Aristotle cares about when he deems a syllogism "explanatory?"  For example, would it matter to him if, say, giraffes originally evolved long necks due to sexual selection (i.e., because proto-giraffes deemed a long neck to be an attractive trait in a potential mate) and only came to eat leaves off of tall trees in the process, because it was easier than stooping down?  I could imagine him saying that this is irrelevant, because after all, however it came to be the case and whether the reason is the same of all land animals or not, the fact remains that land animals that eat leaves off trees have long necks, and thus this "middle term" is still "explanatory" as far as it concerns giraffes.  I could imagine him saying that what I'm really looking for is a statement which explains why land animals that eat leaves off trees have long necks.  Nevertheless, while this may not be the most apt of examples, it at least illustrates in a fumbling way what I'm interested in learning: what is Aristotle's perspective on what makes a "middle term" truly "explanatory?"  In other words, wherein does the "why" arise in a demonstrative syllogism?  Since Aristotle had a deep influence on European thought for a very long time, I'm sort of interested in what the limitations are in terms of how he thinks of the relationship between things like explanations and causes, and to what extent that might have influenced scientific methodology, for better or worse.

In reply to by BT

Peter Adamson on 26 August 2022

Explanation in Aristotle

That is a great question! The short answer would be that the middle term should fit into his theory of types of cause: formal, final, efficent, material. And that could already help to avoid the "mere correlation" problem - like, it's not a mere correlation that butter knives are made of metal, there is a good reason for it.

But another part of the answer would be to recall that a demonstrative syllogism also needs to refer to essential properties of things: the connections being made in the syllogism should not be just by happenstance but should articulate things that must be the case for the subject in question by its very nature.

That doesn't really block your skeptical worry, because one might wonder how we tell that properties are really essential (as opposed to just observed so far, or highly correlated). But it at least means that his criteria for a demonstration do rule out mere correlations, the only worry would be whether we are sure that we in fact have produced a demonstrative proof.

Jdee43 on 11 December 2025

Axiomatic system

Could it be said that for Plato and Aristotle, to understand (to structure, relate, and unify knowledge) is the ability to construct an axiomatic system? And could it be said that their disagreement lies in the source of the axioms? Taking Raphael's famous painting "The School of Athens," for Plato the axioms come from up above (they transcend the physical world), whereas for Aristotle, the axioms come from down below (they are immanent in the physical world).

In reply to by Jdee43

Peter Adamson on 12 December 2025

Axioms

Actually I gather that the School of Athens is making a different point: the reason Aristotle has his hand flat is to signify the ethical doctrine that virtue is the mean. For what it's worth.

But to your main question: I would say that this is not a bad approximation, yes. Aristotle's theory of science is often compared to Euclid's method and it's presumably not a coincidence that he keeps using mathematical examples. Aristotle's first principles are argued in the last chapter of the Posterior Analytics to come from sensation, as you say. With Plato it's trickier because he also seems to have some kind of axiomatic method in mind when he describes a method of hypothesis in the Republic, which would lead to a non-hypothetical principle which grounds all the other things we know. Not clear how that relates to Forms, or for that matter other issues like the theory of recollection. Another caveat is that it depends how you understand "axiom": both Plato and Aristotle seem to be foundationalists of a kind, and the foundations need to consist of certain knowledge. So the axioms can't just be postulated or assumed, they have to be known to be true, and known perfectly.

Jdee43 on 24 December 2025

Axiomatic systems

Maybe to be more precise, one should say for Plato, there is ultimately only one axiomatic system, and it is based on the Form of the Good. For Plato, the Form of the Good is the most fundamental axiom from which all else derives. In contrast, for Aristotle, there are many axiomatic systems, each one corresponding to a different branch of knowledge. 

Plato had a unified vision of knowledge, whereas for Aristotle, there is no unity in knowledge, only a plurality, a plurality of branches.

I think it is in Plato, Aristotle, and Euclid that we see the origins of the West's obsession with deduction, certainty, and axiomatic systems. An axiomatic system becomes the West's ideal of what it means to understand; I understand and am an expert if I can construct an axiomatic system. This remains so into the 20th century, when Gödel shows the limitations of axiomatic systems in his incompleteness theorems, coupled with Heidegger and Gadamer proposing a different ideal, the hermeneutic circle.

 

In reply to by Jdee43

Peter Adamson on 28 December 2025

Axiomatic systems

Well, maybe. In the Republic Plato does speak of an unhypothetical first principle but doesn't say that there is only one, nor that it is identical to the Form of the Good; both of these might be implied though and many Platonists later thought along the same lines as you. In modern Plato scholarship there is no general agreement on this; for instance one idea has been that the Good is not like an axiom but stands for the coherence and "fit" of the Forms with one another.

As for Aristotle I think there you are on firmer ground because different sciences do seem to have different first principles, as you say. The only caveat here is that he talks of metaphysics as "first philosophy" and later on Aristotelians generally thought that all the other sciences somehow derive their principles ultimately from metaphysics; maybe Aristotle also thought this. 

Another thing to consider is what it means to be an "axiom." I'd rather speak of "first principle" because "axiom" to my ear might evoke something more like a mathematical postulate, so something more like an assumption, whereas foundational principles in Plato and Aristotle are known or known to be true and not just posited.   

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