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.



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).


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.



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.



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


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


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.

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