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Did Popper and Quine invent “Aristotelian essentialism”?

Last updated on 21 Jun 2018

There are many narratives told about evolution. One of the most widely told is the Essentialism Story, replayed in textbook, popular storytelling and philosophy alike. It goes like this: Before Darwin, biologists were constrained by essentialist thinking, in which they were committed to species being natural kinds where there were essential characters shared by every member of the species. Darwin changed all this by adopting a kind of nominalism, in which every member of a species, and every species, was a unique object, and no species had members that shared characters that all members exhibited, and which no other species did. Darwin developed a view in which species were populations.

Later, Michael Ghiselin and David Hull developed an individualistic view of species, in which species were, like Darwinian individuals, particulars not classes. This is the new metaphysics of evolution. Anything else is “outmoded metaphysics” (as a review of a colleagues’ paper called it). If you aren’t with the new evolutionary metaphysics, you aren’t modern.

Only, it isn’t historically the case. As I discovered when I was doing my doctoral thesis, there is little evidence that anyone was what I now call a “taxic essentialist”. Sure, people talked about essences, of life, of organs, and so forth. But they never accepted that species had to have what we now call necessary and sufficient conditions, or that members of a species or other taxon would bear such essential properties. I am not the only person to think this. The alarm was sounded by Paul Farber in the 1970s, but recently historian of science Polly Winsor has made the same argument (I sent a copy of my thesis to her and she replied that I was “courageous”, a red flag term for a newly minted PhD if ever there was. Polly cited my thesis in her paper). I discuss the story and its falsity in my book Species.

So, when did the story arise? Polly argued that it was based on the ideas of Arthur J. Cain, taken up and disseminated by Ernst Mayr, Hull and many others. Hull was influenced directly and personally by Karl Popper, whose graduate seminar he had taken in the early 60s, resulting in the famous paper “The Effect of Essentialism on Taxonomy – Two Thousand Years of Stasis” [PDF]. Popper had defined and criticised “methodological essentialism” in his 1945 book, The Open Society and its Enemies, in the first volume on Plato as the founder of ideas that led to the then-threatening views we call fascism:

I use the name methodological essentialism to characterise the view, held by Plato and many of his followers, that it is the task of pure knowledge or science to discover and to describe the true nature of things, i.e. their hidden reality or essence. It was Plato’s peculiar belief that the essence of sensible things can be found in their primogenitors or Forms. But many of the later methodological essentialists, for instance, Aristotle, did not altogether follow him in this, although they all agreed with him in determining the task of pure knowledge as the discovery of the hidden nature or Form or essence of things. All these methodological essentialists also agreed with Plato in maintaining that these essences may be discovered and discerned with the help of intellectual intuition; that every essence has a name proper to it, the name after which the sensible things are called; and that it may be described in words. And a description of the essence of a thing they all called a definition. According to methodological essentialism, there can be three ways of knowing a thing: ‘I mean that we can know its unchanging reality or essence; and that we can know the definition of the essence ; and that we can know its name. Accordingly, two questions may be formulated about any real thing . . . : A person may give the name and ask for the definition; or he may give the definition and ask for the name.’ [p25f]

Now what Popper is critiquing here is sometimes called rationalism: that we can know the natures of things through reflection and reasoning. He contrasts it to

methodological nominalism [which] aims at describing how a thing behaves, and especially, whether there are any regularities in its behaviour.

Popper’s view was widely known and influenced many scientists and philosopher of science, especially when his Logik des Forschung (translated in 1959 as Logic of Scientific Discovery, although one thing it lacked was a theory of discovery) was published. Hull’s paper set the tone, and clearly established the notion that Aristotle was the author of essentialist thinking, whereas Popper and earlier Dewey had suggested it was Plato, which G. G. Simpson, the palaeontologist and one of the major authors of the Modern Synthesis had also thought.

Hull gave a longer historical summary in his 1988 Science as a Process, and Ernst Mayr in his widely read The Growth of Biological Thought in 1982 constantly interpreted, sometimes aggressively selecting sources, the history of biology in terms of essentialism. Clearly one of the influences was Popper, via Hull, through to Mayr (who cited Popper’s definition on page 864).

But Mayr gave only a general, and non-philosophical, account of Aristotelian essentialism:

… a limited number of fixed and unchanging forms, eide (as Plato called them) or essences as they were called by the Thomists in the Middle Ages. [p38]

I think essentia preceded Thomas by a comfortable margin; at the very least his teacher Albertus Magnus used the term frequently. But the issue here is where modern definitions of essentialism come from. Late in the 19th century, the term “essence” was either used carelessly in logic, or wildly in the Hegelian tradition. For example, W. Stanley Jevons said of the term essence

Essence, (essentia, from esse, to be,) “the very being of anything, whereby it is what it is.” Locke. It is an ancient scholastic word, which cannot be really defined, and should be banished from use. [W. S. Jevons, Elementary Lessons in Logic, 1870: 335]

Well I was interested in this and so I started hunting up the term “essentialism”, and oddly it has no great history itself. Apart from a usage in education (essentialism is the claim there are essential things that must be educated, what we now call the canon), it was used shortly after Popper in a philosophical sense in a paper on aesthetics in 1948 (Gallie 1948). These are the two earliest versions I can locate. Here’s the Ngram for “essentialism”:

Essentialism ngram

It gets used – apart from a small spike around 1900 – beginning in 1939. Much of this will be in the logic literature, where it gets discussed in questions of modality, until it becomes more widely used in philosophical literature. And it really picks up after Mayr’s book in 1982.

But the standard definition, and the one that ties it to Aristotle, seems to be one of the most widely read and cited philosophy papers of the century: Quine’s “Two Dogmas of Empiricism”. Quine is attacking a particular theory of meaning:

The Aristotelian notion of essence was the forerunner, no doubt, of the modern notion of intension or meaning. For Aristotle it was essential in men to be rational, accidental to be two-legged. But there is an important difference between this attitude and the doctrine of meaning. From the latter point of view it may indeed be conceded (if only for the sake of argument) that rationality is involved in the meaning of the word ‘man’ while two-leggedness is not; but two-leggedness may at the same time be viewed as involved in the meaning of ‘biped’ while rationality is not. Thus from the point of view of the doctrine of meaning it makes no sense to say of the actual individual, who is at once a man and a biped, that his rationality is essential and his two-leggedness accidental or vice versa. Things had essences, for Aristotle, but only linguistic forms have meanings. Meaning is what essence becomes when it is divorced from the object of reference and wedded to the word.

A commentator of Quine (White 1972) noted that it is unremarkable that Quine did not cite any text of Aristotle in support of this interpretation, since it is only tenuously connected to anything Aristotle wrote. Quine later gave a technical definition (Quine 1953):

. . . Aristotelian essentialism. This is the doctrine that some of the attributes of a thing (quite independently of the language in which the thing is referred to, if at all) may be essential to the thing and others accidental. E.g., a man, or talking animal, or featherless biped (for they are all the same things), is essentially rational and accidentally two-legged and talkative, not merely qua man but qua itself. More formally, what Aristotelian essentialism says is that you can have open sentences – which I shall represent here as ‘Fx’ and ‘Gx’ – such that

(54)       (∃x) (nec Fx. Gx. -nec Gx).

An example of (54) . . .might be

(∃x) (nec (x > 5). there are just x planets,
-nec (there are just x planets)),

such an object x being the number (by whatever name) which is variously known as 9 and the number of the planets.

This introduces the modal necessity version (the “necessary” of the necessary and sufficient definition). What is interesting is that this seems to be the very first use of “Aristotelian essentialism”, and while that’s just a phrase I can’t find much else that marries scientific essentialism with Aristotle. I may be wrong about that, but it looks like one of the preoccupations of modern philosophy of science is no older than the early 1950s, not much older than I am. Here’s the Ngram for the phrase:

Aristotelian essentialism ngram

I can’t find out what the blip around 1900 is. However it is pretty clear that Aristotle was not seen to be a scientific essentialist before Quine’s essay, even if Quine did not think that he was. I suspect that this was inadvertent, and Quine’s status as a philosopher led others to think that this was correct, when in fact it was not the kind of essentialism Aristotle actually held. He thought essences were, as Quine noted, about words, not objects:

I want to claim here that Aristotle’s grasp of modal notions, and of the use of modal operators, is such that he could not clearly express the Quinian distinction between essential and non-essential attributes of a sensible particular. [White, p60. White’s argument is subtle, and has to do with the role sensible particulars play in Aristotle’s metaphysics and epistemology, that is not relevant here.]

In conclusion, I think that the notion of Aristotelian essentialism is a mistake based on a casual reading of various philosophers, including (as I detail in my book) Dewey, logic texts, and Popper, but the particular error of ascribing it to Aristotle is based on Quine’s passing comment. If anyone knows to the contrary, I’d be very pleased to hear of it.

Cain, Arthur J. 1958. Logic and memory in Linnaeus’s system of taxonomy. Proceedings of the Linnean Society of London 169:144-163.

Gallie, W. B. 1948. IV. The function of philosophical æsthetics. Mind LVII (227):302-321.

Ghiselin, Michael T. 1974. A radical solution to the species problem. Systematic Zoology 23:536-544.

Hull, David L. 1965. The effect of essentialism on taxonomy: Two thousand years of stasis. British Journal for the Philosophy of Science 15:314-326, 316:311-318.

–––. 1988. Science as a process: an evolutionary account of the social and conceptual development of science. Chicago: University of Chicago Press.

Jevons, William Stanley. 1878. The principles of science: a treatise on logic and scientific method. 2nd ed. London: Macmillan. Original edition, 1873.

Mayr, Ernst. 1982. The growth of biological thought: diversity, evolution, and inheritance. Cambridge MA: The Belknap Press of Harvard University Press.


Popper, Karl R. 1945. The Open Society and its Enemies. Vol 1, The Spell of Plato. London: Routledge.

–––. 1959. The logic of scientific discovery. Translated by K. Popper, J. Freed and L. Freed. London: Hutchinson.

Quine, Willard Van Orman. 1953. Three Grades of Modal Involvement. Actes du XIème Congrès International de Philosophie XIV: Volume complémentaire et communications du Colloque de Logique:65-81. Republished in 1966. The ways of paradox, and other essays. New York: Random.

–––. 1960. Word and object, Studies in communication. Cambridge: Technology Press of the Massachusetts Institute of Technology. [Contains the “Two Dogmas” paper.]

White, Nicholas P. 1972. Origins of Aristotle’s Essentialism. The Review of Metaphysics 26 (1):57-85.

Winsor, Mary Pickard. 2003. Non-essentialist methods in pre-Darwinian taxonomy. Biology & Philosophy 18:387-400.


  1. You make an interesting distinction here, between just saying that everybody from ancient Greeks to just before Darwin was essentialist (as Dewey does) to saying that Aristotle specifically was (as Quine does). The latter might well be a diagnosable indication of descent.

    A methodological point about the graphs generated by the Google ngram site: They are case sensitive, so (eg) it graphs occurrences of the word ‘essentialism’ but leaves out occurrences of ‘Essentialism’. (I used it to chart ‘natural kind’ across time in a recent paper, and it required downloading the dataset and making my own graphs.)

    Google book search turns up uses of “Aristotelian essentialism” by several critics of Popper (in the late 1940s) that mention his discussion of “Aristotelian ‘essentialism'” in Open Society and its Enemies. The blip around 1900 is elusive, although my brief search turned up writers contrasting Whitehead’s metaphysics with Aristotle’s, calling the latter essentialist.

    • Yes, this is just a rough cut, but I did do variations – Essentialism, essentialist, Essentialist, essentialistic, etc. They all showed much the same trends. Ngram is suggestive, but not definitive.

      When were those writers? Whitehead’s major works on process philosophy are a fair bit after 1900.

  2. Great post; I love tracing down the history of the bits of philosophical folklore that drift around.

    There’s some possibility that the blip at 1900 is just classification error; Google’s metadata is notoriously error-ridden (I once came across a book of theology where the author had been identified as the Holy Trinity, an autobiography perhaps), and sometimes books are just tagged with the wrong date entirely. It could also be an independent use of the phrase, of course. Whatever the blip is, it’s from the English One Million database for 1899.

  3. Chris E Chris E

    Under `essence’ the OED cites a passage where Whewell attributes a kind of essentialism to Aristotle in translating him, under definition 2b. ‘Species of existent being’ (Johnson); an element.’

    >1837 W. Whewell tr. Aristotle in Hist. Inductive Sci. I. 54 There is some essence of body different from those of the four elements.”

    • Lots of writers use the term “essence”, and it is not contentious that Aristotle was essentialistic about terms and ideas. The question is whether he was a Quinean kind of Aristotelian essentialist (the modal kind about sensory experiences), and whether (more interesting for me) he was a scientific essentialist. He was not, I think, despite the four elements.

      In the chapter I am writing that triggered this post, I will argue that a form of essentialism of physics and the universal sciences is feasible (in the end, a complete theory must limn all kinds in the domain that theory covers), but that it is not for the special sciences like biology.

  4. jeb jeb

    “If you aren’t with the new evolutionary metaphysics, you aren’t modern.”

    Millle hominum species et mentis discolor usus;
    Velle suum cuique est, nec voto vivitur uno

    • jeb jeb

      ooops. Trans.
      there are a thousand kinds of men, and different hues they give to things; each one follows his own inclination, neither wishing to live the same way

      Gerald of Wales uses the cite in the preface to his early ethnographic work in which he expresses the desire to explore how the diverse minds of men are influenced by different manners and customs.

      Persius’s original Latin reads “species et rerum” rather than Gerald’s “et mentis” just in case anyone noticed.

  5. Raving Raving

    Was looking at Process Philosophy and Logic and Ontology … I feel like the Cheshire cat

    Time is everything. That makes the mess out of essentialism

    The problem can be made tractable by starting at the point and working backwards (outwards). That however creates an explosion of divergence and discontinuities … There is also Strawson’s conundrum …

    A perceptual model can feasibly capture all (time freezes) while revealing the internal details and workings (time flows) [Description to follow … it is akin to a Swiss watchmaker trying to assemble a single grain of salt. Tricky]

    … time is everything and confusing and nothing
    To weave back and forth between process and ontology it is necessary to capture the essential quality of time and package it.

    Thank you for the inspiration John!

    • teaparty1776 teaparty1776

      > Time is everything.

      Agreed, within a limit.

  6. David Duffy David Duffy

    Perhaps Aristotlean should just be read as Thomistic or neo-scholastic. Aquinas uses exactly the language Quine quotes: necessary accidents, essential features etc.

    • This is better, but there’s still a problem of reference. Lots of writers use this language, and there was a neo-scholastic view arisen around 1880 and neo-Thomism around 1920 that Quine is probably responding to. However, the use of the language alone doesn’t make them scientific essentialists even if they are essentialists about logic or language. Now Quine is not claiming that they are, but those who appeal to this faux historiography based on his comments are and do.

  7. It is important to re-read words like: “I will argue that a form of essentialism of physics and the universal sciences is feasible (in the end, a complete theory must limn all kinds in the domain that theory covers), but that it is not for the special sciences like biology.” to understand why Darwinism is pseudo- science.

    As to the essence – perhaps the concept should be considered more broadly – like substance or better hoc aliquid.
    And Aquinas:
    Ex hac differentia provenit quod Angelus intelligit sine discursu, anima autem cum discursu; quae necesse habet ex sensibilibus effectibus in virtutes causarum pervenire, et ab accidentibus sensibilibus in essentias rerum, quae non subiacent sensui.

  8. Jeb Jeb

    “This is better”

    My comment was a bad attempt at a subtle joke John. I suspect you may be unaware of the way in which biological essentialism has been used to understand medieval concepts of ethnicity.

    The lack of biological essentialisim in medieval concepts of ethnicity has suggested to historians that biological determinism is not a key feature of ethnicity in the middle ages i.e the medieval is similar to contemporary concepts of ethnicity drawn in social science.

    Gerald of Wales comments on the Welsh are used as an example of this ‘historical’ conclusion.

    Does not kill the argument dead but suggests historians perhaps need to tread with care in subjects that appear to be ahistorical wastelands of thought at times I suspect.

    The subject looks as if it may support you’re argument.

    • Jeb Jeb

      p.s I don’t think its a generalization to say that Gerald is viewed as moving against essentialisim in contemporary historical debate.

      I wonder why?

  9. Raving Raving

    My response to essentialism could be … confused … puzzlement … huh? Rather I declare: For Raving, essentialism is the only thing

    I seek out ‘singular categorization’. That means only one single essential quality that tags all members. Want another categorization? It yields a replenished and resampled set of members.

    The singular categorization doesn’t make me a ‘black & white’ type of guy. Just one color please. That single color is everything and the only thing. My focal awareness is occupied by all and only members which possess that single color selection. Everything else is peripheral background noise.

    Popper : According to methodological essentialism, there can be three ways of knowing a thing: ‘I mean that we can know its unchanging reality or essence; and that we can know the definition of the essence ; and that we can know its name.

    Popper sees 3 essential ways of knowing. Raving sees a single essential way of knowing: How are all things static
    held by Plato and many of his followers
    it is the task of pure knowledge or science
    to discover and to describe the true nature of things
    It was Plato’s peculiar belief that the essence of sensible things

    Raving sees that Popper casts all his observations in a single essential form:

    Popper: What is the path by which things approached
    Popper: Here is the axis across which perspective is drawn

    … that is Popper’s perspective (essential quality)

  10. Could it be that Popper, Quine, Mayr projected species fixism into the species and called it essentialism? That is, they thought that their forebears thought that species were fixed because of some unchanging essences when, maybe, the forebears had some external force to do the fixing?

    • Assuming we are speaking of logical species, then I think Aristotle did think there was an immanent essence in the sense of there being something that made a thing the kind of thing it was. However, that is very far from the Necessary and Sufficient Conditions of linguistic essentialism in Quine. It is what I can benign essentialism: there are properties that make things stay in a kind. Homeostasis is one such property (and usually the one that matters most in biology and earth sciences).

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