Lowe lijkt te impliceren dat de real essences volgens Locke toegang bieden tot niet-arbitraire natural sorts - Essay Marketplace

Lowe lijkt te impliceren dat de real essences volgens Locke toegang bieden tot niet-arbitraire natural sorts

Locke’s real essence theory should not be considered as a botched attempt to produce an essentialist semantics for natural kind terms and as fundamentally different from his nominal essence theory. Rather, the two theories should be viewed as parts of a consistent and unified anti-essentialist and nominalist philosophical position.

Lowe lijkt te impliceren dat de real essences volgens Locke toegang bieden tot niet-arbitraire natural sorts. Uzgalis ontkent dit en zegt dat Locke het bestaan van niet-arbitraire natural sorts ontkent. Ik neig eerder naar Uzgalis maar constateer ook dat er een spanning is in de uitspraken van Locke mbt de rol van real essences en (daarop aansluitend) het al dan niet bestaan van natural sorts. Mijn uiteindelijke conclusie is dat ondanks deze spanning Locke vooral neigt naar het probable knowledge mbt het bestaan van natural sorts, vooral ook omdat real essences volgens hem onkenbaar zijn. Uzgalis besteed weinig aandacht aan dit noodzakelijk skeptische aspect van de empirische kenleer van Locke. Onkenbaarheid en niet-waarneembaarheid moet binnen een empirisch raamwerk leiden tot skepticisme, het ontkennen van zekere kennis, en het inruilen daarvan voor waarschijnlijke kennis. Locke lijkt dit meerdere malen nadrukkelijk te erkennen.

• Rode tekst obv Judith Crane (ook overgenomen citaten van Locke)

• Groene tekst obv Uzgalis (ook overgenomen citaten van Locke)



Grappige intro mbt essentie van leren  drawing, erasing, discovering boundaries.

Introduceren natural kinds  vermoeden van arbitraire karakter maar commonsense van het bestaan van niet-arbitraire grenzen.

Visie van Locke hierop  Arbitraire karakter natural sorts (nominal essences)

Bijbehorende vraag / vraagstelling essay: metafysisch of (‘slechts’) epistemisch.

• Dus: kunnen real essences leiden tot een classificatie?

• En: Is deze classificatie al dan niet arbitrair?

• Kort de ideeën van anderen (Lowe, Uzgallis, …, …)

Stellling / conclusie:

• waarschijnlijk beweert Locke metafysisch (no natural kinds in nature) maar skeptische houding op zijn plaats gezien empirische kenleer.

Opbouw essay

But in our search for knowledge of nature, and within the realm of natural science in general, we don’t strive for creative drawings; it is blueprints we often seem to long for.

A relatively large part of Locke’s Essay is, explicitly or implicitly, devoted to kinds, species and genera. And thus it might seem as a surprise that contemporary philosophers are still debating whether Locke held a realist or conventional position regarding natural kinds. A realist position regarding natural kinds…..

In the Essay Locke unquestionably criticizes the Aristotelian or scholastic view on natural kinds and classification. He holds, contrary to them, that our classification of natural kinds is pragmatic and conventional. Certainly, everyday language and, scientific classification probably also, is not a way to discover really existing boundaries in order to classify natural kinds. However, Locke’s view on classification doesn’t automatically mean that these boundaries don’t exist. Contrary to Locke’s clear remarks on our conventional method of classification, he is less explicit about the ontological status of natural kinds. So, it is fair to ask if Locke thought whether fixed and non-arbitrary boundaries really exist in nature, regardless the conventional nature of our present way of classification. Did Locke imply with the introduction of real essences that nature consists of natural kinds? Natural kinds which are separated by really existing and mind-independent boundaries? Could knowledge of these real essences potentially lead to a method of classification that better mirrors those really existing boundaries? A method that is more precise than our conventional one on the basis of nominal essences?

After studying relevant parts of the Essay I conclude that Locke didn’t regard the real essences and nominal essences as two separated, alternative or competing ways to classify reality into natural kinds. Both are related and interdependent within Locke’s empirical and explain how we acquire knowledge of reality and the natural world. It also seems that, despite some contradictory remarks in the Essay, Locke tends to the position that natural kinds, marked of by non-arbitrary and fixed boundaries, don’t exist in reality. Any classification, whether on the level of nominal essences or on the level of real essences, seems necessarily conventional and arbitrary. In my opinion however, considering Locke’s own empirical framework, the conclusion that natural kinds don’t exist in reality can never reach the status of certain knowledge. In the end we have to stay skeptic, agnostic or, better, modest about our knowledge of the existence of fixed kinds and non-arbitrary boundaries in nature. The main purpose of the Essay is to investigate the boundaries of human knowledge; this investigation must lead to the conclusion that our knowledge of nature’s boundaries never transcends the realm of probability.

In order to answer these questions and reach these conclusions I will first give a brief explanation of the Aristotelean view on natural kinds and methodology of classification. This is followed by a treatment of Locke’s critique on the Aristotelians and his own perspective on classification in which the concept of nominal essences plays an important role. Next, I will consider Locke’s distinction between nominal essences and real essences and their role within his empirical framework. After that I examine relevant parts of the Essay with regard to the possibility of classification on the base of the real essences of substances. I will also regard whether such a classification would be non-arbitrary and mind-independent. These considerations will subsequently lead to my conclusion regarding Locke’s position on the ontological status of natural kinds. Finally, I will make some remarks on how this position is related to Locke’s own empirical framework of knowledge. What is its epistemological status?

An Aristotelean and Lockean account of classification

The Aristotelean acoount of classification

• Boundaries: sharp and determinate

• Aim of science: discover the essences of natural kinds and boundaries.

Locke’s attack on the Aristotelean account of classification

• Individuen hebben geen essentiële eigenschappen los van een eventuele (arbitraire) classificatie.

• Er is geen vaststaande classificatie in de natuur (natural sorts) die door de wetenschap ontdekt zou kunnen worden

The Lockean acoount of classification: nominal essences

• Status: Arbitrair / conventioneel / pragmatisch

• Essentieel of nominaal?

In order to understand Locke’s position on natural kinds, it is useful to elaborate shortly on the view on and understanding of nature he was criticizing. One of the primary aims of his discussion on natural kinds in the Essay was to reject the Aristotelean method of classification of nature into fixed kinds separated by sharp boundaries. This Aristotelian method is too complex to explain in just a view sentences, partly because it is radically different than contemporary natural science and its methods. On the other hand, I think it somehow seems like a commonsensical view on reality because it appears to be consistent with the way we describe nature in everyday language. This becomes clear if we look at some central aspects of the Aristotelian position. In Locke’s own words, this Aristotelean method consisted of the “usual supposition” that

[a] there are certain precise Essences or Forms of things, whereby all the Individuals existing are, by Nature, distinguished into Species (III.vi.14).

As articulated by Locke the Aristotelean position can be described in the following way. Firstly, individual things are differentiated, by nature, into separate species. This means that nature contains an objective classification of all the things in it, in such a way that every individual thing belongs to a species. This classification is objective in the sense that it exists independent of human choice and conventions. A second aspect is that in order for such an objective natural classification to obtain, every individual thing has an essence, called its ‘substantial form’ by Aristotelians, which determines to which species the individual thing belongs. Thirdly, in this classification system of nature there are no imprecise or vague boundaries between natural species or kinds. The essences or substantial forms exactly determine to which species an individual thing belongs. And every individual thing belongs to one, and only one, natural kind. So, an important consequence of this Aristotelean view is that nature contains its own division of individual things into kinds independent of human affairs. The goal of an ´Aristotelian scientist´ could be described as the discovery of nature’s own fixed boundaries between species and kinds.

An important indication that Locke won´t support this Aristotelean view is the fact that he already seems to deny the existence of universal natural kinds which determine the categorization of each natural thing. He writes that “all things, that exist, [are] particulars”. However, this immediately gives rise to the question where our general terms come from and how they function within our language. The major part of our language consists of general terms like: horse, human, flower, gold, mammal, etc. All such terms refer to natural kinds and we usually assume that separate individuals or particulars, like two “horses”, belong to one and the same natural kind, like the kind “horse”. This is exactly why the Aristotelian view might appear to a commonsensical one. However, Locke explains that we form general ideas through the mental operation of abstraction. We start with an idea of an individual thing or particular. This is a complex idea because it already consists of many properties or simple ideas we perceive in that particular. By separating from that complex idea those ideas peculiar only to that one, and keeping those we continually find in several objects, we can form an abstract general idea “capable of representing more Individuals than one” (III.iii.6). A general term, like “horse” or “human”, is a word we associate with such an abstract general idea. It is because of the resemblance of individual things that we are able to construct abstract general ideas that refer to all of these things. From this view on abstraction and general terms Locke concludes that

[b] this whole mystery of Genera and Species, which make such a noise in the [scholastic] Schools, and are, with Justice, so little regarded out of them, is nothing else but abstract Ideas, more or less comprehensive, with names annexed to them (III.iii.9)


[c] General and Universal, belong not to the real existence of Things; but are the Inventions and Creatures of the Understanding, made by it for its own use, and concern only Signs, whether Words or Ideas (III.iii.11).

Locke maintains that the classification of particular things into sorts or kinds, denominated or referred to by general terms, has no direct foundation in nature’. It is instead the result of our own complex process of abstraction. [Essay III iii 12-14] Evidently, Locke offers a nominalistic and non-essentialistic account of classification. He wants to eliminate certain problematic universals or at least get rid of the Aristotelean method by which we come to gather them. So an important claim of Locke is that our ideas of species and genera are collections of simple ideas formed by abstraction, which refer to things which have those qualities retained in the abstract ideas. This account explains how general terms work and that they refer to our arbitrary abstract ideas instead of universal substantial forms.

And so, Locke claims, the way we classify the natural world comes forth from our own pragmatic interests and doesn’t mirror really existing and sharply defined ontological kinds in nature. This is in line with Locke’s remarks on language, as being more a pragmatic tool than a scientific one, when he says that the classificatory system of ordinary language were made by ordinary, vulgar and illiterate persons for ease of communication in the conduct of ordinary practical affairs and not by scientists tot mirror the way in which nature divides things into orderly classes. Species and kinds seem to be mind-dependent and arbitrary in the sense that our classification of nature is a matter of human decisions and concentions. He clearly rejects the Aristotelian system to classify nature into distinct species, genera and kinds. But it is important to note that this interest-based, mind-dependent and nominalistic way of classification doesn’t necessarily imply that such ontological kinds don’t exist in nature. It might still be possible that there really are fixed and non-arbitrary boundaries between natural kinds but that we are ignorant of them. It certainly may be that ‘species’ are ‘the workmanship of the understanding’ and the result of our arbitrary formation of abstract ideas; but from this it doesn’t necessarily follow that there is no objective and mind-independent separation of particulars in nature which we could at least strive to mirror with our abstract general ideas. The mind-dependency and arbitrariness of our classification of arbitrary kinds doesn’t necessarily rule out the existence of mind-independent and non-arbitrary kinds in nature. In order to investigate Locke’s position on the existence of natural kinds we have to look at other parts of the Essay, especially those where he writes about the names of substances and the distinction between real essences and nominal essences. It is these parts of the Essay I will turn to now.

It is clear that an important role of Locke’s nominal essence theory is to deliver an alternative view on classification to replace the one provided by the Aristotelean method of classification. 

Nominal essences and real essences (essential properties and real essences)

Real essences and the probability of classification

Real essences and the arbitrariness of classification

• Essentieel of Nominaal?

• Noodzakelijk of arbitrair?

• Tegenstrijdigheden in het werk van Locke!

• De status van kennisuitspraken hieromtrent

o Gezien Locke’s empirische uitgangspunten. Skepticisme?

o Probabilistic ipv certain knowledge

Locke’s account of classification rules out the possibility that species and kinds are universals. He claims that because there are only particulars, there aren’t any naturally occurring universal species or kinds, though they may be invented by humans in the formation of abstract general ideas. However, although Locke’s nominalism rules out the existence of universals like Aristotelean substantial forms, their might still be other possibilities to arrive at an objective, mind-independent and non-arbitrary division of particulars which we could try to mirror with our classification of nature. Maybe particulars can naturally be divided into sharply distinguished groups because they are significantly more similar to each other than to other ones. And in order for such similarities to be significant and objective they should be independent of arbitrary human decisions about the relevance of these similarities. Presumably these significant and objective similarities arise from properties of individuals that are essential to them. Such essential properties might categorize things into distinct groups of natural kinds, which might in principle be discoverable, and thus not merely invented, by us. On this view for there to be natural kinds it is sufficient that individual things have essential properties that have a non-arbitrary basis in nature.

Although we form our general abstract terms in an arbitrary way based on our own decisions, nature might still have an intrinsic classification of things which we might try to discover. As Uzgalis (????) mentions there are “some [contemporary] scholars and philosophers claiming that Locke’s real essences give us Nature’s way of dividing things into classes”. Although these philosophers acknowledge that Locke’s nominal essences are meant to explain our arbitrary way of classification, they regard Locke’s account on real essences as part of an alternative method that might, at least potentially, lead to obtain an objective classification which is non-arbitrary and objective.

In III.vi, Locke argues that individual substances do not have essential properties unless they are considered under a sortal concept. There is nothing essential to an individual particular considered solely on its own. But if particulars lack essential properties, we also don’t have a non-arbitrary method to determine the significance or special position of certain similarities rather than other similarities. Without a decisive non-arbitrary method to identify essential properties, any similarity between properties of individual substances could serve as an indicator to put them under a single species or kind. Locke claims that if we view a particular thing as just an individual and not as a representative of some kind, we cannot determine what is essential to that thing.

[d] take but away the abstract Ideas, by which we sort Individuals, and rank them under common Names, and then the thought of any thing essential to any of them, instantly vanishes (III.vi.4).

He also claims that if we compare two individual substances, it is impossible to suppose that there could be a specific difference between them, “without reference to general Ideas and Names”. This is because

[e] particular Beings, considered barely in themselves, will be found to have all their Qualities equally essential; and every thing, in each Individual, will be essential to it, or, which is more true, nothing at all (III.vi.5).

From this follows that if essential properties only arise in relation to our sortal concepts, by which we categorize things, then we are unable to make use of essential properties for constructing and restricting (framing) these same sortal concepts. This leads to Locke’s central claim that essential properties cannot be discovered prior to, and as an objective and non-arbitrary source for, our sortal concepts.

Next to this argument against the existence of essential properties from their necessarily human and thus arbitrary source, Locke delivers a second argument against the existence of essential properties. Locke writes that

[f] in all the visible corporeal World, we see no Chasms, or Gaps. All quite down from us, the descent is by easy steps, and a continued series of Things, that in each remove, differ very little one from the other. There are Fishes that have Wings, and are not Strangers to the airy Region: and there are some Birds, that are Inhabitants of the Water; whose Blood is cold as Fishes, and their Flesh so like in taste, that the scrupulous are allow’d them on Fish-days. There are animals so near of kin both to Birds and Beasts, that they are in the middle between both: Amphibious Animals link the Terrestrial and Aquatique together; Seals live at Land and Sea, and Porpoises have the warm Blood and entrails of a Hog . . . There are some Brutes, that seem to have as much Knowledge as some that are called Men . . . we shall find everywhere, that the several Species are linked together, and differ but in almost insensible degrees (III.vi.12)

Locke observes that the individual things we are confronted with do not naturally fall into distinct groups. The qualities that we are able to detect do not guide us in realizing a unique and non-arbitrary system of classification. There always seem to be some individuals that will cross the boundaries of the defined natural kinds in such a classificatory system. In these observations Locke’s argument is based upon the observable qualities that we are aware of when we examine the world around us. But is it still a good argument if it is applied to the underlying structure of things which gives rise to these observable qualities? This is where Locke’s concept of real essences becomes relevant. Some philosophers think that Locke claims that the knowledge of the underlying structural properties or real essences could enable us to determine the natural boundaries between species / kinds. These underlying and unobservable structures / real essences might presumably be regarded as more fundamental to a thing, because it is the structure from which the observable properties arise. Locke’s argument about ??? might be stronger if it can also be extended to underlying structure of a thing and thus its real essence.

It is likely that Locke thought that at the level of the underlying structure or real essences the argument works in the same way. Locke explains the possibility of classifying individual things according to their real essences, and thus at the level of their underlying structure, with the help of an analogy. He writes that a watchmaker, surely being accurately informed about the inner workings of watches, might use different qualities to classify distinct sorts of watches. However, Locke wonders

[g] what is sufficient in the inward Contrivance, to make a new Species? There are some Watches, that are made with four Wheels, others with five: Is this a specifick difference to the Workman? Some have Strings and Physies, and others none; some have the Balance loose, and others regulated by a spiral Spring, and others by Hogs and Bristles (III.vi.39).

Surely, there will be “chasms and gaps” between classes of watches, but only after we ourselves have made a decision which qualities to regard as essential in order to classify them. However, there isn’t a non-arbitrary justification to give priority to a particular set of qualities instead of another set. Thinking we can classify watches in a non-arbitrary way is like someone being honestly surprised to find a watch while it was he himself who hide it just a few seconds ago. Such surprise deserves the classification of being naïve.

And so, both on the observable level of appearances or nominal essences and at the unobservable level of the underlying structure or real essences there are different qualities to choose from in order to classify objects / substances. For Locke, their doesn’t appear to be a way to prioritize these qualities of objects in order to classify them. It is not clear what reason there could be to give priority to one set of qualities instead of another. In the last two passages from the Essay Locke implies that there can and always will be some individuals which lacks such an ‘essential quality’.

In the Essay Locke discusses and makes a distinction between nominal essences and real essences. These two sorts of essences should not be seen as two alternatives or distinct from each other but are in fact intimately related within Locke’s empirical framework.

And so, Locke’s nominal essence theory is meant to give an explanation of how we classify things on the basis of the how these things appear to us. The real essences stand for the atomic realities which give rise to or produce these appearances. If these real essence could be known, they would have an explanatory role with regard to the appearances they produce.

My main conclusion is that Locke, contrary to the Aristotelean tradition, leans towards the position that nature does not divide individual things into separate classes (kinds) marked off by sharp and non-arbitrary boundaries.

Knowledge and the existence of boundaries


It is evident that in the Essay Locke is explicitly criticizing the Aristotelian method of classification and its view on natural kinds. The “real species” or, as the Aristotelians call them, substantial forms are a myth according to Locke. From the existence of similarities between individuals, which we apply to classify them, doesn´t necessarily follow that nature divides itself into natural kinds fixed between non-arbitrary boundaries. However, from Locke’s account of nominal essences, the classification on the basis of similarities of appearances, doesn’t necessarily imply that such fixed natural kinds don’t really exist in nature. Maybe we are just ignorant of them and it might still be possible that individual things can be grouped into natural kinds in virtue of some essential properties. But from a critical reading of the Essay it is safe to conclude that Locke thought that the privilege of such essential properties cannot be determined a priori without presupposing a sortal concept. In the end, any method by which we try to classify nature into kinds is necessarily made up by us and thus arbitrary and conventional.

Locke´s view seems to be that any kind of classification of substances into natural kinds, either on the level of nominal essences or real essences, must necessarily be preceded by us making arbitrary choices and human conventions. Without such conventions nothing is necessarily essential to particular substances. Locke also seems to imply in various parts of the Essay that, apart from the human act of classifying, there are no such things as real natural kinds on the metaphysical level. So this leads to the claim that classifying the natural world is necessarily interest-based and doesn’t reflect real ontological kinds in nature. This qualification according to our interests is not a sign of our ignorance of nature’s boundaries, but due to the fact that there are no fixed boundaries of natural kinds in the natural world at all. Rephrasing it more popularly; what isn’t there cannot be discovered but has to be made up by us.

And so, Locke’s nominal essence theory is meant to give an explanation of how we classify things on the basis of the how these things appear to us. The real essences stand for the atomic realities which give rise to or produce these appearances.

My main conclusion is that Locke leans to the position that nature does not divide individual things into distinct classes (kinds) through sharp and non-arbitrary boundaries.

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