Locke: Natural Kinds

In this paper, I will argue that Locke is a substance dualist in the general sense, in that he holds that there are, independent of our classificatory schema, two distinct kinds of substances: wholly material ones and wholly immaterial ones. On Locke’s view, the difference between the two lies in whether they are solid or not, thereby differentiating him from Descartes. My way of establishing Locke as a general substance dualist is to be as minimally committal as possible at the (...) outset, especially with respect to the classic debates on Locke’s positions in this domain, including those concerning substrata, real essences, and the like. Nonetheless, I show that minimal commitments about Locke’s primary/secondary quality distinction are sufficient to derive some substantive conclusions about his positions on these issues, as well as that he is a general substance dualist. (shrink)

It is often claimed that classification, on Locke’s view, proceeds by attending to similarities between things, and it is widely argued that nothing about the sensible similarities between things determines how we are to sort them, in which case sorting substances at the phenomenal level must be arbitrary. However, acquaintance with the “internal” or hidden qualities of substances might yet reveal objective boundaries. Citing what I refer to as the Watch passage in Locke’s Essay (henceforth Watches), many commentators claim that (...) classification at the microphysical level must also be arbitrary. They conclude that sorting is arbitrary at any level of description. I refer to this as the standard reading of Locke on classification. In this paper I argue that Locke does not claim that sorting is arbitrary, either at the phenomenal level, or at the microphysical level. First, Locke does not claim in Watches that sorting is arbitrary at the microphysical level. The existence or nonexistence of objective boundaries at the microphysical level is not Watches’ topic and the passage is in fact silent on that question. Here, the standard reading mistakes a claim about the nature of the task of locating “specific differences” for a claim about the nature of the task of classification. This diagnosis proves instructive, for I argue that a similar conflation underwrites the standard reading’s claim that sorting at the phenomenal level must be arbitrary. Far from arbitrarily choosing how to sort things in terms of their phenomenal similarities, Locke thought that the mind simply follows nature’s lead. This characterization of the mind’s activity, I go on to argue, accords well with Locke’s claim that species are the workmanship of the understanding. (shrink)

Locke has been accused of endorsing a theory of kinds that is inconsistent with his theory of individuation. This purported inconsistency comes to the fore in Locke’s treatment of cases involving organisms and the masses of matter that constitute them, for example, the case of a mass constituting an oak tree. In this essay, I argue that this purported problem, known as ‘The Kinds Problem’, can be solved. The Kinds Problem depends on the faulty assumption that nominal essences include only (...) features observable at a time t. Once this assumption is rejected, new candidates open up for the relevant difference in the world that is included in the nominal essence of e.g. mass but not oak tree. And I argue that there is at least one good candidate for the extrinsic feature observable only over time in which the mass differs from the oak it constitutes, namely its persistence conditions. The Kinds Problem can be solved. (shrink)

In this paper I argue that John Locke is not ontologically committed to corpuscularian real essences. I do this by laying out his antirealist argument against corpuscular real essences within the Essay and then defend it. I then identify a version of real essences to which he is ontologically committed. Recognition of the antirealist argument in the Essay should significantly alter our interpretation of the Essay.

This paper examines the way in which Locke's deep and longstanding interest in the non-European world contributed to his views on species and their classification. The evidence for Locke's curiosity about the non-European world, especially his fascination with seventeenth-century travel literature, is presented and evaluated. I claim that this personal interest of Locke's almost certainly influenced the metaphysical and epistemological positions he develops in the Essay. I look to Locke's theory of species taxonomy for proof of this. I argue that (...) Locke uses evidence gathered from the non-European world to (1) show that in taxonomizing objects we rely on their sensible qualities rather than their real essences and to (2) undermine Scholastic Aristotelian views about a mind-independent species/genera structure to the world. (shrink)

This is my response to Sam Rickless's review article on my book, Locke's Moral Man.

This paper examines the pressures leading two very different Early Modern philosophers, Descartes and Locke, to invoke two ways in which thought is directed at objects. According to both philosophers, I argue, the same idea can simultaneously count as “of” two different objects—in two different senses of the phrase ‘idea of’. One kind of intentional directedness is invoked in answering the question What is it to think that thus-and-so? The other kind is invoked in answering the question What accounts for (...) the success of our proper methods of inquiry? For Descartes as well as Locke, the two kinds of “ofness” come apart as a result of strong rationalist commitments. However, I will suggest that even if we reject such commitments, we go wrong if we assume that a single kind of intentional directedness suffices to address both questions. (shrink)

Matthew Stuart offers a fresh interpretation of John Locke's Essay Concerning Human Understanding, arguing for the work's profound contribution to metaphysics. He presents new readings of Locke's accounts of personal identity and the primary/secondary quality distinction, and explores Locke's case against materialism and his philosophy of action.

Antonia Lolordo presents an original interpretation of John Locke's metaphysics of moral agency, in which to be a moral agent is simply to be free, rational, and a person.

‘Water is H2O’ is one of the most frequently cited sentences in analytic philosophy, thanks to the seminal work of Saul Kripke and Hilary Putnam in the 1970s on the semantics of natural kind terms. Both of these philosophers owe an intellectual debt to the empiricist metaphysics of John Locke's Essay Concerning Human Understanding, while disagreeing profoundly with Locke about the reality of natural kinds. Locke employs an intriguing example involving water to support his view that kinds (or ‘species’), such (...) as water and gold, are the workmanship of the human mind. This is the point of his story about a winter visitor to England from Jamaica, who is astonished to find that the water in his basin has turned solid overnight, and proceeds to call it ‘hardened water’. Locke criticizes this judgement, maintaining that it is more consonant with common sense to regard water and ice as different kinds of substance. Putnam, by implication, disagrees. Deploying his imaginary example of Twin Earth—a distant planet where a watery-looking substance, XYZ, rather than H2O, fills the oceans and rivers—he maintains that common sense supports the judgement that XYZ and H2O, despite their superficial similarity, are not the same kind of substance, precisely because their molecular compositions are different. Here it will be argued that both views are mistaken, but that, in this dispute, Locke has more right on his side than his modern opponents do. (shrink)

John Locke’s theory of classification is a subject that has long received scholarly attention. Little notice has been taken, however, of the problems that were posed for taxonomy by its inability to account for organic processes. Classification, designed originally as an exercise in logic, becomes complicated once it turns to organic life and the aims of taxonomy become entangled with processes of generation, variation, and inheritance. Locke’s experience with organisms—experience garnered through his work in botany and medicine—suggested to him both (...) the dynamism of nature and the artificiality of any a priori system of classification. This reinforced Locke’s critique of classification in the Essay Concerning Human Understanding, and by tracing its influence it is possible to approach Locke’s nominalism from a fresh perspective. (shrink)

RESUMEN: La teoría causal formulada por Kripke y Putnam es la teoría semántica dominante de los términos de género natural y, en especial, de los términos de sustancia. La teoría semántica de los términos de sustancia de Locke ha sido, supuestamente, refutada por aquélla. Según Putnam, la teoría de Locke ha pasado por alto dos importantes contribuciones a la semántica, y principalmente a la referencia, de los términos de sustancia, a saber, la contribución de la sociedad y la del entorno. (...) El objetivo de este artículo es argüir que la teoría de Locke puede incorporar la primera contribución y que alguien que en principio sostuviese una teoría como la de Locke podría verse llevado a aceptar también la segunda contribución.ABSTRACT: The causal theory put forward by Kripke and Putnam is the dominant semantic theory of natural kind terms and especially of substance terms. Locke’s semantic theory of substance terms has supposedly been rebutted by it. Locke’s theory has, according to Putnam, overlooked two significant contributions to the semantics, and mainly to the reference, of substance terms, namely, the contribution of the society and that of the environment. This paper aims to argue that Locke’s theory is able to embrace the first contribution and that someone who initially held a theory like Locke’s could be led to accept also the second one. (shrink)

In this paper I criticize arguments by Pauline Phemister and Matthew Stuart that John Locke's position in his An Essay Concerning Human Understanding allows for natural kinds based on similarities among real essences. On my reading of Locke, not only are similarities among real essences irrelevant to species, but natural kind theories based on them are unintelligible.

Ideas play at least two roles in Locke's theory of the understanding. They are constituents of ‘propositions,’ and some of them ‘represent’ the qualities and sorts of surrounding bodies. I argue that each role involves a distinct kind of intentional directedness. The same idea will in general be an ‘idea of’ two different objects, in different senses of the expression. Identifying Locke's scheme of twofold ‘ofness’ reveals a common structure to his accounts of simple ideas and complex ideas of substances. (...) A consequence is a distinction among substance sorts parallel to one of his distinctions between primary and secondary qualities. (shrink)

One of the more interesting topics debated by Leibniz and Locke and one that has received comparatively little critical commentary is the nature of essences and the classification of the natural world.1 This topic, moreover, is of tremendous importance, occupying a position at the intersection of the metaphysics of individual beings, modality, epistemology, and philosophy of language. And, while it goes back to Plato, who wondered if we could cut nature at its joints, as Nicholas Jolley has pointed out, the (...) debate between Leibniz and Locke has very clear similarities to the topic that has dominated the philosophy of language from the 1970s on: namely, the challenge mounted by Kripke, Kaplan, Putnam, and others against Russellian and Fregean descriptivist accounts of meaning. Yet, this topic is also, as Jolley writes, one of the “most elusive” in the debate between Leibniz and Locke.2 The purpose of this paper is to examine in detail Leibniz’s critique of Locke’s distinction between real and nominal essences. In doing so, I hope to show certain virtues in Leibniz’s account of metaphysics and philosophy of language that usually escape notice. While I wish to provide a general account of Leibniz’s disagreement with Locke, I also plan to focus on the nature of species and natural kinds. In my opinion, those who have treated this topic have not paid sufficient attention to Leibniz’s claims that “Essence is fundamentally nothing but the possibility of the thing under consideration” and “essences are everlasting because they only concern. (shrink)

In this paper, I examine the crucial relationship between Locke’s theory of individuation and his theory of kinds. Locke holds that two material objects—e.g., a mass of matter and an oak tree—can be in the same place at the same time, provided that they are ‘of different kinds’. According to Locke, kinds are nominal essences, that is, general abstract ideas based on objective similarities between particular individuals. I argue that Locke’s view on coinciding material objects is incompatible with his view (...) on kinds. In order for two material objects to be in the same place at the same time, they must differ with respect to at least one nominal essence. However, Locke thinks that it is impossible that x and y have the same real essence but differ with respect to any nominal essence; and coinciding material objects have the same real essence. Therefore, Locke cannot hold what he in fact holds, namely that distinct material objects can be in the same place at the same time. (shrink)

In a well-known paper, Reginald Jackson expresses a sentiment not uncommon among readers of Locke: “Among the merits of Locke’s Essay…not even the friendliest critic would number consistency.”2 This unflattering opinion of Locke is reiterated by Maurice Mandelbaum: “Under no circumstances can [Locke] be counted among the clearest and most consistent of philosophers.”3 The now familiar story is that there are innumerable inconsistencies and internal problems contained in Locke’s Essay. In fact, it is probably safe to say that there is (...) not another canonical, well-respected, and seminal philosopher whose work is so widely thought to be swarming with inconsistencies. I, however, do not think that the common, unflattering view of Locke is accurate as a general view of the Essay. But despite my wishes to the contrary, I do believe that Locke’s chapter ‘Of Identity and Diversity’ (2.27)4 leads to (at least) one intractable problem, a problem that is the subject of this paper. (shrink)

Susanna Goodin, in her article “Locke and Leibniz and the Debate over Species” , argues that Leibniz’s criticisms of Locke’s species conventionalism are inadequate as a refutation of Locke’s arguments, and if Leibniz were to buttress his criticisms by appeal to his own metaphysical commitments, he could do so only at the expense of so radically altering the nature of the debate that Locke’s original concerns would not even arise. I argue, however, that Leibniz has an argument within the Nouveaux (...) Essais which provides him with a mechanistically respectable counterproposal to Locke’s conventionalism and which demonstrates the explanatory superiority of natural kind realism. (shrink)

Locke is often cited as a precursor to contemporary natural kind realism. However, careful attention to Locke’s arguments show that he was unequivocally a conventionalist about natural kinds. To the extent that contemporary natural kind realists see themselves as following Locke, they misunderstand what he was trying to do. Locke argues that natural kinds require either dubious metaphysical commitments (e.g., to substantial forms or universals), or a question-begging version of essentialism. Contemporary natural kind realists face a similar dilemma, and should (...) not appeal to Locke in their defense. (shrink)

The two opinions concerning real essences that Locke mentions in III.iii.17 represent competing theories about the way in which naturally occurring objects are divided into species. In this paper I explain what these competing theories amount to, why he denies the theory of kinds that is embodied in the first of these opinions, and how this denial is related to his general critique of essentialism. I argue first, that we cannot meaningfully ask whether Locke accepts the existence of natural kinds, (...) per se, since he affirms the theory of kinds that is embodied in the second opinion, while he denies the theory that is embodied in the first opinion. Second, I show that his denial of this theory is not solely or even primarily directed against the scholastic/Aristotelian theory of substantial forms, since he is most interested in refuting a corpuscularian version of this theory. And third, I argue that Locke’s anti-essentialism does not follow solely from his denial of (deeply objective) natural kinds, since one could consistently make this denial and affirm the existence of de re essential properties. (shrink)

The focus of this dissertation is the debate over classification and species realism/anti-realism in the new science of mechanism. I argue that Michael Ayers's Interpretation of Robert Boyle as a Lockean on species is incorrect. Boyle is more realist than Locke, indeed, Boyle's theory of classification was more similar to Leibniz's than to Locke's. This realist account of Boyle helps to diagnose an important connection between Leibniz and Boyle, and show Locke as a much more novel philosopher of science. ;I (...) then argue that this account of Boyle's realism reveals a new argument strain in Leibniz that allows him a better reply against Locke's species anti-realism. I thus argue against Susana Goodin's view that Leibniz's reply to Locke's anti-realist arguments in the New Essays are stronger than they appear to be. According to Goodin, Leibniz cannot refute Locke without either changing the subject or appealing to his own deep metaphysics. I argue that Leibniz can reply in a dialectically adequate, non-question begging way to Locke's argument without appealing to anything deeper than the science of mechanism. ;Finally, I show that, contra Ayers, one of Locke's motivations for his anti-realism stems from his theological heterodoxy, not from the corpuscularian hypothesis. This theological strain appears most strikingly within the context of the debate over the status of persons and the human species. In the Essay, Locke denies each of Leibniz's orthodox theses regarding the human species. Locke's denials of the orthodox theses appear to be motivated by his heterodox theological commitments. (shrink)

In his Essay Concerning Human Understanding, Locke famously introduces both the problem of personal identity over time and a controversial solution to it. The problem is to provide a criterion for when a person, A, at a time, t, is the same as a person, B, at a later time, t' . Locke's proposal that A at t is the same person as B at t ' just in case B at t' is conscious of some episode in the mental (...) life of A at t has drawn considerable criticism and given rise to a specialized area of research in metaphysics and the philosophy of mind. I argue that many of what have become standard attacks on Locke's theory of personal identity are vitiated because they divorce Locke's discussion of personal identity from the rest of his argument in the Essay. The criticisms attack, in effect, a consequence of Locke's discussion but not the epistemological assumptions that drive it. In particular, many of the criticisms ignore Locke's empiricist critique of the general idea of substance, which is of central importance in understanding how Locke arrives both at the problem of personal identity and his response to it. (shrink)

Locke's claims about the "inadequacy" of substance-ideas can only be understood once it is recognized that the "sort" represented by such an idea is not wholly determined by the idea's descriptive content. The key to his compromise between classificatory conventionalism and essentialism is his injunction to "perfect" the abstract ideas that serve as "nominal essences." This injunction promotes the pursuit of collections of perceptible qualities that approach ever closer to singling out things that possess some shared explanatory-level constitution. It is (...) in view of this norm regulating natural-historical inquiry that a substance-idea represents a sort for which some such constitution serves as the "real essence," i.e. as that on which all the sort's characteristic "properties" depend. (shrink)

Tandis que l'histoire de la philosophie est traversée par la dichotomie entre le réalisme des universaux et le nominalisme, on tend à négliger la position intermédiaire — le conceptualisme — dont on a fait de Locke le plus illustre représentant, mais qu'on a tenu pour disqualifié par les célèbres critiques de Berkeley ou Leibniz. On peut cependant montrer que le conceptualisme est doublé d'une ontologie sous-jacente qui pourrait fournir aux philosophes contemporains une alternative originale à la philosophie des universaux. Whereas (...) the dichotomy between realism and nominalism, makes the problem of Universais a paradigm case of a philosophical problem, the mediate view put forward by conceptualism is generally neglected as being an erroneous view on language. Nevertheless, conceptualism is the counterpart of an original ontology — the philosophy of Resemblances — which might be regarded an alternative to the philosophy of Universals. (shrink)

I examine two strands in Locke's thought which seem to conflict with his corpuscularian sympathies: his repeated suggestion that natural philosophy is incapable of being made a science, and his claim that some of the properties of bodies--secondary qualities, powers of gravitation, cohesion and maybe even thought--are arbitrarily "superadded" by God. ;Locke often says that a body's properties flow from its real essence as the properties of a triangle flow from its definition. He is widely read as having thought that (...) if we had ideas of a body's real essence, we would be able to perceive a priori a necessary connection between that body's real essence and its observable properties. I argue that this leaves Locke's skepticism without any rationale, making it depend entirely upon our ignorance of corpuscular structures when in fact he never rules out the possibility of our acquiring ideas of corpuscular structures through improvements in microscopy. I argue that Locke's geometrical analogy is better understood as an endorsement of deductivism about scientific explanation. He thinks that knowledge of corpuscular structures is a necessary, but not a sufficient, condition for scientific knowledge of bodies. The deeper source of his skepticism is his view that we cannot have universal and certain knowledge of the laws of nature because they are contingent. ;I approach the subject of Locke's attitude toward mechanism by examining his superaddition doctrine. In contrast with M. R. Ayers, I attribute to Locke what I call strong voluntarism: the view that a body's powers to interact with other bodies are not fully determined by the essence of matter, and that they are at least partly determined by the will of God. I argue that Descartes and Boyle are also strong voluntarists, but that Locke's voluntarism differs in that he maintains that bodies have some powers which are not even partly explicable in terms of the motions of matter. Locke's position is thus incompatible with the mechanism of Descartes and Boyle. (shrink)

John Locke is the greatest English philosopher. _An Essay Concerning Human Understanding_, one of the most influential books in the history of thought, is his greatest work. In this study the historical meaning and philosophical significance of Locke's _Essay_ are investigated more comprehensively than ever before. _Locke_ was originally published in two volumes, _Epistemology_ and _Ontology_. This paperback edition has within its covers the full text of both volumes.

In his Essay concerning Human Understanding, John Locke claimed that sensations enter the mind as unmixed simple ideas. Because we don't observe the necessary connections which unite such simple ideas into the complex ideas we have of substances, Locke concluded that such complex ideas must be constructed by our minds rather than given by nature. Since our ideas of substances, and the consequent ideas of essences that are abstracted from them, are not given by nature but constructed out of judgment (...) and opinion, those essences and the species we derive from them are merely nominal and not real. ;Locke did believe, however, that there were real essences, and, in the case of material substances, those real essences amounted to the arrangements and motions of the insensible particles that made up the internal structures of material substances. Such real essences were of course unknown in Locke's day, but many scholars have contended that Locke believed such an ignorance was temporary and would be overcome in time as science developed powerful enough instruments to peer into the microscopic world. The major thesis of this dissertation is that such a position is incorrect, and the consequence of all that Locke says is that the real essences of substances will never be known in spite of whatever instruments are developed. Furthermore, this dissertation also questions whether any real essences are knowable given Locke's epistemology and rejection of the Aristotelian position that real essences are given in experience. ;Lastly, this dissertation focuses on the consequences of Locke's position concerning our ignorance of real essences. In particular it examines the logical consequences of Locke's idea of essence upon the notions of science and human understanding in general. (shrink)

Locke was a sceptic about the possibility of scientific knowledge of corporeal substance. Scientific knowledge is knowledge which is certain, universal, and instructive. According to Locke, to have certain and instructive knowledge of natural kinds requires knowledge of the real essence of natural kinds. Since a real essence is the foundation for the properties a thing has, it must be known before a deduction of the properties can be done. Locke did not believe that it was possible for humans to (...) know the real essence of corporeal substances. In my thesis, I provide an explanation for why he held these views. ;As my work shows, knowledge of the real essence of a natural kind is an involved process that requires first knowing the nominal essence of the natural kind, and then knowing the inner constitution of each member of the kind, knowing which aspect of the inner constitution of each member correlates to the overlap of properties used to delineate the natural kind, and finally, knowing how that aspect, which is the real essence of the natural kind, produces the properties it does. Without knowledge of the mechanics of how the physical real essence produces the mental ideas we cannot know whether the connection between the real essence and the properties is a necessary connection or a mere correlation. Unless we know why there is a connection, we cannot know, with certainty, that the connection will hold in the future or for other like configurations. Locke relies on the mind-body problem to explain why we cannot know the mechanics behind the connections. ;The mind-body problem has not been given appropriate emphasis in Lockean study. And yet it is uniquely capable of handling the two claims Locke makes about natural science: our knowledge of corporeal bodies can never qualify as scientific knowledge and our knowledge of corporeal bodies can be improved in ways that are useful to human life. (shrink)

Of the many disputes about Locke's views in An Essay Concerning Human Understanding, two very basic ones concern his general theory of word meaning and his position on the question of the ontological status of genera and species, or what are currently called natural kinds. In this dissertation I propose to discuss, though not settle, the first dispute. I do propose to settle the second dispute by arguing that the views in the Essay are positively anti-realist and do not entail (...) the existence of natural kinds. ;My study of the Essay begins with an explication of Locke's central semantic thesis that words signify ideas, "the meaning of words being only the ideas they are made to stand for by him that uses them." Some major criticisms of this thesis are reviewed and ways they might be met are suggested. Once Locke's general theory of meaning has been explicated, I turn to consider its special application for those names which are predicated of natural substances, i.e., words such as 'gold,' 'water,' 'man,' 'cat,' etc. Locke's theory of the meaning of such terms hinges on his distinction between real and nominal essences, thus this discussion includes an account of Locke's view of abstraction, the process upon which the formation of nominal essences depends, as well as a brief statement of Sir Robert Boyle's corpuscular hypothesis, a theory fundamental to Locke's doctrine of real essence. Next, I survey Locke's several arguments in Book III of the Essay against the existence of kinds; these arguments are shown to provide a clear ontic denial of kinds and certain passages which are often cited as explicitly contradicting this denial are further shown to be, on the contrary, consistent with it. After considering Locke's anti-realist arguments and countering the charge that he explicitly acknowledges the reality of kinds, I turn to a refutation of the charge that Locke's doctrine of real essence is implicitly a doctrine of real kinds. Finally, I conclude by placing Locke's theories of word meaning and kinds within the larger context of the epistemological enterprise of the Essay. I also draw two important conclusions from Locke's anti-realism: that Locke does not, as has been argued by Mackie, anticipate Kripke's theory of reference and that although Locke's general theory of word meaning may have application with respect to some kinds of words, because it involves a conventionalist view of kinds, it fails to provide an account of the semantics of natural kind terms. (shrink)