Locke on Identity: Matter, Life, and Consciousness

Edwin McCann

[McCann, Edwin (1999). Locke on Identity: matter, life, consciousness. In Margaret Atherton, ed (1999). The Empiricist: Critical Essays. Rowman and Littlefield, Lanham MD.]

Locke’s general theory of identity has received relatively little attention on its own. The first eight sections of the Essay's chapter "Of Identity and Diversity" [1] are usually treated, if they are discussed at all, as merely prefatory to the theory of personal identity. This gets things backwards. The extended discussion of personal identity in that chapter is meant to illustrate the general theory, as well as to show that the identity of persons can be accommodated within it. [2] In this paper I aim at redressing the balance. I will describe Locke’s general theory of identity, showing that it is a unified and consistent theory that is able to handle such troublesome cases of identity as that of plants, animals, and persons within a mechanist framework. I will then argue that this appreciation of Locke’s theory shows the most widely held recent interpretation of Locke’s theory of personal identity to be mistaken.

To understand Locke’s views on identity we must recognize that the problem of identity to which he is responding is a quite special one. One of the main aims of the Essay was to buttress the new Mechanical Philosophy [3] against its rivals, particularly the Scholastic variants of Aristotelianism which were still so influential in the English universities. The mechanists chiefly objected to the Scholastic doctrine of forms and qualities. The Scholastics taught, to put it very roughly, that each natural object has a substantial form which, as the principle of its unity and operations, unites the matter of which it is composed into a single individual thing (unum per se), constitutes it a member of its species, and thus provides the conditions of its continuing identity. As regards qualities, they held, again roughly, that an object’s accidental qualities

[1] Book II, chapter 27 of Locke’s An Essay concerning Human Understanding. This chapter was added to the second (1694) edition of the Essay. When I give only a section number, I am referring to this chapter, otherwise my references to the Essay are by Book, chapter, section number. Quotations are taken from P. H. Nidditch’s edition of the Essay (Oxford: Clarendon Press, 1975).

[2] This last is an important desideratum for Locke’s theory, in view of the connection between personal identity and such highly charged theological issues as immortality and the resurrection of the body. More on this later.

[3] For background see E. J. Dijksterhuis, The Mechanization of the World-Picture (Oxford: Oxford University Press, 1961), pp. 433 ff.; Marie Boas (Hall), "The Establishment of the Mechanical Philosophy," Osiris 10(1952): 412-541; R. Kargon, Atomism in England from Hariot to Newton (Oxford: Clarendon Press, 1966), esp. chaps. 1, 8 and 9; and Robert Westfall, The Construction of Modern Science (New York: John Wiley & Sons, 1971), esp. chaps. 2 and 4. While Scholastic Aristotelianism was the main alternative to mechanism, it was not the only one. Other important contenders included the followers of Paracelsus, known variously as the iatrochemists, the Spagyritic chemists, or most loosely, the alchemists, who recognized certain vital or living principles as the agents of chemical reactions; and the Cambridge Platonists (most notably Ralph Cudworth and Henry More), who espoused a world-soul as a sort of conscious demiurge carrying out God’s general intentions in creating the world, and subordinate particular vital principles or "Plastick Natures" which are the proximate sources of activity in causation. These views are quite different from one another, and from Aristotelianism, but they all share a commitment to immaterial or non-mechanical principles of unity or activity as real constituents of things. In addition to the works cited above, see my "Lockean Mechanism" in A. Holland, ed., Philosophy: Its History and Historiography (Dordrecht: D. Reidel, 1985).

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are real (though dependent) beings which are the efficient causes of their characteristic effects, as the redness in a body is the cause of the sensations of redness it induces in us. In what follows we’ll be concerned only with forms and their role in individuation, but we should keep in mind that the doctrine of substantial forms is part of a total package which the mechanists rejected in its entirety.

Substantial forms draw the enmity of the mechanist for two reasons. First, forms act as formal causes, and in reference to final causes (in the fourfold Aristotelian scheme of causes); hence any full explanation of the unity, operations, or powers of natural objects must inevitably incorporate teleological considerations. Second, and much more important, these forms are real or actual constituents of natural bodies, in that they provide the causal or metaphysical basis of their individual identity and/or their characteristic powers and operations. In Scholastic jargon, the substantial form is an actuality, and indeed the first actuality of the composite of matter and form which constitutes a natural body. This means at the very least that it is something over and above the matter of which the body is made, which, together with its primary qualities or ‘mechanical affections’ (Boyle’s phrase), is the only real constituent of a body that the mechanists countenanced. The issue will become clearer if we chart the role forms were held to play in the individuation of substances.

Scholastic discussions of the principle of individuation were not so much concerned with formulating a set of abstract necessary and sufficient conditions for being an individual thing (the way we’re apt to think of a principle of identity or individuation) as they were to specify what it is in an individual that gives it its identity, that is, what real constituent of it is the causal basis of its individuality. [4] Not all of the Scholastics shared the same view on this topic. For St. Thomas Aquinas, the principle of individuation for material bodies is quantified matter; [5] Durandus held, according to Suarez, that form by itself is the full and adequate principle of individuation. [6] Suarez, Fonseca, and many other late Scholastics broadly followed Scotus in holding that it is the individual existence, ‘haecceity', or ‘entity’ of a thing that individuates it. [7] But Thomists and Scotists alike held that form plays a fundamental role in individuation. Suarez, for example, writes:

it must be said that in a composite substance, insofar as it is such a composite, the adequate principle of individuation is this matter and this form united to each other. And between these the primary principle is

 

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the form, which alone is sufficient for this composite, insofar as it is an individual of a particular species, to be judged the same numerically. [8]

Aquinas has similar reasons for holding that form is prior both to matter and to the composite of form and matter. [9] The basic picture is this:

as the substantial form of a cow, for example, is the causal basis of its growth, respiration, nutrition, movement, and so forth, it is what unites the different material parts of the cow into one single thing and what, over time, keeps it the same cow through changes in its (accidental) qualities and wholesale, if gradual, changes of its constituent matter.

We should be careful to note that it is the basic tenet of the theory of substantial forms -- that such forms are real or actual constituents of material substances in the sense explained above -- that is in conflict with mechanism. Boyle’s attacks on the theory of substantial forms, for example, are directed against a rather crude version of that theory, one on which substantial forms are themselves substances in their own right, able to exist apart from any matter whatsoever. [10] The views that we have been looking at are much more complicated and subtle than this, but they still conflict with mechanism. For them, forms are real beings, since the form of a thing is the causal basis of its essential properties and the principle unifying the matter of the thing; it is in this sense that they are said to be the first actuality of the form/matter composite. Construed in this way, substantial forms are just as much at variance with mechanism as they are on the cruder view on which Boyle bases his attack.

When Locke offers as a rubric for his account of identity "what is so much enquired after, the principium Individuationis"(II.27.3) he is placing that account squarely within the traditional framework. His problem of identity is thus the traditional one of specifying what it is in virtue of which natural objects, and particularly organisms such as plants, animals and human beings, retain their identity through change of matter. For a mechanist like Locke the problem is especially pressing, since in view of his commitment to there being no real constituents of material substances over and above matter variously figured and moved, he cannot appeal to forms or anything like them in giving an account of what makes a body or organism the same body or organism. [11]

Thus the problem; what is Locke’s solution? I have claimed that he has a consistent general account of identity; I’ll introduce it here, and fill it out more when we come to discuss, in the next three sections, its

 

[8] Fifth Metaphysical Disputation, VIlS, Gracia, p. 132; cf. IV.4, Gracia, p. 107, and TV.7, Gracia, p. 109.

[9] See e.g. Aquinas, Commentary on the Metaphysics of Aristotle, VII.2, secs. 1278-1279, Rowan, vol. 2, p. 498; cf. also V.5, secs. 825-26, Rowan, vol. 1, p. 324.

[10] See Robert Boyle, The Origin of Forms and Qualities (Oxford, 1666), as reprinted in The Works of Robert Boyle (London, 1772), vol.3, pp. 37ff., and in M. A. Stewart, ed. Selected Philosophical Papers of Robert Boyle (Manchester: Manchester University Press, 1979), pp. 53 ff. Boyle himself disassociates Aristotle from the view of substantial forms that he attacks, and even distinguishes between the teachings of the Greek commentators, and the later, Latin commentators, regarding the status of forms as substances.

[11] In a recent article on this topic (Harold Noonan, "Locke on Personal Identity," Philosophy 53 (1978): 343-51) we find the following statement: "Although Locke’s notions of substance and matter are so manifestly unaristotelian, something like Aristotle’s substantial form holds a prominent place in his thought, at least with respect to living creatures" (p. 344). Unless this is only making the point that Locke conceived of the problem of identity in the same way as his predecessors, it is either a gross distortion of Locke’s views or an implicit charge of inconsistency. As we’ll see in the second section of the paper, Locke’s notion of ‘life’ is meant to fill the role the substantial form plays in making for the identity of organisms, but in a way totally different from the way forms do it.

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particular applications. The closest Locke comes to a general statement about identity is in II.27.7, a section which caps the discussion of plant, animal, and human identity (sections 4, 5, and 6 respectively) and which prefaces the ensuing discussion of personal identity, which takes up the remainder of the chapter.

To conceive, and judge of [identity] aright, we must consider what Idea the word it is applied to stands for; It being one thing to be the same Substance, another the same Man, and a third the same Person, if Person, Man, and Substance, are three names standing for three different Ideas; for such as is the Idea belonging to that Name, such must he the Identity. (II.27.7)

It is the (our) idea of the kind of thing whose identity is at issue which determines its identity, and thus which accounts for its being the same thing through changes in its (accidental) qualities and particularly in its matter. There is no question, of course, of this idea’s playing a causal role in organizing the thing’s matter, or being a causal basis for its vital processes; it is in no sense a constituent of the thing. But as long as a spatio-temporally continuous series of masses of matter continues to satisfy the idea, we have the same thing: the same horse, or oak-tree, or whatever; and in that sense the idea keeps the thing the same. Locke tries to make this out by showing how identity differs in different types of case. I now turn to the cases.

 

Matter

 

At the start of II.27.2 Locke notes that "We have the Ideas but of three sorts of Substances; 1. God. 2. Finite Intelligences. 3. Bodies." In the previous section Locke had laid it down as a basic principle concerning identity that it is impossible for two things of the same kind to exist in the same place at the same time, so that "we rightly conclude, that whatever exists any where at any time, excludes all of the same kind, and is there it self alone," and had drawn from this principle a derivative one to the effect that a thing a and a thing b of the same kind are identical just in case a and b have the same beginning of existence, i.e. that a began to exist at exactly the same place and time as did b. [12]

In section 2, just after listing the three sorts of substances of which we have ideas, Locke adds something new: for finite spirits and for

[12] This principle is repeated again towards the end of Section 1, and again in Section 2. It is sometimes asserted that Locke’s basic criterion of identity is this, that two things (of the same kind) are identical just in case both had the same beginning of existence, i.e., began to exist in the same place at the same time. (See for example Baruch Brody, "Locke on the Identity of Persons," American Philosophical Quarterly 9 (1972): 327-34, pp. 327-29; Margaret Atherton, "Locke’s Theory of Personal Identity," Midwest Studies in Philosophy, vol. 8,1983, pp. 280-81.) Even a cursory reading of II.27.1 will reveal, however, that the principle about beginnings of existence is derived from the more general principle mentioned above. Joshua Hoffman, in his "Locke on Whether a Thing Can Have Two Beginnings of Existence," Ratio 22 (1980), pp. 107-8, also notices that the one principle is derived from the more general one.

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bodies "the relation to [the determinate time and place of its beginning to exist] will always determine to each of them its Identity as long as it exists." What, exactly, is "the relation" of which Locke speaks here? It can’t, on pain of circularity, be the relation of being the same thing as something that began to exist at that time and place, or any relation equivalent to this. It seems that the only possibility is that it is the relation of spatio-temporal continuity. This makes sense of the distinction drawn at the end of the section between permanent beings and the actions of those beings; it helps us see why Locke says at the start of the next section that "Existence it self" is the principle of individuation because it "determines a Being of any sort to a particular time and place incommunicable to two Beings of the same kind" (II.27.3). Furthermore, the criterion of identity for body given in that section, where Locke talks of the "continued" existence of an atom, seems to presuppose that "the relation" is one of spatio-temporal continuity, as does the derivation in section one of the principle about beginnings of existence from the general principle that two things of the same kind cannot exist in the same place at the same time. This reading is bolstered, rather than undermined, by the fact that a spirit’s identity is said to be determined by ‘the relation’ to its beginning of existence; for Locke is insistent that spirits are spatio-temporally located (they are where the bodies that they animate are) and that they move through space. [13] Evidently, then, Locke thought spatio-temporal continuity to be the relation determining the identity of body and of spirit. He had every reason to think so, since it seems to be the only relation that is a plausible candidate in the circumstances for providing a non-circular account of identity. [14]

In discussing the identity of bodies, Locke adds a condition to the one he specifies for both finite spirits and bodies (i.e. spatio-temporal continuity); he requires for "every Particle of Matter" that there be "no Addition or Subtraction of Matter" to or from that mass of matter if it is to continue to be the same body. On this criterion, we have the same body when and only when we have masses of numerically the same matter, however differently those masses might be organized and whatever changes of place may have occurred (as long as the changes of place preserve spatio-temporal continuity). In II.27.3 he illustrates how the criterion works within the framework of the atomist hypothesis.

Locke accepted a version of the revived Democritean atomism common to Gassendi, Charleton, and Boyle. Our idea of an atom is, he accordingly says, the idea of "a continued body under one immutable

[13] See 11.23.19-21. I owe this point and the appreciation of its relevance to the present topic to Michael Ayers. He promises a fuller development of it in writings yet to appear.

[14] Hoffmann, in "Locke on Two Beginnings," argues that Locke does not commit himself to spatio-temporal continuity as a condition of the identity of a substance. Hoffman thinks that to do so would have been a mistake, since it overlooks the possibility that a body may go out of existence at one time or place and come back into existence at another time (and perhaps another place as well). He doesn’t tell us, however, how to make sense of this alleged possibility. What would be the grounds for taking a body coming into existence after a period of time has elapsed during which the original body has not been in existence to be numerically identical with the original? Locke does not anywhere suggest that we could make sense out of such a thing as regards bodies or spirits -- as we shall see, persons are a different case -- and his discussion of the difference between creation and causation at II.26.2 gives ground for thinking that he would not be as quick as Hoffman is to assume (implausibly) that the notion of recreation makes sense.

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Superficies, existing in a determined time and place" -- immutable due to its physical indivisibility, determinately located in consequence of its being a finite extended thing. Each atom is "the same with itself" considered at any instant of its existence, and continues the same "as long as its existence is continued: for so long it will be the same, and no other." These specifications seem empty, but they are meant to bring out the fact that atoms, as conceived of by the Gassendist followers of Democritus, are simple substances.

As bodies, or extended solid substances, atoms by their solidity exclude all other bodies or material things from the volume of space which, thanks to their extension, they at any time occupy. Since atoms are physically indivisible, they absolutely exclude all other matter from the volume of space that they occupy: having no parts, they have no empty space inside them to permit the interpenetration that is possible among larger-scale bodies. Atoms are also insusceptible of change with respect to their figure, bulk, number, and unity, again due to their physical indivisibility; among their primary qualities the only ones which are subject to change are their state of motion and their position or situation, and these changes do not threaten the integrity of the body. Thus, the continued existence of an atom is simply a matter of its continuing to occupy space, i.e. its continuing to exist: it cannot be generated or corrupted, but only created or annihilated (by divine action). For this reason, atoms count as simple substances.

The identity of a complex body or mass of matter is then given in terms of the identities of its constituent atoms:

If two or more Atoms be joined together in the same Mass, every one of those Atoms will be the same, by the foregoing Rule: And whilst they exist united together, the Mass, consisting of the same Atoms, must he the same Mass, or the same Body, let the parts be never so differently jumbled: But if one of those Atoms be taken away, or one new one added, it is no longer the same Mass, or Body. (II.27.3).

As Locke indicates, bodies or masses of matter, construed in this way, can undergo many sorts of alteration in respect of their qualities. Their figures and bulks can change, as well as their state of motion and situation; they can vary the arrangement of their constituent atoms (i.e. change in respect of internal and/or surface structure); and so on. As long as the parts, or constituent atoms, of the mass remain "joined together," with no addition or subtraction of any atoms, it is the same body.

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Although the atomist hypothesis figures prominently in II.27.3, its main function is to simplify the illustration of the criterion for the identity of body given in II.27.2. That criterion does not itself presuppose the truth of atomism. The criterion speaks of "particles of Matter" but this phrase does not only cover atoms, since the passage allows for the possibility of

"subtraction" of matter from them. Atoms provide a convenient way of specifying the numerical identity of the aggregated matter making up a complex body. The general criterion of identity for body can be applied, however, even if atomism is false: we simply identify the boundaries of a connected mass of matter, and take the matter located within these boundaries to constitute one body, which it will continue to do as long as the matter coheres together and no matter is added or taken away.

It will help clarify Locke’s theory if we consider an important criticism of it. M. R. Ayers has argued [15] that Locke’s account confuses two disparate conditions: the condition that there be the same stuff or matter, and the condition that there be a continuing coherent or unified parcel of matter. The latter condition, but not the former, can be satisfied by parcels which have undergone a change of constituent matter, as long as the change is gradual; as Ayers points out, bodies or masses of matter understood in this way can be numerically identical with the organisms they can in some sense be said to compose.

For Locke we could respond as follows. The conditions Ayers mentions are disparate but not incompatible, and Locke’s account simply combines them. On his view, a body remains the same as long as it continues as a coherent unified whole and as long as it suffers no addition or subtraction of its matter. The two conditions together give a perfectly consistent and well-defined criterion, one which involves no confusion on Locke’s part so long as he does not intend it as an account of sameness of stuff or matter, [16] or as a faithful analysis of our ordinary talk about bodies; [17] but I see no evidence that Locke takes it for either of these.

What was Locke’s purpose in offering this account of the identity of body? It is clear that he was not trying to prepare the way for a reductive explanation of the identity-conditions of material objects generally in terms to those of parcels or masses of matter. In the last half of section 3 he stresses as much as any Scholastic ever did that the identity-conditions of plants and animals (and humans) cannot be reduced to those of parcels of matter. His further aim, however, is to undermine one of the central tenets of the Scholastic view about the nature of

[15] "Individuals without Sortals," Canadian Journal of Philosophy 4 (1974): 113-48, pp. 125-27.

[16] Cf. Ayers, ibid., p. 126, for cogent objections to such an account.

[17] Locke’s criterion is obviously too strict to match our ordinary talk, where for example we usually count a big rock the same body even after a tiny sliver has been knocked off.

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material substances. It is a leading Aristotelian doctrine that matter cannot by itself (without a form, or principle of unity) constitute a genuine substance or bona fide object: an ens per se. Locke rejects this doctrine, showing that the identity conditions for bodies can be given entirely in terms of matter, i.e. the same numerical matter constituting a cohesive mass (where this means only: all sticking together) and thus constituting it one single thing, a substance. There is no need of form or any other non-material principle of unity. Indeed, on Locke’s view the (connected) parts of substances could themselves be taken to be substances: my big toe, for example, is a body in its own right. In practice, of course, we usually speak only of the largest connected masses (e.g., my whole body) as the body. Locke usually follows this practice, and his conditions accommodate it perfectly well. In any case, all Locke has to claim for his conditions is that they give a coherent and intelligible way of conceiving the identity of bodies; if they do, as I think they do, then he has made a significant thrust against Scholastic hylomorphism.

One last point about the identity of body. In the next two parts of this paper we’ll be concerned with the identities of plants, animals, and persons. Locke evidently has these identities in mind when at II.27.7, summing up the argument of II.27.3-6, he says: " ‘Tis not therefore Unity of Substance that comprehends all sorts of Identity, or will determine it in every Case." He then proceeds to give the general criterion of identity I quoted earlier. This can give the impression that Locke is implying that in cases where identity is determined by unity of substance (the identity of body and of spirit) no idea is involved, in contrast with the case of plant and animal identity, for example. But unity of material substance, no less than any other identity, depends on an idea: the idea of body as an extended solid substance. Thus Locke’s discussion of the identity of atoms, and the derivative identity of masses of matter (the bodies composed of these atoms), takes off from our idea of body. It is the fact that atoms are bodies, cohesive parcels of matter, taken together with certain other facts about them (e.g. their indivisibility), that determines their identity-conditions, and hence those of the larger bodies composed of them. The immutability of the atoms and their primary qualities, and the relations between them (whatever they are) which serve as the causal basis of the cohesion of these atoms into large-scale bodies are, we might say, natural or preconventional facts. Their identity as bodies, however, is a function of our idea of body, which while a close gloss of the physical facts of

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the matter is nevertheless our idea. We turn now to the identities of plants, animals, and persons.

 

 

Life

Near the end of II.27.3, as we have seen, Locke notes that the identity of a living body does not in general consist in that of a body, or mass of matter, since the matter making up such a body can be gradually exchanged for other matter without a change in the identity of the organism. This is no problem for the Aristotelian with his substantial forms, but it is, as we have seen, a pressing problem for the mechanist. Locke outlines his solution to the problem as regards the identity of plants in II.27.4, and in II.27.5 and 6 extends it to animals and human beings. In view of its importance I quote II.27.4 in full:

We must therefore consider wherein an Oak differs from a Mass of Matter, and that seems to me to be in this; that the one is only the Cohesion of Particles of Matter any how united, the other such a disposition of them as constitutes the parts of an Oak; and such an Organization of those parts, as is fit to receive, and distribute nourishment, so as to continue, and frame the Wood, Bark, and Leaves, etc. of an Oak, in which consists the vegetable Life. That being then one Plant, which has such an Organization of Parts in one coherent Body, partaking of one Common Life, it continues to be the same Plant, as long as it partakes of the same Life, though that Life be communicated to new Particles of Matter vitally united to the living Plant, in a like continued Organization, conformable to that sort of Plants. For this Organization being at any one instant in any one Collection of Matter, is in that particular concrete distinguished from all other, and is that individual Life, which existing constantly from that moment both forwards and backwards in the same continuity of insensibly succeeding Parts united to the living Body of the Plant, it has that Identity, which makes the same Plant, and all the parts of it, parts of the same Plant, during all the time that they exist united in that continued Organization, which is fit to convey that Common Life to all the Parts so united.

 

Locke here identifies animal or plant ‘life’ with the organization of the parts of a living body. It is this organization or disposition of parts which is the causal basis of the living thing’s functional or organic unity, and of its ongoing vital functions such as nutrition, respiration, growth,

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etc., some of which involve the exchange of matter with the environment.

In spite of the functional similarities between Locke’s ‘life’ and the Peripatetics’ substantial forms, there is a crucial difference. As II.27.5 makes plain, the organization of parts in which the life of a plant or animal consists is nothing but the mechanical organization of its body. The only difference Locke sees between the fit organization of parts for animal life and that which make an assemblage of gears and wheels and so forth into a watch is that in the former case the motion that sets the parts to work comes from within, whereas in the latter case it comes from without. Just as there is no need of a form (a principle of horological life, as it were) to underlie and explain the function of a watch, so there is no need for such forms as regards plants and animals:

in both cases the characteristic operations of the thing are explained in terms of the putting-together of solid parts, suitably figured and moved.

We might be tempted to read Locke as a straightforward reductionist, attempting to reduce substantial forms to species-typical mechanistic constitutions. The ‘life’ Locke talks about is, after all, species-typical:

the life of an individual horse or oak-tree is the life of an oak, or a horse. Furthermore, Locke certainly proposes to understand this life in terms of the organization of the parts of the thing. We should resist this temptation, as Locke’s view is a bit more complicated than that. This ties up with larger issues concerning Locke’s views on the nature of species and, especially, their objective reality. [18]

The straightforward reductionist view has it that all members of a common species must share a single distinctive mechanistic organization of parts; a given object is a member of the species only because, and only for as long as, it possesses that internal constitution. This mechanical constitution, or real essence of the species, continues the same through all times at which a given individual plant or animal exists, and it is what keeps the organism the same even through changes in its matter.

In Locke’s view, it is the nominal essence, i.e. our abstract idea of the species, that is the essence of the species. [19] Locke gives a general argument for this claim at III.6.6, in the course of which he clarifies the relation between real and nominal essence. [20] The real essence, i.e. the mechanical constitution of the individual thing, is the causal basis of the thing’s powers and qualities. It is styled an essence, however, only

[18] For a fuller discussion see the important recent paper by M. R. Ayers, "Locke versus Aristotle on Natural Kinds" Journal of Philosophy 78 (1981): 247-72. I differ from Ayers, however, in thinking that Locke’s account of kinds is pretty nearly right, even as regards contemporary scientific practice.

[19] See for example III.3.13-14,III.6.2-8, 36-37.

[20] See Ayers, op. cit., pp. 255-59, 261-63. A similar account of III.6.6 is to be found in my unpublished Ph.D. dissertation, Locke’s Theory of Essence (University of Pennsylvania, 1975), pp. 214-18. In his first letter to Stillingfleet (A Letter to the Right Reverend Edward, Lord Bishop of Worcester [London, 1697], pp. 211-12; reprinted in The Works of John Locke [London, 1823], vol. 4, pp. 90-91), responding to Stillingfleet’s remark that "real essences are unchangeable, i.e., the internal constitutions are unchangeable," Locke writes:

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because of its relation to the nominal essence, i.e. our abstract idea of the sort to which the thing belongs:

But Essence, even in this sense, relates to a Sort, and supposes a Species: For being that real Constitution, on which the Properties depend, it necessarily supposes a sort of Things, Properties belonging only to Species, and not to Individuals.

He gives as an example the case of gold. A particular body has, say, the qualities of being yellow, malleable, and soluble in aqua regia; but until we have constructed a nominal essence of gold that makes these qualities definitional of membership in the kind, none of them are properties (in the traditional sense). Once we have put together this definition of the species, however,

Here are Essences and Properties, but all upon supposition of a Sort, or general abstract Idea, which it considered as immutable: but there is no individual parcel of Matter, to which any of these Qualities are so annexed, as to be essential to it, or inseparable from it. That which is essential, belongs to it as a Condition, whereby it is of this or that Sort: But take away the consideration of its being ranked under the name of some abstract Idea, and then there is nothing necessary to it, nothing inseparable from it.

Locke has a shrewd point here. The taxonomic divisions we have set up, more or less arbitrarily, are what determine the level of abstraction at which internal structure is to be described so as to arrive at an internal constitution characteristic of the species. There will, on the individual level, be a great deal of variation in the powers and qualities of members of the same species, reflecting, it is reasonable to assume, variations in their internal structure. [21] So for two things to be the same in constitution there need be no more specific structural similarities between the bodies than that they each have internal structures (however unlike) which are causally responsible for the body’s having the observable characteristics which are definitive of membership in the kind.

We should not overdo the point. Locke takes care to note that the species definitions we construct are based on a long, if not very systematic, process of observing salient resemblances among objects, and it is reasonable to think these surface resemblances reflect deeper resemblances in internal constitution. Thus Locke writes at III.6.36 that

[21] This point is made, for example, in III.6.8.

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This then, in short, is the case: Nature makes many particular Things, which do agree one with another, in many sensible Qualities, and probably too, in their internal frame and Constitution.

It is necessary, of course, that all members of the same species have the sensible qualities contained in the nominal essence of the species; given this degree of similarity they probably will be similar in internal constitution as well. The accent, however, is on probably.

The same goes for an individual existing over time. For it to remain in the same species it must continue to satisfy the nominal essence of that species; given that it does continue to satisfy it, it probably will have certain very general structural features that remain constant. But there is, again, no necessity of this. If, what is perhaps unlikely, the internal constitution of a thing came to be entirely rearranged without a change in the qualities comprised in the nominal essence, it would remain in the same species throughout, and would be the same thing. [22]

For a parcel of matter to have the life of an oak-tree is then simply for it to have an appropriate organization of parts. What determines whether an organization of parts is an appropriate one is our idea, or nominal essence, of an oak-tree. Now in terms of the identity of its constituent matter, this particular parcel of matter will substantially overlap the parcels of matter that at closely preceding and succeeding times are located at or contiguous to the place it’s in. This degree of spatio-temporal continuity is less stringent than that required for the continued identity of body and of spirit, and most important, it is continuity under the idea of an oak-tree. As long as this succession of parcels of matter continues to satisfy our idea of an oak-tree, there will be the same continued life and so the same oak-tree.

Locke is thus able to provide for the identity of plants and animals (including human beings) in a way which transcends the identity of the matter of which they are at any time made up but which is consistent with the mechanistic doctrines of the Essay. It is the life of an oak-tree or a horse that keeps it the same thing through various changes, i.e. its having parts organized in such a way that it has, and continues to have, the sensible qualities definitive of its species. This life cannot in general be reduced to the real essence the thing at any time has, or to a set of features of this real essence. Although the body’s real essence or internal constitution is the causal basis of its qualities and operations, it is the nominal essence that determines what is the life of the thing. Clearly, then, the life is not a further constituent of the organism, a

[22] This last point might seem to conflict with the famous passage in which Locke denies that there is anything essential to individuals:

(Compare III.3.19, and the similar passage in the third letter to Stillingfleet Mr. Locke\ Reply to the Right Reverend the Lord Bishop of Worcester~Answer

to His Second Letter [London, 1699], p. 358; Works, vol. 4, pp. 433-34), and see Ayers’ discussion in "Locke versus Aristotle," pp. 258-59, 262-63.) There is no conflict, however. In the passage Locke is denying that a individual has essential properties when it is considered apart from any abstract idea of its species. We can take Locke to be saying that if we judge his identity as a man, he does not survive the loss of life, but judged as a body, for example, he does remain the same thing before and after death (at least for a time). His point is that there is nothing in the nature of things that requires us to judge of his identity according to the one idea or the other. This way with the passages brings up the question of whether, and if so how far, Locke was a relative identity theorist; I plan to take this up on another occasion.

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real entity over and above the constituent matter with its mechanical affections. It is an artifact of sorts -- one grounded in long and careful observation (natural history) and so too, probably, in underlying facts about the structures of things -- but for all that, an artifact, due primarily to the abstract ideas we construct.

 

 

Consciousness

Locke discusses personal identity at much greater length than any of the other cases of identity. One obvious reason for this has to do with its theological import. There were heated controversies over such Christian doctrines as the eternal punishment or reward of the person after death and the resurrection of the body on the Last Day; the issue of personal identity is clearly implicated in these larger issues. [23] Another reason, I suggest, is that the way the rational soul provides for the identity of a person is a paradigm case of a substantial form’s providing for the continuing identity of a thing. For the Scholastics the soul is the form of the living human body, although able to survive its separation from the body at death and thus secure the identity of the person after death with the person before death. If Locke can account for the identity of persons without calling upon any immaterial principles of unity -- souls, substantial forms -- then he will have snatched the best case away from the Scholastics. And if his account of personal identity also preserves Christian doctrines concerning immortality and personal responsibility, then mechanism will be theologically that much less suspect.

My aim in this section is to show how Locke’s account of personal identity fits into his general account of identity. It is obvious how it fits with the II.27.7 injunction that the identity of a thing is to be judged in accordance with an idea, for Locke explicitly notes there that the subsequent discussion of personal identity is meant to illustrate that point. It is less obvious, however, how much the account of the identity of persons carries over from that of the identity of living things. We will see how Locke exploits the similarities and the differences between persons and living things to serve both philosophical and theological ends.

Simply put, consciousness is the life of persons. Less simply put, consciousness makes for personal identity in just the way life makes

[23] See E. M. Curley, "Leibniz on Locke on Personal Identity," in M. Hooker, ed., Leibniz: Critical and Interpretative Essays (Minneapolis: University of Minnesota Press, 1982), especially pp. 305-6 and 310-14. Curley’s response to those critics who hold Locke’s treatment of amnesia in II.27.20 to be inconsistent with his theory is similar to the one I develop below, although I think the uses to which we put the point are different. For background, see D. P. Walker, The Decline of Hell: Seventeenth Century Discussions of Eternal Torment (Chicago: University of Chicago Press, 1964), and Norman T. Burns, Christian Mortalism from Tyndale to Milton (Cambridge, Mass.: Harvard University Press, 1972); also relevant is R. C. Tennant, "The Anglican Response to Locke’s Theory of Personal Identity’ ‘Journal of the History of Ideas 42 (1981): 73-90. Although I have not yet seen it, I am told that Udo Thiel’s Lockes Theorie der personalen Identitität (Bonn: Bouvier, 1983) has extensive discussion of the theological background.

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for animal or vegetable identity. Early in the discussion of personal identity Locke makes this comparison:

Different Substances, by the same consciousness (where they do partake in it) being united into one Person; as well as different Bodies, by the same Life are united into one Animal, whose Identity is preserved, in that change of Substances, by the unity of one continued Life. For it being the same consciousness that makes a Man be himself to himself, personal Identity depends on that only, whether it be annexed only to one individual Substance, or can be continued in a succession of several Substances. (II.27.10) [24]

Consciousness and life have this in common, that they can ‘unite’ different substances (as judged by the criteria of unity of substance for bodies and, presumably, spirits) into a single thing, a plant, animal, man, or person. [25] More than this, they unite the various substances they at different times qualify by means of ongoing processes characteristic of the kind of thing in question -- vital processes such as nutrition and respiration, in the case of life, and mental processes such as deliberation, reasoning, and most important, memory, in the case of consciousness.

Famously, and in line with his II.27.7 injunction to consider the idea under which identity is to be judged, Locke opens his discussion of personal identity with an account of "what Person stands for" which exhibits consciousness as the key element in our idea of person. It is by virtue of his consciousness that a person has "reason and reflection, and can consider it self as it self, the same thinking thing in different times and places" (Section 9). Sameness of consciousness, accordingly, is the basis of the identity of the person.

Locke never specifies exactly what sameness of consciousness consists in, although it is clear that the ability to remember having had a certain experience or having done a certain action is sufficient for sameness of consciousness. It also is clear that sameness of consciousness is the basic relation making for personal identity, and that memory has its special role to play in personal identity only because of its connection with sameness of consciousness. [26] Thus, section 10:

For as far as any intelligent Being can repeat the Idea of any past Action with the same consciousness it had of it at first, and with the same consciousness it has of any present Action; so far is it the same personal Self. For it is by the consciousness it has of its present Thoughts and Actions,

 

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that it is self to it self now, and so will he the same self as far as the same consciousness can extend to Actions past or to come.

One is conscious of one’s current self by being conscious of what one is now thinking and doing. This does not in any way involve memory, and yet this consciousness is not only germane to personal identity, it is its basis. This passage is of special interest in view of the talk in it of ‘extending’ one’s current consciousness not only to past actions but to actions "to come." Presumably he has some such thing as this in mind:

when I plan what to say in tomorrow’s lecture, for example, I am seeing the actions I am envisioning as mine, as my actions; and when I think about my scheduled root canal the pain I anticipate is my pain. Memory is no doubt an important, perhaps the most important, continuity of consciousness, but it is not the only one. Whatever continuities are involved in sameness of consciousness, it is this sameness of consciousness that makes for personal identity, just as continuity of life is what makes for plant or animal identity.

While consciousness and life are analogous in many ways, there is an important disanalogy between them. Plant and animal identity, and so human identity as well, requires perfect continuity of life: there can be no gaps in the successive sequence of living states of the organism during which it is not alive. Locke talks in Sec. 4, for example, of how the life of an individual oak-tree taken at any one time makes different collections of matter into the same plant in virtue of the fact that it exists "constantly from that moment both forwards and backwards in the same continuity of insensible succeeding parts united to the living Body of the Plant." Consciousness, on the other hand, can unite interrupted stretches of experience into the same person.

In Section 10, Locke takes the interruptedness of consciousness to set the very problem of personal identity, and he later goes on, in Sect. 16 for example, to point to the special ability consciousness has to unite "Existences, and Actions, very remote in time, into the same Person." In the thought-experiment he presents there, where he remembers having seen the Deluge, or having done some action "a thousand years since," and in similar examples, such as that of remembering having done Nestor’s actions at the siege of Troy (Sect. 14), he does not suppose that our remembered experiences are part of a continuous sequence of remembered experiences stretching between the present time and those far-off experiences. He again appeals to the systematic interruptions in the experiences of the day-man and the night-man in

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Sect. 23, and in a similar vein, his case against the Cartesian doctrine that a person must always he thinking consists in pointing out that we have periods of dreamless sleep during which we are not conscious at all, although we certainly wake up as the same persons we were before we went to sleep. [27]

It is crucial to Locke’s account of personal identity that consciousness allows for such interruptions and discontinuities. Locke’s theory is often criticized for allegedly being unable to handle cases of amnesia and the like. Our intuitions say that I am the same person as the infant who poured paprika in my sister’s hair, although I don’t remember doing that; Locke’s theory says that I am not the same person. Recent supporters of the memory theory of personal identity have responded to this problem by looking for a way to include unremembered experiences within the total set of a person’s experiences; these solutions to the problem are often presented as friendly amendments to Locke’s theory. [28] Locke himself, however, with his emphasis on the ability of consciousness to "unite remote Existences into the same Person" (Sect. 23), takes an entirely different tack. His diagnosis is that intuitions such as the one mentioned above are due to confusion. Thus in Sect. 20 he writes:

But yet possibly it will still be objected, suppose I wholly lose the memory of some parts of my Life, beyond a possibility of retrieving them, so that perhaps I shall never be conscious of them again; yet am I not the same Person, that did those Actions, had those Thoughts, that I was once conscious of, though I have now forgot them? To which I answer, here we must take notice what the word I is applied to, which in this case is the Man only.

Locke simply denies that my infant misdeeds, for example, belong to me as a person. I am the same man, or human being, as the infant who did them, but not the same person.

This seems an heroic line to take, especially in light of the almost universal tendency of recent theorists to take such intuitions at face value and attempt to shape the theory to fit them. Locke certainly feels the need to argue for the correctness of his diagnosis. First off, in Sect. 20, he argues that his way with the problem is not so much a revision of our views as a consistent application of them. He gives it out as "the Sense of Mankind in the solemnest Declaration of their Opinions," i.e. in law, that a madman is not the same person as the same man sane;

[27] See II.1.9-19. The day-man/night-man case of II.27.23 is anticipated, by the way, in the first edition of the Essay at II.1.11-12. For a discussion of the differences between the first and second edition treatments of personal identity see Curley, "Leibniz and Locke," pp. 302-8.

[28] See the papers by Quinton, Grice, and Perry in John Perry, ed., Personal Identity (Berkeley and Los Angeles: University of California Press, 1975); see also Perry’s helpful introduction to that volume. Also Margaret Atherton, op. cit., J. L. Mackie, Problems from Locke (Oxford: Clarendon Press, 1976), chap. 6; and David Wiggins, Sameness and Substance (Cambridge, Mass.: Harvard University Press, 1980), chap. 6.

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this is shown by the fact that the madman is not held liable for what he (the same man) did when sane, or the sane man liable for what he did while mad. He finds the same view implied in ordinary ways of talking, where in cases such as this where the same man has "distinct incommunicable consciousness at different times," "we say such an one is not himself or is beside himself." This evidence, it must be admitted, is rather slim.

Locke must have realized this, for he continues his argument in the next two sections. It’s worth looking at them in some detail, as the first has not been much discussed and the second, although often discussed, has been misunderstood.

In Sect. 21 Locke offers to help us to see, what he grants is hard to conceive, that "Socrates the individual Man should be two Persons" by considering what is meant by "the same individual Man." He mentions three proposals: that sameness of man is just that of a soul, or immaterial thinking substance; that it is sameness of an animal (i.e., presumably, a living human body), and that it is sameness of an animal plus sameness of the soul united to that animal. He does not decide between these proposals, although he does note that the first has the uncomfortable consequence that humans born of different women and at different times could turn out to be the same man. In any case, the first proposal allows the same man to be different persons, as long as they have lived "in different Ages without the knowledge of one anothers Thoughts." As regards the second and third proposals, Locke notes that it will be impossible, on them, for Socrates in his earthly life and Socrates after his death to be the same man, since the animal in question would have died. We can’t get around this, he says, by making the identity of a man to be a matter of identity of consciousness, for the following reason:

But then they who place Humane Identity in consciousness only, and not in something else, must consider how they will make the Infant Socrates the same Man with Socrates after the Resurrection.

Locke must be assuming that the person Socrates, resurrected in the body, is the same man as well as the same person as Socrates before death. On Locke’s account the infant Socrates, the mature Socrates, and the resurrected Socrates can be the same man, and the mature and the resurrected Socrates the same person (on the assumption that Socrates resurrected can remember having done and experienced what

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mature Socrates thought and did), but neither of the latter can be the same person as infant Socrates (assuming neither remembers his doings). But on the disastrous proposals Locke is considering, infant Socrates is not only not the same person as mature and/or resurrected Socrates, he is not the same man as either one; at least as regards the mature Socrates, this is extremely counterintuitive. Thus

personal Identity can by us be placed in nothing but consciousness (which is that alone which makes what we call self) without involving us in great Absurdities.

With personal identity thus placed in consciousness, we have the possibility that one and the same man should be two persons.

The next section, Sect. 22, takes up the famous case of the sober man and the drunk man. Locke holds that human judicatures, which can punish only "with a Justice suitable to their way of Knowledge," can punish someone awake and sober for what he (the same man) did while drunk or sleepwalking, even though it is possible that he is not then conscious of having done it. The reason Locke gives for this is that the judicatures "cannot distinguish certainly what is real, what counterfeit" in such cases, and while "the Fact is proved against him" (i.e. the same man did those things), "want of consciousness cannot be proved for him."

This account occasioned one of the rare expressions of dissent from Molyneux. He argues that Locke has assigned the wrong reason for the Court’s not accepting drunkenness as a plea, the real reason, according to him, being that drunkenness is itself a crime. [29] Allison has argued that Locke capitulated to Molyneux on this point, [30] but clearly he did not. In his response Locke acknowledges that Molyneux has stated "the common reason" for the failure of the plea of drunkenness, but, he goes on to say,

This reason, how good soever, cannot, I think, be used by me, as not reaching my case; for what has this to do with consciousness? nay it is an argument against me, for if a man may be punished for any crime which he committed when drunk, whereof he is not allowed to be conscious, it overturns my hypothesisi’

The distinction here is between drunkenness which removes consciousness, and drunkenness which does not. A few sentences further on he writes:

[29] Molyneux’s letter to Locke of 23 December 1693, Letter #1685 in E. S. de Beer, ed., The Correspondence of John Locke (Oxford: Clarendon Press, 1979), vol. 4, p. 767.

[30] Henry Allison, "Locke’s Theory of Personal Identity," as reprinted in I. C. Tipton, ed., Locke on Human Understanding (Oxford: Oxford University Press, 1977), pp. 110-11.

[31] Locke to Molyneux, 19 January 1694 (in this letter and #1712 the year given by the correspondents is of course 1693/4). #1693 in de Beer, Correspondence of Locke, vol. 4. p. 785.

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But drunkenness has something peculiar in it when it destroys consciousness; and so the instances you bring justifie not the punishing of a drunken fact, that was totally and irrevocably forgotten, which the reason that I give being sufficient to do, it well enough removed the objection ... For I ask you, if a man by intemperate drinking should get a fever, and in the frenzy of his disease (which lasted not perhaps above an hour) committed some crime, would you punish him for it? If you would not think this just, how can you think it just to punish him for any fact committed in a drunken frenzy, without a fever? Both had the same criminal cause, drunkenness, and both committed without consciousness. [32]

 

Plainly, Locke never wavers on his main point, which is that human judicatures punish deeds done while drunk because they cannot be sure that in a particular case the drunkenness has removed consciousness. It is Molyneux who capitulates. [33]

Locke holds consistently to the theory that sameness of consciousness makes for personal identity, and is prepared to explain away contrary intuitions. His insistence on this, even in the face of the interruptedness in the existence of persons that is its consequence, is quite understandable given his desire to provide for the possibility of resurrection and judgment at the Last Day, as called for by Christian doctrine. This concern is prominent in Sects. 26 and 27, and is the main motivation for the claim made in Sect. 26 that ‘person’ is a forensic term. There Locke speaks of the Great Day on which God will judge what disposition to make of us in light of our doings in life:

The Sentence shall be justified by the consciousness all Persons shall have, that they themselves in what Bodies soever they appear, or what substances soever that consciousness adheres to, are the same, that committed those Actions, and deserve that Punishment for them.

 

Locke’s eagerness to allow that we can have the same person at the Day of the Judgment as one who lived in Biblical times, say, gives him good reason to dispense with any requirement that there be an uninterrupted stream of experiences uniting any two stages of the same person. [34] And as the sentence just quoted makes clear, one of the signal advantages of Locke’s account of personal identity is that it allows for the resurrection of the dead in a way that requires only minimal metaphysical commitments. As Locke points out to Stillingfleet, one goes beyond the scriptures in requiring that the same body be resur-

[32] Ibid., pp. 785-86.

[33] See Molyneux to Locke, 17 February 1694, #1712 in de Beer, Correspondence of Locke, vol. 5, p. 21; and Locke to Molyneux, 26 May 1694, #1744 in ibid., p. 58. For further discussion see P. Helm, "Did Locke Capitulate to Molyneux?" Journal of the History of Ideas 42 (1981): 669-71. Allison and Nicholas Jolley reply in "Locke’s Pyrrhic Victory," ibid., pp. 672-74; they concede Helm’s main point, but with reservations. These appear to be based on the assumption that Locke was trying to provide an empirically serviceable third-person criterion for assigning responsibility for actions. There is no support in the text for this assumption.

[34] Locke discusses these issues at much greater length in the third of his letters to Stillingfleet. He distinguishes the doctrine of the resurrection of the dead from that of the resurrection of the (same) body, finding scriptural basis only for the former. Locke’s view is that all that is needed for theological purposes is that one’s consciousness, which is what carries personal identity, become associated with some human body, perhaps a newly fashioned one, but in any case one no particle of which need ever have been part of the body the person had while alive. See Mr. Locke’s Reply to the Bishop of Worcester’s Answer to his Second Letter, pp. 162-210; Works, vol. 4, pp. 300-34. Boyle, by the way, discussed this issue in his Some Physico-Theological Considerations about the Possibility of the Resurrection (London, 1675), reprinted in Works of Boyle, vol. 4, pp. 191-202; Stewart, Selected Papers of Boyle, pp. 193-208.

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rected, or even the same immaterial substance; on Locke’s account we need make no such suppositions. [35]

It remains for me to indicate, if only briefly, how our account tends to undermine the currently most popular interpretation of Locke’s views on personal identity. [36] On this interpretation, the identity of a person is constituted by the causal continuity of a ‘core’ or causal basis (usually identified as a certain neural structure or organization) which underlies and explains the psychological continuities characteristic of persons. I see two main motivations for this interpretation: first, it enables us to bring Locke’s view into line with the intuitive judgments we allegedly make to the effect that the amnesiac is the same person with his past self, and second, a point Wiggins emphasizes, it fits the notion of a person into the framework of the most popular recent theories of natural kinds, those of Kripke and Putnam. For ‘person’ to be the general name for a natural kind, on this view, there must be a ‘real essence’ which underlies and explains the possession of the qualities contained in the 'nominal essence’ of a person. [37]

The first thing to be noted about the causal basis interpretation, as I shall call it, is that it has very little, if any, basis in the text of the Essay. The terminology of real and nominal essences, for example, does not figure at all in the chapter, nor is there any sort of speculation on Locke’s part as to the causal mechanisms, if any, underlying the continuity of consciousness, or of plant and animal life. Such passages as the one at II.27.27 where Locke says that we have no idea whether the thinking thing, or self, within us "could or could not perform its Operations of Thinking and Memory out of a Body organized as ours is," or the one at II.27.17 where he speculates about one’s consciousness becoming to be attached to one’s little finger, making the finger the whole person when it is cut off from the rest of the body, do not fit at all well with the causal basis interpretation.

Given what we’ve said so far, this is not surprising. The first alleged advantage for the view is not one that would appeal to Locke. As we have just seen, he clearly and consistently denies that unremembered experiences are part of a person’s history. More important, though, the view that there must be a real essence common to members of species and definitive of the identities of the individual members is in conflict with what we have seen to be Locke’s general views on the matter. There is no more reason to think that persons must have some set of salient structural features in common, or that one person must have some such structural features of his remain unchanged during his con-

 

[35] See e.g. Mr. Locke’s Reply to the Bishop of Worcester’s Answer to His Second Letter, p. 210; Works, vol. 4, p. 334.

[36] D. Wiggins, ibid., and J. L. Mackie, op. cit., pp. 199-203, offer their accounts as emendations or extensions of Locke’s own views. Viorica Farkas, in "Locke on Ideas, Substratum, and the Identity of Persons," unpublished Ph.D. dissertation, UCLA 1982, chap. IV, and M. Atherton, on "I.ocke’s Theory," pp. 287-89, ascribe this view to Locke himself.

[37] See Wiggins, Substance and Swneness, p. 188.

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tinuing life as a person, than there was to think that all plants or animals of a particular species must share an inner structural arrangement, or that it is such a structural arrangement which keeps an individual member of the species the same over time.

As in the case of plants, and animals, and men, in the case of persons it is the idea of the sort that determines the identity by determining the continuity that is required for continuing as the same thing. In the cases of plants, animals, and men, continuity of life permits of no interruption; in the case of persons, continuity of consciousness can and does obtain even when there are significant interruptions. Thus Locke’s last word in the Essay on this subject is:

For whatever be the composition whereof the complex Idea is made, whenever Existence makes it one particular thing under any denomination, the same Existence continued, preserves it the same individual under the same denomination. (11.27.29, last sentence)

The continuities ("the same existence continued") that make for the identity of the object are probably often based in a continuing internal structure the object has in common with other members of its kind. Whether they are or not, it is its continuing to satisfy our idea of the kind that suffices for the object’s continuing identity. As Locke had said in II.27.7, as is the idea, so is the identity.

I have argued that Locke’s theory of identity is a consistent and even subtle attempt to provide for the identities of natural objects, including plants, animals, and persons, within the framework of mechanism. It is a question, and a large one, how defensible Locke’s theory is; but that it is an important part of his brief for the Mechanical Philosophy is, I hope, beyond doubt.

 

Notes

I acknowledge with gratitude the helpful comments of Viorica Parkas and Janet Levm on earlier drafts of this paper. I am especially grateful to Edwin Curley for stylistic suggestions and for advice concerning the Scholastic background, and to Michael Ayers and Jonathan Bennett for their extensive and very valuable sets of written comments.

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