Donald L. M. Baxter

To the question whether Hume believed in mind-independent physical objects (or as he would put it, bodies), the answer is Yes and No. It is Yes when Hume writes “We may well ask, What causes induce us to believe in the existence of body? but ’tis in vain to ask, Whether there be body or not? That is a point, which we must take for granted in all our reasonings.” However the answer is No after inquiring into the causes of that belief, when he writes, “What then can we look for from this confusion of groundless and extraordinary opinions but error and falsehood? And how can we justify to ourselves any belief we repose in them?” My view is that Hume’s Yes and No answers can best be accounted for by seeing him as a Pyrrhonian skeptic in the tradition of Sextus Empiricus. This interpretation, while finding considerable truth in the various positions canvassed, is closest to those of Norton, Fogelin, and especially Popkin.

Hume’s empiricist reason for rejecting “school metaphysics” makes it natural to assume that Hume rejects all metaphysics. A.J. Ayer certainly reads Hume this way. The natural assumption is wrong, however. Hume only rejects the aprioricity of metaphysics, and not the science itself. I will argue that his empirical science of human nature supports three basic metaphysical principles. (1) The Contradiction Principle: The clearly conceivable implies no contradiction. (2) The Conceivability Principle: The clearly conceivable is possible. (3) The Conceptual Separability Principle: Things are different if and only if distinguishable, and distinguishable if and only if separable in conception. On these principles the rest of Hume’s metaphysics is based, including his atomistic ontology and his denial of necessary connection. And so, for Hume metaphysics is an empirical science.

Hume’s critique of traditional abstraction entails a result that undercuts his account of the idea of identity. To save his account of identity, Hume would have to accept abstraction as well. What links these two discussions is (1) Hume’s widely shared assumption that traditional abstraction is separating in the mind what are inseparable in reality, (2) his principle that what are different are mentally separable, and (3) his principle that we cannot conceive of the impossible. Given these, it will turn out that abstraction is mentally separating something from itself, which will entail that abstraction is conceiving of something as distinct from itself. But it is impossible for something to be distinct from itself, and so it is inconceivable. Therefore abstraction is impossible. Yet consider Hume’s account of the idea of identity. On that account, to conceive of an identity is to conceive of something as one single thing viewed one way and as two distinct things viewed another. How we can take these opposing views of the same thing is a problem that I’ve termed Hume’s Difficulty concerning Identity. It will turn out that we can take the opposing views only if we can conceive of the single thing viewed one way as somehow distinct from itself when viewed the other way. That is, we must be able to conceive of something as distinct from itself. However, if we cannot conceive of something as distinct from itself when abstracting, then we cannot do it when conceiving of an identity. So traditional abstraction and Hume’s account of the idea of identity stand or fall together.

Stefanie Rocknak has written an ambitious and challenging book1 in which she argues for a new interpretation of Hume's account of how we come to believe in external objects, and what it is we believe in. I am hampered by the fact that she and I seem to agree on so little. Thus, my criticisms run the danger of simply not seeing what she is up to.A preliminary terminological point: where Rocknak uses the word "object," I will often use the word "body," since I think Hume sometimes uses "object" in a more general sense that includes perceptions.If I understand correctly, Rocknak's Hume argues that we come to believe in bodies through a special kind of causal reasoning. We reason what must exist in order to cause...

There is more than one way to say that composition is identity. Yi has distinguished the Weak Composition thesis from the Strong Composition thesis and attributed the former to David Lewis while noting that Lewis associates something like the latter with me. Weak Composition is the thesis that the relation between the parts collectively and their whole is closely analogous to identity. Strong Composition is the thesis that the relation between the parts collectively and their whole is identity. Yi is right that Strong Composition does not fully reflect my view. We must recognize further what, borrowing Lewis's characterization, could be called the "stronger, and stranger" Composition thesis, or what I'll call the Stronger Composition thesis for short. On Strong Composition, it is only collectively that the parts are identical with the whole. On Stronger Composition, they are individually identical with it as well. I will explain and motivate this thesis.

Is a social complex identical to many united people or is it a group entity in addition to the people? For specificity, I will assume that a social complex is a plural subject in Margaret Gilbert’s sense. By appeal to my theory of Aspects, according to which there can be qualitative difference without numerical difference, I give an answer that is a middle way between metaphysical individualism and metaphysical holism. This answer will enable answers to two additional metaphysical questions: (i) how can two social complexes have all the same members and (ii) how can there be a social complex of social complexes?

Confucius gave counsel that is notoriously hard to follow: "What you do not wish for yourself, do not impose on others" (Huang 1997: 15.24). People tend to be concerned with themselves and to be indifferent to most others. We are distinct from others so our self-concern does not include them, or so it seems. Were we to realize this distinctness is merely apparent--that our true self includes others--Confucius's counsel would be easier to follow. Concern for our true self would extend concern beyond the narrow selves we appear to be. The neo-Confucians held just such a view. They espoused an identity with the universe and everything in it, arguing that this identity explains a natural concern for everyone and everything, not just for our narrow selves. However, many things in the universe differ from each other, that is, some have qualities others lack. If they are all one and the same thing then that one thing differs from itself. I will suggest that the objection can be answered with some metaphysical innovation. I will address the objection by sketching a theory--call it the theory of aspects--that explains how numerically identical things can differ qualitatively.

ABSTRACT An apparent objection against my theory of instantiation as partial identity is that identity is necessary, yet instantiation is often contingent. To rebut the objection, I show how it can make sense that identity is contingent. I begin by showing how it can make sense that identity is temporary. I rely heavily on Andre Gallois’s formal theory of occasional identity, but argue that there is a gap in his explanation of how his formalisms make sense that needs to be filled by appeal to my theory of Aspects.

The ancient theory of substance and accident is supposed to make sense of complex unities in a way that respects both their unity and their complexity. On Hume’s view such complex unities are only fictitiously unities. This result follows from his thoroughgoing critique of the theory of substance. I will characterize the theory Hume is critiquing as it is presented in Locke, presupposing what Bennett calls the “Leibnizian interpretation.” Locke uses the word ‘substance’ in two senses. Call substance in the first sense “individual substance” and in the second sense “pure substance.” I will discuss the seven main parts of Hume’s view: (I) that we have no idea of pure substance, (II) that there is no complex individual substance, except in a loose sense, (III) that the fiction of complex individual substance arises in a way parallel to that of the fiction of identity through time, and (IV) results in the fiction of pure substance, (V) that simple qualities and perceptions satisfy the definition of individual substance, (VI) that there is no such thing as inherence, and (VII) that there is no such thing as pure substance. Hume’s views on substance are often mentioned without being discussed in detail. Kemp Smith, Stroud, and Garrett, for example, mostly summarize various claims of Hume in the course of expounding on his theory of the idea of personal identity. In contrast, I will attempt to present a systematic treatment of Hume on substance as a refutation of Locke.

Oliver's and Rodriguez-Pereyra's important interpretation of the problem of universals as one concerning truthmakers neglects something crucial: that there is a numerical identity between numerically distinct particulars. The problem of universals is rather how to resolve the apparent contradiction that the same things are both numerically distinct and numerically identical. Baxter's account of instantiation as partial identity resolves the apparent contradiction. A seeming objection to this account is that it appears to make instantiation symmetric, since partial identity is symmetric. Armstrong's standard reply is that the difference between a particular and a universal is what makes instantiation asymmetric. Brown suggests, though, that the instantiation of a universal by a universal is sometimes symmetric. However, the examples on which he relies are not universals.

ABSTRACT According to David Lewis, alteration is "qualitative difference between temporal parts of something." It follows that moments, since they are simple and lack temporal parts, cannot alter from future to present to past. Here then is another way to put McTaggart's paradox about change in tense. I will appeal to my theory of Aspects to rebut the thought behind this rendition of McTaggart. On my theory, it is possible that qualitatively differing things be numerically identical. I call these differing, numerically identical things "aspects." I will argue that alteration can be a qualitative difference between temporal aspects of something that lacks temporal parts. So a moment can alter in tense. By rejecting Lewis's assumption my theory can solve this version of McTaggart's paradox.

In this volume--the first, focused study of Hume on time and identity--Baxter focuses on Hume’s treatment of the concept of numerical identity, which is central to Hume's famous discussions of the external world and personal identity. Hume raises a long unappreciated, and still unresolved, difficulty with the concept of identity: how to represent something as "a medium betwixt unity and number." Superficial resemblance to Frege’s famous puzzle has kept the difficulty in the shadows. Hume’s way of addressing it makes sense only in the context of his unorthodox theory of time. Baxter shows the defensibility of that theory against past dismissive interpretations, especially of Hume’s stance on infinite divisibility. Later the author shows how the difficulty underlies Hume’s later worries about his theory of personal identity, in a new reading motivated by Hume’s important appeals to consciousness. Baxter casts Hume throughout as an acute metaphysician, and reconciles this side of Hume with his overarching Pyrrhonian skepticism.

We ordinarily make statements of the form "They are the same thing," if there has been reason to distinguish what we now judge identical. But such statements seem not to make sense. "They" indicates that there are more than one thing, whereas "same" indicates that there is only one thing. How can many be one? Hume's obscure Principle of Identity passage in the Treatise addresses this problem . Call it the Number Problem for Identity. Clarifying Hume's account reveals that, despite its richness and suggestiveness, it is ultimately unsatisfactory. In discussing identity, he tries to solve an apparent number problem at the level of objects of ideas, only to leave himself with a real one at the level of ideas. He tries to solve the number problem for identity by appeal to one continuous whole and its many continuous parts, only to leave himself with a different number problem for parts/whole. He tries to make discontinuity necessary for numerical difference, but neither are. ;I develop his account into a satisfactory one, influenced by British Idealist discussions of Identity in Difference and by Hume's discussion of Distinctions of Reason. In response to I propose the concept of "Difference in Respect" based on the dictum that it is possible for an object in different respects to have and lack a property. In the problematic identity attribution I began with, "they" refers to the object in certain various respects, while "same" indicates that it is one object. This is a solution to the number problem for identity. In response to I solve the number problem for parts/whole by suggesting that parts and whole exist and count in different contexts. Which context is the better one to count in varies with purpose and interest. In response to I suggest that Hume's supposedly necessary conditions for numerical distinctness become criteria for judging between contexts, e.g. for many purposes it is better to count a single continuous whole rather than its many continuous parts. I end by applying my newly developed theory to other problems. I show how the same thing can have or lack a property depending on contexts determined by interest or purpose

Berkeley says both that one sometimes immediately perceives the same thing by sight and touch, and that one never does. To solve the contradiction I recommend and explain a distinction Berkeley himself makes—between two uses of ‘same’. This solution unifies two seemingly inconsistent parts of Berkeley’s whole project: He argues both that what we see are bits of light and color organized into a language by which God speaks to us about tactile sensations, and yet that we directly see ordinary objects. My solution explains how these can come to the same thing.

Despite its central role in his important theories of self and external world, Hume’s account of numerical identity has been neglected or misunderstood. The account is designed as a response to a difficulty concerning identity apparently original with Hume. I argue that the problem is real, crucial, and remains unresolved today. Hume’s response to the difficulty enlists his idiosyncratic, empiricist views on time: time consists of discrete, partless moments, some of which coexist with successions of others. Time is more like a wall of variously sized bricks than like a continuous line. Hume’s arguments that time (and space) are not infinitely divisible have met with literal contempt. I show that his unusual views are motivated and consistent. The topic of identity leads naturally to Hume’s account of personal identity and his later retraction--one of the most widely discussed topics in Hume scholarship. I give a new, straightforward explanation of the retraction, by arguing that Hume’s views on consciousness preclude his prior account of the self as a fiction. I then suggest that Hume’s fundamental problem for personal identity is his general difficulty concerning identity. Discussing Hume’s metaphysics raises perhaps the most central and difficult topic in Hume scholarship--how to reconcile the constructive, theoretical Hume with the skeptical Hume. The prevailing view for the last century has been that Hume’s skepticism is limited, leaving room for his theorizing. I argue, rather, that Hume is an unlimited Pyrrhonian skeptic in relevant respects, and that this interpretation of him best reconciles his two sides.

Hume's Treatise arguments concerning space, time, and geometry, especially ones involving his denial of infinite divisibility; have suffered harsh criticism. I show that in the section "Of the ideas of space and time," Hume gives important characterizations of his skeptical approach, in some respects Pyrrhonian, that will be developed in the rest of the Treatise. When that approach is better understood, the force of Hume's arguments can be appreciated, and the influential criticisms of them can be seen to miss the mark.

There are two inspirations for the theory presented. One is the Kantian idea that a free choice affects a deterministic sequence of events globally rather than just locally. The second is the Leibnizian idea that God chooses for actuality the possible world he deems best. But instead of God choosing, suppose free agents collectively do. Let actuality be an office which deterministic possible worlds are voted in and not of. In this way free choice can change things even if every event is fully governed by deterministic laws: free choice substitutes one deterministic world for another. One way to look at the actual world on this theory is as a patchwork of segments of possible worlds. This gives the theory two advantages over familiar compatibilisms: it explains how the future is unsettled until chosen, and it allows that free choices are spontaneous.

Two things become one thing, something having parts, and something becoming something else, are cases of many things being identical with one thing. This apparent contradiction introduces others concerning transitivity of identity, discernibility of identicals, existence, and vague existence. I resolve the contradictions with a theory that identity, number, and existence are relative to standards for counting. What are many on some standard are one and the same on another. The theory gives an account of the discernibility of identicals using phrases like “insofar as”. And it holds that standards for counting remain or shift depending on our purposes.

Ordinary usage gives a way to think of identity through time: the Pittsburgh of 1946 was the same city as the Pittsburgh of today is--namely Pittsburgh. Problem: The Pittsburgh of 1946 does not exist; Pittsburgh still does. How can they have been identical? I reject the temporal parts view on which they were not but we may speak as though they were. Rather I argue that claiming their identity is not contradictory. I interpret ‘the Pittsburgh of 1946’ as ‘Pittsburgh as it was in 1946’ and suggest that the apparent contradiction results from an ambiguity in the scope of ‘as’.

Hume argues that there are steadfast objects - objects not themselves successions at all, yet which co-exist with successions. Given Hume's account of moments as abstractions from temporal simples, there being steadfast objects entails there being single moments that co-exist with successions of moments. Thus time is more like a wall of variously sized bricks than like a line. I formalize the assumptions behind this surprising view, in order to make sense of it and in order to show that it is consistent. I note also that this view justifies the common-sense assumptions that time flows and is unlike space.

How is it possible for David Hume to be both withering skeptic and constructive theorist? I recommend an answer like the Pyrrhonian answer to the question how it is possible to suspend all judgment yet engage in active daily life. Sextus Empiricus distinguishes two kinds of assent: one suspended across the board and one involved with daily living. The first is an act of will based on appreciation of reasons; the second is a causal effect of appearances. Hume makes the same distinction, only he extends the sort of assent involved in daily life to theoretical matters as well. He is a skeptic both in finding no reason to grant the first sort of assent and in being subject to the second.

Pace Perry, wondering whether perceived things are identical is thinking about them, for Hume, with no thought of perceptions of them. Hume is not a proto-Fregean; Hume's Difficulty is not a version of Frege's Puzzle. Pace Falkenstein, wondering about an identity is not wondering whether clearly distinct things--stages, surfaces, names--are connected in some way. Pace Garrett, wondering about the identity of an observed object is wondering whether it is really one or two things, not whether there is one F or two Fs. Second, Humean consciousness is apperception, not immediate awareness. Third, Hume finds nothing with epistemic merit.

Construing the instantiation of a universal by a particular in terms of my theory of aspects resolves the basic mystery of this "non-relational tie", and gives theoretical unity to the four characteristics of instantiation discerned by Armstrong. Taking aspects as distinct in a way akin to Scotus's formal distinction, I suggest that instantiation is the sharing of an aspect by a universal and a particular--a kind of partial identity. This approach allows me to address Plato's multiple location and One over Many problems, Bradley's problem concerning the instantiation of relations, and the problem of change.