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DON GARRETT

HUME’S NATURALISTIC THEORY OF REPRESENTATION

ABSTRACT: Hume is a naturalist in many different respects and about many different topics; this paper

argues that he is also a naturalist about intentionality and representation. It does so in the course of answering

four questions about his theory of mental representation: (1) Which perceptions represent? (2) What can

perceptions represent? (3) Why do perceptions represent at all? (4) How do perceptions represent what they

do? It appears that, for Hume, all perceptions except passions can represent; and they can represent bodies,

minds, and persons, with their various qualities. In addition, ideas can represent impressions and other ideas.

However, he explicitly rejects the view that ideas are inherently representational, and he implicitly adopts a

view according to which things (whether mental or non-mental) represent in virtue of playing, through the

production of mental effects and dispositions, the functional role of what they represent. It is in virtue of their

particular causal roles that qualitatively identical ideas are capable of representing particulars or general

kinds; substances or modes; relations; past, present, or future; and individuals or compounds.

There are many species of naturalism. Doxastic naturalism, we may say, is the doctrine

that belief formation is an operation of nature. Epistemic naturalism is the doctrine that

beliefs can have epistemic authority and be rightful objects of assent in virtue of the ways

in which they result from operations of nature. Explanatory naturalism is the program of

trying to explain phenomena without appeal to anything outside of nature. Metaphysical

naturalism is the doctrine that nothing exists outside of nature. No doubt there are other

species of naturalism as well.

Different versions of each of these species of naturalism result from different

conceptions of what is, and what would not be, within the scope of ‘nature’—a term of

which Hume remarks that “there is none more ambiguous and equivocal” (T 3.1.2.7)1. He

notes, in connection with this remark, that the “natural” may be contrasted with the

miraculous, the unusual, the artificial, the civil, and the moral; but for contemporary

1 References to “T” are to Hume (2000), with book, part, section, and paragraph numbers.

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naturalists, “nature” is most often understood to exclude at least some of the following:

divine, immaterial, abstract, and universal entities; non-law-governed events or influences

such as miraculous interventions, libertarian “agent” causation, and special intellectual

insight; and inexplicable or irreducible normative and intentional qualities.

Hume is skeptical about a personal God, rejects the question of whether there are

immaterial substances, and includes no abstract or universal entities in his ontology. He

recognizes no miracles, “agent causation,” or instances of special intellectual insight

ungoverned by ordinary causal laws. And while he recognizes normative epistemic, moral,

and aesthetic qualities, he does not regard them as inexplicable or irreducible; instead, he

aims to account for them in terms of the features of cognitions, agents, and objects

(respectively) that produce certain feelings (assent, moral sentiments, aesthetic sentiments)

in human beings, together with the role that those feelings play in human lives. Given these

features of his philosophy, Hume can—and does—adopt quite wide-ranging versions of

doxastic, epistemic, explanatory, and metaphysical naturalism.

It may not be as clear, however, whether Hume allows inexplicable and irreducible

intentional properties. Naturalism about the human mind is a primary focus of

contemporary naturalism, and the attempt to account for the intentionality of mental

states—that is, their ability to represent, or to be of, other things—is a crucial element in

contemporary naturalism about the human mind. Naturalism about the human mind is also

a primary focus of Hume’s naturalism. Before we can fully understand or assess the

relation between Hume’s naturalism and contemporary philosophical naturalism, therefore,

we must understand his view of mental representation.

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In what follows, I will try to answer four main questions about Hume’s theory of

mental representation. Since he uses the term ‘perception’ as the most general term for the

mental constituents of the mind, we may frame each question as one about perceptions.

First, which perceptions represent? Second, what can perceptions represent? Third, why do

perceptions represent—that is, what makes them representational at all? Fourth, how do

perceptions represent what they do—that is, what determines their specific representational

content? The answers to these questions will shed light on Hume’s view of representation

generally and of mental representation in particular.

1. WHICH PERCEPTIONS REPRESENT?

Hume distinguishes perceptions into impressions and ideas. The difference between

impressions and ideas is, for Hume, what we may call a phenomenal difference—that is,

one that constitutes a difference in how it feels to have the perception. It is not, however, a

difference in what we may call their qualitative character—that is, it is not a difference in

the intrinsic, phenomenal, character-determining qualities of perceptions, such as

sweetness, redness, squareness, angriness, or approbation. For it is one of Hume’s central

theses that such qualitative characters may always be shared equally by an impression and

an idea. Rather, the defining difference between impressions and ideas lies in a

phenomenal difference of a fundamentally different sort, which he calls a difference in the

degree of “force and liveliness [or vivacity], with which they strike upon the mind” (T

1.1.1.1; see also EHU 2.32); impressions are distinguished from ideas by their greater force

and liveliness. Hume distinguishes impressions, in turn, into those of sensation and those

of reflection. Impressions of reflection include all of the various passions (such as love, 2 References to “EHU” are to Hume (2001), with section and paragraph numbers.

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hatred, pride, humility, hope, fear, joy, sorrow, benevolence, anger, desire, and aversion),

plus volitions, moral and aesthetics sentiments, and feelings of the mind’s operations (such

as those of determination or “necessity” and facility or “ease”); they differ from

impressions of sensation in being caused, in large measure, by other perceptions (T 1.1.2).

Finally, he distinguishes ideas into those of memory and those of the imagination—the

former retain the order and a particularly great share of the force and liveliness of the

impressions from which they are derived, while the latter do not (T.1.1.3).

Hume seems clearly committed to the view that all ideas, whether of memory or

imagination, represent; for he remarks that “ideas always represent their objects or

impressions” (T 1.3.14.6; see also T 1.2.3.11). Among impressions, on the other hand,

passions, at least, do not represent, for he writes:

A passion is an original existence, or, if you will, modification of existence, and

contains not any representative quality, which renders it a copy of any other

existence or modification. When I am angry, I am actually possest with the

passion, and in that emotion have no more a reference to any other object, than

when I am thirsty, or sick, or more than five foot high. (T 2.3.3.5)

This claim may seem paradoxical, for Humean passions are typically, if not universally, of

at, or for someone or something.3 However, Hume does not deny that representation is

involved in having passions; he claims only that the passion itself is a non-representational

impression of reflection, while the representational content involved in the passion’s being

of, at, or for someone or something is provided by one or more associated ideas. Moral and

aesthetic sentiments (which are like passions in being impressions of reflection) are also

typically associated with ideas having representational content; but these sentiments may,

3 For this reason, Baier (1991, 160-164) characterizes the quoted passage as “unfortunate” and a “very silly paragraph.”

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in addition, be regarded as themselves representing, in at least some way, the particular

qualities—such as virtue and vice, beauty and deformity—that, on his account, their

occurrence allows us to “sense” (see T 3.1.2, “Moral distinctions derived from a moral

sense”). Indeed, moral and aesthetic sentiments may represent moral and aesthetic qualities

in much the same way that impressions of color or other secondary qualities (to which he

regularly compares them) represent whatever qualities in bodies produce the relevant

sensory impressions—or as impressions of hunger represent emptiness in the stomach. In

any case, Hume also recognizes as impressions of reflection such feelings of features of the

mind’s own operations as the feelings of determination or “necessity” (that is, lack of

voluntary control) and facility or “ease” (in making a mental transition); and these feelings

seem clearly to represent, in his view, those features of the mind’s operations whose

presence they reliably indicate. Of course, these operations themselves typically involve

ideas that represent other things, so that an impression may represent the mind’s

determination or facility in the transition between one particular representational idea and

another.

Hume thus holds that some impressions of reflection represent, while others do not; but

does he hold that impressions of sensation represent? He allows that at least some of them

do, for he remarks that they sometimes “represent as minute and uncompounded what is

really great and compos’d of a vast number of parts (Treatise 1.2.1.5)4 and that “that

compound impression, which represents extension, consists of several lesser impressions,

that are indivisible to the eye or feeling” (Treatise 1.2.3.15). In An Enquiry concerning

Human Understanding, moreover, he goes so far as to assert: 4 The complete sentence reads: “The only defect of our senses is, that they give us disproportion’d images, and represent as minute and uncompounded what is really great and compos’d of a vast number of parts.” It is clear from the context that these “images” provided by the senses are impressions of sensation.

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[N]o man, who reflects, ever doubted, that the existences, which we consider,

when we say, this house and that tree, are nothing but perceptions in the mind,

and fleeting copies or representations of other existences, which remain uniform

and independent. (EHU 12.9; emphasis added)

Furthermore, he never claims—in pointed contrast with his remarks about the passions—

that impressions of sensation fail to represent, even when appeal to such a general principle

would, if he held it, be very much to the point to support a more specific conclusion.

When, for example, he argues that impressions of touch are not suited to represent solidity,

he gives a highly complex argument that is specific to the case, without any suggestion that

sensations considered more generally are incapable of representing anything (T 1.4.4.14).

Nonetheless, some commentators have denied that Hume regards impressions of

sensation as capable of representing anything. In a passage sometimes cited in support of

this interpretation, he writes:

[S]ince nothing is ever present to the mind but perceptions, and since all ideas are

deriv’d from something antecedently present to the mind; it follows, that ’tis

impossible for us so much as to conceive or form an idea of any thing specifically

different from ideas and impressions. (T 1.2.6.8)

David Owen and Rachel Cohon (1997) explain Hume’s meaning in this passage as

follows:

We think we can conceive of external objects different from but resembling the

impressions of sensation they cause, but this is a mistake. The content of all our

ideas comes from impressions. We cannot even conceive what it would be like for

a perception of the mind to resemble something that is not a perception of the

mind. To paraphrase Berkeley, nothing can be like a perception of the mind but

another perception of the mind. Impressions and ideas resemble each other. But

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ideas are derived from impressions, not the other way around. So ideas can

represent, but impressions cannot.

It remains true of course that we (or at least philosophers) believe that

impressions of sensation are caused by and resemble, and hence represent,

external objects. And Hume himself sometimes speaks that way …. (Owen and

Cohon 1997, 54-55)

In fact, however, Hume’s remark does not at all entail that bodies distinct from

perceptions of the mind are inconceivable; it entails only that we cannot conceive of them

as being specifically different from ideas and impressions. He recognizes two aspects to

this limitation on our conception. First, we cannot conceive of bodies as having an

irreducibly different kind of existence from that of perceptions—such as, for example, that

which Locke regularly calls “real existence” or “external existence,” as opposed to “ideal

existence.”5 It was in part to make the point that we have only one conception of existence

itself that he wrote the section of the Treatise—entitled “Of the idea of existence, and of

external existence”—that contains the quoted passage. Second, we also cannot conceive of

bodies as having any specific intrinsic qualities that are different from those that qualify

impressions of sensation. For on Hume’s view, unlike the views of most of his

predecessors, the familiar sensible qualities such as size, shape, color, taste, smell, and heat

are all literally qualities of impressions themselves. The most we can do, therefore, by way

of conceiving a body as differing from impressions in intrinsic qualities is, he claims, to

employ a relative idea—that is, an idea of a thing conceived not as it is specifically, but

rather as that which stands in a certain specified relation to known objects. Just as one can

use a relative idea to conceive an otherwise entirely unknown individual as a brother of

5 See, for example, Locke (1979) 4.1, 4.4.6, and 2.17.16.

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Sally who is not Sam, for example, so one might use a relative idea to conceive of a quality

of a body as a space-filling quality that is not a color. Thus he goes on almost immediately

to write in concluding the section:

The furthest we can go towards a conception of external objects, when supposed

specifically different from our perceptions, is to form a relative idea of them,

without pretending to comprehend the related objects. Generally speaking, we do

not suppose them specifically different; but only attribute to them different

relations, connexions, and durations. But of this more fully hereafter. (T 1.2.6.8;

emphasis added)

As the penultimate sentence of this passage indicate, Hume thinks that we typically

conceive of bodies not by using relative ideas but rather by attributing to them the very

same intrinsic qualities that are possessed by impressions of sensation while attributing to

them different (though readily-conceived) “relations, connexions, and durations”—that is,

as he goes on to explain in detail in Treatise 1.4.2 (the referent of ‘more fully hereafter’),

by conceiving them as continuing to exist when not perceived, as being situated external to

the mind, and as causally independent of the mind in existence and operation.

In order to stress the point that such “continu’d and distinct” objects differ from the

perceptions of the mind neither in kind of existence nor in intrinsic qualities, Hume at one

point (T 1.4.2.56) calls them, with conscious irony, “a new set of perceptions.” Yet we can,

he explicitly argues, easily and properly conceive such continued and distinct objects to

lack the pattern of relations of causal interaction with other perceptions that would, on his

theory, constitute their membership in a mind (T 1.4.2.39-40);6 and in doing so, we thereby

6 In giving this argument, Hume specifically refers forward to his account of the mind as a bundle of perceptions, presented in full in Treatise 1.4.6 (“Of personal identity”). Later, when arguing in the Appendix to the Treatise that there is no perception of an enduring substantial self, Hume does ask us to “suppose the mind to be reduced even below the life of an oyster. Suppose it to have only one perception, as of thirst or

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conceive of these objects as things that are not parts of, or perceptions in, any mind. Thus,

contrary to the suggestion of Owen and Cohon in the passage quoted previously, Hume

would reject Berkeley’s dictum that “nothing can be like a perception of the mind but

another perception of the mind,” for he argues explicitly that things having the same

intrinsic qualities as perceptions of the mind can exist without being perceived by any

mind.

To be sure, Hume argues that what he calls the “philosophical” belief in bodies, as

continuing objects distinct from and represented by the more transitory perceptions of the

mind, involves several egregious confusions in its etiology and cannot be established by

reasoning (T 1.4.2); he also emphasizes that the most specific and readily conceived

version of that belief (i.e., the one eschewing any use of “relative ideas”) is incompatible

with modern philosophers’ persuasive argument that bodies lack any qualities resembling

our impressions of color, sound, taste, smell, heat, and cold (T 1.4.4, “Of the modern

philosophy”). However, he never says that the philosophical belief that there are bodies

distinct from the perceptions of the mind is false. On the contrary, he claims that one of

this belief’s two competitors (the “vulgar” view that the very things we immediately

perceive are themselves continued and distinct existences) can be shown to be false by a

few simple experiments and that its other competitor (the denial of all continued and

distinct existences) is literally incredible.7 These claims strongly suggest that he accepts

the philosophical view—albeit with the degree of caution and non-dogmatism suitable to

hunger” (T Appendix 16). However, the proposed supposition is only that the mind has a single perception at a particular time (“consider it in this situation”), not that such a momentary perception would by itself constitute a mind. 7 Hume does remark that the “philosophical” view of bodies is “liable to the same difficulties” as the vulgar view (T 1.4.2.56); but these difficulties cannot include being shown to be false by a few simple experiments, for the experiments in question (such as pressing one’s eyeball) have no tendency to rebut the philosophical view and, indeed, serve as the primary motivation to adopt it.

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his self-proclaimed status as a “mitigated” skeptic (EHU 12.24-25; see also T 1.4.7.14-

15)—as true. Moreover, such acceptance is implied in dozens if not hundreds of remarks

throughout his philosophical writings8—including, to take just one example from a passage

already quoted, his claim to be (i.e., to have a continuously existing body) “more than five

foot high.”

2. WHAT CAN PERCEPTIONS REPRESENT?

We have seen that some impressions of reflection can evidently represent aesthetic or

moral qualities, on Hume’s view, while others can represent features of the mind’s

operations; and impressions of sensation, he allows, can represent bodies and their

qualities. He also holds that impressions, whether of reflection or sensation, can at least

sometimes be of, and so represent, “ourselves.”9 Ideas, however, can represent an even

wider range of things than can impressions. Like impressions, ideas can represent minds or

bodies—“streets and houses” (T 1.1.1.4), for example, and grains of sand that have far

more parts than do the ideas with which we represent them (T 1.2.1.3)—plus their

qualities; but they can also represent impressions, for, as we have seen, he holds that “ideas

always represent their objects or impressions.” In addition, he asserts, some ideas represent

other ideas (T 1.3.8.16). Indeed, on the Humean assumption that thinking about something

requires having an idea of it, the very thoughts about ideas that much of the Treatise is

devoted to expressing would be impossible without the use of ideas of ideas. For the same

8 Grene (1994) discusses a number of these passages. 9 Hume denies, of course, that there can be any impression of a substantial self, and also that there is any impression that persists uniformly throughout one’s entire life (T 1.4.6.1-4 and Appendix 11). But he does not deny that there are impressions of oneself, and he appeals to them explicitly in his account of sympathy (T 2.1.11.4). Presumably any impression, whether of sensation or reflection, can also be an impression of oneself, for it can be an impression from which an (abstract) idea of oneself (as a bundle of perceptions) can be derived. For more discussion of this topic, see Garrett (1979, 167-69).

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reason, his explicit reference in the Treatise to ideas of ideas implies that there must also

be (third-order) ideas of ideas of ideas.

Nor is this all. The various sections of Part 1 of Book 1 of the Treatise display the

remarkable range of ways in which ideas can represent. For example, while some ideas

represent things simply as individual, others represent things as parts of a compound (T

1.1.2 and 1.2.4). Indeed, it later appears that ideas can even represent things as compounds

whose various parts include bodies, impressions, and ideas—as when one has an idea of

the “self” taken in the broader Humean sense that includes one’s own body (THN 2.1.8.1

and THN 2.1.9.1). Ideas can also represent things as existing in the present, in the past (T

1.1.3), or—as Hume’s references to expectation and “the concern we take in ourselves” (T

1.4.6.5) indicate—in the future. Ideas can represent relations (T 1.1.5), and they can also

represent substances or modes (T 1.1.6). Some ideas represent things as particulars, while

others represent all things of a kind—not just a particular man, for example, but all men (T

1.1.7.2).10

3. WHY DO PERCEPTIONS REPRESENT?

But why are perceptions able to represent anything at all? Hume characterizes the

difference between having impressions and having ideas as a difference between thinking

and feeling (T 1.1.1.1; EHU 2.3); given this and the implicit contrast suggested by his

previously quoted remark that a “passion …contains not any representative quality,” it

might be natural to suppose that he regards ideas, at least, as having an irreducible quality

that renders them inherently representational entities. Such a view (which is of course

10 Hume notes that ideas can also “be of”—although he does not say “represent”—things that have never existed, such as the New Jerusalem or the Roman gods Mars, Venus, and Jupiter (T 1.3.10.6).

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compatible with the obvious fact that representation also gives rise to a relation between

what represents and what is represented) would be entirely within the philosophical

mainstream of the early modern period. In supposing that ideas contain, by nature,

“objective reality” as well as formal reality, for example, Descartes seems to be attributing

just such an intrinsic representational quality to ideas11; and Leibniz and Locke, to mention

just two others, seem to treat the representational capacity of ideas as a basic fact about

their natures, not in need of further explanation.

Hume, however, rejects the view that ideas are intrinsically representational; instead,

he asserts explicitly that “the reference of the idea to an object [is] an extraneous

denomination, of which in itself it bears no mark or character” (T 1.1.7.6). This is as it

should be, for it would be difficult for him to reconcile a claim that ideas are intrinsically

representational with his admission that passions are not representational, given his central

doctrine that impressions and ideas “differ from each other only in their different degrees

of force and vivacity” (T 1.3.7.5).12 Furthermore, such a claim would be incompatible with

his doctrine that there are only the seven philosophical relations (viz., resemblance,

identity, relations of time and place, proportion in quantity or number, degrees in any

quality, contrariety, and causation) that he lists in Treatise 1.1.5 (see also T 1.3.1.1 and T

3.1.1.18-21); for an inherent and otherwise inexplicable representational quality would

give rise to relations of representation that could not be understood in terms of any of those

11 Note that this distinction involves a theory of two kinds of reality or existence of just the kind that Hume denies in Treatise 1.2.6, “Of the idea of existence, and of external existence.” The distinction is most prominent, of course, in Descartes’s Third Meditation (Meditations on First Philosophy, Descartes 1984-1991). See, however, Simmons 1999 for discussion of the representational character of sensations in Descartes. 12 Hume uses this doctrine to argue that impressions and ideas cannot differ in other aspects of their intrinsic natures, such as determinacy (T 1.1.7.5), and to explain why impressions and beliefs have similar effects on thought and action. In the Appendix to the Treatise (T Appendix 22), he allows that two ideas of the same object may differ in feeling in respects other than force and vivacity; but he does not give any examples.

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seven. The acceptance of a brute representational capacity for ideas would constitute a

disappointing explanatory failure for his science of man—and one that would leave the

differences in representational capacity among impressions still to be accounted for.

If the representational capacity of ideas and other perceptions that represent is not

intrinsic, then upon what “extraneous denominations” does it depend? Clearly one relation

of great significance for Hume is resemblance. Thus he writes of

the great resemblance betwixt our impressions and ideas in every other particular,

except their degree of force and vivacity…. When I shut my eyes, and think of my

chamber, the ideas I form are exact representations of the impressions I felt; nor

is there any circumstance of the one, which is not to be found in the other. In

running over my other perceptions, I find still the same resemblance and

representation. (T 1.1.1.3)

Moreover, when arguing against those he calls “curious reasoners concerning the material

or immaterial substances,” he suggests that it would be at the very least difficult for an

impression to represent a substance without resembling it:

As every idea is deriv’d from a precedent impression, had we any idea of the

substance of our minds, we must also have an impression of it; which is very

difficult, if not impossible, to be conceiv’d. For how can an impression represent

a substance, otherwise than by resembling it? And how can an impression

resemble a substance, since, according to this philosophy, it is not a substance,

and has none of the peculiar qualities or characteristics of a substance? (T 1.4.5.3)

On the other hand, representation cannot require exact resemblance for Hume. As we

have already observed, he allows that a perception having a smaller number of parts can

represent an object having a greater number of parts; and he allows that an idea can

represent Paris without capturing precisely all of its streets and their proportions to one

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another (T 1.1.1.4). Indeed, since falsehood consists, on his account, in a failure of ideas to

“conform” to or “agree” with what they represent (T 3.1.1.9), there could hardly be false

beliefs about existing things unless it were possible to represent those things by means of

ideas that did not entirely resemble them. Furthermore, while resemblance may be

important to representation, it is not in general sufficient for it. As Hume must surely

recognize, things can resemble other things without representing them: for example,

identical twins can resemble one another without either of them representing the other, and

(to take an instance from his own theory of mind) impressions can resemble ideas without

representing them.

Resemblance is not, however, the only relation that Hume mentions in connection with

the representational capacity of ideas; he also emphasizes the significance of causal

derivation:

Ideas always represent the objects or impressions from which they are derived,

and can never, without a fiction, represent or be applied to any other. (T 1.2.3.11)

Yet even resemblance and causal derivation combined—together amounting to copying—

do not appear to be sufficient, in general, for representation: for example, a decorative

motif appearing on one building need not represent the same motif on the building from

which it was copied. Furthermore, these conditions do not, in general, appear to be

necessary either: a pebble can represent a bridge in an impromptu military diagram without

resembling it or being causally derived from it. It would be disappointing if Hume failed to

appreciate such elementary facts.

In pursuing the question of whether Hume did fail to appreciate such facts, it is

instructive to examine some of his references to those representations that are not

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perceptions. Among the most obvious such representations are words, which, he remarks,

may represent objects and facts (T 1.3.9.12), impressions and sentiments (T 2.1.2.1), and

may “stand for” ideas (EPM 3.4213). But he recognizes many other examples of non-

mental representations as well. He notes, for example, that a theater can “represent” the

“determinate portion of space” (say, a castle in Scotland) where the action of a play is

supposed actually to occur (EHU 3, editions E-N only). In exploring the psychology of

pride and humility, he remarks that children can “represent” their parents’ families—most

often the family of the father, but sometimes (due to a “superiority” of one kind or another)

that of the mother (T 2.1.9.13). In explaining the causes of love and hatred, he asserts that

money “implies a kind of representation of [beautiful or agreeable] objects by the power it

affords of obtaining them” (T 2.2.5.6). One action, he observes, can represent another, as

“the giving of stone and earth” can represent the delivery of a manor in property law, or the

conveying of the key to a granary can represent the delivery of the corn contained in it; and

“tapers, habits, or grimaces” can represent religious mysteries (T 3.2.4.2).14 The lower

house of Parliament, he claims, “represents the entire commons” (“Of the First Principles

of Government,” Hume 1987, 35).

In some of these cases—the lower house of Parliament representing the entire

commons, for example, or children representing their parents’ families—there may, at least

typically, be both some resemblance and some causal derivation. In other cases,

13 References to “EPM” are to Hume (1999), followed by section and paragraph numbers. 14 The passage reads in full:

Thus the giving the keys of a granary is understood to be the delivery of the corn contained in it; the giving of stone and earth represents the delivery of a manor. This is a kind of superstitious practice in civil laws, and in the laws of nature, resembling the Roman Catholic superstitions in religion. As the Roman Catholics represent the inconceivable mysteries of the Christian religion, and render them more present to the mind, by a taper, or habit, or grimace, which is supposed to resemble them; so lawyers and moralists have run into like inventions for the same reason, and have endeavoured by those means to satisfy themselves concerning the transference of property by consent.

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however—the theater and the space represented, or some symbolic actions in the civil or

religious spheres—there may be some resemblance (real or at least supposed), but no

original causal derivation. In the case of words representing their objects, there may be

causal derivation, but (except in onomatopoeia) no resemblance. In the case of money

representing beautiful or agreeable goods, there seems to be neither resemblance nor

causal derivation of the representation from what is represented.

It is possible, of course, that Hume thinks there is no significant relation between the

mental and non-mental species of representation, so that these latter cases shed no light on

the representational capacities of perceptions. But such an attitude would be out of keeping

with his fundamental conception of the mind as an integral part of nature. If we examine

more closely what all his examples of non-mental representations have in common, we

find that, in each case, the representation (i) is playing a significant functional role of the

represented, and (ii) is doing so specifically in virtue of generating mental effects such as

associated ideas, beliefs, sentiments, passions, and volitions, plus mental dispositions to

have further associated ideas, beliefs, sentiments, passions, and volitions. Nor is this

accidental; in each of the cases just cited, Hume mentions the relation of representation

precisely because he is discussing the way in which the representation stands functionally

in the place of the thing represented—in giving rise to dramatic spectacles, passions, legal

ownership, religious faith, or political action, respectively. Moreover, in each case (except

that of Parliament, which he mentions briefly in the context of a political discussion rather

than in a discussion of the mind’s operations) the ability of the representation to play this

role is quite clearly being explained through its effects on the human mind. It is a

reasonable hypothesis, therefore, that all representation consists, for Hume, of one thing

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playing, by means of mental effects and mental dispositions, a significant functional role of

something else. Mental representations—i.e., perceptions that represent—constitute, on

this Humean view, a special case of representation: they not only play the functional role

of what they represent by evoking mental effects and dispositions, but they are also

themselves mental entities. Ideas, in turn, constitute yet a further special case: for they are a

class of mental representations that are copied from other mental entities and always have

other mental entities as their proximate causes.

Once we think of representation in these terms, we can see why Hume would regard

copying—that is, resemblance through causal derivation—as naturally conducive to

representation. For on the one hand, a high degree of resemblance makes it much more

likely that the representation has the needed causal powers to stand in for the represented

object—as a son may do for a father in performing a task requiring traits they share, or as

an idea may do for an impression in causing related ideas.15 And on the other hand, causal

derivation can help to determine, from all the various objects having otherwise similar

causal powers, the specific object whose functional role is being played. Thus, in Hume’s

instance of a son representing his illustrious family in producing pride in his friends, it is

the son’s causal relation to his forebears that allows his friends to take pride in those

forebears’ accomplishments, even while taking no pride in the accomplishments of

unrelated individuals who equally resemble their friend; and similarly, the causal

derivation of a current memory idea from a particular past impression in one’s own mind

makes it a memory of that impression rather than a memory of a qualitatively identical

15 Indeed, Hume’s doctrine that “the same effect never arises but from the same cause” (Rule 4 of his “Rules by which to judge of causes and effects” (T 1.3.15.2) entails that wherever there are similar effects, there must be a resemblance of some kind between the causes, so that cases in which one thing can play the functional role of something else without any obvious resemblance to it will always call for special explanation in terms of hidden resemblance.

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impression that occurred at another time or in another mind. In neither case is the role of

causal derivation in determining the object of representation at all mysterious: the mind is

so structured as to feel pride in a family’s accomplishments depending on whether the

family is judged to be causally related to a friend (or to oneself), and it is so structured as

to regard the time and date of an event remembered in idea as being the same as that of

whatever resembling impression is judged to have caused the idea. Yet when a

representation has little natural resemblance to what it represents—as in the cases of

words, money, and, perhaps, some civil and religious symbols—an associative connection

(whether natural or acquired) to an idea that does have a natural resemblance to the

represented object can often serve as a source of the required mental effects and

dispositions. And when a representation otherwise having the needed general profile of

causal powers is not causally derived from the represented object—as in the case of

money, theaters, and some civil and religious symbols—it may often still be assigned that

functional role by convention or design.

The ability of a perception to represent something by playing its functional role

through the evocation of mental effects and mental dispositions is most obvious in the case

of those ideas that are also beliefs. As Hume emphasizes in the section “Of the influence of

belief” (T 1.3.10), ideas with the degree of force and liveliness that he regards as

constitutive of belief play a causal role very similar to that of their corresponding

impressions in generating associated ideas, inferences, sentiments, passions, and volitions.

It is, he remarks, very fortunate that ideas less lively than beliefs do not have all the same

effects on our inferences, passions, and volitions; but even these less lively ideas have

nearly all of the same associations with other ideas that the corresponding impressions

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have. Moreover, these less lively ideas even give rise to a kind of “hypothetical” inference,

the conclusions of which concern what would be true rather than what is true (T 1.3.4.2),

and they often produce ideas of those sentiments, passions, and volitions that would be

produced by livelier versions of themselves. Thus, even those ideas that are not sufficiently

lively to serve as beliefs can still serve as representations of impressions. Moreover, ideas

(whether beliefs or not) may also serve to represent bodies, on this view, so long as those

perceptions are capable of producing effects in the mind that are similar to the effects that

are or would be produced by the bodies themselves. These body-produced effects may be

effects in the external world that are paralleled by similar effects produced in the mind by

the representation (as when a match’s production of flame is paralleled by an idea of the

match producing an idea of flame); but they may also include effects in the mind itself that

are either mediated or duplicated by the representation (as when a match makes one think

of flame through the mediation of an idea of a match that then produces an idea of flame).

An idea may even represent another idea, on this view, so long as it can take on, via its

mental effects, the functional role of that other idea; indeed, an idea may, under

appropriate circumstances, represent the entire bundle of impressions and ideas that

constitutes a mind or self, or even the compound of mind and body that constitutes a “self”

or person in the broader sense.

Of course, impressions, too, and even non-perceptions such as words, may represent

bodies, minds, persons, and their qualities, on this view, so long as they produce the mental

effects and dispositions that are required to play the functional role of whatever they

represent. Yet while a certain degree of resemblance is always conducive to representation,

a role for resemblance may well be essential in the special case of ideas. Objects outside

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the mind, like words or money, can easily come to acquire representation-permitting roles

that generate new mental associations, inferences, sentiments, passions, and volitions

without resembling what they represent; and impressions in the mind, such as those of

beauty or smell or mental determination, may represent qualities of bodies or of minds by

indicating the presence of those qualities (and thereby mediately producing the effects of

those qualities in the mind) even without resembling them.16 But in such cases, the external

objects or impressions in question are generally not especially suited by resemblance to

represent anything else, and hence there is little or no competition for their representational

content. The causal roles of ideas within the mind, in contrast, are already largely

determined and limited, to a very considerable degree, by their own qualitative character;

and these causal roles already naturally parallel, to a very considerable extent, impressions

and objects that these ideas resemble, so that the ideas are already poised to play their

functional roles. In addition, ideas can rarely acquire new mental associations or other

mental effects without the impressions or objects that they already resemble also acquiring

parallel associations and other mental effects. For these reasons, we may surmise, it would

be impossible or nearly impossible to make ideas play a functional role other than that of

some or all of the very impressions, objects, or other ideas that they resemble—except in

the indirect case in which ideas can represent non-resembling objects but only in virtue of

those ideas’ resemblance to impressions that already represent those things.

16 Accordingly, Hume’s previously cited argument that we cannot have an impression that represents substance—in the sense of a substratum, not in the sense of a specific substance such as gold—is best interpreted as depending in part on difficulties specific to that highly problematic notion of substance. Note that he writes only that it “is very difficult, if not impossible, to be conceiv’d” how an impression could represent substance without resembling it (emphasis added). Similarly, the rhetorical question that follows is limited in scope to the case of substance: “For how can an impression represent a substance, otherwise than by resembling it?” (T 1.4.5.3; emphasis added).

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Similarly, causal derivation, while always conducive to representation, may also be

essential in the special case when the representing entity is itself an idea in the mind. Two

reasons may be distinguished for this. First, because all ideas are copied from resembling

impressions, causal derivation is the basic source of the resemblance that representation by

ideas requires. Second, nearly all ideas resemble indefinitely many impressions and other

ideas, while many of them also resemble indefinitely many bodies; and at least some

assistance from the relation of causal derivation seems necessary to determine, from

among all of the indefinitely many resembling bodies, impressions, or ideas having

otherwise similar causal powers, which is the object, impression, or other idea whose

functional role is being played by a given idea.17

It should be emphasized that Hume does not explicitly state this general theory of

representation, according to which things represent other things in virtue of playing their

functional roles through the generation of mental effects and dispositions; indeed, he does

not explicitly state any general theory of representation, for he does not make the topic of

representation a separate object of inquiry. It is, however, the only plausible theory of

17 As noted previously, Hume claims that “Ideas always represent the objects or impressions from which they are derived, and can never, without a fiction, represent or be applied to any other” (T 1.2.3.11; emphasis added). All fictions involve proceeding as though we have an idea representing something when in fact we do not have an idea that can properly represent that thing, because we lack an idea derived from it. The most philosophically innocent of these cases are poetical fictions, in which an idea is taken as representing an object—such as the god Jupiter—that does not actually exist and hence from which it could not be derived. Such an idea would be suitable for representing such a god as Jupiter, however, had one existed. In more philosophically suspect cases, we take an idea to represent what it is not even well-suited to represent, as is indicated by the fact that the idea could not be copied from it. For example, when we treat an idea involving an empty expanse between two points as representing a “distance,” or an idea of an unchanging object as representing a “duration” (T 1.2.5), our ideas could not have been derived from impressions of distance or duration (which require intervening objects or changes, respectively, on Hume’s view); and because the idea of the “fictitious distance” or “fictitious duration” differs from ideas copied from real distances or durations, our resulting inferences employing these ideas as if they were of real distances or durations are likely to be mistaken. In the most philosophically objectionable cases of fiction, we take ourselves to have ideas meeting certain representational conditions—in the case of “substance,” for example, the condition of representing something that unites complex and interrupted items into something simple and identical—without actually having any idea at all (T 1.1.6.1; T 1.4.3). For more discussion of fictions in Hume, see Traiger (1987).

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representation that is compatible with the many and various things that he does say about

representation, both generally and in examples, in the course of his philosophical

investigations. Although no perception is inherently representational, on this theory, the

“extraneous denominations” on which things’ representational capacities depend are

nevertheless closely and essentially related to mentality—for it is only in the networks of

causally related perceptions that constitute minds, as Hume conceives them, that the

associations, inferences, sentiments, passions, and volitions required to make

representation possible can occur.

4. HOW DO PERCEPTIONS REPRESENT WHAT THEY DO?

Impressions can represent bodies, minds, and persons, along with their qualities; but ideas,

as we have seen, can represent not only these but also impressions and other ideas.

Moreover, ideas can vary in content by representing things in different ways: simply as

individuals or as parts of a compound; past, present, or future; in or out of relation to other

things; as modes or substances; and as particulars or as general kinds. If Humean

perceptions indeed represent in virtue of the functional roles they play, then we should

expect that the specific representational content of an idea on a particular occasion will be

determined by and explained through its causal capacities on that occasion. Conversely, if

the representational content of ideas on particular occasions is determined by their causal

capacities on Hume’s view, then that, in turn, will be further confirmation that he regards

perceptions as representing in virtue of their functional roles.

That Hume does regard the representational content of ideas as determined by their

causal capacities is most obvious in the case of particulars and general kinds. He

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emphasizes that qualitatively identical ideas can represent a particular (say a triangle or a

man) on one occasion, and an entire kind (all triangles or all men) on another. As he

explains in Treatise 1.1.7 (“Of abstract ideas”), an idea is able to represent an entire kind

when it becomes an “abstract or general idea” (what we would call a concept); and it

becomes an abstract or general idea not by changing or losing its fully determinate

qualitative character but rather by being associated, via custom, with a general term that

allows the mind to be disposed to call up ideas of other members of the kind (related to the

first idea by resemblance in the relevant respect) as needed to support or reject proposed

claims and inferences. The abstract or general idea thereby takes on the functional roles of

all of the members of the kind together. Indeed, ideas with the same qualitative character

may represent, on different occasions, various different kinds, depending on the terms with

which they are then associated and the set of other ideas that the mind is then disposed to

recall for use. Thus, in Hume’s example, different tokens of the same idea type may

represent on different occasions a particular equilateral triangle, or all equilateral triangles,

or all triangles, or all regular figures, or all rectilinear figures, or even all figures (T

1.1.7.9-10).

Complex ideas composed of ideas that are closely associated in the mind by relations

of contiguity and causation may represent either a substance or a mode, for Hume,

depending not on the identity of the component ideas (as in Locke18) but on the causal role

of that complex idea on a particular occasion—specifically, on whether additions to the

compound may be made without a change of associated term:

The idea of a substance as well as that of a mode, is nothing but a collection of

simple ideas, that are united by the imagination, and have a particular name 18 See especially Locke 1979, 2.12.

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assigned them, by which we are able to recall, either to ourselves or others, that

collection. But the difference betwixt these ideas consists in this, that the

particular qualities which form a substance, are commonly referred to an

unknown something, in which they are supposed to inhere; or granting this fiction

should not take place, are at least supposed to be closely and inseparably

connected by the relations of contiguity and causation. The effect of this is, that

whatever new simple quality we discover to have the same connexion with the

rest, we immediately comprehend it among them, even though it did not enter into

the first conception of the substance.

… The simple ideas of which modes are formed, either represent qualities, which

are not united by contiguity and causation, but are dispersed in different subjects;

or if they be all united together, the uniting principle is not regarded as the

foundation of the complex idea. The idea of a dance is an instance of the first kind

of modes; that of beauty of the second. The reason is obvious, why such complex

ideas cannot receive any new idea, without changing the name, which

distinguishes the mode. (T 1.1.6.2-3)

Although Hume does not describe in detail how ideas can represent relations, ideas

presumably represent things as standing in relations when they occur in the mind standing

in parallel relations (spatial, temporal, or other, as when one idea is above or occurs after

another). However, to make a conceptualized judgment that a pair (triple, quadruple, etc.)

of things stand in a relation presumably requires including the idea of that pair (triple, etc.)

within the scope of an abstract idea (i.e., a concept) of that relation. An abstract idea of a

relation, in turn, is presumably an idea of a particular and determinate pair (triple, etc.) of

objects that exemplify (or are taken to exemplify) the relation, existing together with a

disposition of the mind, evoked by an associated general term, to call up ideas of other

pairs (triples, etc.) exemplifying the relation in a way that allows ideas of those other pairs

(triples, etc.) to be used in assessing claims and inferences. This account of ideas of

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relations seems to be confirmed by Hume’s remark, concerning the specific relation of

cause and effect, that

We must not here be content with saying, that the idea of cause and effect arises

from objects constantly united; but must affirm, that it is the very same with the

idea of these objects. (T 2.3.1.16; emphasis added)

While the particular liveliness of memory ideas accounts for the degree of belief or

assent that they involve, that alone could hardly account for their representation of objects

or events as being in the past, rather than in the present. Nor can their representation of

objects or events as past lie in the qualitative character of the ideas themselves, for these

determine only the character of the objects or events remembered, not their time of

occurrence. Instead, an idea’s representation of something as past seems to consist, for

Hume, in the association of that idea with other ideas in a temporal sequence of closely

associated lively ideas, a sequence that concludes with ideas of the mind’s other sustained

present perceptions and that cannot be broken or altered without losing the ideas’

distinctive degree of liveliness. For he writes:

There is another difference betwixt these two kinds of ideas, which is no less

evident, namely, that though neither the ideas of the memory nor imagination,

[i.e.,] neither the lively nor faint ideas, can make their appearance in the mind,

unless their correspondent impressions have gone before to prepare the way for

them, yet the imagination is not restrained to the same order and form with the

original impressions; while the memory is in a manner tied down in that respect,

without any power of variation.

It is evident, that the memory preserves the original form in which its objects were

presented … The chief exercise of the memory is not to preserve the simple ideas,

but their order and position. (T 1.1.3.2-3; emphasis added)

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When memory preserves the “order and position” of lively ideas, it will make their

sequential occurrence at least difficult to interrupt, and it will tend to cause any member of

the sequence, whenever it occurs, to be followed by the subsequent portion of the

sequence. Presumably, when ideas have a similarly close association with other ideas in an

ordered sequence leading up to ideas of the present state of the mind but without the

particularly high degree of liveliness that is distinctive of memory, then their objects will

either be just believed to be past (but without the assurance of memory) or merely

conceived as past—depending on the degree of liveliness that they do possess.

Correspondingly, a representation of the future, we may suppose, is for Hume the result of

an idea’s being closely associated with a different kind of temporal sequence of

perceptions: one beginning, rather than concluding, with ideas of the mind’s (sustained)

present perceptions. While Hume does not actually propose this account—or any other—of

thought about the future, it would parallel his apparent account of thought about the past;

and it would provide him with a ready explanation of why the inference of an effect from a

present impression of its cause naturally and automatically constitutes anticipation of that

effect, rather than a belief in its present or past existence.

As the case of substances and modes already suggests, ideas can represent things as

parts of a compound thing when they are sufficiently closely related by such associative

relations as resemblance, contiguity, and causation:

Were ideas entirely loose and unconnected, chance alone would join them; and it

is impossible the same simple ideas should fall regularly into complex ones (as

they commonly do), without some bond of union among them, some associating

quality, by which one idea naturally introduces another. (T 1.1.4.1)

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This degree of association allows the ideas that are compounded to play much the same

functional roles as the interrelated parts of the compound itself, and hence to represent

them.

Following these examples, we are now in a better position to see how ideas having the

very same qualitative character can also represent, under different circumstances, bodies,

minds, persons, impressions, or other ideas. An idea will represent the corresponding

impression from which it is copied whenever it plays the functional role of that impression

in virtue of the mental effects and dispositions it produces. Hence, an idea representing an

impression will tend to produce most or all of the same associated ideas—including those

constituting causally inferred conclusions, whether affirmed or hypothetical—that the

impression itself would produce. In addition, the idea will also tend to produce at least

ideas of most or all of the sentiments, passions, and volitions that the impression itself

would produce; and when the representing idea is a belief or memory, it will tend to

produce those passions and volitions themselves.

When an idea represents a body, however, it will also be disposed to produce mental

effects and dispositions that go beyond those just mentioned. These additional effects and

dispositions will involve additional associated ideas, inferences, sentiments, passions, and

volitions—or at least associated ideas plus hypothetical inferences and ideas of sentiments,

passions, and volitions, depending on whether the idea is a belief or memory, or not. These

additional effects and dispositions will be of just the kind that would have been produced

by impressions resembling the body-representing idea had such resembling impressions

been perceived at spatio-temporal locations other than those at which resembling

impressions are represented as actually having been perceived. Thus, in Hume’s own

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example, the hearing of a squeaking noise while one is facing the fireplace is followed by

the sight of a porter, and these impressions give rise to a lively idea of a moving door plus

a lively idea of stairs leading to the door and supporting the porter in the recent past (T

1.4.2.20). These lively ideas may give rise to, or be disposed to give rise to, yet further

associations, inferences, sentiments, passions, and volitions; and all of this may occur even

though there is no current or recently past impression of a door or stairs. In nevertheless

giving rise to such effects and dispositions, the lively ideas represent the door and the stairs

as continuing to exist and able to operate when unperceived, independently of the mind—

that is, it represents them as bodies. In acquiring these additional causal capacities,

moreover, ideas need not cease to represent their corresponding impressions. Thus, an idea

may represent a body as itself sometimes immediately perceived—for this is how the

“vulgar” (which includes all of us, at least most of the time, according to Hume) represent

bodies. Or, on the other hand, an idea may instead represent a body as never itself

immediately perceived but rather only as producing separate impressions that are

immediately perceived, as the “philosophical” theory has it; in such a case, the

representing idea produces many of its associated ideas, inferences, sentiments, passions,

and volitions not directly, but through its association with a second idea, an idea of a

corresponding impression. In either case, however, an idea plays the functional role of a

body not only by producing effects in the mind that are similar or identical to those

produced in the mind by the body itself; the idea also plays the functional role of a body by

producing ideas in the mind that are similar to and represent the effects produced by the

body in the external world.

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An idea may represent another idea, in contrast, when it is copied from that idea and

plays a causal role parallel to that of the original idea in the production of mental effects

and dispositions. It will not typically give rise to the same associated ideas, inferences,

sentiments, passions, and volitions that the original idea produced, however, but rather

only ideas of them. Hume claims that a distinctive feeling—presumably another

impression of reflection of the kind that represents mental operations—occurs whenever

the mind has an idea:

[W]e need not be surprized to hear of the remembrance of an idea; that is, of the

idea of an idea, and of its force and vivacity superior to the loose conceptions of

the imagination. In thinking of our past thoughts we not only delineate out the

objects of which we were thinking, but also conceive the action of the mind in the

meditation, that certain je-ne-scai-quoi, of which it is impossible to give any

definition or description, but which every one sufficiently understands. (T

1.3.8.16)

Thus, although it appears that all ideas are accompanied by this feeling, an idea of an idea

will, in addition, be associated with an idea of the feeling of this “action of the mind” in

thinking. When the idea of this feeling is a memory, it will have sufficient force and

liveliness to sustain affirmative inferences from the past occurrence of the original idea to

other beliefs (i.e., lively ideas). A (third-level) idea of an idea of an idea will—in addition

to its other associative relations and tendency to produce ideas of ideas of inferences,

sentiments, passions, and volitions—presumably be associated with a pair of ideas of “the

action of the mind in thinking”: one corresponding to the occurrence of the original idea

and one to the occurrence of the idea of the original idea. Ideas of impressions and bodies,

in contrast, may be distinguished from ideas of ideas in part by their not being directly

associated with ideas of this feeling.

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Finally, an idea may represent a mind when it represents the entire bundle of

perceptions—both impressions and ideas—related by causation and resemblance that

constitute a mind on Hume’s view. Given the many perceptions included in a mind, the

idea presumably represents the entire bundle by functioning as an appropriate abstract

idea—that is, as an idea of some particular perception or perceptions together with a

disposition to call up as necessary ideas of other perceptions suitably related by causation

and resemblance. An idea may even represent a person or “self,” in the broad Humean

sense that includes both mind and body, when it consists of a compound of an idea of a

mind and an idea of a particular body that is causally related to it.19

5. CONCLUSION

Hume’s theory of mental representation is often regarded as a mere historical curiosity,

hamstrung both by an inability to accommodate representation of an external world and by

a simplistic identification of representation with copying. If the interpretation presented

here is correct, however, the range of Hume’s theory is not limited to the contents of the

mind—either in what is represented or in what represents—and he agrees that copying is,

in general, neither necessary nor sufficient for representation. It is only in the special case

of ideas that copying has a strong claim to be a necessary condition for representation; and

even in that special case, the qualitative character of the idea is not sufficient by itself to

determine its specific representational content. For example, one idea may represent a

particular past impression of a dog; another idea, qualitatively indistinguishable from it but

19 While one may have a non-abstract idea of a human body that is simply copied from a particular impression of it, most ideas of human bodies are likely to be abstract ideas as well, functioning as concepts that encompass, through dispositions to have other ideas, the entire history of the body as it would be viewed and felt from a variety of perspectives.

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having a different functional role, may represent all of a general class of enduring

substances, such as all collies; and a third may represent the mode of mammalhood.

Hume is, of course, a thorough-going determinist (T 1.3.12.1-5, 1.3.8.14, 2.3.1.3,

2.1.12; and EHU 8.4). Hence, because he holds that qualitatively identical ideas can

nevertheless have different representational contents as a result of different causal roles, he

must accept that qualitatively identical ideas can differ from one another either in intrinsic

but non-phenomenal respects or (more likely) in their relations to phenomenally

inaccessible background mechanisms of the mind, such as those that might be housed in

the brain. But Hume is in any case committed to the existence of such differences, for he

readily allows that the sequence of thoughts in a human mind cannot, in general, be

predicted deterministically by causal laws formulated in terms of the phenomenal

characteristics of perceptions alone; he admits that our only general predictive guide, the

principles of association, describe at best a “gentle force” making some sequences of

perceptions more probable than others (T 1.1.4.7).

Accounts of mental representation often differ from one another over the relative

importance of intrinsic character and functional role (including inferential role). For Hume,

I have argued, the taking on of specific functional roles, performed by producing mental

effects and dispositions, is essential to all representation, whether mental or non-mental;

but intrinsic character can place natural constraints on what functional roles a potential

representation can play, and these constraints are particularly significant when the

representations are themselves mental entities, such as ideas, with causally efficacious

qualitative phenomenal character. He rejects the scholastic and Cartesian theory that

mental entities possess an intrinsic “objective reality” that makes them inherently

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representational, in favor of the view that their representational character is an “extraneous

denomination” based on causal capacities limited, but not alone fully determined, by

qualitative character. On this view, perceptions represent at all only because of the

associative, inferential, sentimental, emotional, and conative causal networks in which they

participate. Indeed, given the centrality of causal inference, in particular, to these

networks, he could well accept the Kantian claim that there could be no thought or

experience at all without causal inference. The theory of mental representation that results

constitutes an important and provocative element in, and not an exception to, Hume’s

naturalism.

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ACKNOWLEDGEMENTS

I am indebted for useful comments and suggestions to Lorne Falkenstein, Tito Magri, Saul

Traiger, Karl Schafer, Geoffrey Sayre-McCord, Michael Ridge, and participants in the

Hester Seminar on Hume’s Naturalism held at Wake Forest University, April 8-10, 2005.

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