Hegel and Hume on Perception and Concept-Empiricism

Kenneth R Westphal. Journal of the History of Philosophy. Volume 36, Issue 1. January 1998.


My thesis is that the chapter on “Perception” in Hegel’s Phenomenology of Spirit is a critique of the section of Hume’s Treatise titled “Of Scepticism with regard to the senses” (I.iv sec2). Both discussions proceed under the assumption that the objects of perception are ordinary things around us, each of which has various perceptible properties. Both discussions examine the capacity of concept-empiricism to account for the concept of the identity of a perceptible thing-a crucial component of the belief in ordinary physical objects. However, to extend his concept-empiricism to handle the nonlogical concept of the identity of a perceptible thing, Hume is forced to introduce a variety of psychological “propensities” to generate, in effect, a priori concepts; he is forced to confront a certain kind of “contradiction” in the concept of the identity of a perceptible thing; and ultimately he is forced to regard this concept as a “fiction.” Hegel reexamines Hume’s account to show that the concept of the identity of a perceptible thing is indeed nonlogical and cannot be defined in accordance with concept-empiricism. This is an important point in favor of Hegel’s concept-pragmatism. This point is also important in connection with the quite general problem of how we bring various sensations together into the perception of any one object.

“Of Scepticism with regard to the senses” is an extremely important section of Hume’s Treatise. Though Hume’s skepticism received growing attention in Germany at the turn of the nineteenth century, Hegel was alone among his contemporaries in recognizing the importance of this section. I admit that Hegel makes no bibliographic reference to Hume’s Treatise-at least not in his surviving manuscripts. However, close consideration of the historical background of Hegel’s analysis of perception, along with the many ways in which Hume’s skepticism is especially important for Hegel, shows that it is altogether likely that Hegel read Hume’s Treatise, including the above-named section. Hegel’s concern with that section is further supported by the fact that referring to it affords a complete, intelligible, and sound reconstruction of the aim and course of Hegel’s argument in “Perception.” On this reconstruction, Hegel’s argument constitutes a two-pronged reductio ad absurdum of two key empiricist theses: on the one hand, the thesis that the concept of the identity of a perceptible thing can be reduced to or defined in terms of the two quantitative concepts “unity” and “plurality” (or analogously “whole” and “part”), and on the other hand, the thesis that human perception only involves passive reception of sensations. Justifying this interpretation of Hegel’s chapter requires of course a complete reconstruction, which is more than can be undertaken here. I provide a full reconstruction elsewhere. Here I summarize the main grounds supporting my interpretation and show one key point at which Hegel’s analysis and conclusions refer to Hume’s.


The fundamental importance of Hume’s skepticism for Kant has been long recognized. Unlike Kant, who expressly acknowledged Hume’s stimulus to his own thought, Hegel only rarely names his main sources and opponents, especially in the Phenomenology. However, Hegel recognized early in his career that a philosophical view, including his own, cannot be justified merely by its proclamation; it can be justified only through critical engagement with alternative views. Hume’s Treatise provides an important philosophical point of reference which alone affords an intelligible and self-sufficient interpretation of Hegel’s analysis of perception in the Phenomenology. Such an interpretation is crucial to the aim of Hegel’s arguments in the Phenomenology. Only by reference to common problems in the history of philosophy, independent of Hegel’s own proposed system, can Hegel’s Phenomenology provide an exoteric “ladder” to-that is, a philosophically sound proof of-the “actuality” of absolute knowledge. In other words: only by engaging with alternative philosophies on their own terms can Hegel, in accord with his own methodological requirements of the Phenomenology, avoid one of the main objections of Pyrrhonian skepticism, namely, that philosophers inevitably presume what they propose to prove.


Six points in the historical background of Hegel’s analysis of perception clearly indicate Hegel’s study of Hume’s epistemology, including Treatise, I.iv sec2.

3.1. Hegel’s notebooks from 1789 on Locke, Berkeley, Hume, and Kant are unfortunately lost. Hume’s Treatise was first translated (rather freely) into German in 1790. Jakob’s translation of Hume’s Treatise was reviewed at least five times between 1790 and 1793, including in journals which Hegel read. Right at the beginning of his long review of 1790 Feder wrote the following about Hume’s Treatise “The manifold value of this work is already for most [philosophers] so crucial that I don’t believe it is necessary to say anything about it.” I submit that it is altogether improbable that the bibliophile Hegel didn’t read such a crucial philosophical masterpiece, one which gathered increasing attention in Germany after 1790, during the roughly fifteen years prior to writing the Phenomenology in 1806.

3.2. In an important passage from the Jena “Logic” manuscript Hegel designates impressions as “Hume’s substances” and as “that which Hume calls things.” Now only in “Of Scepticism with regard to the senses” does Hume try to show that individual, isolated “impressions” can exist independently of the mind (of “bundles of perceptions”), and indeed Hume only mentions this idea in this section. Impressions can count as “things” or “substances” only if they are mind-independent. Consequently, this passage from Hegel’s early logic manuscript provides clear evidence that Hegel had read Hume’s Treatise by 1804, and indeed, that he paid attention to “Of scepticism with regard to the senses.”

3.3. My interpretation builds on Hegel’s heretofore unexplained subtitle: “Perception or the Thing and Deception.” The apposition of “perception” and “deception” (Tauschung) may suggest that Hegel refers to perceptual illusions, which served as main premises in both ancient and modern arguments for representational theories of perception. However, this topic is hardly discussed in Hegel’s chapter on “Perception”—and it is also hardly discussed by Hume in “Of scepticism with regard to the senses.

An important clue for interpreting Hegel’s subtitle is found in the concluding section of Book I of Hume’s Treatise, where Hume designates causality as a mere “illusion” of the imagination. By following the history of the German reception of Hume’s synopsis of his view of causality we can see, first, that Hegel was indeed in a position to pay special attention to this summary, and moreover, that Hegel had compelling grounds to examine closely the background of Hume’s view of causality, and thus to examine Hume’s view of the identity of perceptible things, which Hume also presents as a kind of deception or illusion.

The concluding section of Book I of Hume’s Treatise was translated by J. G. Hamann and published in Summer 1771 in his Konigsbergsche Zeitung. This section apparently provided Kant “the recollection of David Hume” as the final impetus to write the first Critique. Subsequently Kant recapitulated Hume’s synopsis, though much more briefly. In the long Remark to the Preface of the Metaphysical Foundations of Natural Science (1786) Kant summarizes Hume’s view of causality as “mere deception [Tauschung] due to habit.” The next year, in the second Critique, Kant summarizes Hume’s view of causality in similar terms.

Hegel studied Kant’s Metaphysical Foundations and its crucial role within Kant’s Critical system very carefully by 1801. It is altogether likely that Hegel noted Kant’s summary of Hume’s view of causality there. Schelling noticed this topic, and surely brought it to Hegel’s attention. However, unlike Kant and Schelling, in his chapter on “Perception” Hegel connects “deception,” not with causality, but with the “thing” and “perception.” Why does he do this? As noted above, in his Jena Logic manuscript of 1804-1805 Hegel examines the causal relations among sensory impressions or empirical intuitions and maintains that the problem of such relations arises equally in Hume’s and in Kant’s philosophies. This issue amounts to the problem of perceptual synthesis, and this problem is closely allied with the concept of the identity of perceptible things. Now Hume develops his views on the identity of perceptible things only in the Treatise, not in the first Enquiry, and indeed only in “Of scepticism with regard to the senses.” What led Hegel, unlike Kant and his successors, to analyze Hume’s view of the concept of the identity of perceptible things?

3.4. This question can be answered by considering three subquestions. These subquestions concern three central issues in Hume’s analysis in “Of scepticism with regard to the senses”: (1) the a posteriori derivation of the concept of causality; (2) the lack of justification of the common-sense belief in external things; and (3) the fictional derivation of the concept of the identity of perceptible things from the imagination. Briefly stated, Kant responds as follows. (1) In the second Analogy of Experience Kant argues (correctly) that, despite the a posteriori sources of our beliefs in particular causal relations among things or events, the general concept of causality cannot be derived a posteriori, especially not by Humean principles of psychological association. (2) The belief in external things is justified by Kant’s “Refutation of Idealism,” an argument which was already sketched in the first-edition Paralogisms. (3) However, Kant would not have regarded the third subquestion as requiring a special answer. According to Kant’s “Refutation” we must have, and be able to use, an objectively valid concept of empirical (perceptible) things. Although Kant was deeply influenced by Hume, he never doubted that we have a priori concepts. Kant is confident from the outset that we have two distinct sources of knowledge, sensibility and understanding, from which we obtain the two components of any empirical cognition, intuitions and concepts. Kant’s question was only whether, or which, a priori concepts are objectively valid. Our a prior concepts, the Categories, can be derived from a Table of Judgments, including the concept of substance, which through a complete (transcendental and empirical) schematism would supposedly serve as a concept of the identity of perceptible things. Kant would not view himself as needing to respond directly to Hume’s empiricist critique of the concept of the identity of perceptible things.

Hegel responds to the first subquestion, that regarding the concept of causality, in the third chapter of the Phenomenology (“Force and Understanding”), not in “Perception.” Hegel responds to the second subquestion, that regarding the evidence for or justification of our belief in outer things, in his analysis of “Self-Consciousness.” Concerning the third subquestion, however, Hegel must take a very different approach than Kant. Due to his penetrating internal critique of Kant’s transcendental idealism, by 1801 Hegel had already rejected Kant’s sharp distinction between a priori and a posteriori concepts. However, that does not mean that Hegel no longer maintained that some conceptions count as relatively a priori and others count as relatively a posteriori. It does mean, however, that Hegel cannot simply assume that some concepts are a prior, and especially he cannot assume that such concepts can be derived from a Table of Judgments. Hegel must prove the a priori status of any and every supposed (relatively) a priori conception. Moreover, in accord with his regressive method of proof, Hegel must demonstrate the a priori status of each such conception through an internal critique of the opposed concept-empiricist derivation of that concept from elementary sensory experiences. These requirements hold, of course, for the main point of Hegel’s analysis of “Perception,” namely, the concept of the identity of perceptible things. Now Hegel already justified some (relatively) a priori conceptions in the first chapter of the Phenomenology (“Sense-Certainty”). However, he must justify each such conception. Moreover, his analysis of the concept of the identity of perceptible things extends his critique of a key thesis of concept-empiricism which is not examined in “Sense-Certainty,” namely the derivation or definition of complex concepts by logical conjunction of simple sensory concepts (i.e., names of simple sensory qualities). Third, the concept of the identity of perceptible things is important to Hegel because he purports to show that this concept contains a special kind of objectively valid contradiction-a result which can be obtained by critical examination of Hume’s view of the concept of the identity of perceptible things!

By studying Hume’s text and issues, Hegel recognized that Hume’s notion of “deception” applies not only to causality but also to the validity, indeed to the very possibility, of the concept of the identity of perceptible things. Strictly speaking, according to Hume’s empiricism the “deception” lies precisely in the fact that we are naturally convinced that perceptible things exist outside of us. According to Hume’s concept-empiricism this belief is neither true nor intelligible, precisely because the concept of the identity of perceptible things is a mere “fiction.” Precisely because we have no legitimate concept of perceptible things or their identity (“legitimate” vis-a-vis concept-empiricism), Hume himself speaks in this connection of “illusion” and “deception.” Hence Hegel’s subtitle.

3.5. The next important point to notice about the philosophical reception of this issue in Germany is that, because Kant concerned himself with perceptual synthesis while disregarding Hume’s challenge to the a posteriori derivation or definition of the concept of the identity of perceptible things, the attention of post-Kantian German philosophers was directed to perceptual synthesis, but not to the concept of the identity of perceptible things. Skepticism about the external world was widespread in Germany after Kant’s first Critique because many philosophers were unconvinced that Kant had adequately answered Hume’s skepticism about causality and outer objects. The term Tauschung (deception) was frequently used in this connection. In 1792 G. E. Schulze defended Hume’s skepticism against Kant and his followers. Schulze stressed the general problem of the “deceptiveness [Truglichkeit] and unreliability of all sensory knowledge” and he summarized Hume’s criticisms of causality and induction. Now Schulze did not use the term Tauschung in this connection, nor did he discuss Hume’s section, “Of scepticism with regard to the senses.” However, he did stress a closely related problem, namely, the issue (if not the term) of the synthesis of sensory intuitions in Reinhold’s philosophy. It is well known that Hegel studied both Reinhold and Schulze thoroughly; surely both of them called his attention to the issue of perceptual synthesis. The topic of perceptual synthesis is closely associated with the topic of the concept of the identity of perceptible things. This topic was also emphasized by Solomon Maimon, insofar as he formulated the connection between deception (he uses the term Tauschung), perceptual synthesis, and skepticism about outer objects, a connection which is also found in Hume-at least in post-Kantian retrospect. However, Maimon, like his contemporaries, disregarded Hume’s problem about the concept of the identity of perceptible things. Maimon’s “psychological explanation” of Kant’s principles only attempted to revalidate Humean principles of psychological association.

3.6. In the Differenzschrift (1801) Hegel criticized the weakness of Reinhold’s concept of synthesis and in the “Skepticism” essay of 1802 Hegel generalized the problem. However, instead of losing Hume’s problem in this generalization, Hegel used this generalization to sharpen the problem. It is important to note that Hegel already sees that the familiar problem of causal relations among physical substances is recapitulated as a problem concerning the representative relation among “sensations, perceptions, sensory representations, or whatever he [sc. Kant] wants [to call them].” The main point is that, on Hume’s view as on Kant’s the relata of a supposed causal relation, or analogously our sensory representations of that relation, “Which succeed one another or [stand] next to one another” are originally “of themselves altogether indifferent to each other.” That holds of Humean “objects,” which are supposed to be indifferently either outer things or sensory impressions, and it holds as well of Kantian sensations (Empfindungen): in principle they are completely independent of each other. In order to solve the problem of causal relations, as well as to solve the problem indicated here (if not named in these terms) of perceptual synthesis, Hegel already recognizes that their relata must be reconceived in fundamentally different terms.

Furthermore, Hegel concerned himself in this same manuscript with the closely related issue of the concept of the identity of perceptible things. In this connection Hegel expressly stresses the numerical unity of a perceptible object as a subject of predication along with the plurality of its properties. Already in this manuscript Hegel is concerned with the problem of the identity of perceptible things as a semantic, epistemological, as well as metaphysical problem. In this regard Hegel already concerned himself with the numerical identity of a perceptible thing and the plurality of its properties, or alternatively the plurality of their individual sensations or perceptions. In this way he prepared himself for the much clearer and more thorough analysis of the concept of the identity of perceptible things in the “Perception” chapter of the Phenomenology.


Five further points regarding the setting of Hegel’s problems show that Hegel must and did concern himself with Hume’s epistemology, including the epistemological analysis undertaken in “Of Scepticism in regard of the senses.”

4.1. As Henry Harris has shown, Hegel came across the general skeptical problem of outer things already in the Frankfurt fragment “Glauben ist die Art.” Through his polemic David Hume uber den Glauben (1785) Jacobi informed Hegel about Hamann’s fideist appropriation of Hume’s skepticism. According to Hamann, Hume had shown that our belief in outer things is rationally neither provable nor refutable-just like our belief in God (according to Hamann and Jacobi). Consequently, Hegel recognized empiricist skepticism with regard to outer things as the fulcrum on which faith hoists itself above reason. In order to defend the cognitive claims of philosophy Hegel must thoroughly refute empiricist skepticism.

4.2. The attempt to understand the identity of a thing in terms of the concepts of unity and plurality has a long history, well known to Hegel, not only in Plato (Theatetus, Timaeus), but already in Empedocles. In his “Lectures on the History of Philosophy” Hegel objected, not only to Empedocles, but also to his modern followers-recall Hegel’s comments on Reinhold, and perhaps also on Hume and Kant-that they always stress alternatively and sequentially the unity or the plurality of a thing, but fail to combine these two aspects of a thing. In his lectures Hegel stressed a point which went unnoticed by the Greeks, but which was especially emphasized by Hume, a point which gave Hume’s skepticism special importance for Hegel: Through his critique of causality and induction Hume, far more than any other empiricist, “purified the opposition between the sensible and the universal and expressed it more sharply,” indeed to the point of depriving the sensible of all universality, and thus Hume had “annulled [aufgehoben] the objectivity of the determinations of thought [Denkbestimmungen], their being in and for themselves.” In this connection Hegel states directly that necessity and universality are only examples of the determinations of thought attacked by Hume. This is to say that Hegel recognized Hume had contested other concepts or universals (“determinations of thought”) in addition to universality and necessity. Only Hume had carefully examined, not only the applicability, but moreover the very content of the concept of the identity of perceptible things, and had rejected it as a mere “fiction” of our imagination. Unlike Hume, the other ancient and modern treatments of this problem simply overlooked the key question about perception: How-on the basis of what concept of a thing are we able to bring together various specific sensations or perceptions and relate them to some one single object instead of to another? That is precisely the main question in Hegel’s chapter on “Perception” in the Phenomenology, and careful reconstruction of Hegel’s analysis shows that precisely Hume’s rejection of the concept of the identity of perceptible things is the main topic of Hegel’s discussion. Because Hume is aware of this question, as well as of the possibility of deception about the very existence of outer things that it involves (if indeed the concept of identity is a “fiction”), Hume counts, in Hegel’s view, as the historical representative of perceptual consciousness, which, as the observed form of consciousness examined in Hegel’s chapter, is likewise conscious of this possibility of deception.

4.3. Hegel must answer Hume’s rejection of the concept of the identity of perceptible things in order to carry through his examination and defense of the “actuality” of our knowledge. In the Encyclopedia (sec22 and Zusatz) Hegel expressly formulates a crucial fallacy underlying the whole modern (as well as current) epistemological debate between empiricism and rationalism about skepticism and relativism, namely, the uncritical assumption that only a passive kind of cognition can be reconciled with realism, and conversely that any sort of active cognition inevitably leads either to skepticism or to relativism, because any cognitive activity must (re)create the supposed objects of our knowledge and thus obscure rather than reveal what they truly are. Hegel, for the first and almost the only time in the history of philosophy, expressly intended to combine realism about the objects of knowledge with an activist account of knowledge. Hegel was already aware of this issue in 1801/1802, as is shown by his criticism of Reinhold in the Differenzschrift and by his Introduction to the Critical Journal of Philosophy. This same issue is announced at the beginning of the Introduction to the Phenomenology of Spirit by the metaphors of knowledge as an instrument or a medium.

Hegel’s epistemology is distinguished from the skeptical tradition, as well as from the skeptical underpinnings of modern philosophy from Descartes to Kant and his successors, precisely by his attempt to show that our basic conceptual categories are not only subjectively but also objectively valid—”objectively valid” in the sense that they hold of things which exist and have characteristics regardless of what we say or think about them-even though we construct these conceptions a priori. Exactly how we refer our a priori constructed conceptions to the actual structure of the world and thereby assess, revise, and justify them is a crucial and complex matter which I have analyzed in detail elsewhere. Here I can only mention, e.g., that Hegel aims to show in “Perception,” not only with Hume that the concept of the identity of perceptible things cannot be reduced to or defined in terms of the concepts of unity and plurality, but also against Hume that this concept is no mere a priori “fiction,” but instead that it is objectively valid, even though it can only be used in an active kind of cognition. Moreover, Hegel proposes to demonstrate this objective validity without espousing any kind of transcendental idealism cum Critical skepticism about “things in themselves.” Only by revalidating the objective validity of our basic conceptual categories can Hegel develop philosophy beyond philo sophia to genuine scientific (systematic) knowledge, and only thus can he restore the priority of reason over faith, whether fideism or Kantian practical faith. Both kinds of faith are based on deep skepticism, though of different kinds. Hamann’s, Hume’s, and also Kant’s skepticisms all highlight the fact that Hegel’s attempt to justify the objective validity of our basic conceptual categories is absolutely fundamental to his aim in the Phenomenology to justify his claim that philosophy not only aspires to but achieves absolute knowledge, “namely… the actual knowledge of what truly is.” The subquestions regarding the content and the objective validity of the concept of the identity of perceptible things are especially important in the second and third phases of Hegel’s analysis in “Perception”; Hegel stresses the subquestion regarding the activity of our cognition throughout his analysis.

4.4. Hume’s analysis of the concept of the identity of perceptible things in “Of Scepticism with regard to the senses” is absolutely crucial for the assessment of concept-empiricism, because Hume in fact shows that the concept of a physical object (Hume speaks of “body” in general) cannot be derived from or defined in terms of logical conjunctions of (names of) elementary sensory experiences or impressions. (This, in a word, is why he must take recourse to “fictions.”) In addition, Hume in fact (if unintentionally) shows that the concept of the identity of perceptible things cannot be reduced to merely quantitative concepts. Those are two main results of Hegel’s analysis in “Perception.” The third, closely related, result is that human knowledge is not passive, but active. This thesis is also partly confirmed by Hume, insofar as he repeatedly must introduce conceptual “fictions,” which we produce and must produce (by innate psychological “propensities”) in order to have a belief in outer things at all. These three theses are absolutely central to Hegel’s analysis in “Perception,” and prior to Hegel they are only found in Hume, indeed, only in “Of Scepticism with regard to the senses.” Hegel’s contemporaries did not follow Hume’s analysis so deeply. They contested the applicability of the concept of a thing or (analogously) of substance as a substratum for properties, but they did not concern themselves with either the content (definition) or the derivation of the concept of the identity of a perceptible thing.

4.5. Considering some key features of Kant’s view of sensations and their role in perception helps to highlight some important features of perceptual synthesis, features which are important to Hegel and help to show the importance to him of Hume’s examination of the concept of identity. Kant rejected two of Locke’s central theses concerning perception, first, that sensations caused in us by outer events or objects either are or can be treated as pictures of objects, and second, that there is a genuine question whether these sensory representations correspond or fail to correspond to the objects which supposedly cause them. Consequently, on Kant’s view, no object can be represented at all, either correctly or incorrectly, without the use of a priori functions of judgment. Rolf George has shown that Kant held a certain kind of “sensationism.” Kant expressed this doctrine clearly in his distinction between sensations and empirical intuitions. According to this doctrine, sensations are (normally) caused by objects or events in our environment, although this causal relation does not suffice for sensations to represent objects (or events). Consequently we must (re)construct our representations of outer objects or events, where some characteristics of our representations are due to the objects we perceive, while other characteristics derive from our synthesizing cognitive functions. This doctrine is fundamental to Kant’s epistemology, insofar as it alone provides the context for Kant’s fundamental question, formulated in his famous letter to Herz.

According to Kant, the synthesis by which alone empirical sensations come to represent objects must be a function of the kinds of judgment of which we are capable, simply because there is no other possible source of such syntheses. In the “Metaphysical Deduction” of the Categories Kant purports to show that our basic kinds of logical judgments indicate our basic kinds of cognitive judgments. If there were a valid Table of (logical) Judgments, it would be quite plausible to share Kant’s assumption that this Table of Judgments must ground an analogous Table of Categories. For present purposes the important point is that, on Kant’s view, sensations only become components of actual perceptions and only represent objects insofar as they are integrated-synthesized by cognitive judgments based on our conceptual Categories.

The characteristic weakness of sensationist theories of perception lies in the lack of a convincing explanation of the origin and nature of the synthesizing functions which integrate sensations into perceptions of objects. Kant tried to solve this problem with his Tables of Judgments and Categories. Already at the beginning of his study of Kant’s epistemology, Hegel had grave doubts about the adequacy of Kant’s Tables and (as mentioned above) by 1801/1802 Hegel had developed a powerful internal critique of Kant’s transcendental idealism which showed that Kant’s sharp distinction between a prior and a posteriori concepts must be rejected. Now Hegel also espoused sensationism. After rejecting Kant’s view of our synthetic cognitive judgments, Hegel had to develop a new view of the synthetic functions of perceptual judgment.

Hume’s examination of the concept of identity takes on special interest in this connection. Hume, of course, was no sensationist. In Hume’s view sensory impressions are objects of conscious awareness; sensations of the sensationist variety are not. However, like the sensationists, Hume holds that sensory impressions are caused by objects in our environment-although he cannot support this view philosophically. However, Hume’s attempt to explain the common-sense belief in the persisting and mind-independent existence of outer things on the basis of sensory impressions in fact addresses the key problem facing sensationism: How are we able to bring specific series of impressions (or sensations) together, in order to relate them to some one specific object which (supposedly) caused them? What kind of concept of the object is presupposed by such “bringing together” of sensations, i.e., what concept guides perceptual synthesis? The fact that Hegel devoted such attention to Kant’s doctrine of perceptual synthesis, and moreover that he expressly examined Kant’s view of synthesis in close connection with Hume’s discussion “Of Scepticism with regard to the senses,” shows beyond doubt that Hume’s influence on Hegel’s epistemology-both directly and as conveyed through Kant-is very important indeed. Precisely because Hume was the sole modern philosopher before Hegel who seriously examined the origin, nature, and content of the concept of the identity of perceptible things, it is not at all surprising that Hegel would pay close attention to Hume’s examination of this question in “Of Scepticism with regard to the senses.” The technical issues in philosophical psychology about sensations as analyzed by sensationism are not, of course, appropriate to Hegel’s treatment of “Perception” in the Phenomenology. Nevertheless, the more general question about the concept of the identity of perceptible things certainly is appropriate to “Perception” in the Phenology.


I turn now to some main points of Hume’s analysis of identity, beginning with a more general point about his view of substance. Hume, of course, considered perceptible objects in connection with the concept of substance and the plurality of a thing’s properties. Near the beginning of the Treatise he states:

We have therefore no idea of substance, distinct from that of a collection of particular qualities, nor have we any other meaning when we either talk or reason concerning it.

The idea of a substance … is nothing but a collection of simple ideas, that are united by the imagination, and have a particular name assigned to them, by which we are able to recall, either to ourselves or others, that collection.

Very similar, if not identical, accounts of the concept of substance can be found throughout modern philosophy. Now Hume does not discuss the concept of substance in “Of Scepticism with regard to the senses,” but it is certainly relevant to the issues raised there. Hume often repeats, including in this section (I.iv 2), that it is “a gross illusion to suppose, that our resembling perceptions are numerically the same; and `tis this illusion, which leads us into the opinion, that these perceptions are uninterrupted, and are still existent, even when they are not present to the senses.” In “Of Scepticism with regard to the senses” Hume only examined the diachronic aspect of the concept of identity. However, in the brief subsequent section, “Of the ancient philosophy,” Hume recognizes that the basic contradiction within the concept of identity appears also in the synchronic aspect of the identity of things because the main contradiction lies in the opposition of the unity of a thing with the plurality of its properties:

‘Tis confest by the most judicious philosophers, that our ideas of bodies are nothing but collections form’d by the mind of the ideas of the several distinct sensible qualities, of which objects are compos’d, and which we find to have a constant union with each other. But however these qualities may in themselves be entirely distinct, `tis certain we commonly regard the compound, which they form, as ONE thing, and as continuing the SAME under very considerable alterations. The acknowledg’d composition is evidently contrary to this suppos’d simplicity, and the variation to the identity.

The source of the “contradictions” Hume identifies is this: If the thing or if a substance were in fact “simple,” it would be unitary but it could have no internal differentiation. However, without internal differentiation it cannot have any plurality of properties. Recourse to “simplicity” of this sort stems from Hume’s presumption that the identity of things can be understood solely in terms of the quantitative concepts of unity and plurality. Given concept-empiricism, complex concepts can be understood only as logical conjunctions of simple concepts (or ideas). Quantitatively, “unity” is a simple; pluralities are complexes, not units. Hence Hume must assume that a genuinely unitary thing is also simple. Hence nothing can be both genuinely unitary and have a plurality of characteristics or properties.

In “Of Scepticism with regard to the senses” Hume notes that the concept of identity is distinct from the concepts of unity and plurality and that it can neither be derived from nor defined in terms of these latter. According to Hume, the concurrent perception of an unchanging impression and of at least two other successive impressions causes us to produce the “fiction” that the first (unchanging) impression is an unchanging object. Every unchanging object gives us only the concept of unity. However, by means of the altogether common “fiction” of the imagination that an unchanging object partakes in the changes of coexisting but changeable objects (by persisting through the same period of time as their changes), we can consider a single object in connection with two distinct times. If we attend to the distinct times, we’re given the concept of the plurality in connection with some one thing. Hume concludes: “Here then is an idea, which is a medium betwixt unity and number; or more properly speaking, is either of them, according to the view, in which we take it: And this idea we call that of identity.” This passage shows how Hume attempts to construct a concept of identity from the quantitative concepts of unity and plurality, and how he recognized, at least implicitly, that the concept of identity cannot be reduced to or defined in terms of them. This result was so important to him that he repeated it twice more. This main result of Hume’s analysis is, we shall see, absolutely fundamental for Hegel’s analysis of “Perception.”

This is not all. It is fundamental for perceptual consciousness’s third and final strategy that the plurality of the properties of a perceptible thing is only apparent to consciousness-and is only ascribable to the thing-in the thing’s relation to other things. Similarly, in Hume’s view of time, the plurality of moments through which a single object endures is only apparent in the thing’s relation to other (changing) things. According to Hume, if we attend in particular to the persistence of an object through a change of time, the object gives us the idea of unity. On Hume’s view of time, an unchanging object is literally timeless. Consequently, such an object, at least temporally, must be simply unitary. That is, the supposed series of moments through which the unchanging object passes cannot be recognized in the object itself. Taken in isolation, an unchanging object is simply unitary; only in relation to other changing objects does an unchanging object appear to display a temporal plurality.

The view adopted by the observed perceptual consciousness in its third and final phase is an exact synchronic analog to Hume’s diachronic model of the identity of perceptible things. Perceptual consciousness presupposes that identity and numerical unity are the same. This is to say, perceptual consciousness conceives self-identity in strictly numerical terms and uses this numerical conception of identity as its criterion of truth. Given this conception of identity and this criterion of truth, perceptual consciousness must avoid the contradiction and under these assumptions it is a contradiction-between the unity of a thing and the plurality of its perceived properties. Consciousness’s third and most sophisticated strategy for resolving or avoiding this contradiction consists in distinguishing the different aspects of the perceived thing, referring them to different perspectives, and acknowledging them only under those different perspectives. In order to keep these aspects of the perceived thing distinct, perceptual consciousness “must therefore say, that the thing, insofar as it is for itself, is not for another.” That is to say, what a thing essentially is, it is independently of and apart from any relation to other things. However, by this stage perceptual consciousness has also experienced that the perceived thing does display two aspects, as a multitude of properties and as a particular unity. In its third phase perceptual consciousness regards these two aspects only in distinct perspectives. It regards the isolated thing as “self-identical” and it regards the plurality of its properties only in the thing’s relation to other things. Perceptual consciousness thus preserves both its conception of the identity of perceptible things as simple numerical unity and also its experience of the ineliminable plurality of the thing’s properties by distinguishing these two aspects and referring them to different “objects,” namely, to the isolated thing or to the thing only in its relations to other things. Accordingly, the perceived thing is, for itself, a unity, and the opposite moment, the plurality of its properties, is preserved both outside the (isolated) thing and outside of consciousness itself. Hegel states: “The thing is thus indeed self-identical in and for itself; but this unity with itself is disturbed by other things; thus the unity of the thing is retained.” This strategy preserves Hume’s view that each object gives us the idea of unity, and transfers Hume’s diachronic view, that we can only recognize the identity of a thing through the concurrent change of other things, to the synchronic identity of a thing with regard to the plurality of its properties, by ascribing this plurality of properties to it only with regard to the thing’s relations to other things. Because, on Hume’s view of time, a single unchanging object is literally timeless, the single object in and for itself is (temporally) simple. Only in regard to the changes undergone by other things can we represent-through a “fiction”-the unchanging, temporally simple thing as “participating” temporally in those changes in other things. Hume’s view is an exact diachronic analog to the synchronic view adopted by perceptual consciousness in its third phase, according to which an object, taken in isolation, is a simple, unitary “one,” which when taken in relation to other things displays an apparent plurality of properties.

Hegel’s argument against this view is very complex and can only be summarized here, but this suffices to see how Hegel’s conclusion relates to Hume. In its third phase the observed perceptual consciousness maintains that, insofar as a perceived thing is for itself, it is a “simple determinateness,” that is, it is some one specific thing; but insofar as the thing has a manifold constitution (Beschaffenheit), it is “for” or related to other things. Only the first aspect is essential to the thing; the second aspect, although necessary, is inessential. In this way perceptual consciousness retains the simple numerical unity of the thing, and its opposed aspect, i.e., its manifold of properties, is preserved outside the essence of the thing and also outside of consciousness itself. Through his phenomenological examination of this view Hegel purports to show that the perceived thing is the true and that it has being unto itself. The perceived thing is distinct from other things, not because it has the simple determinateness of being for itself; it is distinct from other things due to its constitution. Things themselves are thus essentially manifold in their constitution; they are mutually distinct because of their necessary and thus essential plurality of properties. In this way perceptual consciousness recognizes that the manifold constitution, that is, the plurality of properties, is as essential to the thing as its unitary being for itself. Consequently, the essence of the thing as a unitary being for itself lies in its complement, in the manifold constitution of its properties. On this basis Hegel draws the following conclusion:

In this way the last insofar, which separated the being for itself from the being for others, falls away. Instead the object is in one and the same regard the opposite of itself; it is for itself insofar as it is for another, and it u for another insofar as it is for itself the object is for itself, it is reflected into itself, it is one. But this being for itself, this reflection into itself, this being one, is posited in one unity with its opposite, with its being for an other. Consequently this being for itself (etc.) is posited only as sublated.

Hegel emphasizes that the thing is “the opposite of itself” because it is a single object, and likewise it is for other things (and for consciousness) only because it unifies a plurality of properties within itself. The main point here is that these two aspects of the thing, “in one and the same regard” are “posited in one unity.” Hegel’s result stands in express opposition to Hume’s. Recall that Hume reached the “more properly” formulated conclusion that the concept of identity “is either of them [i.e., unity or plurality], according to the view, in which we take it.” Thus despite his insight that the concept of identity must somehow combine both unity and plurality, Hume retains a strictly quantitative conception of this concept and he attempts to the very end to avoid the numerical contradiction between the unity of a thing and the plurality of its properties by distinguishing various perspectives in which to emphasize one or the other subconcept or aspect. Hegel’s analysis of perceptual consciousness purports to show that these strictly quantitative conceptions of unity and plurality are necessary but not sufficient for constructing the concept of the identity of perceptible things. The problem facing perceptual consciousness is this. At the outset perceptual consciousness has only the three necessary partial concepts of a perceptible thing, namely, its being unitary, its being a medium for properties, and its many properties. However, it does not have a unified, integrated concept of a perceptible thing. Perceptual consciousness rightly assumes that its criterion of self-identity is and must be numerical identity. However, through his diachronic analysis Hume in fact demonstrates exactly the same point that Hegel deepens and reconfirms through his synchronic analysis, namely, what results when one attempts to comprehend an internally complex thing without having an adequate, integrated concept of that kind of thing, or when one uses only the strictly quantitative concepts of unity and plurality. Without a properly integrated concept of the thing one can grasp neither the thing’s identity nor its distinction from other things. The concept of the identity of perceptible things requires an integrated concept of the internally complex thing, along with the quantitative concepts of unity and plurality. Hegel shows this by demonstrating that neither can the unity of the thing be understood without the plurality of its properties, nor can the plurality of its properties be understood without the unity of the thing. Both aspects of a perceptible thing are integrated in one unity in any regard in which the perceptible object can be considered. In an adequate concept of a perceptible thing both aspects “are posited only as sublated. “ That is the positive, indeed “speculative,” result of Hegel’s determinate negation of Hume’s view of identity.

This also provides the basic point of Hegel’s claim that the concept of identity of perceptible things contains an objectively valid contradiction. Michael Wolff has shown that Hegel’s view of “dialectical” contradictions neither denies nor violates the law of noncontradiction. Instead, Hegel holds that certain important truths can only (or at least can best) be expressed by using what appears to be a formal contradiction. In the case at hand, it can appear-as it did to Hume, and as it must to a concept-empiricist-that the two partial concepts contained in the concept of the identity of perceptible things, namely, unity and plurality, contradict each other. In the case of perceptible things and the relation between things and properties, this is not the case. On the contrary, both aspects are interdependent; there are no unitary things without a plurality of properties and there are no properties without unitary things of which they are properties. Indeed, Hegel’s point could now be expressed using a biconditional statement: Something is a perceptible thing if and only if it unifies a plurality of properties-and vice versa, if one will: Something is a plurality of properties if and only if they are unified in some one thing. An adequate concept of perceptible things integrates the two quantitatively opposed partial concepts, “unity” and “plurality.” Only with such an integrated concept of perceptible things can one grasp their identity.

Finally, two important and related points about the activity involved in cognition follow directly. First, we can perceive things only if we integrate the various sensations they cause in us; that is one cognitive activity on our part. Second, to integrate sensations or perceptions of things we must use a (relatively) a priori conception-a conception which cannot be defined or derived in accordance with concept-empiricism, and this is a conception we must ourselves produce in order to perceive any outer thing. This is a second cognitive activity on our part. Both of these cognitive activities are, obviously, compatible with common-sense realism about the objects of perception.


In sum, Hegel argues in “Perception” by reductio ad absurdum that the relation “thing-property” cannot be reduced to the relation “one-many” or, analogously, to the relation “whole-part” (which would involve the same quantitative difficulties). Only in Hume does one find the explicit attempt to avoid an apparent numerical contradiction within the concept of the identity of perceptible things by distinguishing “perspectives” in which to regard the thing. This attempt is fundamental to the third and final phase of Hegel’s analysis of perceptual consciousness, although neither the position nor the philosopher to which or to whom Hegel thereby refers have been previously identified. Examining the course of Hegel’s argument in context shows, I believe, that Hegel reached his results through an exacting reconsideration of a crucial section from Hume’s Treatise, “Of Scepticism with regard to the senses.”