The Hidden-Content Problem for Hatfield’s Theory of Cartesian Sensory Representation

September 10, 2026

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Does Phenomenal Color Represent Corporeal Microstructure? Gary Hatfield on Sensory Representation, Objective Reality, and Material Falsity

Gary Hatfield’s “Descartes on Sensory Representation, Objective Reality, and Material Falsity” (2012) offers one of the most sophisticated attempts to interpret Cartesian sensations of color, heat, cold, pain, and other sensory qualities as genuinely representational while preserving Descartes’s mechanistic account of bodies and avoiding the conclusion that God systematically gives human beings intrinsically false sensory representations. Hatfield argues that sensory ideas represent corporeal properties by resemblance, but in the case of secondary qualities the represented property is not phenomenal redness, coldness, sweetness, or pain. Rather, the sensory idea obscurely represents the corporeal microstructure that causes it. This post critically assesses Hatfield’s interpretation and contrasts it with my DTOI (Descartes’s theory of ideas) account on which secondary-quality sensations are formally real phenomenal modes that need not themselves possess objective reality representational content (OR), although they can function externally as lawfully connected signs of their corporeal causes.¹ The current component-level account of when content bears objective reality representations is developed in “When Does Content in an Idea Have Objective Reality?,” while the distinction between internal representation and external lawful signification is set out systematically in “DTOI & Non-DTOI Baselines for AI Models.” 🪂

Abstract

Hatfield develops a unified interpretation of Descartes’s theory of sensory ideas, objective reality, externalization, and material falsity. His central claim is that all sensory ideas represent by resemblance. In the case of shape and size, the resemblance is comparatively straightforward because spatial sensory content can correspond structurally to spatial properties of bodies. In the case of secondary qualities, however, Hatfield proposes that a sensation such as phenomenal red obscurely represents the microphysical surface configuration that causes it. He nevertheless rejects the view that materially false secondary-quality ideas intrinsically misrepresent bodies. Their obscurity instead makes them occasions for false judgments concerning what qualities bodies possess.

This post argues that Hatfield is right to reject intrinsic sensory misrepresentation and right to emphasize the lawful world-directedness and practical usefulness of sensation.² His positive account of secondary-quality representation, however, does not establish that the corporeal microstructure causing a sensory mode is also objectively contained in that sensory mode as its representatum. The central objection is a Hidden-Content Problem: if nothing in the phenomenal character of a red sensation discloses the microstructure supposedly represented, and that microstructure can be identified only through independent natural-philosophical reasoning, what makes the microstructure an internally represented object rather than merely the lawfully connected corporeal cause of the sensation? Hatfield’s appeals to obscurity and resemblance do not independently answer that question. My DTOI account therefore retains Hatfield’s rejection of intrinsic misrepresentation while replacing his hidden objective content with a distinction between phenomenal presentation, internal representation involving objective reality, and external representation through lawful signification. For the current account of which content within a cognition, if any, bears objective reality, see “When Does Content in an Idea Have Objective Reality?.”

Introduction

Gary Hatfield’s chapter, “Descartes on Sensory Representation, Objective Reality, and Material Falsity,” appears in Karen Detlefsen , ed., Descartes’ Meditations: A Critical Guide (Cambridge: Cambridge University Press, 2012), pp. 127–50. Hatfield’s paper is especially important because it does not treat material falsity as an isolated puzzle. Instead, it attempts to integrate Descartes’s views about the metaphysics of ideas, objective reality, sensory phenomenology, spatial localization, externalization, the mechanistic theory of matter, the teachings of nature, and the distinction between material and formal falsity.

Hatfield summarizes his interpretation by saying that “all sensory ideas represent by resemblance” and that materially false ideas of color and similar qualities “do not intrinsically misrepresent” (Gary Hatfield, “Descartes on Sensory Representation, Objective Reality, and Material Falsity,” in Karen Detlefsen , ed., Descartes’ Meditations: A Critical Guide [Cambridge: Cambridge University Press, 2012], 128). These two claims should be kept distinct. The first attributes genuine representational content to secondary-quality sensory ideas. The second denies that this content falsely attributes phenomenal sensible qualities to bodies.

That combination makes Hatfield’s position considerably stronger than interpretations according to which a sensation of cold or red intrinsically misrepresents its external cause as possessing a quality resembling phenomenal coldness or redness. Nevertheless, the central question remains whether Hatfield has established the first claim. Does a phenomenal secondary-quality sensation itself internally represent the corporeal microstructure that causes it, thereby possessing objective reality of that microstructure? Or can the same Cartesian evidence be explained more economically by treating the sensory mode as a formally real presentation that functions as a lawfully instituted sign of its bodily cause? The latter possibility follows directly from the component-level account defended in “When Does Content in an Idea Have Objective Reality?,” according to which the question is not whether an entire cognition has OR, but which content within it, if any, is OR-bearing.

The second interpretation is preferable. Hatfield correctly identifies important truths about the world-directed function of sensation, but he converts a causal and signifying relation into an internal representational relation without sufficient independent argument.

Hatfield’s General Theory of Sensory Representation

Hatfield begins from Descartes’s general characterization of ideas as thoughts that are, in one important sense, “as if the images of things” [my preferred translation]. In the Third Meditation Descartes distinguishes among his thoughts and writes [in the Cottingham translation] that “some of my thoughts are as it were the images of things, and it is only in these cases that the term ‘idea’ is strictly appropriate.” (AT VII 37; CSM II 25; bold not in original) This passage is crucial because it identifies a strict class of ideas whose representational character cannot simply be generalized to every mental state that Descartes elsewhere calls an idea.

My DTOI interpretation therefore distinguishes a strict sense of idea, applicable to genuinely representational thoughts, from a broader sense according to which the form of a thought can count as an idea without possessing an internal representatum. (AT VII 160; CSM II 113)

The strongest current defenses of this distinction are “Condensation: Why Objective Reality Cannot Be Descartes’s Theory of Thought: Burman, Common Notions, and the Failure of the Strict Idea Model, (a condensed version of the full post): “Why Objective Reality Cannot Be Descartes’s Universal Theory of Thought: Burman, Common Notions, and the Collapse of the Strict-Idea Model,” and “Why Objective Reality Cannot Be Universal in Descartes’s Theory of Ideas: Nothing, Eternal Truths, Sensations, and Fear with Claude Opus 4.6.”

This matters because Hatfield’s interpretation requires more than the claim that sensations are mental modes or even that Descartes calls them ideas. A related debate over whether Cartesian sensations should count as internally representational and OR-bearing is examined in my “Alison Simmons on sensations as representations and objective reality,” which helps isolate the same question that arises for Hatfield: whether world-directed sensory function is sufficient for objective-reality-bearing internal representation. To conclude that a sensation of red possesses objective reality of a corporeal microstructure, Hatfield must establish that the sensation belongs to the narrower representational category relevant to Descartes’s doctrine of objective reality. The mere fact that a sensation is a conscious mental mode is insufficient.

Descartes’s later broad definition of idea confirms the distinction rather than eliminating it. In the Second Replies he defines an idea as “the form of any given thought, immediate perception of which makes me aware of the thought” (AT VII 160–61; CSM II 113–14). This definition readily includes sensory, affective, and volitional states as forms of thought without establishing that every such form contains objectively real representational content. The distinction between the strong universal thesis that all ideas contain OR and the weaker universal thesis that all ideas are internally representational is developed explicitly in “Why Objective Reality Cannot Be Descartes’s Universal Theory of Thought: Burman, Common Notions, and the Collapse of the Strict-Idea Model” and its shorter companion “Condensation: Why Objective Reality Cannot Be Descartes’s Theory of Thought.”

Hatfield himself makes the relevant universalizing move explicit:

“I not only take Descartes at his word when he says that ‘the objective mode of being belongs to ideas by their very nature’ (7: 42), but I also take him to be saying with this phrase that all ideas represent.” (Gary Hatfield, “Descartes on Sensory Representation, Objective Reality, and Material Falsity,” in Karen Detlefsen, ed., Descartes’ Meditations: A Critical Guide [Cambridge: Cambridge University Press, 2012], 144)

Hatfield’s sentence therefore supports two claims that should be distinguished: the stronger thesis that objective being belongs to all ideas by their nature and the weaker thesis that all ideas represent. His argument uses the former to support the latter. My DTOI interpretation challenges the unrestricted scope of both claims rather than denying that every strict idea is OR-bearing and representational. Descartes has already distinguished the strict ideas to which “the term ‘idea’ is strictly appropriate” from broader forms of thought, and the later objective-reality argument should not simply be extended from the former to every item that can be called an idea in the broader sense. See my “Strict And Broad Ideas In DTOI.”

Phenomenal Redness and Corporeal Microstructure

Hatfield’s most distinctive proposal concerns secondary qualities. Descartes’s physics allows bodies only geometrically and mechanically intelligible properties such as extension, figure, size, position, motion, rest, and arrangements of matter. Phenomenal redness therefore cannot simply resemble a literally red quality formally inhering in an external body.

Hatfield nevertheless wishes to preserve the claim that the sensory idea represents by resemblance. His solution is to identify the representatum not with phenomenal redness but with the corporeal microstructure responsible for causing the sensory state. He writes:

“The sensory idea of red is an obscure representation of a surface texture.” (Gary Hatfield, “Descartes on Sensory Representation, Objective Reality, and Material Falsity,” in Karen Detlefsen, ed., Descartes’ Meditations: A Critical Guide (Cambridge: Cambridge University Press, 2012), 134)

This is a subtle position. Hatfield is not claiming that phenomenal redness resembles the surface texture in the ordinary phenomenological sense. Indeed, contemplation of redness does not reveal the shape, arrangement, or motion of corpuscles. The represented microstructure is supposed to be present only obscurely.

The distinction between the phenomenal reality of the sensory mode and any alleged objectively real content is essential here. As argued in “When Does Content in an Idea Have Objective Reality?,” formal actuality and objective reality answer different questions at the level of constituent content. Phenomenal redness can actually exist as a formally real modification of mind without thereby containing redness, a surface texture, or anything else as objectively real representational content.

The difficulty for Hatfield can therefore be put sharply. Suppose a corporeal microstructure M lawfully causes a phenomenal red sensation R. From the causal proposition

M causes R

it does not follow that

R internally represents M.

Still less does it follow that R resembles M. A further account is required to explain how causal dependence becomes objective representational content.

The DTOI alternative is instead:

M → lawfully causes R → R functions as a natural sign of M.

This preserves the systematic relation between bodies and sensations without putting the corporeal cause inside the sensory mode as its objectively real representatum. My interpretation entirely agrees with Hatfield that “The sensory idea of red is an obscure representation of a surface texture.” Still, I interpret the phrase “obscure representation” as an external representation, a sign of that micro-physical structure. The obscurity results from secondary quality sensations, such as cold, having only formally real phenomenal properties and no internal representatum (an item internally represented). See my supporting posts “Do Cartesian Sensations Have Objective Reality?: Strict Ideas, Broad Ideas, And Material Falsity In Descartes’s Theory Of Ideas” and “Why There Are No Successful Candidates For SQ-Sensations Objective Reality Content.”

The distinction between internally representing something and functioning externally as a law-governed sign of it is developed most explicitly in “DTOI & Non-DTOI Baselines for AI Models” and in “Presentation Without Representation: Material Falsity, Availability of Ideational Content, and Internal/External Representation in Descartes.”

Why “Obscure Representation” Does Not Establish Representational Content

Hatfield can respond that the microstructure is not absent from the sensory idea. It is merely represented obscurely. But this answer presupposes precisely what requires proof.

There is a categorical difference between representing X obscurely and not representing X while being causally related to X. Before “obscurely” can qualify an act of representation, there must already be reason to hold that representation occurs. Obscurity can explain why represented content is difficult to discriminate; it cannot independently establish that a particular content is represented in the first place.

The problem becomes particularly acute because the person experiencing phenomenal red need possess no conception of the microphysical configuration Hatfield identifies as its content. The relevant corpuscular structure becomes identifiable only through independent metaphysical and natural-philosophical reasoning. The philosophical question is therefore whether natural philosophy discovers what the sensation had represented all along or instead discovers what bodily state had been causing the sensation all along. Hatfield needs an argument for the former rather than the latter.

“When Does Content in an Idea Have Objective Reality?” supplies the relevant DTOI criterion: phenomenal determinacy or conscious presentation does not by itself make content OR-bearing. Phenomenal coolness, for example, can be immediately presented to consciousness without thereby being an objective representation either of phenomenal coldness or of an external bodily property. The complementary availability argument in “Presentation Without Representation: Material Falsity, Availability Of Ideational Content, And Internal/External Representation In Descartes” sharpens the problem for hidden microstructure: obscurity does not license attributing permanently inaccessible internal representational content to the sensation merely because natural philosophy can later identify its cause.

If the only evidence that R represents M is that M systematically causes R, then the account threatens to identify causal covariance with internal representation. But causal covariance can explain natural signification without objective reality. A pain can signify tissue disturbance without containing tissue disturbance as its internal representational object. A sensory quality can likewise distinguish corporeal circumstances without objectively containing their microstructure.

The Resemblance Problem

Hatfield’s appeal to resemblance creates an additional difficulty. In ordinary cases of representational resemblance, some relevant common structure can be specified. A geometrical diagram can resemble a geometrical figure because spatial relations in the diagram correspond to spatial relations in what it depicts. But no comparably identifiable geometrical or structural feature is manifest in a sensory idea of phenomenal red that corresponds to the size, shape, motion, or arrangement of the microscopic particles allegedly represented.

This creates a dilemma. If Hatfield intends resemblance in a robust representational sense, he must identify some feature or structure within the sensory idea of red by virtue of which that idea resembles the corpuscular surface texture. If no such internally available structure can be identified and the relation consists only in lawful correspondence under divinely instituted psychophysical laws, then the account has effectively become one of external signification rather than resemblance.

The latter result strongly favors my DTOI account. The sensation need not reproduce or internally represent the structure responsible for causing it. It need only reliably discriminate bodily states through the psychophysical laws governing mind–body union. “DTOI & Non-DTOI Baselines for AI Models” and “Presentation Without Representation” formulate precisely this distinction between internal representation involving objective reality and external representation by law-governed signification.

Primary Qualities Are a Different Case

Hatfield’s account is considerably stronger when applied to spatial perception. Visual cognition can contain determinate spatial articulation: figure, location, relative size, distance, and motion. In such cases it is intelligible that some structure within cognition corresponds to the geometrical structure of its object.

Nothing in my DTOI interpretation requires denying that a sensory episode can occur together with OR-bearing spatial content. The relevant question is not whether a cognition is globally “sensory” or “intellectual,” but which content within the cognition, if any, is OR-bearing. A complex perceptual cognition might therefore contain an internally represented figure while its accompanying phenomenal redness remains merely a formally real sensory mode.

This yields an important asymmetry:

Shape: may be internally represented as a genuine mode of extension and therefore bear objective reality.
Phenomenal redness: is immediately presented as a formally real mode of sensation.
The microstructure causing redness: can be externally signified by the sensation without being objectively contained within it.

Hatfield’s attempt to treat both shape and color through the same resemblance-based representational architecture therefore risks erasing a philosophically important Cartesian difference. The component-level distinction between the formal actuality of the cognition and the objectively real content within it is developed directly in “When Does Content in an Idea Have Objective Reality?.”

Spatial Localization Does Not Entail Objective Reality

Another attractive feature of Hatfield’s interpretation is his emphasis on spatial localization. Sensory qualities do not normally appear as phenomenally unlocated modifications. Redness appears distributed across a region of the visual field identified with the surface of an object. Pain appears located in a hand, foot, tooth, or other bodily region. Heat can appear located in an external object or bodily location.

This phenomenology helps explain externalization, but externalization by itself does not establish objective reality content. Pain can phenomenally occur “in the foot” without the pain itself representing a pain-quality formally inhering in corporeal foot matter. Similarly, phenomenal redness can appear spread over an apple-shaped region without phenomenal redness thereby objectively representing the apple’s microscopic surface configuration.

Spatial organization can therefore explain where a sensory state directs the perceiver while causal coordination explains which bodily condition the sensation tracks. Neither fact entails that the sensory quality itself contains an internal representatum. This component-level analysis is developed in “When Does Content in an Idea Have Objective Reality?,” while the distinction between internal OR-bearing representation and external lawful signification is developed in “DTOI & Non-DTOI Baselines for AI Models.”

Hatfield on Material Falsity

Hatfield’s treatment of material falsity is one of the strongest parts of his interpretation. He expressly denies that materially false ideas of color and similar sensory qualities “intrinsically misrepresent” bodies (Hatfield 2012, p. 128). This places Hatfield much closer to the DTOI interpretation than accounts on which a sensation intrinsically attributes to a body a sensible quality resembling its phenomenal character.

Descartes initially introduces the problem in Meditation III when considering ideas of heat, cold, light, colors, sounds, tastes, and other sensory qualities. Of materially false ideas he writes that they “represent non-things as things” (cum non rem tanquam rem repraesentant) (AT VII 43; CSM II 30).

The central DTOI claim is that the verb translated as “represent” in this context need not mean that the sensory idea contains false objectively real representational content. The sensory mode can instead present phenomenal coldness or redness positively to consciousness. This presentational character can make the sensory mode naturally apt to be taken as disclosing a corresponding positive quality in a body even though no such sensible quality exists there.

This interpretation is developed in detail in “What Makes an Idea Materially False in Descartes’s Theory of Ideas?: Why Mere Error-Causation Is Insufficient, Why the Three Main Cases Form an Analogical Unity, and Why Hoffman Mislocates the Relevant Non-Thing with ChatGPT 5.4 Thinking” and in “Presentation Without Representation: Material Falsity, Availability of Ideational Content, and Internal/External Representation in Descartes.” These posts jointly argue that the intrinsic ground of sensory material falsity need not be false objective content and must be stronger than the bare fact that an idea happens to cause a subsequent false judgment.

Why Mere Error-Causation Is Too Weak

Hatfield interprets materially false sensory ideas as affording occasions for false judgments. This is correct as far as it goes, but it risks making material falsity too weak. Almost any perfectly legitimate idea can occasion a false judgment. Someone can contemplate a perfectly adequate idea of a triangle and falsely judge that triangles have four sides. The possibility that an idea occasions error does not make that idea materially false.

Something intrinsic to the materially false idea must explain why it furnishes materia erroris in the relevant special way. Descartes explains in the Fourth Replies that materially false ideas are “such as to provide subject-matter for error” (AT VII 231; CSM II 162).

The better interpretation makes the sensory episode’s own phenomenal presentation responsible for its special propensity toward error. Phenomenal coldness presents itself positively. Because this sensory presentation fails to determine what, if anything, corresponds to it in bodies, the perceiver can easily take that positivity to belong to an external corporeal object. Material falsity therefore exists prior to the false judgment without itself being a false judgment or an intrinsically false internal representation.

The distinction is central to “What Makes an Idea Materially False in Descartes’s Theory of Ideas?: Why Mere Error-Causation Is Insufficient, Why the Three Main Cases Form an Analogical Unity, and Why Hoffman Mislocates the Relevant Non-Thing with ChatGPT 5.4 Thinking.” Its principal point applies directly against a weak reading of Hatfield: being capable of producing a false judgment cannot by itself be sufficient for material falsity.

The God-Deceiver Constraint

Hatfield is right to take seriously the theological constraint imposed by Descartes’s doctrine that God is no deceiver. An interpretation on which normal sensory faculties systematically produce intrinsically false representations of bodies creates an obvious difficulty. If God instituted the ordinary connection between bodies and sensory states, why would the proper operation of those faculties itself consist in representing bodies as having properties they do not possess?

Hatfield’s solution is ingenious: the sensory idea of red does not falsely represent a body as possessing phenomenal redness; instead, it obscurely but correctly represents the real microphysical surface configuration that produces it. The sensory faculty is therefore representational without being inherently deceptive.

But this is not the only available solution. The DTOI account blocks divine deception more directly. If the sensation does not internally assert, depict, or represent that the external body possesses a quality resembling phenomenal redness, then there is no false internal representation for God to have caused. God need only institute a reliable psychophysical correlation by which different corporeal structures generate discriminably different sensory modes.

Thus there is a third possibility between accurate internal representation and inaccurate internal representation:

the sensory state is not an OR-bearing internal representation of its corporeal cause at all;
it is nevertheless lawfully and reliably connected to that cause;
it therefore functions as a natural sign useful to the embodied human being.

This third possibility is articulated systematically in “DTOI & Non-DTOI Baselines for AI Models” and “Presentation Without Representation,” while its consequences for the ontology of OR-bearing content are developed in “When Does Content in an Idea Have Objective Reality?.”

The Third Meditation Cold Passage Creates a Special Problem for Hatfield

The Third Meditation discussion of heat and cold is especially difficult for Hatfield’s theory. Descartes says that these sensory ideas are so obscure and confused that he cannot determine from them whether cold is a privation of heat, heat a privation of cold, both are real qualities, or neither is a real quality (AT VII 43–44; CSM II 30).

If Hatfield is correct, however, the sensation possesses a determinate positive corporeal representatum: a microphysical configuration of extension, figure, and motion. The perceiver simply cannot discern that content because it is represented obscurely.

This interpretation is possible, but it is not what the Third Meditation passage itself establishes. The text establishes an epistemic insufficiency: examining the sensation does not tell the meditator whether anything corresponding to its phenomenal positivity is a positive quality, a privation, or neither. Hatfield converts that insufficiency into the stronger thesis that a determinate bodily structure is already represented but hidden through obscurity.

My DTOI interpretation takes the passage more literally. The cold sensation does not contain internally determinate object-fixing content concerning what bodily property corresponds to it. Hence the perceiver cannot read such content out of the sensation. The broader argument that secondary-quality sensations block the inference from broad-sense ideahood to objective reality or to universal internal representation is developed in “Why Objective Reality Cannot Be Descartes’s Universal Theory of Thought,” “Condensation: Why Objective Reality Cannot Be Descartes’s Theory of Thought,” and “Why Objective Reality Cannot Be Universal in Descartes’s Theory of Ideas.”

The same conclusion is incorporated into the more recent component-level account in “When Does Content in an Idea Have Objective Reality?,” which argues that phenomenal coolness can be determinate and consciously presented without contributing objective reality of its own. “Presentation Without Representation” adds the further point that genuinely internal ideational content should not be postulated as permanently inaccessible hidden content merely to preserve a universal representational theory.

The Fourth Replies Support Presentation Rather Than Hidden Objective Content

The Fourth Replies make the problem even sharper. Descartes explains that, because the idea of cold is obscure and confused, he cannot determine whether what it exhibits to him is something positive existing outside his sensation (AT VII 234; CSM II 164).

Most importantly, Descartes explains why the meditator comes to posit an external cold object:

“But the obscurity of the idea is the only thing that leads me to judge that the idea of the sensation of cold represents some object called ‘cold’ which is located outside me; and this obscurity in the idea does not have a real cause but arises simply from the fact that my nature is not perfect in all respects.” (René Descartes, Fourth Replies, AT VII 233; CSM II 164)

This passage creates difficulty for the claim that the sensation already contains a determinate corporeal representatum. Descartes does not say here that obscurity prevents the meditator from recognizing which external object the sensation really represents. He says that the obscurity is what leads him to judge that the sensation represents some external object called “cold.” The objectifying representational interpretation therefore appears at the level of judgment.

This text plays a central role in “What Makes an Idea Materially False in Descartes’s Theory of Ideas?: Why Mere Error-Causation Is Insufficient, Why the Three Main Cases Form an Analogical Unity, and Why Hoffman Mislocates the Relevant Non-Thing with ChatGPT 5.4 Thinking” and “Presentation Without Representation.” It provides strong evidence against locating a positive external sensible representatum within the sensation itself.

Objective Reality Is the Deepest Disagreement

The deepest disagreement between Hatfield and DTOI is therefore not ultimately about material falsity. Both reject a simple intrinsic-misrepresentation theory. The fundamental disagreement concerns objective reality.

Objective reality is not simply whatever a thought concerns, whatever causes it, or whatever it enables us to discriminate. It is the reality possessed by a representatum insofar as that represented content exists objectively in an idea. The most precise current formulation of this point is developed in “When Does Content in an Idea Have Objective Reality?,” which distinguishes the formal actuality and other determinations of a cognition from the OR-bearing representational content by which a representatum is internally present as represented.

Hatfield’s account can grant this distinction. The dispute is not whether Hatfield distinguishes formal reality from objective reality, but whether he has shown that the corporeal microstructure is objectively present in the sensation rather than merely lawfully related to it as cause or signified condition.

The proper criticism is therefore more precise: Hatfield has not established that the formally real sensory modification contains its corporeal cause objectively in addition to being lawfully caused by and correlated with it.

This is precisely the burden imposed by “When Does Content in an Idea Have Objective Reality?”: the formal actuality, phenomenology, or determinacy of a cognition does not itself establish the presence of an OR-bearing representatum. Hatfield must identify the content within the red sensation by which the microstructure is internally present as represented. The same burden appears in “Why Objective Reality Cannot Be Descartes’s Universal Theory of Thought”: once universal internal representation is rejected as a default assumption, each alleged representatum must be established rather than presupposed.

The Hidden-Content Problem

Hatfield’s theory can now be confronted with what may be called the Hidden-Content Problem.

Suppose a sensory mode R of phenomenal red contains microstructure M objectively. Then M is supposed to be the representational content by virtue of which R is an idea of M. Yet all of the following can be true:

the phenomenal character of R does not disclose M;
reflection on R cannot reveal M;
the perceiver need possess no conception of M;
the perceiver may possess no corpuscular physics capable of describing M;
M is identified only through independent natural-philosophical investigation;
the causal connection between M and R already explains why R reliably covaries with M.

The question is therefore unavoidable: what makes M content of R rather than merely cause of R?

Saying that R “obscurely represents” M restates the disputed thesis. Saying that God institutes a lawful connection between them establishes signification, not objective containment. Saying that they systematically covary establishes a reliable causal relation, not internal representation. And saying that R resembles M requires an independently identifiable dimension of resemblance.

The Hidden-Content Problem therefore exposes the central explanatory deficit in Hatfield’s account. His theory adds objective reality to a causal and sign-theoretic structure that already explains the sensory phenomena. As argued in “The Core DTOI Argument: Sensations Without Cartesian Objective Reality,” “DTOI & Non-DTOI Baselines for AI Models,” “Presentation Without Representation: Material Falsity, Availability of Ideational Content, and Internal/External Representation in Descartes,” and “Privations, Sensations, and Objective Reality: A Closer Look At Arnauld’s Misinterpretation Of Descartes’s Ideas With ChatGPT 4o,” the body can lawfully cause a sensory mode that phenomenally presents itself to consciousness while functioning externally as a dependable sign of bodily conditions, without containing those bodily conditions as objectively real internal content. The further ontological point—that formal actuality and phenomenal determinacy do not by themselves establish OR-bearing content—is developed in “When Does Content in an Idea Have Objective Reality?.” The simpler theory is that the body causes the sensory mode, the mode phenomenally presents itself to the mind, and the law-governed relation between them enables the sensory mode to signify bodily circumstances externally. No hidden microstructural representatum is required.

This conclusion follows the criterion developed in “When Does Content in an Idea Have Objective Reality?”: OR belongs specifically to content by which an ontologically eligible representatum is internally present as represented. Lawful covariance and phenomenal determinacy do not suffice. The complementary sign-theoretic and availability accounts appear in “DTOI & Non-DTOI Baselines for AI Models” and “Presentation Without Representation.”

What Hatfield Gets Right

The objections above should not obscure several important strengths in Hatfield’s interpretation. He correctly resists treating Cartesian sensations as wholly disconnected subjective qualia that have no systematic relation to the world. Sensory modes belong to a divinely instituted psychophysical system that enables embodied human beings to distinguish environments, objects, benefits, harms, bodily conditions, and changes in external circumstances.

Hatfield is also right to reject the claim that materially false sensations must therefore intrinsically misrepresent external objects. That rejection is a major point of agreement with my DTOI interpretation. It avoids placing systematic falsity inside normal God-given sensory functioning and keeps formal falsity where Descartes officially locates it: in judgment. Agreement on this negative point does not entail agreement on the positive ground of material falsity: Hatfield emphasizes obscurity as permitting false judgment, whereas my DTOI interpretation locates the distinctive source of materia erroris in the sensory mode’s own phenomenally positive presentation.

Finally, Hatfield rightly stresses that the sensory system has genuine cognitive and practical value even when it does not disclose the intrinsic natures of bodies. The legitimate teachings of nature need not amount to direct revelation of corporeal essence. Different sensations can reliably indicate genuine differences among corporeal causes and genuine differences in what benefits or harms the mind–body composite.

My DTOI interpretation can retain all three insights without accepting Hatfield’s attribution of objective reality to secondary-quality sensations. The resulting position is not that sensations have no world-directed role. It is that world-directed function does not entail internal OR-bearing representation.

A Better Cartesian Model of Secondary-Quality Sensation

My DTOI alternative can be represented schematically:

Corporeal microstructure: a formally real configuration of extended matter.
Causal relation: the corporeal configuration participates through the sensory organs, nerves, and brain in causing a sensory mental mode.
Sensory mode: phenomenal redness, coldness, pain, taste, or another formally real mode of thought is presented immediately to consciousness.
External signification: because the sensory mode is lawfully correlated with bodily and environmental conditions, it can function as a natural sign of those conditions.
No necessary internal OR: the bodily microstructure need not exist objectively as a representatum inside the sensation.
Material falsity: the phenomenal positivity and obscurity of the sensory mode furnish subject-matter for erroneously judging that a corresponding sensible quality exists in a body.

The ontology of this model is developed most precisely in “When Does Content in an Idea Have Objective Reality?,” while the intrinsic sensory mode/external sign distinction is formulated systematically in “DTOI & Non-DTOI Baselines for AI Models” and “Presentation Without Representation.” The arguments that secondary-quality sensations provide counterexamples both to universalizing objective reality and to treating every broad-sense Cartesian idea as a strict internal representation are further developed in “Why Objective Reality Cannot Be Descartes’s Universal Theory of Thought” and “Why Objective Reality Cannot Be Universal in Descartes’s Theory of Ideas.”

Revising the Earlier Objection to Hatfield

A full reading of Hatfield’s paper requires one important refinement of a simpler objection that might initially be directed against him. Hatfield should not be accused of merely confusing formal reality with objective reality. His position is more sophisticated. The phenomenal sensory state is formally real as a modification of the mind, while the corporeal microstructure allegedly exists objectively in that sensory idea as what it represents.

The stronger criticism is accordingly not:

Hatfield confuses the formal reality of the sensory mode with its objective reality.

It is instead:

Hatfield has not established that the formally real phenomenal mode contains the causally relevant microstructure objectively in addition to being lawfully caused by and correlated with it.

This formulation preserves the genuine sophistication of Hatfield’s account while placing the burden of proof exactly where it belongs. The distinction between the formal existence and other determinations of a mental modification and the objective reality of any representational content within it is developed directly in “When Does Content in an Idea Have Objective Reality?.”

Conclusions

Hatfield’s interpretation is valuable because it sees that Descartes’s account of sensory cognition must satisfy several constraints simultaneously. Sensations are genuine conscious modes. They are systematically connected with the world. They are useful for embodied life. Secondary-quality phenomenology does not straightforwardly resemble sensible properties formally existing in bodies. Materially false sensations must somehow furnish subject-matter for error without making ordinary sensation a form of intrinsic divine deception.

Hatfield’s theory handles many of these constraints well. In particular, his insistence that secondary-quality sensations “do not intrinsically misrepresent” is substantially correct and should be retained. His account of the legitimate teachings of nature also properly emphasizes that sensory experience reliably differentiates bodily circumstances without revealing bodies exactly as they are in themselves.

The central weakness lies in Hatfield’s positive theory of what secondary-quality sensations represent. The inference from a corporeal configuration’s lawfully causing a sensory mode of phenomenal redness to that sensory mode’s internally representing the configuration is not secured merely by calling the representation obscure. Nor does appeal to resemblance solve the problem unless some genuine feature or structure within the sensory idea can be identified by virtue of which it resembles the corpuscular configuration.

The Hidden-Content Problem exposes the issue most clearly. If a perceiver cannot find the alleged microstructural content in the sensation, need possess no conception of that content, and discovers the relevant microstructure only through an independent causal theory, then a further argument is required to show that natural philosophy has discovered what the sensation represents rather than merely what causes it.

No such additional internal representational content is needed. The better model distinguishes three relations that Hatfield’s account tends to draw too closely together: phenomenal presentation, internal representation involving objective reality, and external representation through lawful signification. The ontological restriction on OR-bearing content is developed in “When Does Content in an Idea Have Objective Reality?,” while “Presentation Without Representation” and “DTOI & Non-DTOI Baselines for AI Models” distinguish internal representational content from phenomenal presentation and external lawful signification.

On this alternative, the corporeal microstructure formally exists in the body. Through Descartes’s psychophysical laws it causes a formally real phenomenal sensory mode in the mind. The sensation presents phenomenal redness, coldness, pain, or another qualitative character directly to consciousness. Through its lawful causal relation to bodily configurations, it can function externally as a natural sign of those configurations. Nothing requires the corporeal cause also to be duplicated within the sensation as an objectively real representatum.

This account also gives material falsity a more precise role. A cold sensation need not internally misrepresent a body. Its own phenomenally positive yet externally indeterminate presentation can nevertheless furnish subject-matter for judging that a corresponding positive cold quality exists in an external object. As argued in “What Makes an Idea Materially False in Descartes’s Theory of Ideas?: Why Mere Error-Causation Is Insufficient, Why the Three Main Cases Form an Analogical Unity, and Why Hoffman Mislocates the Relevant Non-Thing with ChatGPT 5.4 Thinking,” this allows material falsity to belong intrinsically to the sensory presentation without turning it into either formal falsity or false objectively real content.

The most important question for Hatfield’s interpretation can therefore be stated in a single sentence: What independent Cartesian reason is there for holding that the corporeal microstructure which lawfully causes a red sensation is objectively contained as that sensation’s representatum, rather than holding simply that the sensation is a formally real phenomenal mode functioning as a divinely instituted sign of that microstructure?

Hatfield’s paper does not provide a sufficient answer. Once causal dependence, phenomenological presentation, and natural signification have been distinguished from internal objectively real representation, the latter no longer appears necessary. Much of Hatfield’s account can therefore be retained—especially his rejection of intrinsic sensory misrepresentation and his emphasis on the useful world-directedness of sensation—while his central attribution of hidden microstructural objective reality to secondary-quality sensations can be rejected.

References and Related DTOI Posts

NOTES

1
See Anna Ortín Nadal, “Descartes on Natural Signs and the Case of Sensory Perception,” Journal of Modern Philosophy 6 (2024): 77–87. ↩︎
2
For the current DTOI account of why material falsity need not consist in intrinsically false objective content, see “What Makes an Idea Materially False in Descartes’s Theory of Ideas?: Why Mere Error-Causation Is Insufficient, Why the Three Main Cases Form an Analogical Unity, and Why Hoffman Mislocates the Relevant Non-Thing with ChatGPT 5.4 Thinking.”

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