A Reidian Response to the Problem of Secondary Qualities

A Reidian Response to the Problem of Secondary Qualities

A Dissertation Prospectus

By Christopher Shrock

Words: 6,872

When I perceive the world, it presents itself to my senses as filled with colors, sounds, smells, and tastes. Objects are short or long, of particular shapes, hard or soft, solid or viscous. But science, humankind’s best systematic attempt to understand the world, offers a different picture. The scientific world consists of quantum fluctuations, bosons and fermions, curved space-time, and wave-particle dualities. And it seems that, if the scientific depiction is true, then my perceptions deceive me by presenting me a false world. Even if scientists can make sense of length, hardness, and solidity, other qualities, like colors, sounds, and smells, have no place among the entities and qualities that science posits. Howard Robinson goes as far as to claim that science has shown that objects do not possess these qualities intrinsically.[1] Furthermore, as I am certain that I see colors, hear sounds, and smell smells, the truth of the scientific image of the world seems to imply a deceptiveness on the part of my sense perceptions. What I see is illusory, and at least some objects of my perceptions are neither real physical objects nor their qualities.

Scientists and philosophers from Galileo to the present claim that secondary qualities (i.e., colors, sounds, smells, tastes, and heat and cold) are illusory.[2] I intend to offer a possible reconciliation of the worlds of science and sense perception based on Thomas Reid’s account of primary and secondary qualities as he describes them in his direct realist theory of perception. Sense perceptions are not deceptive. The immediate objects of sense perceptions, including the secondary qualities, are real qualities of physical objects (hereafter, bodily qualities) despite claims to the contrary. Reid’s account of primary and secondary qualities marries the disparate deliverances of perception and science. The perceptual and the scientific are not vastly different worlds, but rather different understandings of the same world. My response will consist of an exposition of Reid on primary and secondary qualities and their role in his direct realist theory of perception, as well as a defense of Reid’s primary-secondary quality distinction in light of contemporary science. In particular, I will introduce a Reidian theory of color, and, perhaps, assess scientific progress towards a theory of heat.

Dissertation Outline

I plan to make my argument in four chapters. The first two will explicate the problem of secondary qualities and introduce a new reading of Reid’s account of primary and secondary qualities that shows its role in solving the problem. The last two chapters will develop that solution in two ways. First, I will show how my reading solves a historical problem in Reid interpretation, namely, by offering a correct and coherent interpretation. Then, I will defend Reid’s doctrine, by proposing a theory of color.

Chapter 1. Because the problem of the illusoriness of secondary qualities lies deep within the early modern (and contemporary) discussion, the first chapter will expose the importance of secondary qualities for science and perception. I will show how scientific theories create problems for direct realism. And, beginning with the early modern understanding of the physical world, I will explain why scientists and philosophers reject secondary qualities as real qualities of bodies, how this rejection naturally leads to skepticism about the external world, and why secondary qualities continue to pose a problem for direct realism.

Chapter 2. The second chapter will introduce my interpretation of Reid on primary and secondary qualities and describe the importance of the primary-secondary quality distinction in Reid’s direct realist account of perception. I will discuss the role of these qualities in Reid’s answer to the external world skeptic. Then, I will detail the ways that Reid’s diction provides a framework for marrying the worlds of science and sense perception. Moreover, I will explain the relationship of primary and secondary qualities to Reid’s doctrine of natural signs and his account of original and acquired perceptions.

Chapter 3. I will explain how my interpretation differs from other contemporary readings and why mine should be preferred. This exercise will lead me to flesh out my various interpretive commitments from the previous chapter. I will argue that visible figure is not a primary quality, differentiate Reid’s primary-secondary quality distinction from his historical account of the errors of other philosophers, and show the distinction’s relevance to his philosophy of science.

Chapter 4. I will argue that Reid’s distinction remains tenable in the world of contemporary science. I will show how Reid’s predictions about scientific progress have faired in the cases of two secondary qualities, heat and color. In the later case, I will show how Reid’s primary-secondary quality distinction grounds a theory of color on which colors are intrinsic qualities of bodies but color terms (i.e., “red,” “green,” “blue,” etc.) are not names for natural kinds.

Chapter 1 Summary

Our sense perceptions lead us to believe that secondary qualities are intrinsic qualities of physical bodies. They exist apart from us and our perceptions of them, and they cause those perceptions by means of our five senses. These include colors, sounds, smells, tastes, and heat and cold. According to my senses, the brownness of the table before me is as real as its hardness. Its coolness is as present to my senses as its smoothness. The primary and secondary qualities of the table blend to make a single and coherent whole. However, according to science, the table is not at all as my senses suggest. Perhaps it is somewhat hard and smooth. These qualities explain its virtue as a writing surface. But brownness and coolness are really nothing more than my own projections of mental phenomena onto the physical table.

For some philosophers, this disparity between the scientific and perceptual worlds is enough to demonstrate the importance of the problem of secondary qualities. But, for Reid, the problem runs much deeper. Reid’s primary target in his attack on the ‘Way of Ideas,’ Hume’s Treatise of Human Nature, infers from the illusoriness of secondary qualities to the non-existence of matter in a mere three pages.[3] I will not rehearse Hume’s or any other argument from the problem of secondary qualities to external world skepticism here, but I do plan to devote a small section in the dissertation to explaining the importance of the problem of secondary qualities as it relates to skepticism. My present task is merely to explain why our perceptual and scientific understandings of the world are in conflict.

Secondary Qualities according to Science

The terms ‘primary quality’ and ‘secondary quality’ originate with seventeenth century scientist Robert Boyle (1627-1691) and receive their most famous treatment from his student John Locke (1632-1704). But the distinction between primary and secondary qualities itself appears somewhat earlier in the philosophy accompanying the Scientific Revolution. Galileo (1564-1642), for example, sees tastes, odors, and colors as unnecessary “accompaniments” to qualities like location, motion, number, and contact with other bodies.[4] Because they seem superfluous to understanding the physical world, he adopts the opinion that secondary qualities reside only in the mind. One finds the same sentiment repeated in the writings of scientists and philosophers up to Hume (1711-1776), who characterizes the whole of philosophy this way:

The fundamental principle of [the modern] philosophy is the opinion concerning colours, sounds, tastes, smells, heat and cold; which it asserts to be nothing but impressions in the mind, deriv’d from the operation of external objects, and without any resemblance to the qualities of the objects.[5]

I have appended a selection of passages that evidence the prevalence of this opinion among the early moderns, as well as among contemporary scientists and philosophers of perception. As these passages reveal, the moderns are not perfectly consistent in their opinions about which qualities count for primary or secondary, but neither are they radically diverse. Detailing inconsistencies among lists of primary and secondary qualities is beyond the scope of this project. Reid’s lists contain nothing unusual or controversial, so I will assume that these category distinctions refer to the qualities as Reid designates them. The primary qualities are extension, divisibility, figure, motion, solidity, hardness, softness, and fluidity. And the secondary qualities: colors, sounds, smells, tastes, and heat and cold .[6]

Both modern and contemporary scientists and philosophers of perception dismiss secondary qualities as illusory on the same grounds. Physicists can describe the causal interactions of physical objects, including the operations of our sense organs, without reference to colors, odors, or sounds. Perceptions of colors, for example, occur when we are in a particular brain state that is triggered by a nervous impulse from excited retinal cones. Retinal cones become excited by light at certain combinations of wavelengths and intensities. And the relevant characteristics of the light are determined by lighting conditions and the microphysical structures of reflective objects. This process completely accounts for the physical causes of the perceiver’s perceptual experiences, so there is no need to posit an additional property—color—to explain the “colored” object’s interaction with the perceiver’s sense organs.

The modern mechanistic science tells a similar story. The causal process between the perceiver’s experience and the secondary qualities perceived does not involve those qualities. Robert Adams offers the following illustration:

The quality of redness that is immediately present to my mind seems to be entirely different from, and additional to, any geometrical property or motion. As such, if it is present outside the mind, in the apple, it cannot have any effect on my eye, or on any other body, according to the exclusively mechanical theory of explanation. If the quality of redness is there at all, it is causally useless. The geometrical properties and motions of the apple, of its parts, and of other particles of matter would cause me to have exactly the same perceptions of the apple whether or not such a quality of redness is present in it. This consequence of the mechanical theory of explanation may well cause me to doubt that my perceptions give me any reason to believe that the quality of redness that is immediately present to my mind is also present in the apple.[7]

Attributing color and other secondary qualities to physical objects means unnecessarily introducing causally impotent (or perhaps redundant) properties into the physicist’s ontology. But such an addition serves no explanatory purpose. We desire a simple ontology, so long as all the relevant causal interactions are explained, so it is preferable just to omit such qualities from our theories of the physical world.

Moreover, inert qualities fail to explain our perceptions of secondary qualities. A perceiver of explanatorily inert qualities has the same perceptual experiences in the actual world as in a possible world in which those qualities do not exist, so long as that world has the same causally potent qualities acting in the same way. In another possible world that is populated with secondary qualities but not with the same causal qualities, the perceiver fails to have appropriately informative perceptual experiences.[8] If secondary qualities are causally irrelevant, then perceptual experiences of them do not count as evidence for their existence.

Like the early moderns, contemporary philosophers are inclined to omit secondary qualities from their ontologies of the physical world. Howard Robinson states the problem thus:

The idea that objects do not possess secondary qualities intrinsically rests fundamentally on the thought that such qualities do not figure in the basic scientific—that is, the physicist’s—account of the world. This is because scientific explanations of events always operate in terms of primary qualities: as secondary qualities are causally idle no purpose is served by attributing them to objects intrinsically.[9]

Although the precise ontological status of secondary qualities is a matter of debate,[10] it is clear that many scientists and philosophers are not inclined to include them among qualities like length, shape, or solidity. As I mentioned before, Robinson even claims that science has shown that physical objects do not possess secondary qualities intrinsically.[11]

Secondary Qualities according to Sense Perceptions

Contrary to the conclusions of Robinson’s science, sense perception leads us to believe that secondary qualities are bodily qualities. For Reid, such beliefs are even partially constitutive of those perceptions. He describes what it is like to come to a belief on the basis of perception. Reid begins by making a sharp distinction between sense perceptions and mere sensations. When a perceiver perceives a quality, whether primary, secondary, or otherwise, two things happen: the perceiver experiences sensations or feelings and the perceiver forms a conception of and a belief in the quality perceived. The conception and belief together constitute the perception, while the sensation or feeling merely prompts it. Reid claims that every sensation yields a conception and belief of this sort. And perceptual conceptions and beliefs do not occur without sensations—“We never find them disjoined.”[12]

For Reid, the perceptual conceptions are intentional. They take physical qualities as objects or have them as “referential contents.” But they also apply some characterization to the perceived objects. They consider their objects under a description, the conception’s “descriptive contents.” [13] Perceptual beliefs are beliefs in the referential contents of the conceptions as the descriptive contents of the conception describe them. One’s senses do not simply alert one to the existences of perceptual qualities. They give the perceiver particular understandings of those qualities, convictions about their characteristics.

According to Reid, sense perceptions lead perceivers to believe in perceived qualities as bodily qualities. Sensations serve as strong “suggestions” for bodily qualities.[14] Perceptions present us with many types of bodily qualities,[15] but among them are the primary and secondary qualities. The world of sense perception is inhabited by bodies with particular lengths, widths, shapes, and hardnesses, as well as colors, smells, and sounds. According to our common sense perceptual experiences, the primary and secondary qualities stand side-by-side with full and equal membership in physical reality. If Robinson is right and secondary qualities are not bodily qualities, then some of our most important epistemic faculties regularly mislead us.

Chapter 2 Summary[16]

In what follows, I explain Reid’s primary-secondary quality distinction and its importance in Reid’s account of perception—how a perceiver comes to believe that both primary and secondary qualities are real qualities of bodies without warranting external world skepticism. First, I describe Reid’s account of perception, pointing out the sense in which it is direct. Second, I note the importance that Reid places on perceptual experiences in one’s coming to conceptualize a world beyond the mind. Then, I’ll state the primary-secondary quality distinction and discuss the roles of primary and secondary quality perceptions in originating our notions of an external world. The dissertation’s second chapter will be an expanded version of this summary.

How Reid’s Realism is Direct

In his attack on the ‘Way of Ideas,’ Reid makes a key distinction between perception and sensation, which he accuses Hume and others of conflating.[17] The first line of Hume’s Treatise on Human Nature reads, “All the perceptions of the human mind resolve themselves into two distinct kinds, which I shall call impressions and ideas.”[18] Among Hume’s “impressions” are sensations, passions, and emotions. Reid responds, “I believe, no English writer ever gave the name of a perception to any passion or emotion.”[19] Furthermore, sensations are not a species of perception but a different kind of mental operation altogether. Reid explains the semantics of his own position,

Sensation, and the perception of external objects by the senses, though very different in their nature, have commonly been considered as one and the same thing.

…

Thus, I feel a pain; I see a tree: the first denoteth a sensation, the last a perception. The grammatical analysis of both expressions is the same: for both consist of an active verb and an object. But, if we attend to the things signified by these expressions, we shall find, that in the first, the distinction between the act and the object is not real but grammatical; in the second, the distinction is not only grammatical but real.

The form of the expression, I feel pain, might seem to imply, that the feeling is something distinct from the pain felt; yet, in reality, there is no distinction. As thinking a thought is an expression which could signify no more than thinking, so feeling a pain signifies no more than being pained. What we have said of pain is applicable to every other mere sensation.[20]

For Reid, sensations are neither species of nor constituents of sense perceptions. Rather, they are triggers for perceptions—“natural signs.” In the same way that, in language, the word “gold” serves as a signification for gold metal, so sensations serve as signs for qualities. There is, for example, a tactile sensation that leads one to think of the bodily quality of hardness.[21]

The perception, on the other hand, consists of conception and belief. Reid explains,

If, therefore, we attend to that act of our mind which we call perception of an external object of sense, we shall find in it these three things:—First, Some conception or notion of the object perceived; Secondly, A strong and irresistible conviction and belief of its present existence; and, Thirdly, That this conviction and belief are immediate, and not the effect of reasoning.[22]

Reid says that conception is a simple operation of the mind that lacks a definition. He compares it to imagining, apprehending, understanding, and having a notion of a thing. Conception is one’s way of entertaining an idea without committing to a judgment or belief.[23] Judgment, on the other hand, is a mental act of affirmation or denial. Unlike conceptions, they are propositionally expressed if they are expressed at all.[24] So, while my conception of my computer might be verbally represented as “the computer on my desk,” my belief in that computer would require something like “There is a computer on my desk.”

Reid insists that objects of perception exist simultaneously with their being perceived, as the past is the memory’s epistemic domain. I think that time lag objections pose an obvious problem for Reid’s account. For example, on his theory, lightning and many stars turn out to be illusory. But I suspect that Reid’s thoughts may be alterable to overcome these objections. An extensive answer to the time-lag argument is beyond the scope of my project, but I hope to offer some suggestions in passing.

Reid’s theory of perception is “direct” because the third characteristic—the perceiver’s conception and belief are not the result of inference. A sensation triggers both the conception of and the belief in the object perceived—the quality causing the sensation—even if the perceiver has never had such a conception before. The belief follows naturally, without effort and even against a perceiver’s efforts to resist it.[25] Sensations do not serve as evidence for which the objects of perception seem to provide a best explanation. Rather, according to Reid’s sign theory, the sensation prompts the mind to conceive of and believe in the quality that causes of the sensation directly, without any theorizing or inferences.

Realism and Innate Ideas

Reid subscribes to the Lockean view that there are no innate notions or conceptions. Without certain perceptual experiences, Reid claims, one would never form conceptions of the extra-mental world or of the bodies and qualities that inhabit it.[26] The challenge for Reid, then, is to explain our acquisition of these external world notions.

Reid responds that a special set of sensations act as natural signs for bodily qualities. That is, the conceptions triggered by these sensations naturally have external physical qualities as their descriptive contents. And, if we are not misled, the referential contents of those conceptions will match. The physical causes of these special sensations, primary qualities, will indeed be bodily qualities of the sort denoted by the descriptive contents of the conceptions that those sensations prompt. Reid offers no real explanation of how sensations work. He says that sensations caused by primary qualities generate such conceptions “by a natural kind of magic.”[27] We are born with the Rosetta Stone for interpreting the sensations and, consequently, the ability to acquire conceptions and beliefs about an external world.

Direct realism and Primary Qualities

For Reid, the quality types that populate the primary and secondary categories are Locke’s, minus a few like texture and number. Primary qualities include extension, divisibility, figure, motion, solidity, hardness, softness, and fluidity, and the secondary qualities are sound, color, taste, smell, and heat and cold.[28] Reid’s explanation for the distinction is his own:

There appears to me to be a real foundation for the [primary and secondary quality] distinction; and it is this—that our senses give us a direct and distinct notion of the primary qualities and inform us what they are in themselves. But of the secondary qualities, our senses give us only a relative and obscure notion. They inform us only, that they are qualities that affect us in a certain manner—that is, produce in us a certain sensation; but as to what they are in themselves, our senses leave us in the darks.[29]

Both primary and secondary qualities are extra-mental, real qualities of physical bodies, yet there is a distinction. In the case of primary qualities, one’s senses convey information about the natures of those qualities that allow one to understand them intrinsically. Sensory perceptions of secondary qualities, on the other hand, only yield information about those qualities as they relate to the perceiver. The perceiver’s understandings of secondary qualities are initially limited to extrinsic facts about their effects.

In the case of primary qualities, the conception one has of a bodily quality by way of sense perception is “direct and distinct”[30]—fully understood in itself without reference to any other quality or mental object. The sensation brings the perceiver to conceive of the perceived quality in absolute terms. For example, conceptions of hardness, as occasioned by tactile sensations, describe that quality as the firm adhesion of the parts of a body.[31]

Primary qualities, experienced through touch, bridge the gap from the perceiver’s original state, lacking notions of external physical objects, to a state in which he conceives of and believes in bodily qualities and understands them as external and physical. No other sense will do, not even sight. Although we naturally acquire the ability to visually see three dimensional objects, we do so by correlating the variations in the color appearances with information we receive tactilely. So, according to Reid, a perceiver who lacks a sense of touch, but who has the other normal human perceptive faculties, would never come to understand the world as three dimensional.[32] Moreover, Reid claims, someone who receives sight after being blind from birth will be unable at first to identify spheres, cones, and other three dimensional objects by sight.[33]

The understanding of primary qualities as conveyed by sense perception goes far beyond describing them as bodily. Because we understand primary qualities so well (indeed, perfectly),[34] our vocabulary for them also serves as our language for the mathematical sciences.[35] These are the qualities that enable straightforward talk of and reasoning about physical objects and their interactions.

In cases of secondary quality perceptions, sensations yield only “relative and obscure” conceptions. One’s senses deliver the sensation, but one’s conception of the quality—that is, the sensation’s cause—lacks the lucidity of primary quality conceptions. The referential content of the conception is analogous—i.e., the object of one’s conception in this case is also the cause of the sensation. But the descriptive content describes the object of perception relatively, as the cause of a particular sensation. Although the perceiver understands secondary qualities as bodily, their intrinsic natures remain hidden so long as the perceiver’s notions of them are derived only from sense perceptions.

In perceptions of primary qualities, the referential content of the conception is a real physical quality of a body. The same goes for perceptions of secondary qualities. However, conceptions of primary and secondary qualities involve vastly different descriptive contents. Sense perceptions of secondary qualities are insufficient for providing the perceiver with any direct understanding of the object perceived. The descriptive contents are relative, and so uninformative with respect to the qualities’ intrinsic natures. The vocabulary of secondary qualities does not play a role in the scientist’s description of physical interactions of bodies (including his account of the perception itself) because obscure and relative notions are of little help in explaining such things. The scientist does mention secondary qualities when describing the causal interactions of the universe, just not under the descriptions given in perception.

Chapter 3 Summary

The interpretation I introduce in Chapter 2 will be one among many conflicting understandings of Reid on primary and secondary qualities. It is natural, then, that I bolster my reading by comparing it to and defending it against other interpretations. First, I will differentiate the primary-secondary distinction from Reid’s suppositions about the distinction’s contribution to the errors of philosophers and scientists. Second, I will explain why my version of Reid’s distinction should be preferred over other contemporary interpretations. This will also serve to illuminate the details of Reid’s account as it pertains to his comments on visible figure, his philosophy of science, and other related topics. What follows is a summary of Reid’s error theory of the Way of Ideas and some preliminary criticisms of rival interpretations.

Where the Way of Ideas went Wrong

The Hume’s argument against our knowledge of the external world hangs on his contention that ‘ideas’ are dull copies of ‘impressions,’ which Reid takes to mean that conceptions bear at least a faint resemblance to sensations. He fancies that he has been more careful and tedious in attending to his own mental activity than anyone before him in order to test Hume’s claim. The difficulty, he explains, arises because we are not naturally inclined to attend to our sensations, but rather to the objects of our perceptions.[36] He confesses in a letter to Rev. Dr. Blair,

When I had acquired the power of thus attending to my Sensations, I was soon perswaded that I had never made them objects of thought before & that those Sensations which I had felt every day, perhaps every hour of my life, had notwithstanding been as much unknown to me as if I had never felt them, because I had never given any attention to them.[37]

In acquiring the ability to attend to his own sensations, Reid believes he has discovered a key insight into where Descartes, Malebranche and Locke go wrong. Concerning secondary quality perceptions, although they acknowledge a distinction between sensations and their causes, these philosophers insist on applying the words “smell,” “color” and “sound” only to sensations. But, even if these words can pick out sensation types, ordinary language users typically use them to indicate the causes of sensations. The philosophers seem to be misusing the words.

In the case of primary qualities, Reid claims, sensations go completely overlooked. The perceiver’s keen understanding of those qualities leads her to focus on the qualities itself and, consequently, to neglect the sensations. The philosophers of the Way of Ideas, likewise, fail to attend to their sensations and are led to suppose that those sensations resemble bodily qualities, that ideas are merely faint replicas of impressions.[38] We ignore primary quality sensations as a matter of habit. If Reid is right, then one of his most important philosophical accomplishments is overcoming this habit.

Problems with Interpretation

Contemporary interpretations of Reid’s account are unsatisfactory—misidentifying the primary-secondary quality distinction, misunderstanding its implications, or offering only a partial treatment of it.[39] The following is an extensive, although not exhaustive, survey of problems in the secondary literature on Reid’s distinction.[40]

Jennifer McKitrick, Tony Pitson, and James van Cleve all offer interpretations that commit Reid to affirming secondary qualities as both dispositions and their causal bases. [41] I find this view untenable.[42] There is reason to think that Reid would not identify dispositions with their causal bases. He clearly distinguishes between “tendencies” and their causal bases in his discussion on gravity.[43] Reid describes colors as dispositions but not as causal bases, and, when Reid never indicates that other secondary qualities might be dispositions. Smells are effluvia, sounds are vibrations, and heat is either “a particular element diffused through nature” or “a certain vibration of the parts of the heated body.”[44] Moreover, no one suggests that primary qualities might be dispositions identical with their causal bases.

Like Nichols, Pitson and Keith Lehrer make Reid’s primary and secondary quality distinction two-fold instead of one. They claim that, in addition to the epistemic difference in conceptual contents, according to Reid, primary and secondary qualities also differ phenomenologically:[45] Perceivers notice sensations of secondary qualities, but not of primaries. Pitson goes so far as to call the sensations of primary qualities “not distinct.”[46] Although Reid does claim that the sensations associated with primary qualities often go unnoticed,[47] he characterizes this as an unsurprising, but also unnecessary, consequence of the primary-secondary distinction, not an essential feature of it. Moreover, Reid claims that he has overcome this consequence, having learned to pay close attention to even the subtle sensations of primary qualities. Reid’s analysis of the tendency to overlook the sensations of primary qualities is part of his error theory, not an additional criterion by which to distinguish the quality types.

Chapter 4 Summary

In this chapter, I will argue that Reid’s distinction between primary and secondary qualities, and therefore his answer to the problem of secondary qualities, remains tenable. When discussing primary and secondary qualities, Reid issues instructions to scientists, whom he calls “philosophers,” to discover the intrinsic natures of secondary qualities.[48] This seems strange since Robinson objects to secondary qualities as real physical qualities of bodies on the basis of science. Contemporary scientists do not use secondary quality terms when describing causal interactions of the physical world. Have they failed to complete the task assigned them by Reid? Or have they followed Reid’s direction only to conclude that secondary qualities do not exist? I do not think so. Since Reid’s time, scientists have made some valuable advances in understanding secondary qualities. But color has proven difficult. The growing consensus is that colors simply cannot be independent of perceivers. In this chapter, I will trace out natural philosophy’s progress toward a theory of heat and propose a theory of color compatible with both Reid’s primary-secondary quality distinction and contemporary science.

Reid and Analytic Specification

According to my understanding, Reid means “heat,” “smell,” “taste,” “color,” and “sound” as names for types of secondary qualities. That is, the objects of the perceptions, or the referential contents of the notions involved, are the things denoted by these terms. However, the descriptive contents of secondary quality notions say nothing about what those qualities are intrinsically. They provide descriptions by which one connects the notion to the object. In some cases, says Reid, scientists have made (and probably will continue to make) significant accomplishments toward understanding more about the intrinsic natures of the objects of our secondary quality perceptions.[49] For example, “smell” indicates the quality that causes smell sensations, effluvia. Likewise, “sound” indicates the quality that causes auditory sensations, namely vibrations.

Suppose that a full analysis could be given of any secondary quality in the same way that H₂O is an analysis of water. H₂O does much more than specify a few of water’s intrinsic characteristics. The chemical formula explains what water is. Necessarily, a substance is water if and only if it is H₂O because water is identical to H₂O. The chemical formula and the term “water” are two names for the same natural kind. Call such an analysis an “analytical specification.”[50] Reid intends that scientists would pursue analytical specifications with regard to secondary qualities. Tracing out each of the secondary quality types to see what sorts of a posteriori identifications are available, given the discoveries of contemporary science, would be an interesting project. But such an endeavor is much too large to fit within the scope of the present project. In the dissertation, I will give an account of the possibilities for an analytic specification of heat because it appears to be a successful example of this sort of project.

On Color

Color, on the other hand, appears to be a failed example. Consider a particular color term, like “red.” If one seeks a clearly defined analytic specification for redness, one will find oneself disappointed. Suppose one begins with a list of red things—tomatoes, roses, barns, and oxygenated blood—and considers what is similar about these things that explains their abilities to cause the red-type sensations that they do. There is really no good answer. They do not share chemical compositions, electron configurations, or even spectral reflectance distributions.[51] The fact that they all cause red-type sensations is explained by the limited number of cone types found in the human eye, the distribution of those cones in a particular retina, the sensitivities of the cones, the way that the optic nerve transmits information from the retina to the brain, the concentration of a yellowish pigment on certain parts of the retina, and other factors.[52] The grouping of the tomatoes, roses, barns, and blood depends as much on the physiology of the observer as on any identifiable similarity among the objects themselves. There is simply no good analytic specification of color terms, because the extrinsic similarity of producing a certain type of visual sensation in perceivers does not correspond to any intrinsic similarity among the causes.

This problem has led philosophers to deny that colors are real physical qualities of bodies, suggesting a host of other options instead. The early Frank Jackson, for example, makes colors into purely mental properties.[53] Realist primitivism takes colors to be coextensive with but not identical to certain reflectance types. The colors themselves are not analyzable.[54] Jonathan Cohen claims that colors are relations between perceivers and physical objects.[55] These positions, however, are not available to Reid. Perceptions of secondary qualities, according to Reid’s direct realism, involve conceptions of those qualities as causes of color sensations (and little else). These other approaches accept Robinson’s criticism that colors are non-causal. If colors are not causal, then the perceiver’s natural conception of them as such is false, and they are indeed illusory. The descriptive content of the conception is “the cause of this sensation.” If colors are not causal, then the descriptive content of color perceptions is wrong.

I propose that the most reasonable response to the problem of colors for a Reidian direct realist is to deny that color terms denote natural kinds, what some might call a “token-identity” view of color. Suppose one perceives the color of a tomato. A red-type sensation triggers a conception of and belief in a quality under a description like “the cause of this red-type sensation.” One might take the tomato to the laboratory to see what about it causes the sensation, and discovers that it has something to do with the carotenoids in the tomato’s chromoplasts. The carotenoids have such-and-such spectral reflectance distribution, and so cause light to reflect in such a way so as to cause the perceiver’s red-type sensation. Thus, the color of the tomato does appear subject to analytic specification. The color is either the carotenoids’ distribution to reflect certain kinds of light or the carotenoids themselves. And one could perform the same sort of investigation for the rose, the barn, and the blood. In every case, it seems that one could analytically specify the cause of the sensation.

Conclusion

Through this dissertation, I mean to answer a key argument against direct realism, the problem of secondary qualities. Although the scientist and the perceiver seem to have contradictory understandings of the physical world, I claim that Reid offers reconciliation. Moreover, in spelling out Reid’s theory of primary and secondary qualities, I contribute a convincing interpretation to a troubled area of Reid studies, and I offer a promising theory of color.

Appendix: Selection of Quotations about Primary and Secondary Qualities

The following is a selection of quotations from various philosophers and scientists who either view secondary qualities as illusory or ascribe such a view to the learned. This sample is by no means exhaustive. I include them primarily to motivate the importance of the problem to which I am offering a solution, but they are also interesting from a purely historical point of view.

By convention there are sweet and bitter, hot and cold, by convention there is color; but in truth there are atoms and the void.

--Democritus

Moreover, we must hold that the atoms in fact possess none of the qualities belonging to things which come under our observation, except shape, weight, and size, and the properties necessarily conjoined with shape.

--Epicurus

But think not haply that the primal bodies

Remain despoiled alone of colour: so,

Are they from warmth dissevered and from cold

And from hot exhalations; and they move,

Both sterile of sound and dry of juice; and throw

Not any odour from their proper bodies.

--Lucretius

But first I must consider what it is that we call heat, as I suspect that people in general have a concept of this which is very remote from the truth. For they believe that heat is a real phenomenon, or property, or quality, which actually resides in the material by which we feel ourselves warmed. Now I say that whenever I conceive any material or corporeal substance, I immediately feel the need to think of it as bounded, and as having this or that shape; as being large or small in relation to other things, and in some specific place at any given time; as being in motion or at rest; as touching or not touching some other body; and as being one in number, or few, or many. From these conditions I cannot separate such a substance by any stretch of the imagination. But that it must be white or red, bitter or sweet, noisy or silent, and of sweet or foul odor, my mind does not feel compelled to bring in as necessary accompaniments. Without the senses as our guides, reason or imagination unaided would probably never arrive at qualities like these. Hence I think that tastes, odors, colors, and so on are no more than mere names so far as the object in which we place them is concerned, and that they reside only in the consciousness.

--Galileo

In early life the mind was so closely bound to the body that it attended to nothing beyond the thoughts by which it perceived the objects that made impression on the body; nor as yet did it refer these thoughts to anything existing beyond itself, but simply felt pain when the body was hurt, or pleasure when anything beneficial to the body occurred, or if the body was so highly affected that it was neither greatly benefited nor hurt, the mind experienced the sensations we call tastes, smells, sounds, heat, cold, light, colours, and the like, which in truth are representative of nothing existing out of our mind, and which vary according to the diversities of the parts and modes in which the body is affected.

--Descartes

Such Qualities, which in truth are nothing in the Objects themselves, but Powers to produce various Sensations in us by their primary Qualities, i.e. by the Bulk, Figure, Texture, and Motion of their insensible parts, as Colours, Sounds, Tasts, etc. These I call secondary Qualities. To these might be added a third sort which are allowed to be barely Powers though they are as much real Qualities in the Subject, as those which I to comply with the common way of speaking call Qualities, but for distinction secondary Qualities. For the power in Fire to produce a new Colour, or consistency in Wax or Clay by its primary Qualities, is as much a quality in Fire, as the power it has to produce a new Idea or Sensation of warmth or burning, which I felt not before, by the same primary Qualities, viz. The Bulk, Texture, and Motion of its insensible parts.

--John Locke

For the rays [of light], to speak properly, are not colored. In them there is nothing else than a certain power and disposition to stir up a sensation of this or that color.

--Isaac Newton

But the modes of body may be yet farther distinguished. Some of them are primary modes or qualities, for they belong to bodies considered in themselves, whether there were any man to take notice of them or no; such are those before-mentioned, namely, shape, size, situation, &c. secondary qualities, or modes, are such adeas as we ascribe to bodies on account of the various impressions which are made on the senses of men by them, and these are called sensible qualities, which are very numerous; such ar all colours, as red, green, blue, &c. such are all sounds, as sharp, shrill, loud, hoarse; all tastes, as sweet, bitter, sour; as smells, whether pleasant, offensive, or indifferent; and all tactile qualities, or such as affect the touch or feeling, namely, heat, cold, &c. These are properly called secondary qualities, for though we are ready to conceive them as existing in the very bodies themselves which affect our senses, yet true philosophy has most undeniably proved, that all these are really various ideas or perceptions excited in human nature by the different impressions that bodies make upon our senses by their primary modes, that is, by means of the different shape, size, motion, and position of those little invisible parts that compose them.

--Isaac Watts

--David Hume

I have settled down to writing these lectures and have drawn up my chairs to my two tables. Two tables! Yes; therea re duplicates of every object about me—two tables, two chairs, two pens… One of them has been familiar to me from earliest years. It is a commonplace object of that environment which I call the world… It has extension; it is comparatively permanent; it is coloured; above all it is substantial… Table No. 2 is my scientific table. It is a more recent acquaintance and I do not feel so familiar with it… My scientific table is mostly emptiness. Sparsely scattered in that emptiness are numerous electric charges rushing about with great speed; but their combined bulk amounts to less than a billionth of the bulk of the table itself… There is nothing substantial about my second table. It is nearly all empty space—space pervaded it is true by fields of force, but these are assigned to the categories of ‘influences’ not of ‘things.’

--Sir Arthur Eddington

Descriptions which embody it, though they maybe not explicitly mention or include a distinctively human perspective, recognizably and diagnosibly come from that perspective. One can in describing an unobserved scene properly describe it as amusing, but if one’s attention were specifically directed to describing it as it was without observers, one would have good reason to leave that concept aside. It is much the same with ‘green’ or any other secondary quality term: they may not mention their human relativity, but they only too obviously display it to reflection.

--Bernard Williams

It is a commonplace that there is an apparent clash between the picture Science gives of the world around us and the picture our senses give us. We sense the world as made up of coloured, materially continuous, macroscopic, stable object; Science and, in particular, Physics, tells us that the material world is constituted of clouds of minute colourless, highly-mobile particles.

--Jackson

The idea that objects do not possess secondary qualities intrinsically, rests fundamentally on the thought that such qualities do not figure in the basic scientific—that is, the physicist’s—account of the world. This is because scientific explanations of events always operate in terms of primary qualities: as secondary qualities are causally idle no purpose is served by attributing them to objects intrinsically.

--Howard Robinson

Preliminary Bibliography

Reid’s Works

Reid, Thomas. Essays on the Intellectual Powers of Man: A Critical Edition. University Park, PA: Pennsylvania State University Press, 2002.

________. An Inquiry into Human Mind on Principles of Common Sense. Universtiy Park, PA: Pennsylvania State University Press, 2001.

________. On the Animate Creation: Papers Relating to the Life Sciences. University Park, PA: Pennsylvania State University Press, 1996.

Reid, Thomas and Paul Wood. The Correspondence of Thomas Reid. University Park, PA: Pennsylvania State University Press, 2003.

Other Historical Texts

Aristotle. Aristotle: On the Soul. Parva Naturalia. On Breath. (Loeb Classical Library No. 288). Rev Ed ed. London: Loeb Classical Library, 1975.

________. Aristotle: Metaphysics, Books I-IX (Loeb Classical Library No. 271). London: Loeb Classical Library, 1979.

Berkeley, George. Three Dialogues Between Hylas and Philonous. Indianapolis: Hackett Pub Co Inc, 1979.

________. Three Dialogues Between Hylas and Philonous (Oxford Philosophical Texts). New York: Oxford University Press, USA, 1998.

________. A Treatise Concerning the Principles of Human Knowledge (Oxford Philosophical Texts). New York: Oxford University Press, USA, 1998.

Boyle, Robert, Edward Bradford Davis, and Michael Cyril William Hunter. The Works of Robert Boyle (Pickering Masters). London: Pickering & Chatto Ltd, 2000.

Descartes, Rene. Meditations on First Philosophy/Meditations De Prima Philosophia (Bilingual Edition). Bilingual ed. Notre Dame: University of Notre Dame Press, 1990.

________. Descartes: Meditations on First Philosophy: With Selections from the Objections and Replies (Cambridge Texts in the History of Philosophy). Revised ed. New York: Cambridge University Press, 1996.

Drake, Stillman, and C. D. O'malley. Controversy on the Comets of 1618 Galileo : Grassi : Guiducci : Kepler. Phildelphia: University Of Pennsylvania, 1960.

Empiricus, Sextus. Sextus Empiricus: Against the Professors (Loeb Classical Library No. 382). London: Loeb Classical Library, 1949.

Hume, David. A Treatise of Human Nature (Oxford Philosophical Texts). New Ed ed. New York: Oxford University Press, USA, 2000.

________. An Enquiry Concerning Human Understanding (The Clarendon Edition of the Works of David Hume). New York: Oxford University Press, USA, 2006.

Locke, John. An Essay Concerning Human Understanding (Clarendon Edition of the Works of John Locke). New Ed ed. New York: Oxford University Press, USA, 1979.

Maxwell, James Clerk. The Scientific Papers of James Clerk Maxwell 2 Volume Set (Cambridge Library Collection - Physical Sciences). New York: Cambridge University Press, 2010.

________. Theory of Heat. Toronto: Nabu Press, 2010.

Newton, Sir Isaac. Opticks: Or a Treatise of the Reflections, Refractions, Inflections & Colours of Light-Based on the Fourth Edition London, 1730. New York: Dover Publications, 1952.

Young, Thomas. Miscellaneous Works of the Late Thomas Young .... Toronto: Nabu Press, 2010.

Secondary Works on Reid and Related Resources

Ackroyd, C., N. K. Humphrey, and E. K. Warrington. "Lasting Effects of Early Blindness: A Case Study." Quarterly Journal Of Experimental Psychology 26 (1974): 114-124.

Ben Ze'ev, Aaron. "Reid's Direct Approach to Perception." Studies in history and philosophy of science 17 (1986): 99-114.

Borge, Steffen. "Some Remarks on Reid on Primary and Secondary Qualities." Analytica 22 (2007): 74-84.

Callergard, Robert. An Essay on Thomas Reid's Philosophy of Science (Stockholm Studies in Philosophy). Uppsala, Sweden: Stockholm Universitet, 2006.

Dalgarno, Melvin, and Eric, eds. Matthews. The Philosophy of Thomas Reid (Philosophical Studies Series). 1 ed. New York: Springer, 1989.

Falkenstein, Lorne. "Nativism and the Nature of Thought in Reid's Account of Our Knowledge of the External World." The Cambridge Companion to Thomas Reid (Cambridge Companions to Philosophy). New York: Cambridge University Press, 2004. 156-179.

Fine, I.. "Long-term Deprivation Affect Visual Perception and Cortex." Nature Neuroscience 6 (2003): 915-916.

Greco, John. "Reid's Reply to the Skeptic." The Cambridge Companion to Thomas Reid (Cambridge Companions to Philosophy). New York: Cambridge University Press, 2004. 134-155.

Greenberg, Arthur R.. "Reid on Primary and Secondary Qualities." Canadian Journal of Philosophy 4 (1978): 207-218.

Gregory, R. L.. Recovery from early blindness: A case study (Experimental Psychology Society; Monographs;no.2). University of Texas Press: Heffer, 1963.

________. "Seeing After Blindness." Nature Neuroscience 6 (2003): 909-910.

________. Eye and Brain. 5 Reprint ed. Princeton: Princeton University Press, 1997.

Hopkins, R.. "Thomas Reid on Molyneux's Question." Pacific Philosophical Quarterly 86 (2005): 340-364.

Latta, R.. "Notes on a Case of Successful Operation for Congenital Cataract in an Adult." British Journal of Psychology 1 (1904): 135-150.

Lehrer, Keith. "Reid on Primary and Secondary Qualities." The Monist 61 (1978): 184-191.

McKitrick, Jennifer. "Reid's Foundation for the Primary/Secondary Quality Distinction." Philosophical Quarterly 52 (2002): 478-494.

Nichols, Ryan. "Reid's Inheritance from Locke, and How He Overcomes It." Journal of the History of Philosophy 41 (2003): 471-491.

________. Thomas Reid's Theory of Perception. New York: Oxford University Press, USA, 2007.

Pappas, George. "Sensation and Perception in Reid." Nous 23 (1989): 155-167.

Pitson, Tony. "Reid on Primary and Secondary Qualities." Reid Studies 5 (2001): 17-34.

Van Cleve, James. "Reid's Theory of Perception." The Cambridge Companion to Thomas Reid (Cambridge Companions to Philosophy). New York: Cambridge University Press, 2004. 101-133.

Wolterstorff, Nicholas. "Reid on Common Sense." The Cambridge Companion to Thomas Reid (Cambridge Companions to Philosophy). New York: Cambridge University Press, 2004. 77-100.

________. Thomas Reid and the Story of Epistemology (Modern European Philosophy). New Ed ed. New York: Cambridge University Press, 2004.

Wood, Paul. "Thomas Reid and the Culture of Science." The Cambridge Companion to Thomas Reid (Cambridge Companions to Philosophy). New York: Cambridge University Press, 2004. 53-76.

Other Secondary Works

Anstey, Peter R.. Philosophy of Robert Boyle (Routledge Studies in Seventeenth-Century Philosophy, 5). 1 ed. New York: Routledge, 2000.

Broadie, Alexander. "The Human Mind and its Powers." The Cambridge Companion to the Scottish Enlightenment (Cambridge Companions to Philosophy). New York: Cambridge University Press, 2003. 60-78.

Jackson, Reginald. "Locke's Distinction between Primary and Secondary Qualities." Mind n.s., 38 (1929): 56-76.

Keating, L.. "Boyle on Primary and Secondary Qualities." History of Philosophy Quarterly 10 (1993): 305-23.

Klemme, Heiner F.. "Scepticism and Common Sense." The Cambridge Companion to the Scottish Enlightenment (Cambridge Companions to Philosophy). New York: Cambridge University Press, 2003. 117-135.

Mackie, J. L.. Problems from Locke. New York: Oxford University Press, USA, 1976.

Silver, Bruce. "A Note on Berkeley's New Theory of Vision and Thomas Reid's Distinction Between Primary and Secondary Qualities." Southern Journal of Philosophy 12.2 (1974): 253-263.

Wood, Paul. "Science in the Scottish Enlightenment." The Cambridge Companion to the Scottish Enlightenment (Cambridge Companions to Philosophy). New York: Cambridge University Press, 2003. 94-116.

Perception

The Contents of Experience: Essays on Perception. New York: Cambridge University Press, 1992.

Fish, William. Perception, Hallucination, and Illusion. New York: Oxford University Press, USA, 2009.

Hacker, P.M.S.. Appearance and Reality: A Philosophical Investigation into Perception and Perceptual Qualities. Cambridge, MA: Blackwell Publishers, 1987.

Huemer, Michael. Skepticism and the Veil of Perception (Studies in Epistemology and Cognitive Theory (Unnumbered).). Lanham: Rowman & Littlefield Publishers, Inc., 2001.

Landesman, C.. The Eye and the Mind: Reflections on Perception and the Problem of Knowledge (Philosophical Studies Series). 1 ed. New York: Springer, 1993.

McGinn, Colin. The Subjective View: Secondary Qualities and Indexical Thoughts. New York: Oxford University Press, USA, 1983.

________. Knowledge and Reality: Selected Essays. New York: Oxford University Press, USA, 2002.

Mundle, C.W.K.. Perception: Facts and Theories.. New York: Mundle, C.W.K. Perception: Facts And Theories. Oxford University Press, 1971. 192pp. Quality Paperback. Pages Yellowing, Else Vg Condition., 1971.

Perception and identity: Essays presented to A. J. Ayer, with his replies. 1st Edition/1st Printing ed. Ithaca: Cornell University Press, 1979.

Robinson, Howard. Perception (Problems of Philosophy). 1 ed. New York: Routledge, 2001.

Smith, A. D.. "Of Primary and Secondary Qualities." Philosophical Review 99 (1990): 221-254.

________. The Problem of Perception. 1st ed. Cambridge: Harvard University Press, 2002.

Stout, G. F.. "Primary and Secondary Qualities." Proceedings of the Aristotelian Society 4 (1903): 141-160.

Tye, Michael. Consciousness, Color, and Content (Representation and Mind). London: The Mit Press, 2002.

Villanueva, Enrique. Perception (Philosophical Issues Series No 7) (Philosophical Issues Series No 7) (Philosophical Issues Series No 7). Atascadero, CA: Ridgeview Pub Co, 1996.

Vision, Gerald. "Primary and Secondary Qualities: An essay in epistemology." Erkenntis 17.2 (1982): 135-169.

Warren, R.M., and R.P. Warren. Helmholtz on Perception: Its Physiology and Development. Hoboken, New Jersey: John Wiley & Sons Inc, 1968.

Color, Heat, and Related Topics

Averill, Edward Wilson. "Color and the Anthropocentric Problem." Readings on Color, Vol. 1: The Philosophy of Color. London: The Mit Press, 1997. 11-32.

Broackes, J.. The Nature of Color. New York: Routledge, forthcoming.

Byrne, Alex, and David Hilbert. "Color Primitivism." Erkenntis 66 (2007): 73-105.

Chang, Hasok. Inventing Temperature: Measurement and Scientific Progress (Oxford Studies in Philosophy of Science). New York: Oxford University Press, USA, 2004.

Clark, Austen. Sensory Qualities (Clarendon Library of Logic and Philosophy). New York: Oxford University Press, USA, 1996.

________. "True Theories, False Colors." Philosophy of Science 63.3 (1996): S143-S150.

Cohen, Jonathan. The Red and the Real: An Essay on Color Ontology (Oxford Applied Mathematics and Computing Science Series). 2 ed. New York: Oxford University Press, USA, 2009.

Dedrick, D.. "Can Color be Reduced to Anything." Philosophy of Science 63 (1996): S134-S142.

Edwards, J.. "Secondary Qualities and the A Priori." Mind 101 (1992): 263-272.

Hall, R. J.. "The Evolution of Color Vision without Colors." Philosophy of Science 63 (1996): S125-S133.

Hardin, C. L.. Color for Philosophers: Unweaving the Rainbow. Expanded ed. Indianapolis: Hackett Pub Co, 1988.

________. "Color and illusion." Mind and Cognition: A Reader. Malden: Blackwell Pub, 1990. 555-567.

________. “A Spectral Reflectance Doth Not a Color Make.” Journal of Philosophy 100 (2003): 191-202.

Hilbert, David R.. Color and Color Perception: A Study in Anthropocentric Realism (Center for the Study of Language and Information - Lecture Notes). 1 ed. Standford: Center For The Study Of Language And Inf, 2002.

Jackson, Frank. "The Primary Quality View of Color." Metaphysics: Philosophical Perspectives (Philosophical Perspectives Annual Volume). Malden, MA: Wiley-Blackwell, 1996. ??.

Jacquette, D.. "Color and Armstrong's color realism under the microscope." Studies in history and philosophy of science 26 (1995): 389-406.

Kraut, R.. "The Objectivity of Color and the Color of Objectivity." Philosophical Studies 68 (1992): 265-287.

Landesman, Charles. "Why nothing has a color: color skepticism." The Theory of Knowledge: Classical and Contemporary Readings. 2 ed. Belmont, CA: Wadsworth Publishing Company, 1993. 121-126.

________. Color and Consciousness: An Essay in Metaphysics. Philadelphia: Temple University Press, 1989.

Matikas, Petras. Color Perception: Physiology, Processes and Analysis. New York: Nova Science Pub Inc, 2009.

Maund, Barry. Colours: Their Nature and Representation (Cambridge Studies in Philosophy). 1 Reissue ed. New York: Cambridge University Press, 2009.

Smart, J. J. C.. "On Some Criticisms of a Physicalist Theory of Colors." Readings on Color, Vol. 1: The Philosophy of Color. London: The Mit Press, 1997. 1-10.

Thompson, Evan. "Colour vision, evolution, and perceptual content." Synthese 104 (1995): 1-32.

________. Colour Vision: A Study in Cognitive Science and the Philosophy of Perception (Philosophical Issues in Science). 1 ed. New York: Routledge, 1995.

Westphal, Jonathan. Colour: A Philosophical Introduction (Aristotelian Society Series, Vol 7). 2 ed. Cambridge, MA: Blackwell Publishers, 1991.

Wittgenstein, Ludwig. Wittgenstein: Remarks on Colour (Cloth). Berkeley: University of California Press, 1992.

Other Works

Jackson, F., R. Pargetter, and E. Prior. "Three Theses About Dispositions." American Philosophical Quarterly 19 (1982): 251-257.

Bonevac, Daniel, Josh Dever, and David Sosa. "The Conditional Fallacy." Philosophical Review 115.3 (2006): 273-316.

Helmholtz, H. von. Epistemological Writings: The Paul Hertz/Moritz Schlick centenary edition of 1921, with notes and commentary by the editors (Boston Studies in the Philosophy of Science). 1 ed. New York: Springer, 1977.

Kripke, Saul A.. Naming and Necessity. Cambridge: Harvard University Press, 2006.

[1] Howard Robinson, Perception (New York: Routledge, 1994), 59.

[3] David Hume, A Treatise of Human Nature, ed. by David Fate Norton and Mary J. Norton (New York: Oxford University Press, 2000), 1.4.4.2-9/149-151.

[4] Galileo, The Assayer, in Discoveries and Opinions of Galileo, trans. by Stillman Drake (New York: Anchor Books, 1957), 284.

[6] Essays on the Intellectual Powers of Man (hereafter, EIP) (University Park, PA: Penn State Press, 2002), 2.17/201.

[7] Robert Merrihew Adams, “Introduction” in George Berkeley, Three Dialogues between Hylas and Philonous (Indianapolis: Hackett, 1979), xiv-xv.

[8] This amounts to perceptual beliefs in secondary qualities failing to be either safe or sensitive. That is, the perceiver forms false beliefs about secondary qualities in nearby possible worlds that lack those qualities, and he fails to form true beliefs about those qualities in possible worlds with different causally active qualities.

[9] Robinson, 61. A similar argument appears in Frank Jackson, Perception: A Representative Theory (Cambridge: Cambridge University Press, 1977), 122.

[10] Colors, for example, are argued to be dispositions, relations, or somehow primitive. I discuss such views below.

[11] Robinson, 59. In fact, the only perceivable quality Robinson ascribes to physical objects is their spatial location (p. 74).

[12] Ibid., 2.17/210. The exception Reid mentions (EIP 2.18/214) is an amputee’s phantom limb pain. Even in this case though, the amputee’s sensations would lead him, almost forcefully, to believe that his non-existent limb was being tickled, burned, or whatever, except that he knows full well that the limb is gone.

[13] I borrow these terms from J. Todd Buras, “The Problem with Thomas Reid’s direct realism,” in The Philosophy of Thomas Reid: A Collection of Essays, eds. John Haldane and Stephen Read, (Malden, MA: Blackwell Pub, 2003), 44-64. It is repeated in “Three Grades of Immediate Perception: Thomas Reid’s Distinctions,” Philosophy and Phenomenological Research, 76: 3 (2008): 603-632; and “The Function of Sensations in Reid,” Journal of the History of Philosophy, 47: 3 (2009): 329-355.

[14] Inquiry into the Human Mind on the Principles of Common Sense (hereafter IHM) (University Park, PA: Penn State Press, 1997), 2.7/36-8.

[15] Reid adds states of conditions of the perceiver’s own body (i.e., the circumstances of one’s own kinesthetic positions and movements as well as one’s health), mechanical and chemical powers (e.g., inertia and gravity), medical powers (e.g., that quality of a drug which makes it effective), and vegetable and animal powers to grow and nourish themselves. See, EIP 2.18/211-212.

[16] My exposition here is heavily influenced by James Van Cleve’s “Reid’s Theory of Perception,” in The Cambridge Companion to Thomas Reid, eds. Terence Cuneo and Rene van Woudenberg (New York: Cambridge University Press, 2004), 101-133.

[33] IHM 6.4/84-85. Although there have been a few cases like the one Reid describes, there is not enough consistency in the data to determine whether Reid is correct or not. See Steffen Borge, “Some Remarks on Reid on Primary and Secondary Qualities,” Analytica 22 (2007): 74-84.

[39] For a partial treatment, I have in mind Arthur R. Greenberg, “Reid on Primary and Secondary Qualities,” Canadian Journal of Philosophy 4 (1978): S207-S218. I know of nothing false in Greenberg’s article, but it lacks the kind of detail due its subject. In particular, it contains almost nothing about the primary qualities.

[40] Among those interpretations not explored in the present survey are Vere Chappell, “The Theory of Sensations,” in The Philosophy of Thomas Reid (Dordrecht: Kluwer, 1989), 49-64, and Aaron Ben Ze’ev, “Reid’s Opposition to the Theory of Ideas,” 91-102 in the same volume.

[41] Nicholas Wolterstorff, Thomas Reid and the Story of Epistemology (Cambridge: Cambridge University Press, 2001), 112-113; McKitrick, 485-488; Tony Pitson, “Reid on Primary and Secondary Qualities,” Reid Studies 2 (2001): 20-32; Van Cleve, 109-111..

[42] Ryan Nichols, Thomas Reid’s Theory of Perception (New York: Oxford University Press, 2007), 174, suggests that Reid’s used of “disposition” may be unclear. Perhaps this is the case. I know of no other place where Reid uses the word with reference to anything but people.

[45] Nichols, 165-169, also sees Reid’s distinction as two-fold, but he adds a formational distinction rather than a phenomenological one. Nichols argues that at least some primary qualities are perceptible without sensations functioning as natural signs and that such perceptions are important for distinguishing Reid’s position from the Way of Ideas. I think Nichols confuses Reid’s understanding of “direct.” As I explained above, perception for Reid is direct in virtue of its independence from inferential reasoning, not from sensations.

[50] This term and the water example are also borrowed from Putnam. To relate Putnam’s language to Kripke’s, an analytic specification is a particular type of a posteriori identity wherein a thing is described in terms of its parts.

[51] See C. L. Hardin, “A Spectral Reflectance Doth Not a Color Make,” Journal of Philosophy 100 (2003): 191-202.

[52] A good description of the eye’s functioning with regard to color is available in Roy S. Berns, Fred W. Billmeyer, and Max Saltzman, Billmeyer and Saltzman’s Principles of Color Technology, 3d ed. (New York: John Wiley & Sons, 2000).

[54] E.g., Alex Byrne and David Hilbert, “Color Primitivism,” Erkenntis 66 (2007): 73-105, entertain and reject such a view.

[55] Jonathan Cohen, The Red and the Real (New York: Oxford, 2009).