This work represents an interdisciplinary attempt at the development of a-- scientific theory of norms and normativity. Normativity, understood in its most general interpretation as value determinations and prescriptions, has traditionally been troublesome to account by science and difficult to “place” within a scientific worldview. Such an accomplishment is attempted by the joining in conversation of two bodies of literature. The first of these is Steve Fuller’s naturalist epistemology and the second corresponds to the situated study of cognition, along with (...) the epistemologies that have resulted from their findings. These two bodies of literature constitute the most radically naturalist attempts at developing a viable frame of epistemological and/or normative reference within their respective fields. (shrink)

One prominent ambition of theories of colour is to pay full justice to how colours are subjectively given to us; and another to reconcile this first-personal perspective on colours with the third-personal one of the natural sciences. The goal of this article is to question whether we can satisfy the second ambition on the assumption that the first should and can be met. I aim to defend a negative answer to this question by arguing that the various kinds of experienced (...) colour resemblances – notably similarities in hue distance, sameness in superdeterminables, and colour resemblances between surfaces, volumes and illuminants – cannot be accounted for in terms of the mental representation of the scientifically studied properties, which colours are best identified with in response to the second ambition. (shrink)

This paper is an essay in counterfactual epistemology. What if experience have high-level contents, to the effect that something is a lemon or that someone is sad? I survey the consequences for epistemology of such a scenario, and conclude that many of the striking consequences could be reached even if our experiences don't have high-level contents.

Develops an empirical argument against naive realism-disjunctivism: if naive realists accept "internal dependence", then they cannot explain the evolution of perceptual success. Also presents a puzzle about our knowledge of universals.

I will develop a new problem for almost all realist theories of colour. The problem involves fluctuations in our colour experiences that are due to visual noise rather than changes in the objects we are looking at.

Colours and consciousness both present us with metaphysical problems. But what exactly are the problems? According to standard accounts, they are roughly the following. On the one hand, we have reason to believe, about both colour and consciousness, that they are identical with some familiar natural phenomena. But on the other hand, it is hard to see how these identities could obtain. I argue that this is an adequate characterisation of our metaphysical problem of colour, but a mischaracterisation of the (...) problem of consciousness. It mischaracterises the problem by presenting consciousness as more 'colour-like' than we have reason to take it to be. The real problem of consciousness is, I suggest, that almost nothing theoretically useful is known about this phenomenon at present. I also explore some implications of this perspective on the problem of consciousness. Given the shape of the problem, I argue that we can't rule out all forms of eliminativism about consciousness. Nor can we rule out that future research will close the ' explanatory gap' that consciousness gives rise to. (shrink)

Suppose our visual experiences immediately justify some of our beliefs about the external world — that is, justify them in a way that does not rely on our having independent reason to hold any background belief. A key question now arises: Which of our beliefs about the external world can be immediately justified by experiences? I address this question in epistemology by doing some philosophy of mind. In particular, I evaluate the following proposal: if your experience e immediately justifies you (...) in believing that p , then (i) e has the content that p , and (ii) e ’s having the content that p is fixed by what it is like to have e . I start by clarifying this proposal and surveying the case in its favour. I then argue against the proposal and develop an alternative. The discussion shows what role visual consciousness plays and does not play in the justification of perceptual beliefs. (shrink)

Color vision provides accurate measures of the phase and intensity of daylight, and also a means of discriminating between objects. Neither property implies that objects are colored.

Cohen begins by defining ‘Color Physicalism’ so that the position is incompatible with Color Relationalism (unlike Byrne and Hilbert 2003, 7, and note 18). Physicalism, in any event, is something of a distraction, since Cohen’s argument from perceptual variation is directed against any view on which minor color misperception is common (Byrne and Hilbert 2004). A typical color primitivist, for example, is equally vulnerable to the argument. Suppose that normal human observers S1 and S2 are viewing a chip C, as (...) in Cohen’s example. C looks unique green to S1, and bluish green to S2. The problem, as Cohen has it, is to explain “what could (metaphysically) make it the case” that S1, say, and not S2, is perceiving C correctly. He purports to find the explanation “extremely hard to imagine”, and so concludes that both S1 and S2 are perceiving C correctly. (That is not the only option, of course: Hardin concludes that neither is perceiving the chip correctly.). (shrink)

Color-vision defects constitute a spectrum of disorders with varying degrees and types of departure from normal human color vision. One form of color-vision defect is dichromacy; by mixing together only two lights, the dichromat can match any light, unlike normal trichromatic humans, who need to mix three. In a philosophical context, our titular question may be taken in two ways. First, it can be taken at face value as a question about visible properties of external objects, and second, it may (...) be interpreted as the more intangible question of “what it’s like” to be color-blind. (shrink)

Physicalism about colour is the thesis that colours are identical with response-independent, physical properties of objects. I endorse the Argument from Structure against Physicalism about colour. The argument states that Physicalism cannot accommodate certain obvious facts about colour structure: for instance, that red is a unitary colour while purple is a binary colour, and that blue resembles purple more than green. I provide a detailed formulation of the argument. According to the most popular response to the argument, the Physicalist can (...) accommodate colour structure by explaining it in terms of colour experience. I argue that this response fails. Along the way, I examine other interesting issues in the philosophy of colour and colour perception, for instance the relational structure of colour experience and the description theory of how colour names refer. (shrink)

Thomas Reid famously claimed that our perceptual experiences reveal what primary qualities are in themselves, while providing us with only an obscure notion of secondary qualities. I maintain that this claim is largely correct and that, consequently, any adequate theory of perception must explain the fact that perceptual experiences provide significantly less insight into the nature of secondary qualities than into the nature of primary qualities. I maintain that neither naïve realism nor the standard Russellian variety of the content view (...) can provide a satisfying explanation; instead, in order to provide a satisfying explanation, we must posit that perceptual experiences represent properties via Fregean modes of presentation. Further, I maintain that we must depart from the standard Fregean variety of the content view in two important respects. First, the relevant modes of presentation must be characterized without appealing to causal relations between perceptual experiences and perceived properties; and second, we must posit that primary and secondary qualities are represented via modes of presentation of different kinds. The resulting view is that primary qualities are represented via perceptual modes of presentation analogous to highly detailed descriptions, while secondary qualities are represented via perceptual modes of presentation analogous to impoverished descriptions. (shrink)

According to Satosi Watanabe's "theorem of the ugly duckling", the number of predicates satisfied by any two different particulars is a constant, which does not depend on the choice of the two particulars. If the number of predicates satisfied by two particulars is their number of properties in common, and the degree of resemblance between two particulars is a function of their number of properties in common, then it follows that the degree of resemblance between any two different particulars is (...) also constant, which is absurd. Avoiding this absurd conclusion requires questioning assumptions about infinity in the proof or interpretation of the theorem, adopting a sparse conception of properties, or denying degree of resemblance is a function of number of properties in common. After arguing against both the first two options, this paper argues for a version of the third which analyses degree of resemblance as a function of properties in common, but weighted by their degree of naturalness or importance. (shrink)

A preview of my book *Perception*. Discusses the relationship between perception and the physical world and the issue of whether reality is as it appears. Useful examples are included throughout the book to illustrate the puzzles of perception, including hallucinations, illusions, the laws of appearance, blindsight, and neuroscientific explanations of our experience of pain, smell and color. The book covers both traditional philosophical arguments and more recent empirical arguments deriving from research in psychophysics and neuroscience. The addition of chapter summaries, (...) suggestions for further reading and a glossary of terms make Perception essential reading for anyone studying the topic in detail, as well as for students of philosophy of mind, philosophy of psychology and metaphysics. (shrink)

I argue that experiences can have microphenomenal structures, where the macrophenomenal properties we introspect are realized by non-introspectible microphenomenal properties. After explaining what it means to ascribe a microstructure to experience, I defend the thesis against its principal philosophical challenge, discuss how the thesis interacts with other philosophical issues about experience, and consider our prospects for investigating the microphenomenal realm.

This paper concerns the question of which properties figure in the contents of perceptual experience. According to conservatives, only low-level properties figure in the contents of perceptual experience. Liberals, on the other hand, claim that high-level properties, such as natural kind properties, artifacts, and even moral properties, can figure in the contents of perceptual experience. I defend a novel argument in favor of liberalism, the Epistemic Argument, which hinges on two crucial claims. The first is that many perceptual experiences of (...) even neurotypical human beings can justify beliefs in high-level properties without providing justification for their low-level constituents. The second claim, roughly, is that any experience that alone provides (defeasible) justification for beliefs about some property p, other things being equal, has p as part of its content. In short, certain perceptual experiences represent high-level but not low-level properties, which entails that liberalism is true. (shrink)

How could perceptual experiences reveal matters of essentiality? Answering this question is crucial for vindicating a thesis about the epistemic import of experience, commonly known as Revelation. The thesis comes in a weak and a strong version. Only on the strong one could it make up an authoritative piece of common sense. But this version also seems to demand too much of our experiences, namely that they can reveal essentiality. However, the impression that our experiences are not suited for this (...) turns out to be due to a non-mandatory assumption about how the revelation of essentiality would work. (shrink)

Quantities like mass and temperature are properties that come in degrees. And those degrees (e.g. 5 kg) are properties that are called the magnitudes of the quantities. Some philosophers (e.g., Byrne 2003; Byrne & Hilbert 2003; Schroer 2010) talk about magnitudes of phenomenal qualities as if some of our phenomenal qualities are quantities. The goal of this essay is to explore the anti-physicalist implication of this apparently innocent way of conceptualizing phenomenal quantities. I will first argue for a metaphysical thesis (...) about the nature of magnitudes based on Yablo’s proportionality requirement of causation. Then, I will show that, if some phenomenal qualities are indeed quantities, there can be no demonstrative concepts about some of our phenomenal feelings. That presents a significant restriction on the way physicalists can account for the epistemic gap between the phenomenal and the physical. I’ll illustrate the restriction by showing how that rules out a popular physicalist response to the Knowledge Argument. (shrink)

This collection brings together a selection of my recently published or forthcoming articles. What unites them is their common concern with one of the central ambitions of philosophy, namely to get clearer about our first-personal perspective onto the world and our minds. Three aspects of that perspective are of particular importance: consciousness, intentionality, and rationality. The collected essays address metaphysical and epistemological questions both concerning the nature of each of these aspects and concerning the various connections among them. More generally, (...) given that intentionality and ratio- nality are both normative phenomena, the main theme of the articles is the relationship between consciousness and normativity and the centrality of this relationship to our first-personal perspective. -/- This focus culminates in the defense of two specific views, experiential rationalism and experiential intentionalism. The first is, very roughly, the view that how our mental episodes are given in consciousness reflects their rational role in our mental lives: it is part of what our mental episodes subjectively are like that we phenomenally experience them as providing and/or responding to certain kinds of reasons. The central claim of the second view, on the other hand, is that the intentionality of our mental episodes is essentially linked to consciousness and involves a token-reflexive element: they intentionally present not only the world, but also themselves as being a certain way. -/- Some of the essays also deal with the contrast between our first- and our third-personal perspectives and the — to some extent related — division of labour between philosophy and the empirical sciences. Both perspectives have their limitations and sometimes conflict with each other, raising the question of what the consequences are for accounts of our first-personal knowledge and its internal or external objects. (shrink)

I offer a new objectivist theory of the contents of color language and color experience, intended especially as an account of what normal intersubjective variation in color perception and classification shows about those contents. First I explain an abstract account of the contents of color and other gradable adjectives; on the account, these contents are certain objective properties constituted in part by contextually intended standards of application, which are in turn values in the dimensions of variation associated with the adjectives. (...) Then I propose an explanation of normal variations in linguistic color classification; these are postulated to be effects of differences in intended standards for the color adjectives appearing in the classifying predicates. Next, I consider a potential objection to this explanation, based on the suggestion that contextual content should be more accessible than the explanation predicts. In reply, I point out that contextual content is occasionally opaque to unsophisticated reflection. Finally, I present a companion account of the contents of color experiences on which these represent an object as lying on certain salient intervals in the chromatic dimensions, and I show how the account accommodates intersubjective variation in color perception. (shrink)

Byrne & Hilbert conceive of color perception as the representation of a physical property “out there.” In our view, their approach does not only have various internal problems, but is also apt to becloud both the intricate and still poorly understood role that “ color ” plays within perceptual architecture, and the complex coupling to the “external world” of the perceptual system as an entirety. We propose an alternative perspective, which avoids B&H's misleading dichotomy between a purely subjective and a (...) realist conception of “ color.”. (shrink)

Reflectance physicalism only provides a partial picture of the ontology of color. Byrne & Hilbert’ account is unsatisfactory because the replacement of reflectance functions by productance functions is ad hoc, unclear, and only leads to new problems. Furthermore, the effects of color contrast and differences in illumination are not really taken seriously: Too many “real” colors are tacitly dismissed as illusory, and this for arbitrary reasons. We claim that there cannot be an all-embracing ontology for color.

Our reply is in three parts. The first part concerns some foundational issues in the debate about color realism. The second part addresses the many objections to the version of physicalism about color ("productance physicalism") defended in the target article. The third part discusses the leading alternative approaches and theories endorsed by the commentators.

The target article is an attempt to make some progress on the problem of color realism. Are objects colored? And what is the nature of the color properties? We defend the view that physical objects (for instance, tomatoes, radishes, and rubies) are colored, and that colors are physical properties, specifically types of reflectance. This is probably a minority opinion, at least among color scientists. Textbooks frequently claim that physical objects are not colored, and that the colors are "subjective" or "in (...) the mind." The article has two other purposes: first, to introduce an interdisciplinary audience to some distinctively philosophical tools that are useful in tackling the problem of color realism and, second, to clarify the various positions and central arguments in the debate. (shrink)

In many cases of variation in color vision, there is no non-arbitrary way of choosing between variants. Byrne and Hilbert insist that there is an unknown standard for choosing, while eliminativists claim that all the variants are erroneous. A better response relativizes colors to perceivers, thereby providing a color realism that avoids the need to choose between variants.

Whether or not one endorses realism about colour, it is very tempting to regard realism about determinable colours such as green and yellow as standing or falling together with realism about determinate colours such as unique green or green31. Indeed some of the most prominent representatives of both sides of the colour realism debate explicitly endorse the idea that these two kinds of realism are so linked. Against such theorists, the present paper argues that one can be a realist about (...) the determinable colours of objects, and thus hold that most of the colour ascriptions made by competent speakers are literally true, while denying that there are any positive facts of the matter as to the determinate colours of objects. The result is a realistic colour realism that can certify most of our everyday colour ascriptions as literally correct, while acknowledging the data regarding individual variation. (shrink)

H. H. Price (1932) held that experience is essentially presentational. According to Price, when one has an experience of a tomato, nothing can be more certain than that there is something of which one is aware. Price claimed that the same applies to hallucination. In general, whenever one has a visual experience, there is something of which one is aware, according to Price. Call this thesis Item-Awareness.

Nat Hansen builds a new argument for subjectivism about the semantics of color language, based on a potential kind of intersubjective disagreements about comparative color statements. In reply, I note that the disagreements of this kind are merely hypothetical, probably few if actual, and not evidently relevant as test cases for a semantic theory. Furthermore, even if they turned out to be actual and semantically relevant, they would be intuitively unusable by the subjectivist.

Larry Hardin has been the most steadfast and influential critic of physicalist theories of color over the last 20 years. In their modern form these theories originated with the work of Smart and Armstrong in the 1960s and 1970s1 and Hardin appropriately concentrated on their views in his initial critique of physicalism.2 In his most recent contribution to this project3 he attacks Michael Tye’s recent attempts to defend and extend color physicalism.4 Like Byrne and Hilbert5, Tye identifies color with the (...) reflecting properties of objects (“reflectance physicalism”). Specifically, the determinate and determinable colors are identified with types of reflectances. (Setting some complications aside, the reflectance of an object is the proportion of light that it reflects at each wavelength in the visible spectrum.) These reflectance types are, in the terminology of Hilbert, anthropocentric—in the terminology of Lewis6, they are not very “natural”. (shrink)

Primitivism is the view that colors are sui generis properties of physical objects. The basic insight underlying primitivism is that colours are as we see them, i.e. they are categorical properties of physical objects—simple, monadic, constant, etc.—just like shapes. As such, they determine the content of colour experience. Accepting the premise that colours are sui generis properties of physical objects, this paper seeks to show that ascribing primitive properties to objects is, ipso facto, ascribing to objects irreducible dispositions to look (...) coloured, and that anything that primitive redness can do, the non-reductive disposition to look red can do just as well. What makes primitivism suspect is not the commitment to sui generis properties, but instead the claim that colours are more than dispositions. Since, as I show, whatever primitivism appeals to for the purpose of arguing that colours are more than dispositions—objectivity, explanation, causation, phenomenology, constancy, etc.—can also be invoked... (shrink)

Adverbialism is the view that to have a conscious perceptual experience is to be consciously experiencing in a certain way, and that this way is not to be understood in relational or representational terms. We might compare what it is for a conscious being to be experiencing in a certain way with what it is for a string to be vibrating in a certain way. This paper makes a new case for adverbialism by appealing to the fact that we can (...) pick out ways of experiencing by treating them as information-bearing signals. In both presenting and defending the view, it will be crucial that information is not the same as representational content, but can still concern objects and the properties of those objects. The resulting information-theoretic adverbialism can answer or deflect the most influential objections to adverbialism. (shrink)

One popular materialist response to the explanatory gap identifies phenomenal concepts with type-demonstrative concepts. This kind of response, however, faces a serious challenge: that our phenomenal concepts seem to provide a richer characterization of their referents than just the demonstrative characterization of 'that quality'. In this paper, I develop a materialist account that beefs up the contents of phenomenal concepts while retaining the idea that these contents contain demonstrative elements. I illustrate this account by focusing on our phenomenal concepts of (...) phenomenal colour. The phenomenal colours stand in a similarity space relative to one another in virtue of being complex qualities—qualities that contain saturation, lightness, and various aspects of hue as component elements. Our phenomenal concepts, in turn, provide a demonstrative characterization of each of these component elements as well as a description of how much of that element is present in a given phenomenal colour. The result is an account where phenomenal concepts contain demonstrative elements and yet provide a significantly richer characterization of the intrinsic nature of their referents than just 'that quality'. (shrink)

I argue that Byrne & Hilbert (B&H) have not answered Hardin's objection to physicalism about color concerning the unitary-binary structure of the colors for two reasons. First, their account of unitary-binary structure seems unsatisfactory. Second, pace B&H, there are no physicalistically acceptable candidates to be the hue-magnitudes. I conclude with a question about the justification of physicalism about color.

Colours appear to instantiate a number of structural properties: for instance, they stand in distinctive relations of similarity and difference, and admit of a fundamental distinction into unique and binary. Accounting for these structural properties is often taken to present a serious problem for physicalist theories of colour. This paper argues that a prominent attempt by Byrne and Hilbert to account for the structural properties of the colours, consistent with the claim that colours are types of surface spectral reflectance, is (...) unsuccessful. Instead, it is suggested that a better account of the structural properties of the colours is provided by a form of non-reductive physicalism about colour: a naïve realist theory of colour, according to which colours are superficial mind-independent properties. (shrink)

Colours appear to instantiate a number of structural properties: for instance, they stand in distinctive relations of similarity and difference, and admit of a fundamental distinction into unique and binary. Accounting for these structural properties is often taken to present a serious problem for physicalist theories of colour. This paper argues that a prominent attempt by Byrne and Hilbert to account for the structural properties of the colours, consistent with the claim that colours are types of surface spectral reflectance, is (...) unsuccessful. Instead, it is suggested that a better account of the structural properties of the colours is provided by a form of non-reductive physicalism about colour: a naïve realist theory of colour, according to which colours are superficial mind-independent properties. (shrink)

Those who identify colours with physical properties need to say how the content of colour experiences relate to their favoured identifications. This is because it is not plausible to hold that colour experiences represent things as having the physical properties in question. I sketch how physical realists about colour might tackle this item of unfinished business.

In this paper, it is argued that those who claim that the dispositionalist theory of color has even a prima facie advantage over color physicalism in accommodating the similarity relations that seem to hold among the colors are mistaken. The appearance that dispositionalists can handle the relevant similarity claims stems from the unexamined assumption that the similarity of two dispositions is simply a matter of the similarity of the manifestations of those dispositions. A more careful treatment of the ways in (...) which two dispositions can be similar to, or different from, one another must consider both the bases and the manifestation conditions of those dispositions in addition to their manifestations. After examining cases of dispositions from outside the domain of colors, it is argued that attention to conditions of manifestation provides a particularly strong reason for rejecting the assumption that similarity of manifestations entails similarity of dispositions. Without this assumption, dispositionalists about color are shown to be in the same position as non-dispositionalists regarding similarity relations among the colors. This way of responding to color dispositionalism is compared with two other responses [offered by Byrne :641–665, 2003) and McLaughlin ], and shown to be a candidate to strengthen, rather than replace, either one. (shrink)

As demonstrated by several example displays, color illusions challenge color realism, because they involve a one-to-many reflectance-to-color mapping. Solving this problem by differentiating between veridical and illusory colors corresponding to the same reflectance is hampered because of the lack of an appropriate criterion. However, the difference between veridical and illusory color perception can still be maintained.

“The problem of color realism” as defined in the first section of the target article, is crucial to the argument laid out by Byrne & Hilbert. They claim that the problem of color realism “does not concern, at least in the first instance, color language or color concepts” (sect. 1.1). I argue that this claim is misconceived and that a different characterisation of the problem, and some of their preliminary assumptions makes their positive proposal less appealing.

The nature of the colors—what they are like, whether they are instantiated by objects or are projected by our minds, whether their nature is revealed to us in color perception, and whether there could be alien colors (e.g. reddish-green)—has been one of the central topics in philosophy for centuries. This entry focuses on the contemporary philosophical debate about the nature of the colors.

There are 2,000 hair cells in the cochlea, but only three cones in the retina. This disparity can be understood in terms of the differences between the physical characteristics of the auditory signal (discrete excitations and resonances requiring many narrowly tuned receptors) and those of the visual signal (smooth daylight excitations and reflectances requiring only a few broadly tuned receptors). We argue that this match supports the physicalism of color and timbre.

Byrne & Hilbert defend color realism, which assumes that: (a) colors are properties of objects; (b) these objects are physical; hence, (c) colors are physical properties. I accept (a), agree that in a certain sense (b) can be defended, but reject (c). Colors are properties of perceptual objects – which also have underlying physical properties – but they are not physical properties.

In recent work, David Chalmers argues that “Edenic shapes”—roughly, the shape properties phenomenally presented in spatial experience—are not instantiated in our world. His reasons come largely from the theory of Special Relativity. Although Edenic shapes might have been instantiated in a classical Newtonian world, he maintains that they could not be instantiated in a relativistic world like our own. In this essay, I defend realism about Edenic shape, the thesis that Edenic shapes are instantiated in our world, against Chalmers’s challenge (...) from Special Relativity. I begin by clarifying the notion of an Edenic shape by reference to Chalmers’s notion of the “Edenic” content of perceptual experience. I then reconstruct Chalmers’s argument that Edenic shapes could not be instantiated in a relativistic world. His reasoning proceeds from two assumptions. The first is that the only shape properties instantiated in a relativistic world are those which somehow involve relations to frames of reference. This is thought to follow from the phenomenon of Lorentz contraction, a consequence of Special Relativity. The second assumption is that Edenic shapes do not involve relations to frames of reference. One reason to accept the second assumption is that it seems that Edenic shapes could be instantiated in a classical Newtonian world, where the notion of a frame-relative shape has no meaningful application. I then proceed to defend RES against Chalmers’s argument by arguing that Special Relativity, properly understood, provides no support for Chalmers’s first assumption. More generally, I argue, by way of a careful analysis of the geometric structure of Minkowski space–time and Galilean space–time Newtonian physics), that Edenic shapes are no less at home in a relativistic world than in a classical Newtonian world. (shrink)

The thesis is intended to contribute to the growing understanding of the indispensable role played by phenomenal consciousness in human cognition, and specifically in making our concepts of the external world available. The focus falls on so called observational concepts, a type of rudimentary, perceptually-based objective concepts in our repertoire — picking out manifest properties such as colors and shapes. A theory of such concepts gets provided, and, consequently, the exact role that perceptual consciousness plays in making concepts of this (...) sort available gets settled. In the first half of the thesis, observational concepts get construed as a special type of recognitional concepts. On an analogy with perceptual demonstratives, having such concepts would involve having non-trivial knowledge of their reference. The experiential basis of such concepts would, among other things, provide for such constitutive knowledge. The theoretical background relevant to the hypothesis gets provided in the first chapter. A defence of the hypothesis follows in the second. In the second half of the thesis, care is taken to distinguish among two ways in which the constitutive knowledge of the reference of an observational concept could be fleshed out. In the third chapter, perceptual experience is shown to provide the basis both for knowledge of observational properties by acquaintance, and for knowledge of the essence of such properties — provided that knowledge of essence gets construed in the right, modest way. It might be natural to take knowledge by acquaintance to be the sort relevant to observational concept possession, especially given that in the case of perceptual demonstratives this is the role likely played by experience. However, this initial impression proves to be mistaken. The constitutive knowledge of the referent of an observational concept turns out to consist in the capacity to determine a priori the essence of the respective property. To show this, an argument gets provided in the penultimate fourth chapter, based on the key role played by experiences of instances of observational properties in optimal viewing conditions in enabling the possession of the respective observational concept. (shrink)

Byrne & Hilbert propose that color can be identified with explicit properties of physical surfaces. I argue that this claim must be qualified to take into account constraints needed to make recovery of surface color information possible. When these constraints are satisfied, then a biological visual system can establish a correspondence between perceived surface color and specific surface properties.

The reflectance types that Byrne & Hilbert identify with colors count as types only in a way that is more dependent on, and more relative to color perceivers, than their account suggests. Their account of perceptual content may be overly focused on input conditions and distal causes.