Derek H. Brown

Mazviita Chirimuuta’s The Brain Abstracted (2024) is a fascinating intervention into the philosophy of mind and neuroscience, containing deeply interesting ideas and arguments. Our aim is to critically probe whether Haptic Realism is neutral on some substantive issues which Chirimuuta would like it to be neutral on. Firstly, it is unclear whether Haptic Realism is compatible with Chirimuuta’s metaphysical neutrality. Causal notions feature heavily in Haptic Realism, including construction and interaction, without which it is unclear what the haptic component of Haptic Realism amounts to. We argue that the interpretation of these causal notions forces a choice that jeopardises metaphysical neutrality, since it is doubtful that there are any relevantly neutral theories of causation. Secondly, we ask the question ‘Do all brains have neurons?’ Haptic Realism trades on the idea of ideal patterns, patterns that are coaxed into existence by the interaction between practitioners and the world. If ideal patterns only exist within the confines of the lab, and neurons are idealizations, then brains out in the wild do not have neurons. Worryingly, this commitment of Haptic Realism undermines our ability to project neurological knowledge that we gain from studying particular brains to what is happening inside the everyday human beings.

Pretheoretically, our senses give us immediate access to the world around us. Perceptual demonstratives (e.g. uttering “that is a bottle” while pointing at a bottle) seem to directly refer to their intended referents. Should we explain such referential directness by perceptual immediacy? Bermúdez (2000) argues that we should, and offers a powerful theory of immediate and mediate perception (Naturalized sense-datum theory) to explain how. He also argues that a different but influential theory of immediate and mediate perception (that found in traditional sense-datum theory) cannot explain referential directness by perceptual immediacy. I argue that his criticisms fail in instructive ways. Following this I assess the extent to which Bermúdez’s theory can explain a critical perceptual challenge, that of explaining the experiential similarities between perceptual experiences with varying degrees of veridicality. I argue that Bermúdez’s theory can only meet this challenge by embracing a veil of perception akin to that of his opponent – something he sought to avoid. Before concluding, I present the underlying framework of this debate devoid from any appeal to sense-datum theories. The reason is because that framework has considerable power and relevance to a number of contemporary issues in philosophy of perception.

This policy report arises from the research project Augmented Reality: Ethics, Perception, Metaphysics, conducted at the University of Glasgow’s Centre for the Study of Perceptual Experience between November 2021 and November 2023. It was funded by a grant from the Royal Society of Edinburgh. The project brought together experts in various academic fields, with partners from industry and regulatory bodies, to explore the nature of augmented and mixed reality technology, the theories underpinning them, and the ethical and legal questions prompted by new technology in this domain.

From David Hume's famous puzzle about 'the missing shade of blue' to current research into the science of colour, the topic of colour is an incredibly fertile region of study and debate, cutting across philosophy of mind, epistemology, metaphysics and aesthetics as well as psychology. Debates about the nature of our experience of colour and the nature of colour itself are central to contemporary discussion and argument in philosophy of mind and psychology, and philosophy of perception. This outstanding Handbook contains twenty-nine specially commissioned contributions by leading philosophers and examines the most important aspects of philosophy of colour. It is organised into six parts: The Importance of Colour to Philosophy The Science and Spaces of Colour Colour Phenomena Colour Ontology Colour Experience and Epistemology Language, Categories and Thought. The Routledge Handbook of Philosophy of Colour is essential reading for students and researchers in philosophy of mind and psychology, epistemology, metaphysics and aesthetics, as well as for those interested in conceptual issues in the psychology of colour.

Colour variation is the fact that what colour physical objects look to have depends on viewing conditions and a perceiver’s visual system. Both Colour Relationalists and Colour Eliminativists regard their analyses of colour variation as central to the justification for their respective views. Yet the analyses are decidedly different. Colour Relationalists assert that most instances of colour variation are veridical and infer from this that colours are relational properties of objects that are partly determined by perceivers. By contrast, Colour Eliminativists assert that colour variation is too unsystematic to ground the claim that many or most instances of colour variation are veridical. From this they infer that objects don’t have colours. I argue that the Eliminativist analysis is superior. On my view, the Relationalist account of veridical colour experience reduces to the assertion that objects have colour simply because they cause perceivers to have colour experiences of them. In this context, I argue, the resulting conception of veridicality is vacuous. More directly, the foundational idea of Eliminativism is the opposite claim: the fact that objects cause perceivers to have colour experiences of them is on its own not sufficient to justify or ground the claim that objects have colour. The Relationalist, I argue, has failed to justify anything stronger than this. In this debate we should thus side with the Eliminativist: objects do not possess colour; they merely cause us to undergo colour experiences.

Studying colour vision across various species suggests that different species perceive different colours (the Disunity Hypothesis). It is plausible that all species’ color visual systems are, at least in principle, equally correct/veridical regarding colour (Ecumenicism). Assuming that colours are mind-independent features of material objects (Objectivism), it follows that objects simultaneously have different colours for different species (Pluralism). But are all these colours compatible with one another? Some have argued that they are on grounds that, while comparisons between colours are possible within a given species’ colour space, they are not possible across the colour spaces of different species. Since colours from different spaces are not comparable, they cannot be incompatible. Hence, a given object can have a colour from as many colour spaces as needed to explain interspecies variations in colour perception. I argue that this reasoning is flawed in two ways. First, colour spaces that are non-comparable in pure or abstract reasoning, may nonetheless be comparable in applied contexts. Second, in our applied context – our world – evidence suggests that incompatibilities between colours from different species’ spaces are extremely likely when Colour Objectivism is presumed. But then the Pluralist solution to interspecies variation seems unavailable to the colour objectivist.

Projectivism is the thesis that we project at least some subjective aspects of perception into what we experience as the world outside ourselves. It is familiar from various phantom pains, afterimages, and hallucinations. Strong Projectivism asserts that all perceptual experiences involve and only involve direct awareness of projected elements. Strong Projectivism is an unpopular and I argue underappreciated variety of intentionalism (or representationalism). It straightforwardly explains the transparency of experience (section 2) and phenomena qualia theorists offer to avoid intentionalism such as blurry vision and spectrum inversion (section 3). Finally, projectivism illuminates residual qualia-friendly cases involving imagination and emotion (section 4). Ultimately, instances of non-projected, non-intentional aspects of experience are hard to identify. Thus, the notion of phenomenal presence drawn from projectivism does justice to a great many of the forces at play in debates surrounding qualia and intentionalism. We should bound toward Strong Projectivism.

Sensory substitution devices (SSDs) are most familiar from their use with subjects who are deficient in a target modality (e.g. congenitally blind subjects), but there is no doubt that the use and potential value of SSDs extend to persons without such deficits. Recent work by Amedi and his team (in particular Levy-Tzedek et al. 2012) has begun to explore this. Their idea is that SSDs may facilitate behavioural transference (BT) across sense modalities. In this case, a motor skill learned through visual perception might be subsequently employed in response to auditory perception, using an SSD as a mediator. They infer from the existence of such BT that the learned skill is amodally represented. After a brief overview I identify ways to more fully test for BT within this experimental paradigm and argue that their conclusion about amodal representation is premature. Additionally, I argue that their preferred SSD (Eyemusic) is of limited value for the project. While my remarks are critical, my intention is to be constructive, particularly in light of the fact that Levy-Tzedek et al. (2012), is, I believe, the first output from Amedi's lab concerning this line of research.

This chapter explores the broad thesis that most if not all perceptual experiences are infused or soaked with imaginings. To begin, the author articulates a sense of imagination useful for this discussion, avoids some pitfalls, and incorporates the result into a schematic guidance principle. The thought behind the principle is that imaginative contributions to perceptual experiences are self-generated ingredients to perception that have a reasonably direct, ampliative impact on the relevant perceptual experiences. This framework is then applied to three sets of case studies: object-kind and object-sameness experiences (Strawson 1970); colour (Macpherson 2012); and amodal completion (Nanay 2010) and perceptual constancy. Although the case studies have interesting differences, they all conform to the guidance principle. Since each has the potential to independently justify the thesis that perceptual experiences are infused with imaginings, they collectively provide sound motive to provisionally endorse it.

At first pass, colour constancy occurs when one sees a thing in one’s environment to have a stable colour despite differences in the way it is illuminated. The phenomenon is intuitively grounded for example in everyday experiences in which something is partly shadowed but, in some sense, looks to be uniformly coloured. After a brief introduction to the colour constancy concept (§0) and the science of colour constancy (§1), my focus is on the significance of colour constancy for two intertwined philosophical issues. The first is colour ontology, where constancy has been used to argue for the objectivity of colour, and in particular for a reductive form of it (see §2). The second is colour constancy’s complicated connection to colour experience and colour epistemology. Colour constancy is a subtle phenomenon: it is situated at the intersection of perceptual experience and judgement; it is influenced by myriad forces within our visual-cognitive systems; and is likely a composite of interestingly disparate phenomena. I approach this suite of issues from the perspective of the given in colour perception (§3). As will become plain, the ontological and epistemic issues are related in important ways. This does not, however, detract from the value of focusing on each individually.

The essays in this volume concern the points of intersection between analytic philosophy and the philosophy of the exact sciences. More precisely, it concern connections between knowledge in mathematics and the exact sciences, on the one hand, and the conceptual foundations of knowledge in general. Its guiding idea is that, in contemporary philosophy of science, there are profound problems of theoretical interpretation-- problems that transcend both the methodological concerns of general philosophy of science, and the technical concerns of philosophers of particular sciences. A fruitful approach to these problems combines the study of scientific detail with the kind of conceptual analysis that is characteristic of the modern analytic tradition. Such an approach is shared by these contributors: some primarily known as analytic philosophers, some as philosophers of science, but all deeply aware that the problems of analysis and interpretation link these fields together.

This essay is an introduction to the Routledge Handbook of Philosophy of Colour. Why has the examination of many different aspects of colour been a prominent feature in philosophy, to such an extent that the topic is worthy of a handbook? Here are two related answers. First, colours are exceedingly familiar, seemingly simple features that become enigmatic under scrutiny, and they are difficult to capture in any familiar-sounding, unsophisticated theory. Second, through colour one can confront various problems that span the breadth of philosophy, including problems pertaining to perception, the mind-body relation, the nature of science, scepticism, vagueness, meta-ethics, and aesthetics. In this introduction we elaborate and guide the reader to the essays in the rest of this volume.

I outline five issues in philosophy of colour that deserve greater attention and provide skeletal frameworks for how future work on these topics could be carried out. The issues are: colour and metaphilosophy, colour and artistic practice, colour and virtual/augmented reality, colour and imagination, and colour and the predictive mind. Some of these issues have been a focus of important recent works. Thus, colour conjoined with each of metaphilosophy, artistic practice and imagination have all been examined in at least a few recent publications – see below for references. It is clear, however, that these recent works are signals that there is much still to be done. By contrast, while at present there is a great deal of interest in the predictive mind, the intersection of colour and the predictive mind is vastly underexplored. This is despite the fact that the philosophy and science of colour are rather developed disciplines. Finally, while there have been some very important recent works on virtual and augmented reality, the significance of colour for these studies has yet to be examined. It is my hope that after reading this article readers are convinced not only that the philosophy of colour has a rich, recent history, but also a very bright future.

From David Hume's famous puzzle about 'the missing shade of blue' to current research into the science of colour, the topic of colour is an incredibly fertile region of study and debate, cutting across philosophy of mind, epistemology, metaphysics and aesthetics as well as psychology. Debates about the nature of our experience of colour and the nature of colour itself are central to contemporary discussion and argument in philosophy of mind and psychology, and philosophy of perception. This outstanding Handbook contains twenty-nine specially commissioned contributions by leading philosophers and examines the most important aspects of philosophy of colour. It is organised into six parts: The Importance of Colour to Philosophy The Science and Spaces of Colour Colour Phenomena Colour Ontology Colour Experience and Epistemology Language, Categories and Thought. The Routledge Handbook of Philosophy of Colour is essential reading for students and researchers in philosophy of mind and psychology, epistemology, metaphysics and aesthetics, as well as for those interested in conceptual issues in the psychology of colour.

© The Authors 2017. Published by Oxford University Press on behalf of The Analysis Trust. All rights reserved. For Permissions, please email: [email protected] Colour is a welcome work in history and philosophy of science.1 The opening chapters offer a fresh take on the history of perceptual theory and a broad overview of contemporary philosophy of colour. This is followed by the central fourth chapter, which introduces readers to a cluster of empirical data that to this point have not received explicit treatment in philosophy. The core message is that instead of thinking of colour vision as filling in or painting the experienced world of primary qualities, we should think of colour vision as helping us to experience primary qualities. The colour visual system does not colour in an experiential world of primary qualities, it uses colour for the experience of those qualities. This colouring...

I defend indirect perceptual realism against two recent and related charges to it offered by A. D. Smith and P. Snowdon, both stemming from demonstrative reference involving indirect perception. The needed aspects of the theory of demonstratives are not terribly new, but their connection to these objections has not been discussed. The groundwork for my solution emerges from considering normal cases of indirect perception (e.g., seeing something depicted on a television) and examining the role this indirectness plays in demonstrative assertions. I argue that indirectness routinely if not typically plays a justificatory role in such judgements, and not a semantic one, and that the same can be said of such judgements when considered within the indirect realist framework. The denial of this, on my analysis, is essential to the criticisms of Snowdon and Smith. The discussion is extended to include scenarios involving the sorts of misconceptions Smith employs.

This is a review of Athanassios Raftopoulos "Cognition and perception: How do psychology and neuroscience inform philosophy?" (MIT Press, 2009). Raftopoulos defends the modularity of vision, i.e. early vision not penetrable by other processes. He maintains that early vision forms and outputs a kind of nonconceptual content to subsequent stages of vision and cognition. The work is heavily informed by visual neuroscience and embedded in familiar debates about scientific realism. It is also an important contribution to the now-popular debates about the cognitive penetration of perception.

The claim that perceptual illusions can motivate the existence of sense-data is both familiar and controversial. My aim is to carve out a subclass of illusions that are up to the task, and a subclass that are not. It follows that when we engage the former we are not simply incorrectly perceiving the world outside ourselves, we are directly perceiving a subjective entity: one’s grip on the external world has been marginalized – not fully lost, but once-removed. However, admitting that various illusions do not give evi¬dence for sense-data considerably limits the power of the argument from illusion (Section 6) and brings out its distinctness from the argument from perceptual relativity (Section 7). To reach these conclusions we will examine the role of ambiguity in perception (Section 3), its connection to illusion (Section 4), and the link reference has to every element of this dis¬course (Sections 2 and 5).

A dual referent approach to colour theory maintains that colour names have two intended, equally legitimate referents. For example, one might argue that ‘red’ refers both to red appearances or qualia, and also to the way red objects reflect light, the spectral surface reflectance properties of red things. I argue that normal cases of perceptual relativity can be used to support a dual referent approach, yielding an understanding of colour whose natural extension includes abnormal cases of perceptual relativity. This contrasts with Peacocke’s multi-referent view, according to which such abnormal cases force us to introduce a wholly distinct kind of colour experience. I also argue that the two uses of colour names, arising from their two referents, have different extensions, even in normal perceptual circumstances, a consequence which conflicts with the heart of Rosenthal’s dual referent view.

Indirect realists maintain that our perceptions of the external world are mediated by our 'perceptions' of subjective intermediaries such as sensations. Multiple reference occurs when a word or an instance of it has more than one reference. I argue that, because indirect realists hold that speakers typically and unknowingly directly perceive something subjective and indirectly perceive something objective, the phenomenon of multiple reference is an important resource for their view. In particular, a challenge that A. D. Smith has recently put forward for indirect realists can be overcome by appreciating how multiple reference is likely to arise when a projectivist variety of indirect realism is interpreted by speakers adhering to a naïve direct realism.

Loosely put, colour constancy for example occurs when you experience a partly shadowed wall to be uniformly coloured, or experience your favourite shirt to be the same colour both with and without sunglasses on. Controversy ensues when one seeks to interpret ‘experience’ in these contexts, for evidence of a constant colour may be indicative a constant colour in the objective world, a judgement that a constant colour would be present were things thus and so, et cetera. My primary aim is to articulate a viable conception of Present Constancy, of what occurs when a constant colour is present in experience, despite the additional presence of some experienced colour variation (e.g., correlating to a change in illumination). My proposed conception involves experienced colour layering – experiencing one opaque colour through another transparent one – and in particular requires one of those experienced layers to remain constant while the other changes. The aim is not to propose this layering conception of colour constancy as the correct interpretation of all constancy cases, but rather to develop the conception enough to demonstrate how it could and plausibly should be applied to various cases, and the virtues it has over rivals. Its virtues include a seamless application to constancy cases involving variations in filters (e.g., sunglasses) and illuminants; its ability to accommodate experiences of partial colours and error-free interpretations of difficult cases; and its broad theoretical-neutrality, allowing it to be incorporated into numerous perceptual epistemologies and ontologies. If layered constancy is prevalent, as I suspect it is, then our experiential access to colours is critically nuanced: we have been plunged into a world of colour without being told that we will rarely, if ever, look to a location and experience just one of them.

Intentionalism debates seek to uncover the relationship between the qualitative aspects of experience—phenomenal character—and the intentionality of the mind. They have been at or near center stage in the philosophy of mind for more than two decades, and in my view need to be reexamined. There are two core distinct intentionalism debates that are rarely distinguished (Sect. 1). Additionally, the characterization of spectrum inversion as involving inverted qualities and constant intentional content is mistaken (Sect. 3). These confusions can be witnessed from an often-ignored and lonely perspective, that of the sense-datum theorist, and in particular of the projectivist (Sect. 2). In my view we have been so wary of sense-datum theory in recent years that we have failed to see that, even if false, it may permit perspectives on intentionalism issues difficult to occupy from other views.

We perceive the objective world through a subjective perceptual veil. Various perceived properties, particularly “secondary qualities” like colours and tastes, are mind-dependent. Although mind-dependent, our knowledge of many facts about the perceptual veil is immediate and secure. These are well-known facets of sense-datum theory. My aim is to carve out a conception of sense-datum theory that does not require the immediate and secure knowledge of a wealth of facts about experienced sense-data (§1). Such a theory is of value on its own, given well-known challenges to epistemic foundationalism. Beyond this such a theory helps demonstrate how sense-datum theory can accommodate challenging perceptual phenomena like shape and size constancies (§3). These ideas are bridged by the roots of perceptual ambiguity (§2). In brief, tapering acquaintance knowledge creates space for perceptual representation to resolve the ambiguities in presented objects seemingly inherent in scenarios involving perceptual constancies. Thus, I offer a two-factor (acquaintance-representation) sense-datum theory to meet the challenge posed by constancies. Following Smith (2002), from whom this challenge is drawn, my focus is on shape and size constancies. Other constancies, notably colour constancy, are treated elsewhere (Brown 2014).

Colour Relationalism asserts that colours are non-intrinsic or inherently relational properties of objects, properties that depend not only on a target object but in addition on some relation that object bears to other objects. The most powerful argument for Relationalism infers the inherently relational character of colour from cases in which one’s experience of a colour contextually depends on one’s experience of other colours. Experienced colour layering—say looking at grass through a tinted window and experiencing opaque green through transparent grey—demands a contextual interdependency of one’s experience of one of these colours on one’s experience of the other. However, most if not all colour ontologies, and core perceptual experiential mechanisms like acquaintance and representation, can accommodate colour layering. It follows that experienced colour layering is consistent with colours being non-relational—this contextual interdependency of colours does not entail the constitutive dependency of one colour on the other. I utilize colour layering to examine the inference from the contextual to the constitutive interdependency of colours as it is employed in a well-known argument for Relationalism. I conclude that our justification for Relationalism is far weaker than Relationalists suggest. I first introduce readers to colour layering, then to Relationalism, and following this focus on the intersection of these topics.