Acid flower

Full colour visions

Parmenides, who is often referred to as the father of metaphysics, steadfastly believed in a colourless reality. He denied that things in the world are coloured, let alone change colour. In his poem On Nature, the Eleatic adjudges those who believe otherwise to be victims of a falsehood or ‘naming error’, borne out of an all-too-human tendency to confuse appearance for reality.

…To these things all will be a name, which mortals establish, having been persuaded they are real: to come to be and to perish, to be and not to be, and to change location and exchange bright colour throughout.

Living around 500 BC, Parmenides was likely the first philosopher to argue a kind of colour eliminativism, the view which denies that physical objects have any properties that can be identified with colours. His position was the logical entailment of a purely rationalist account of reality that worked out the radical implications of the concept of Being. This led him to declare that true reality is One – unitary, unchanging, and eternal – and that all claims about diversity, qualities, motion, and change are false.1

Modern-day colour eliminativists operate on a different, albeit distantly related metaphysical schism that also divides appearance from reality: a Galilean ontology that carves up phenomenal experience into ‘primary qualities’ and ‘secondary qualities’. According to Galileo’s perceptual schema, primary qualities include extension, shape, size and motion, which are objective properties of objects. Secondary qualities on the other hand include colour, sound, smell, and taste, which are no more than mental constructions that have no resemblance to anything in reality, save for the ‘dispositions’ of things to cause them in our perception.

Many cognitive scientists and neuroscientists still cleave to this seventeenth century metaphysics through the inherited beliefs of the British empiricist John Locke, only with the added twist of a mutant Cartesianism. On this modern account, so-called ‘secondary qualities’ remain mere mind stuff, but the mind is now identified with the brain, which combines various bits of information via sensory processing to generate an internal representation of the visual field. This model of perception implies that the ‘out there’ of conscious experience isn’t really out there at all, and that we’re living in a figment of our imagination. When we look at the sky, for example, we’re perceiving a picture of the sky that is inside the skull, while reality itself is reduced to ‘a dull affair, soundless, scentless, colourless; merely the hurrying of material,’2 which only a mathematical-mechanistic language can faithfully articulate.

This image of our experience seems intuitively false. Aside from creating unresolvable philosophical problems, it ignores the fact that perception is an act that is continually performed by a sensing body in touch with its environment. Perception is in no way akin to picture-viewing. When we engage with our environment, we do not passively scan a pictorial representation located within the brain, but carve out a niche determined by our abilities and actions, in a world that reciprocally determines those actions. Moreover, it is not the brain which sees, but the person herself who is doing the seeing. To say otherwise is to credit the brain with properties only correctly ascribable to the whole person as a living, breathing, exploratory organism, while substituting the traditional idea of the soul for a Cartesian shadow-image imprisoned in the head. In short, the predicates that dualists ascribe to the immaterial soul are falsely applying them to the brain instead.

Perhaps worst of all, this inherited dualistic view indirectly invokes the spectre of idealism. For if representations are all we have, then cognitive scientists play fast and loose with their metaphysics when they treat their own observations of functioning brains as empirical facts. Surreptitiously they must switch from idealism to materialism in order to transform their own perceptual representation of a brain into an extant thing – the material cause behind all representations whose power extends beyond what is immediately presented to the mind. After naturalizing the relations between the brain and the world, which by the definitions of physics are undivided, scientists err by making the interactions between the two the equivalent of one of them.

To claim that colours are ‘in the head’ or even ‘in the world’ (known as colour realism) betrays a Cartesian subject-object model of discourse that mischaracterizes the nature of perception. Colours, as such, are nowhere – they have no physical location. Wavelengths of light stimulate the cells of the retina, which affects the optic nerve and excites cells in the hyper columns of the striate cortex. Seeing colour is not the end result of this causal interaction. The whole series of events is constitutive of colour perception. This fact is disruptive only because we tend to think of colours as being either brain-centred, as a result of sensory processing (neuroscientific reductionism), or located in space, as a real property of things in the world. In the latter case, we naturally assume that colours correspond with light reflected from a specific area. This naivety is simply a result of millions of years of evolution that has made the visual system incredibly efficient at smoothing over changes in a world that is perpetually in flux.

For example, we usually take it for granted that the color of an object remains largely the same regardless of its illumination and surroundings, but vision scientists have demonstrated that the light signals that bounce off an object and reach our eyes can vary considerably even when our perception of the object’s color stays the same. A green leaf for example typically reflects a high level of middle-wave light, but when viewed as part of a complex scene, green leaves can continue to look green even if they reflect more long-wave and short-wave light. This phenomenon is referred to as colour constancy.

A related phenomenon of vision occurs when two areas in a scene reflect light of the same spectral composition, yet display different colours depending on their surroundings. This effect, known as simultaneous colour contrast, is dependent not just on the overall colour composition of the backdrop, but on its specific chromatic distribution relative to the perceived object and its spectral reflectance properties.

That the light an object reflects can be independent of the colour we perceive it to be is only surprising because our perception of colour continually adapts to variations in illumination, as one might encounter within the flickering corona cast by a fire, or amid the variegated tapestry of sunlight rendered beneath a canopy of trees. As it turns out, this colour adaptivity constitutes all the dimensions of our visual experience, including the boundaries, surfaces, and textures that make up the visual manifold. This can be demonstrated simply by observing that it is impossible to separate a leaf from its colour, since it is the colour contrast itself that forms the outline of the leaf. Seeing colours as constant literally allows us to specify objects in our environment.

These facts of experience tend to pass us by during our everyday lives, but the introduction of a psychedelic drug into the nervous system typically reduces goal-directed behaviour and enables the natural activity of perception to drift, which can allow for fascinating insights into the phenomenal character of colour and pattern. A bucolic landscape painting, timeworn and impoverished by the dulling effects of familiarity, suddenly sparkles with opalescent tones and novel juxtapositions which seem almost distinct from the history of the forms they depict, as if they operated outside of time. A field of grass sheds the appearance of uniformity and presents a seamless multiplicity of iridescent hues.

For Alan Watts, the depth of light and structure in a bursting bud ‘go on forever’, while the pattern of wood grain seems ‘carved out with infinite patience and skill’ to the degree that ‘a rotten log bearing rows of fungus and patches of moss becomes as precious as any work of Cellini.’ For Aldous Huxley, plants reveal ‘innumerable shades of difference’, while the structure of a leaf ‘imparts a cavernous intricacy of the most delicate green lights and shadows’, as the perception of colour invariance recedes in concert with a diminishing concern for motor possibilities. The perennial philosopher frames the artificial duality in terms of seventeenth century metaphysics:

…the so-called secondary characters of things are primary. Unlike Locke, it evidently feels that colors are more important, better worth attending to, than masses, positions and dimensions.

In perceiving a fine-grained intensification of colour, Huxley is not viewing his brain’s accented mis-representation of a pre-given world. But neither is he seeing reality in an unfiltered light, ‘as it really is’, for that simply smuggles a subtler form of Cartesianism through the back door by presuming epistemic contact with an ‘objective’ pre-given world. Rather, his experience of colour is the result of a shift of interest, constituted by perturbations of light hitting the retina and novel states of nervous system activity triggered by a psychedelic drug. In short, it describes an alternative configuration of the prototypical body-brain-world nexus which is not immediately subsumed to cognitive expectancies, memory, and linguistic acquisition.

Psychedelics reinforce the fact that the body and the environment are tightly interwoven so as to constitute a mutually specifying continuity. Indeed, contra Parmenides and Galileo, only by acknowledging that continuity is ontologically prior to analysis will we recognise that perception is not an internal process of integration, but an open-ended act of decomposition – of breaking up what is a precarious, dynamic, and irreducible movement of energy into stable objects with sensible qualities (like colour) in order to make them available for manipulation.

In sum, we cannot understand an organism apart from the world it interacts with, nor can we understand the part of the world it interacts with apart from the body. Colour perception in this sense is one of the body’s ways of articulating our embeddedness in reality as if we were independent of it, while psychedelics are capable of disclosing this articulatory process, with potentially liberating results.


1 Parmenides was responding to his contemporaries’ belief that every thing has an ‘essence’, or a collection of properties that makes it the kind of thing it is, and since all things exist, they must all share the property of Being. Parmenides’ contribution was to show the radical implications of this image – of Being-entities separated by and moving within a void of non-being. He argued that if non-being existed, then by definition it would have the property of Being. But if that was the case, it wouldn’t be non-being at all. Therefore, non-being cannot exist. Without non-being, there can be no boundaries or separation. Likewise, claims about diversity, qualities, motion, or change, all implicitly assume non-being, which is an error. That being the case, to be must mean to be completely, once and for all. Therefore reality is One, unitary, unchanging, and eternal, while the world that the senses present to us — a plurality of entities that come into and go out of existence — is illusory.

2 Alfred North Whitehead, The Concept of Nature, Cambridge, 1920, CUP.