The Simple Objectivist View of Colour is that there are in nature colours of the kind specified by the natural concept. Colours are simple intrinsic, non-relational, non-reducible properties, supervenient on micro-physical features. Such a view has been presented by P.M.S. Hacker (1987) and by J. Campbell (1994).

The main problem the illusion theorist finds with the Simple Objectivist View is with reconciling the putative character of the intrinsic colour features that fit together to comprise colour solids with the distinctive structure, with the causal role of such features in the recognition and identification of colours. The problem is addressed by Hacker in his defence of the claim that colours are intrinsic features of physical bodies. He forthrightly rejects not only the physicists' view, and Reid's view on colours, but also the dispositionalist account offered by McGinn, McDowell and Dummett. He insists that colours are properties which are used to provide causal explanations. There is no more reason to deny this, he says, than there is to deny the parallel claim for solidity and liquidity. In particular, he claims that we can provide causal explanations for why colours affect colour perceivers. The explanation is not vitiated by the discovery that microstructural processes are involved, any more than explanations concerning solidity and liquidity are rendered otiose by the discovery of the microstructural base for these properties.

It is doubtful that this manoeuvre works, for a number of reasons. One is that we would need to specify the criteria that make it the case that an object is intrinsically red. Not all perceivers agree in their judgements. It is not that there are colour blind people who can, after all, be said to be colour-deficient. There is a small but still significant number of colour-anomalous people, who can make all the same colour discriminations as regular people, but who disagree about which samples are pure red, green, etc. That is, it seems that their colour solid is skewed from the normal. It seems arbitrary that we decide that the real colour is the one that the majority pick. Secondly, if there were an evolutionary shift, or an eugenics program, the minority could become the majority.

There is a more important reason against Hacker's proposal, however, which depends on the fact that for colours, microstructural explanations cannot be provided for all the relevant, important features. Specifically the complex internal relationships between the colours cannot be explained by the microstructural properties of physical bodies, except through their affecting the perceivers. That is, to explain why the colours have the relationships they do requires giving an account of the structure of the perceiver's perceptual apparatus. At a minimum, this requires an account of the response curves of cells in the retinae, but also required would be an account of the appropriate neural processes. In short, the explanation will have to work via an explanation of how things appear, that is, of how one's perceptual experiences have the content that they do.

There is a difference between solidity/liquidity and the colours. In the case of solidity and its sister concepts, there is a range of features that are associated with them, including causal relationships. If we have been given adequate scientific explanations at the microstructural level for solidity, then adequate microstructural explanations will need to be given for these other features. The reason why it is important to preserve the concepts of solidity and liquidity is that such concepts unify sets of properties that are useful to have unified, and this unification is lost if we retreat to the microstructural level.

The important difference for colours is that there are crucial features of colours that are not reproduced at the microstructural level of the physical objects, nor are they explained at that level. The features are those that colours have, by virtue of which they are capable of forming systems of properties with internal relationships. This structural property is not explained at the microstructural level of physical samples of colours. To try to explain the structure physically, the best we could hope to do is to try to explain it in terms of dispositions, e.g., to induce a certain ratio of light sensitive retinal cells. Even if that were to work, it is the wrong kind of explanation to help Hacker. He wants to hold that colours are intrinsic qualities of physical objects, not relational, dispositional ones.