Is the chair that I see on the floor before me blue?
To a non-philosopher, this question will seem frivolous - the chair is blue. To a philosopher, however, this question requires a rather more complex answer, and one which raises very important questions about how we should view the world around us. For all intents and purposes, in day to day existence, we refer to the chair on the floor before me as a 'blue chair' as though 'blue' is a property of the chair. The chair appears to have a colour which is sufficiently similar to other objects we have learnt are 'blue' to also deserve that description. The points this question raises for the philosopher, however, are whether or not and to what extent the 'blueness' of the chair is objective or subjective, that is, inherent in the properties of the chair, or in the eye of the beholder.
The initial requirement mentioned above - that the chair can be said to be 'blue' as it is of a colour similar to other objects we recognise as blue is not sufficient. There is no logical origin of the property of 'blueness' in this criterion. We must find an appropriate 'root' or 'ground' for this property, to see if 'blueness' is a quality of the chair. One of the problems of simply defining the chair as having the colour-property 'blue' is as follows: There arise circumstances in which the chair does not appear blue. For instance in the dark, or under red light, the chair will appear black, yet we would not refer to the chair as a 'black' chair. Also, the colour of the chair, in this case 'blue' may appear differently to every other person - the question of whether or not what we see as 'blue' is the same as what other people see as 'blue' arises. The first logical conclusion we arrive at from these observations is that 'blue' and any colour for that matter is something we see in our mind's eye, and does not resemble any of the real properties of the chair. This is an idea described in philosophy as Primary and Secondary quality.
Simply defined, a primary quality is an actual property possessed by the object. These include 'solidity', extension, figure, motion or rest, and number. A secondary quality is one which does not resemble any real feature of the object, but it is a the power of the object to create such sensory responses in order to create that quality. These include colour, sound, taste, heat/coldness, etc. This distinction between primary and secondary qualities was first conceived by Boyle, and refined by Locke. Although this seems to be a fairly harmless distinction, it has caused prolonged argument in the philosophical community for centuries.
Locke, in his explanation of the distinction between primary and secondary qualities, speaks of the relationship between the qualities of the object, and the ideas of those qualities in our minds. He says that the idea of a primary quality will resemble the 'ground of powers that produce them', while the idea of a secondary quality will not. The 'ground of powers' that produce a primary quality is the cause of the idea in our mind; the real quality which that idea represents. For a secondary quality, the idea does not represent the feature in the object which is the 'ground of powers that produced it'. For example, there is no feature of the chair that actually 'is' blue - the blueness is just the way the mind through the body interprets the frequency of light reflected off the surface of the chair. The idea of 'blue' does not resemble any property of the chair, whereas the idea of 'extended' does resemble a property. Locke would claim this is because the first is a secondary quality, while the latter is primary.
There are arguments against this distinction. The first to be examined shall be the objection of Berkeley to this distinction. Berkeley argues that since secondary qualities are the only ones that do not resemble their cause, then it is only in secondary qualities we should suffer illusion. It can be seen, he argues, that it is possible to suffer illusion in primary qualities as well, for instance as to the shape or size of a distant structure. This argument summarised is that since primary qualities 'resemble' the real qualities of an object then it should not be possible to have illusions regarding them. This argument, however, is based on a misunderstanding of Locke's original distinction. Berkeley has interpreted Secondary quality as the idea of a secondary quality. This means that illusion should be possible in our secondary qualities, but not in primary. Secondary qualities however, are the powers which produce the sensory information upon which the ideas of secondary qualities are based, and therefore illusion is irrelevant to the distinction, as ideas, which is where the illusion occurs - in mistaken differences between our ideas of an object and its qualities.
The most forceful argument against Locke's distinction between primary and secondary qualities is that the primary qualities of which we are mostly aware are geometric, there is little indication as to what the object actually is - what is it that is taking up the space, and not allowing other objects to occupy that space. Locke uses the term solidity to describe this quality, but many philosophers have complained that this is insufficient. The answer to this question appears to rest in physics and not in philosophy, however, and the actual nature of the particles which make up the object are of more concern to science than to philosophy.
It would seem in the face of these objections that the distinction between primary and secondary qualities stands up fairly well. The distinction that Locke sets out, albeit in a rather disorganised fashion, when clarified, does provide a good method of describing the causal relationships between objects and our sensations of them, and a way of more clearly interpreting the world around us. In this case, the with the question of the chair sitting on the floor before me, it would seem that to say 'the chair is blue' is a drastic over-simplification of the causal chain at work. A more complete answer would be that the primary qualities of the surface of the chair, its actual structure, is arranged in such a way as to reflect the certain wavelength of light which our sensory organs receive and our mind recognises as resembling the idea of the colour blue. One point which was not brought up in this essay was the issue of colour blindness, and the effect that question has on the distinction between primary and secondary qualities. In brief the answer to that in this case would be that the idea one has of 'blue' would be slightly different, and that is a problem of confusion in either the sensory organs or the mind, not the qualities of the chair itself.