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From the horse's mouth: Locke's Essay Book II, Chapter VIII, Sections 7-26.
We have considered John Locke as helping to revolutionise the conception of an individual thing, and therefore of the nature of the universe.
There is another respect in which Locke helped establish Modernity: he articulated and defended a distinction between primary and secondary qualities.
Here is Locke expounding it:
| "Qualities thus considered in bodies are: First, such as are utterly inseparable from the body ...[namely] solidity, extension, figure, and mobility ... Secondly, such qualities which in truth are nothing in the objects themselves but powers to produce various sensations in us by their primary qualities, ie by their bulk, figure, texture, and motion of their insensible parts, as colours, sounds, tastes, etc. These I call secondary qualities." An Essay concerning human Understanding, Bk II, Ch. VIII, Section 9. |
First notice that ideas are to be distinguished from qualities.
A quality is a power. It is the power a thing has to give rise to an idea in our mind.
There are two sorts of qualities: primary and secondary.
A primary quality gives rise to an idea which resembles it. Secondary qualities give rise to ideas, but the ideas are not 'like' the qualities that give rise to them.
Think for example, the particular taste which you get when you take sugar. The taste is an idea. But what type of feature is it that gives rise to that idea?
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| Introductory words on taste. |
Locke followed the new science in thinking that taste was produced by the shape and size configuration of the particles of which the sugar was made. He didn't have (I don't think) a specific account, but he thought that when we had acquired one, through research, it would have the general form of explaining taste in terms of the basic properties of particles - their shape, their size, their configuration.
| Locke was not alone in subscribing to this theory. Galileo had said much the same earlier in the revolutionary period. |
There was, he held, nothing like taste actually in the sugar itself: there was only a collection of particles, each with a shape, each with a size, with the collection organised in a particular way. It was these features of the particles that made a thing up which gave rise to the taste sensation we experience when we put the sugar in our mouths.
Compare that to the idea we have of motion.
We look at a moving body and that gives rise in us to the idea of motion.
In this case Locke holds the body we are looking at has a property which is 'like' the idea it gives rise to. The body is moving. The idea it gives rise to is the idea of motion.
Motion thus qualifies as a primary quality.
Thus one attempt to distinguish two sorts of qualities is this:
A secondary quality is a quality which gives rise to an idea which does not resemble it.
Let us list some qualities that appear primary according to this test, and some secondary ones:
| PRIMARY | SECONDARY |
| motion | smell |
| shape | roughness |
| extension | shininess |
| mass | sound |
Here are some of the arguments Locke makes in trying to establish the primary/secondary distinction.
'Let
us consider the red and white colours in porphyry. Hinder light from striking
on it, and its colours vanish; it no longer produces any such ideas in us:
upon the return of light it produces these appearances on us again. Can any
one think any real alterations are made in the porphyry by the presence or
absence of light; and that those ideas of whiteness and redness are really
in porphyry in the light, when it is plain it has no colour in the dark?
It has, indeed, such a configuration of particles, both night and day, as
are apt, by the rays of light rebounding from some parts of that hard stone,
to produce in us the idea of redness, and from others the idea of whiteness;
but whiteness or redness are not in it at any time, but such a texture that
hath the power to produce such a sensation in us.'
We can imagine a black dog turning grey, but not losing its extension.
A piece of paper can lack smell but not size.
'The ideas of the primary alone really exist. The particular bulk, number, figure, and motion of the parts of fire or snow are really in them,- whether any one's senses perceive them or no: and therefore they may be called real qualities, because they really exist in those bodies. But light, heat, whiteness, or coldness, are no more really in them than sickness or pain is in manna. Take away the sensation of them; let not the eyes see light or colours, nor the ears hear sounds; let the palate not taste, nor the nose smell, and all colours, tastes, odours, and sounds, as they are such particular ideas, vanish and cease, and are reduced to their causes, i.e. bulk, figure, and motion of parts.'
'Ideas being thus distinguished and understood, we may be able to give an account how the same water, at the same time, may produce the idea of cold by one hand and of heat by the other: whereas it is impossible that the same water, if those ideas were really in it, should at the same time be both hot and cold. For, if we imagine warmth, as it is in our hands, to be nothing but a certain sort and degree of motion in the minute particles of our nerves or animal spirits, we may understand how it is possible that the same water may, at the same time, produce the sensations of heat in one hand and cold in the other; which yet figure never does, that never producing- the idea of a square by one hand which has produced the idea of a globe by another. But if the sensation of heat and cold be nothing but the increase or diminution of the motion of the minute parts of our bodies, caused by the corpuscles of any other body, it is easy to be understood, that if that motion be greater in one hand than in the other; if a body be applied to the two hands, which has in its minute particles a greater motion than in those of one of the hands, and a less than in those of the other, it will increase the motion of the one hand and lessen it in the other; and so cause the different sensations of heat and cold that depend thereon.'
'Pound an almond, and the clear white colour will be altered into a dirty one, and the sweet taste into an oily one. What real alteration can the beating of the pestle make in any body, but an alteration of the texture of it?'
(Descartes had argued (among other things): Secondary qualities are only perceptible through a single sense.
Malebranche had argued: the perception of secondary qualities varied with the position of the observer, and so cannot be 'in' the object. E.g. a thing appears to have a different colour depending on the angle of perception, or the light.)
Remember the idea of atomism (or corpuscularianism):
The phenomena of the natural world are to be explained by thinking of that world as made up of small particles, each particle having a limited number of properties. It was these particles, with their properties and in various configurations which produced everything that we could see about us.
You can understand how big things like tables can be thought of as made up of many smaller things grouped together. This is part of corpuscularianism.
But a second part is that some of the properties of the big things are to be explained in terms of a simpler set of properties of the elementary things. The elementary things have a limited number of elementary properties. It is part of corpuscularianism that all the properties of the big things are to be explained in terms of the elementary properties of the elementary things.
Can we be more precise about which qualities are which? Which are the primary ones, the ones which are supposed to explain the others?
and :
"[D]ivision ... can never take away either solidity, extension, figure,
and mobility."
Essay,
Bk II, Ch. VIII, Section 9.
- a peculiar list, you may think. But still, the basic idea is there.
Locke says that primary qualities are really 'in' the bodies that have them, whereas secondary qualities are not. Is this helpful?
It is perhaps best seen as a point about the scientific world view that Locke was helping to form. A world view that 'privileges' some features of the world at the expense of others - ? It would make the world out to be, in itself, a severe and forbidding construction: just atoms moving about, with nothing but size, shape, solidity and motion. Most of the things which give human beings pleasure are not there in reality, but somehow constructed by human beings themselves: colours, smells, sounds, tastes. (Though I have to agree shape and motion can in context be very important.)
Comment by Alfred North Whitehead, thanks to Jenny Tyler, 2004 |
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This is a much duller picture if the colours are reduced (as my computer thinks of it, anyhow) to two. How much duller if they are eliminated altogether? |
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