Locke's Argument on the Primary Qualities of Objects - Assignment Example

I shall argue that the distinction is well-grounded and interesting, that Locke had grasped an important truth about it, and that Berkeley's treatment of this matter is impercipient and unhelpful. Berkeley assimilated the primary/ secondary distinction to that monolithic 'theory of material substance' which he thought he detected in Locke's writings, and I shall argue that that is the dominating fact about his failure to deal competently with the distinction between primary and secondary qualities.

Locke has two general, true things to say about the primary/ secondary distinction. One of them is his thesis that primary qualities are such as are utterly inseparable from the body, in what state soever it be; and such as in all the alterations and changes it suffers, all the force can be used upon it, it constantly keeps, and such as sense constantly finds in every particle of matter which has bulk enough to be perceived. In most of Locke's theorizing, a thing's primary qualities are taken to consist in its being spherical, two feet across, and falling rapidly; but here they are thought of rather as a thing's being shaped, of some size, mobile, etc.

That is, in the thesis that primary qualities are ones which a body cannot lose, it is determinable qualities that are in question and not determinate ones. Locke's example reinforces this reading: 'Take a grain of wheat, divide it into two parts; each part has still solidity, extension, figure, and mobility: divide it again, and it remains still the same qualities.' It is not clear that 'solidity' is a determinable, either in its normal meaning or in Locke's specialized sense in which 'solid' means 'impenetrable'.

Locke has a good point here, but he ought not to express it as though it were a prediction about the outcome of an experiment, for really it is a point about the meaning of the word 'body', or about the concept of a body or a physical thing. Indeed the word 'primary' for Locke partly means that these are qualities a thing must have to count as a 'body'. Locke's discussions of the concept of body involve detailed points which are of some interest but which lie beyond my present scope. His general thesis that the raw materials which constitute the concept of the body are to be found within the realm of primary qualities, and that secondary qualities are conceptually inessential, seems safe enough.

Yet Berkeley apparently denies it: 'It is not in my power to frame an idea of a body extended and moved, but I must withal give it some color or other sensible quality. In short, extension, figure, and motion, abstracted from all other qualities, are inconceivable.' The quoted passage is, as it stands, true: a thing's being extended, or it is taking up space, must involve some spatial region's being occupied by something--some quality must be manifested in that region other than mere extension.

But the quality could be solidity, which is on Locke's list of primary qualities. If Berkeley really is saying only that 'body' could not be defined out of the extension, figure and motion, without recourse to solidity.