Abstract

In this paper I make a new attempt to interpret Locke's fascinating theory of primary and secondary qualities. The function of primary qualities, I argue, is to provide us with an idea of what the insensible corpuscles are like, of which every portion of matter is composed. Therefore, these qualities must be common both to sensible bodies and insensible corpuscles, and their ideas must resemble them. The function of secondary qualities is to make the primary qualities of the corpuscles accessible to us. Secondary qualities are called immediately perceivable if they can be read off from the very body whose corpuscles they make appear; and they are called mediately perceivable, or bare powers, if they must be read off from another body. The classes of primary and secondary qualities depend upon the acuteness of our senses, and membership in them can be ascertained by ' Locke's method of division'. Despite all its ingenious calibration in experience, his distinction must be acknowledged, eventually, to go far beyond the bounds of sense allowed within by his type of empiricism