THE CORPUSCULARIAN CONCEPTION OF BODY

Locke's treatment of such central philosophical issues as substance, qualities, identity, natural kinds, and the structure and limits of scientific explanation was fundamentally shaped by the conception of body (or as we would say it nowadays, the basic nature of material things) that he inherited from Gassendi and Boyle. This conception of body was part of what Boyle called the corpuscularian hypothesis, or corpuscularianism. This doctrine, a form of mechanistic atomism, had the following core tenets:

1. The matter of all bodies is the same in kind, namely, extended solid substance.

2. All bodies are either (a) individual atoms or corpuscles, which are physically indivisible and which have as their only qualities (in addition to extension and solidity) size, shape, location, motion or rest, and number; or (b) aggregates or collections of atoms. There are no physically real components or constituents of a body beyond its component atoms (except for the material that “glues” the atoms together, if any). Compound bodies have a further quality, their “texture,” which is the arrangement of their component atoms resulting from their various sizes, shapes, relative situations, and relative motions.

3. All changes of state of bodies are due to a change in texture (note that atoms cannot change their size or shape, since they are indivisible); and all changes in texture are the result of impact or contact action of one body upon another. That is to say, all causation involving bodies is mechanical causation.