Further Arguments against Naive Realism
We have seen that the argument that we tend to think of as the principal argument for sense-data-the argument from illusion-figured hardly at all in the writings of the early modern philosophers. This, I suggested, was because it did not spring in any special or direct way from the atomism of seventeenth-century science. Among the arguments that were rooted in science perhaps the most important rested on the distinction between primary and secondary qualities. The argument can be sketched informally as follows:
Science has shown that physical objects do not possess secondary qualities intrinsically. As they are clearly possessed by that of which we are aware in perception, that of which we are aware in perception is not the physical object itself. The only plausible way to understand the relation between physical objects and secondary qualities is to think of the objects as possessing dispositions to produce the qualities in us as properties of our sense-data.