Thomas Reid and the problem of secondary qualities.

Direct Realism is the view that human perception takes physical entities and their mind-independent properties as immediate objects. Although this thesis is supported by common sense, many argue that it can be dismissed on philosophical or quasi-scientific grounds. This essay attempts to defend Direct Realism against one such argument, which I call the “Problem of Secondary Qualities,” using the ideas of Scottish Common Sense philosopher Thomas Reid. The first chapter of this work offers a detailed introduction to the Problem of Secondary Qualities. The Problem of Secondary Qualities arises from the claim that science has shown that physical objects do not possess secondary qualities (color, smell, sound, taste, and heat). This is a problem for Direct Realism because secondary qualities are certainly possessed by at least some perceivable objects. As I present it, the Problem rests on three commitments: (1) that an analysis of secondary quality perceptions should extend to perception in general, (2) that we perceive secondary qualities, and (3) that physical objects do not possess secondary qualities without our perceptions of them. I conclude that Direct Realism requires an account of secondary qualities on which secondary qualities are perceiver-independent but identifiable with other causally relevant properties. In Chapter Two, I introduce Thomas Reid’s doctrine of primary and secondary qualities, in the context of his theory of perception, as a viable response to the Problem of Secondary Qualities. On Reid’s view, secondary qualities are both perceiver-independent and identical to scientific properties, and Reid offers many useful conceptual resources for responding to objections. Most important are Reid’s claims that (a) sensation or sense experience is casually related to, but not essential for, perception and that (b) our perceptions of secondary qualities give us very little knowledge concerning their natures. The final chapter shows how the Reidian theory holds up against four key objections to accounts of secondary qualities on which they may be identified with perceiver-independent, scientific properties. In most cases, the Reidian approach finds solutions without compromising our intuitions or received opinions.