Abstract

It has long been a philosophical problem to explain the commonly accepted distinction between two kinds of qualities: primary and secondary. While the roots of this debate can be traced back to Plato’s Euthyphro, it was John Locke who, more clearly than others, articulated the distinction and introduced the terms “primary quality” and “secondary quality.” Similar distinctions, under labels such as “primary affections,” “primary attributes,” or “original qualities,” also appear in the writings of earlier thinkers, including Galileo Galilei, Robert Boyle, and René Descartes. This article’s focus is not on the historical development of the distinction, but rather on Crispin Wright’s contemporary and well-known “Judgment-Dependent” account of this distinction, which aims to provide a criterion for determining whether a quality should be regarded as secondary. Metaphysically, a primary quality is often understood as a quality whose instantiation or existence is constituted, or metaphysically determined, by something independent of human responses formed under certain conditions, such as seeing, smelling, or touching. Typical examples include shape, extension, motion, solidity, and number. These qualities are said to be objective because, for instance, if an object’s surface is square-shaped, it has this shape regardless of whether one perceives it as such. In other words, such qualities are mind-independent. Epistemologically, knowledge that an object’s surface is square-shaped is not infallible precisely because the fact that the object possesses this quality is independent of how one perceives it or what one believes about it. Therefore, even if one’s beliefs about these qualities are formed under optimal conditions, they can still be false. By contrast, a secondary quality is one whose instantiation or existence depends on how one perceives, judges, or responds to it. Typical examples include color, taste, smell, and sound. Consequently, these qualities are often considered subjective. For example, whether an object is red appears to depend on how it looks or how one sees it under certain conditions. Thus, the quality of being red is said to be mind-dependent. Epistemologically, knowledge that an object is red can be infallible because the object’s having that quality depends on one’s perception: if one’s beliefs about these qualities are formed under optimal conditions, they will be guaranteed to be correct. Wright’s judgment-dependent account offers a criterion for determining whether a given quality is treatable as secondary or “judgment-dependent,” as Wright prefers to call it. By employing this account, he aims to answer two fundamental questions: one metaphysical and one epistemological. If the account successfully shows that a quality is judgment-dependent, Wright can claim that facts about whether an object has that quality are metaphysically determined by the judgments of a suitable subject. The epistemological question, that is, how the subject knows such facts, is answered by appealing to the subject’s direct knowledge of her own judgments. In what follows, this account is introduced step by step and then applied to several crucial cases.