qualities properties or characteristics. There are three specific philosophical senses. (1) Qualities are physical properties, logical constructions of physical properties, or dispositions. Physical properties, such as mass, shape, and electrical charge, are properties in virtue of which objects can enter into causal relations. Logical constructions of physical properties include conjunctions and disjunctions of them; being 10 # .02 cm long is a disjunctive property. A disposition of an object is a potential for the object to enter into a causal interaction of some specific kind under some specific condition; e.g., an object is soluble in water if and only if it would dissolve were it in enough pure water. (Locke held a very complex theory of powers. On Locke’s theory, the dispositions of objects are a kind of power and the human will is a kind of power. However, the human will is not part of the modern notion of disposition.) So, predicating a disposition of an object implies a subjunctive conditional of the form: if such-and-such were to happen to the object, then so-and-so would happen to it; that my vase is fragile implies that if my vase were to be hit sufficiently hard then it would break. (Whether physical properties are distinct from dispositions is disputed.) Three sorts of qualities are often distinguished. Primary qualities are physical properties or logical constructions from physical properties. Secondary qualities are dispositions to produce sensory experiences of certain phenomenal sorts under appropriate conditions. The predication of a secondary quality, Q, to an object implies that if the object were to be perceived under normal conditions then the object would appear to be Q to the perceivers: if redness is a secondary quality, then that your coat is red implies that if your coat were to be seen under normal conditions, it would look red. Locke held that the following are secondary qualities: colors, tastes, smells, sounds, and warmth or cold. Tertiary qualities are dispositions that are not secondary qualities, e.g. fragility. (Contrary to Locke, the color realist holds that colors are either primary or tertiary qualities; so that x is yellow is logically independent of the fact that x looks yellow under normal conditions. Since different spectral reflectances appear to be the same shade of yellow, some color realists hold that any shade of yellow is a disjunctive property whose components are spectral reflectances.) (2) Assuming a representative theory of perception, as Locke did, qualities have two characteristics: qualities are powers (or dispositions) of objects to produce sensory experiences (sensedata on some theories) in humans; and, in sensory experience, qualities are represented as intrinsic properties of objects. Instrinsic properties of objects are properties that objects have independently of their environment. Hence an exact duplicate of an object has all the intrinsic properties of the original, and an intrinsic property of x never has the form, x-stands-in-suchand-such-a-relation-to-y. Locke held that the primary qualities are extension (size), figure (shape), motion or rest, solidity (impenetrability), and number; the primary qualities are correctly represented in perception as intrinsic features of objects, and the secondary qualities (listed in (1)) are incorrectly represented in perception as intrinsic features of objects. (Locke seems to have been mistaken in holding that number is a quality of objects.) Positional qualities are qualities defined in terms of the relative positions of points in objects and their surrounding: shape, size, and motion and rest. Since most of Locke’s primary qualities are positional, some non-positional quality is needed to occupy positions. On Locke’s account, solidity fulfills this role, although some have argued (Hume) that solidity is not a primary quality. (3) Primary qualities are properties common to and inseparable from all matter; secondary qualities are not really qualities in objects, but only powers of objects to produce sensory effects in us by means of their primary qualities. (This is another use of ‘quality’ by Locke, where ‘primary’ functions much like ‘real’ and real properties are given by the metaphysical assumptions of the science of Locke’s time.) Qualities are distinct from representations of them in predications. Sometimes the same quality is represented in different ways by different predications: ‘That is water’ and ‘That is H2O’. The distinction between qualities and the way they are represented in predications opens up the Lockean possibility that some qualities are incorrectly represented in some predications. Features of predications are sometimes used to define a quality; dispositions are sometimes defined in terms of subjunctive conditionals (see definition of ‘secondary qualities’ in (1)), and disjunctive properties are defined in terms of disjunctive predications. Features of predications are also used in the following definition of ‘independent qualities’: two qualities, P and Q, are independent if and only if, for any object x, the predication of P and of Q to x are logically independent (i.e., that x is P and that x is Q are logically independent); circularity and redness are independent, circularity and triangularity are dependent. (If two determinate qualities, e.g., circularity and triangularity, belong to the same determinable, say shape, then they are dependent, but if two determinate qualities, e.g., squareness and redness, belong to different determinables, say shape and color, they are independent.) See also DISPOSITION , PROPERTY, QUALIA. E.W.A.