Quality (philosophy)

A feature or property by which something is characterized, distinguished, or described. Philosophical accounts examine how qualities relate to the things that bear them and whether they exist independently.

Property: A feature, relation, or attribute predicated of an object or situation. Quality is commonly treated as a kind of property, though philosophers dispute the fit.
Primary and secondary qualities: A distinction between qualities attributed to objects themselves and those dependent on perceivers. This distinction asks whether qualities like shape and color belong to objects in the same way.
Inherence: The relation in which a feature exists in and depends on a substance or bearer. It describes the traditional relation between a quality and the thing possessing it.
Aristotle: An ancient Greek philosopher whose works shaped logic, metaphysics, and natural philosophy. His categories and account of substance made qualities central to describing beings.
Color: A perceptual feature associated with the spectral properties of light and the visual system's responses. Color is a familiar case for asking whether a quality belongs to objects or perceivers.
Substance: An entity understood as existing in itself rather than as a feature of another. The substance–quality distinction contrasts bearers with the features attributed to them.
Qualia: The subjective felt character of conscious experiences, such as the sensation of red. Qualia focus on experiential character rather than qualities treated as ordinary properties.
Identity of indiscernibles: The principle that no two distinct entities can share all the same properties. It tests whether qualities suffice to distinguish one entity from another.
Categories (Aristotle): Aristotle's treatise classifying kinds of things said of or present in a subject. It gives a foundational classification of qualities among kinds of predication.
Shape: The spatial form or outline of an object. Shape serves as a standard candidate for a quality attributed to objects themselves.

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Robert M. PirsigRelated: Pirsig makes quality the starting point for reconsidering reality and value.