qualitas

Qualitas is a Latin term meaning quality or kind, derived from qualis, “of what kind.” In historical and philosophical contexts, qualitas denotes the properties or attributes that qualify a thing, as opposed to measures of amount or extension.

In Aristotelian and scholastic philosophy, qualitas is treated as one of the categories of being, encompassing the intrinsic properties that belong to a subject, such as color, texture, or temperament. Scholastic writers distinguished qualitas from quantitas (quantity) and from other categories like relation, place, and time. Within this framework, qualities can be further analyzed as essential to a thing’s nature or as accidental to its existence, influencing discussions of substance, change, and identity.

In discussions of mind and perception, the term qualitas is sometimes used in older or Latin-text sources to refer to the qualities of objects that are perceived by the senses. In modern philosophy of mind, the related English term qualia designates the subjective, experiential aspects of sensory experience; qualia are often contrasted with objective properties and are not identical to the broader medieval notion of qualitas.

Outside strictly philosophical discourse, qualitas remains a general word in Latin and Romance languages, where cognates mean “quality” in everyday language, describing the characteristics or standard of something.

See also: qualia, quality, property, accident, ontology.