substantialia

Substantialia is a term used in philosophy, particularly within scholastic traditions, to refer to the fundamental essence or "whatness" of a thing. It denotes the intrinsic reality and self-sufficiency of a being, distinguishing it from accidental qualities that can be added or removed without altering its core identity.

In Aristotelian metaphysics, substantialia are considered the primary substances, the independent entities that exist in their own right. These are contrasted with accidents, which depend on a substance for their existence. For example, a person is a substance, possessing substantialia, while their hair color or height are accidents.

The concept of substantialia helps to understand the notion of identity over time. Despite changes in appearance or characteristics, a thing retains its substantialia, which is its underlying reality. This philosophical concept has been a subject of debate and interpretation throughout the history of philosophy, influencing discussions on existence, being, and the nature of reality. It provides a framework for distinguishing between essential properties and non-essential attributes.