supervenes

Supervenes is a term used in metaphysics and philosophy of mind to describe a dependence relation between sets of properties or facts. A property A supervenes on a set of base properties B if any two situations that are indistinguishable with respect to B-properties are indistinguishable with respect to A-properties. In effect, once the base properties are fixed, the higher-level properties cannot vary; any difference in A must be accompanied by a difference in B. The phrase can be read as “A depends on B in a way that fixes A once B is fixed.” The term comes from the Latin supervenire, meaning to come upon or arise from.

There are two common formulations. Weak or global supervenience says: for any two possible worlds, if the base properties are the same across the entire world, then the supervening properties are the same across the entire world. Strong or local supervenience says: for any two tokens (such as two particular objects or events) that share all their base properties, they must share all their supervening properties. In practice, base properties are often taken to be physical or microphysical features, while supervening properties are mental, social, or higher-level physical features.

Examples often cited include mental states supervening on physical brain states or color properties supervening on microstructural arrangements of pigment. Supervenience is a form of dependence that does not by itself entail reduction or explanation, nor does it guarantee a causal account. It is compatible with multiple realizability, where the same mental state can be realized by different physical states, yet the mental state would still supervene on the underlying physical bases.

In scholarly use, supervenience helps formalize when higher-level distinctions are determined by lower-level features, shaping debates about reduction, emergentism, and the nature of scientific explanation.