In philosophy, the asymmetrical relation of ontological dependence that holds between two generically different sets of properties (e.g., mental and physical properties) if and only if every change in an object's properties belonging to the first set
the supervening properties
entails and is due to a change in properties belonging to the second set (the base properties).
Supervenience has often been appealed to by philosophers who want to uphold physicalism while rejecting the identity theory : Though it may be impossible to identify mental properties with physical properties in a one-to-one fashion, mental properties may still supervene on, and thus be grounded in, physical properties. Thus, no two things that are physically alike can be mentally (or psychologically) different, and a being's mental properties will be determined by its physical ones.