functionalism

Short definition from Wiktionary

Noun

1. 1
   A doctrine, in several fields, that the function of something should be reflected in its design and the materials used in its construction.
2. 2
   The definition of mental states in terms of their causes and effects.
3. 3
   The idea that social and cultural cohesion are a function of the interdependence and interactions of the institutions of a society.
4. 4
   The theory that the Holocaust was the result of a gradual escalation of decisions and procedures at the operational level (approved but not necessarily preconceived by Hitler).
5. 5
   A general school of thought that considers psychological phenomena in terms of their role in adaptation to the person's environment.
6. 6
   Synonym of functional linguistics.