Supervenience as a concept in philosophy was first introduced as a description of properties in a complex system that supervene on the lower-level (called "base" or subvenient) properties of the system's components. For example, the laws and properties of chemistry are consistent with, but supervenient on, the laws of physics. More specifically, the properties of molecules supervene on atoms, the properties of biological cells supervene on molecules, plants and animal supervene on cells, etc. This view of supervenience was held by the "British emergentists," - C. Lloyd Morgan, Samuel Alexander, and C.D. Broad. This is not to claim that the upper level emergents can be completely explained by and are reducible to the subvenient or "base" properties. Reductionists are those who claim that causal laws of nature in the base level must causally determine the laws of the emergent level. These thinkers usually have a highly simplistic, materialistic, and deterministic view of the most fundamental laws of nature, namely the laws of classical physics. For example, Jaegwon Kim, the leading critic of supervenience as a non-reductive physicalism that explains mental causation, says:
The most fundamental tenet of physicalism concerns the ontology of the world. It claims that the content of the world is wholly exhausted by matter. Material things are all the things that there are; there is nothing inside the spacetime world that isn't material, and of course there is nothing outside it either. The spacetime world is the whole world, and material things, bits of matter and complex structures made up of bits of matter, are its only inhabitants.Donald Davidson gave the term supervenience a specific philosophical meaning within analytic philosophy in his 1970 essay "Mental Events." In order to allow mental events to cause physical events, yet not be reducible to them, Davidson developed the following set of arguments.
"Worlds that are indiscernible in all physical events are indiscernible in all mental events."