Supervenience is a dependence relationship between two sets of properties where -properties supervene on -properties if there cannot be a difference in the state of affairs at the level of without a difference in the state of affairs at the level of . If and are sciences, we say that supervenes on if any two possible worlds that differ in facts must also differ in facts.
The claim of reductionism in the philosophy of science includes the view that the language and facts of all the other sciences supervene on the language and facts of physics, the most fundamental science. For example, there could not be two worlds that are economically different—such as having different levels of inflation—while being physically identical.
concept-question Is this more precisely physicalism?
Notes
- “What’s supposed to make physics stand out is, as it were, that the language physics uses is the one that’s maximally fine-grained.” (2025-04-09)
- Suppose we have the state space of the fundamental physical theory (e.g., Newtonian mechanics) and that this theory is deterministic, meaning if you know where the universe is at some given time, you can determine where it will be at any later time using the fundamental physical laws.
- Then given a law in a supervening theory, such as the economic law that government spending causes inflation, there must be regions in the state space that correspond to events involved in the supervening law, such as a region properly described by “the government is spending money” and another region described by “there is inflation going on.”
- In this case, most of the states that start in the “spending money” region should end up in the “inflation” region, as a matter of the fundamental physical laws.
- Which states are supervening states are a matter of the physical state, and which physical situations lead to other physical situations are a matter of the laws of physics.