Physicalism is the philosophical view that the basic furniture of the world is physical. On this view, all entities, properties, and events are either physical in themselves or ultimately depend on physical entities and processes. Physicalism is often associated with scientific naturalism because it treats the successful methods and theories of natural science as the principal guide to what exists, but it is primarily a metaphysical claim about what kinds of things there are.
Core claims and main variants
Different formulations of physicalism emphasize different relations between the physical and the non‑physical. Common variants include:
- Reductive physicalism: higher‑level phenomena (like mental states) are identical to or can be reduced to physical states.
- Non‑reductive physicalism: mental or social properties are dependent on but not reducible to physical properties; they supervene on the physical.
- Type vs. token physicalism: type physicalism identifies general kinds with physical kinds, while token physicalism holds that each particular instance is a physical event though kinds may not match.
- Emergentism: some higher‑level properties arise from complex physical systems but are still grounded in physical processes.
History and development
Physicalism grew from the historical doctrine of materialism and gained prominence in the 20th century alongside advances in physics, chemistry, and biology. Philosophers refined materialist ideas to address new problems in philosophy of mind and metaphysics, introducing technical notions such as supervenience and functional realization. Debates about consciousness and mental causation spurred distinctions between reductive and non‑reductive accounts.
Supporters argue that the explanatory power of the physical sciences and the continuity between biological and physical explanations make physicalism the most economical ontology. Critics respond that certain phenomena — notably conscious experience, intentionality, and normative facts — resist straightforward physical explanation.
Central challenges include the so‑called "hard problem" of consciousness, thought experiments about conceivability and knowledge, and concerns about multiple realizability (the idea that the same mental state could be realized by different physical substrates). Typical philosophical responses refine the account of realization or appeal to emergent properties that remain physically grounded.
Physicalism is often contrasted with dualism (which posits fundamentally distinct mental and physical substances) and idealism (which gives primacy to mind or experience). For continued study, see discussions linking metaphysics and philosophy of mind and resources on how scientific theories inform ontological claims. For example, some introductions treat the role of physical entities and others discuss material composition in philosophical contexts.