What panpsychism claims

Panpsychism (from Greek pan, all, and psyche, mind) is the view that mentality is fundamental and widespread. Modern versions usually claim that the basic constituents of matter, such as particles or fields, have some extremely simple form of experience, and that the rich consciousness of humans and animals is built out of it. Rocks and chairs are not conscious subjects on this view; they are aggregates whose parts are not organised into a single mind.

Why philosophers take it seriously

The appeal comes from the hard problem. If physical science describes only structure and behaviour, it is hard to see how experience could ever emerge from it. Rather than accept a mysterious leap from non-experience to experience, the panpsychist puts experience at the bottom of reality from the start. Philosophers such as Galen Strawson and Philip Goff have argued that this is the most economical way to fit consciousness into a scientific picture of the world.

Russellian monism

An influential version draws on Bertrand Russell’s observation that physics tells us what matter does, its mathematical structure, but not what it intrinsically is. Russellian monists suggest that the intrinsic nature behind physical structure might be experiential, or proto-experiential. On this picture physics is complete as a description of structure, and consciousness fills the gap physics leaves silent.

The combination problem

William James raised the classic objection in 1890: a hundred separate feelings, however closely packed, do not add up to one feeling of a hundred. How do countless micro-subjects combine into a single unified subject like you? Panpsychists have proposed various answers, from new laws of combination to a cosmopsychist reversal in which a single cosmic consciousness is fundamental and individual minds are parts of it. None has won general acceptance.

Its cousins: idealism, dual-aspect monism, illusionism

• Idealism holds that reality is fundamentally mental and that matter is how mind appears from the outside. Bernardo Kastrup is a prominent contemporary defender.
• Dual-aspect monism treats the mental and the physical as two aspects of one underlying reality that is neither, a view with roots in Spinoza.
• Illusionism, defended by Keith Frankish, takes the opposite route: the “extra” phenomenal quality that seems to resist physical explanation is an introspective illusion, so there is nothing to put at the bottom of reality.