defended versions of both positions as plausible.[52] Traditional dualists such as Descartes believed the
mental and the physical to be two separate substances, or fundamental types of entities (hence "substance
dualism"); some more recent dualists, however, accept only one substance, the physical, but state it has
both mental and physical properties (hence "property dualism").[107]
Meanwhile, panpsychism and neutral monism, broadly speaking, view consciousness as intrinsic to
matter.[52] In its most basic form, panpsychism holds that all physical entities have minds (though its
proponents take more qualified positions),[112] while neutral monism, in at least some variations, holds
that entities are composed of a substance with mental and physical aspects—and is thus sometimes
described as a type of panpsychism.[113]
Forms of panpsychism and neutral monism were defended in the early twentieth century by the
psychologist William James,[114][115][note 2] the philosopher Alfred North Whitehead,[115] the physicist
Arthur Eddington,[116][117] and the philosopher Bertrand Russell,[112][113] and interest in these views has
been revived in recent decades by philosophers including Thomas Nagel,[115] Galen Strawson,[115][118]
Philip Goff,[115] and David Chalmers.[112] Chalmers describes his overall view as "naturalistic
dualism",[1] but he says panpsychism is in a sense a form of physicalism,[52] as does Strawson.[118]
Proponents of panpsychism argue it solves the hard problem of consciousness parsimoniously by making
consciousness a fundamental feature of reality.[43][119]
A traditional solution to the hard problem is idealism, according to which consciousness is fundamental
and not simply an emergent property of matter. It is claimed that this avoids the hard problem
entirely.[120] Objective idealism and cosmopsychism consider mind or consciousness to be the
fundamental substance of the universe. Proponents claim that this approach is immune to both the hard
problem of consciousness and the combination problem that affects panpsychism.[121][122][123]
From an idealist perspective, matter is a representation or image of mental processes. Supporters suggest
that this avoids the problems associated with the materialist view of mind as an emergent property of a
physical brain.[124] Critics argue that this then leads to a decombination problem: how is it possible to
split a single, universal conscious experience into multiple, distinct conscious experiences? In response,
Bernardo Kastrup claims that nature hints at a mechanism for this in the condition dissociative identity
disorder (previously known as Multiple Personality Disorder).[125] Kastrup proposes dissociation as an
example from nature showing that multiple minds with their own individual subjective experience could
develop within a single universal mind.
Cognitive psychologist Donald D. Hoffman uses a mathematical model based around conscious agents,
within a fundamentally conscious universe, to support conscious realism as a description of nature—one
that falls within the objective idealism approaches to the hard problem: "The objective world, i.e., the
world whose existence does not depend on the perceptions of a particular conscious agent, consists
entirely of conscious agents."[126]
Type-E Dualism
Type-F Monism
Idealism and cosmopsychism