Editing Hard problem of consciousness (section)

=== Chalmers' formulation ===
{{Quote|text=. . .even when we have explained the performance of all the cognitive and behavioral functions in the vicinity of experience—perceptual discrimination, categorization, internal access, verbal report—there may still remain a further unanswered question: ''Why is the performance of these functions accompanied by experience?''|author=David Chalmers|title=Facing up to the problem of consciousness|source=}}The problems of consciousness, Chalmers argues, are of two kinds: the ''easy problems'' and the ''hard problem''.

==== Easy problems ====
The easy problems are amenable to reductive enquiry. They are a [[logical consequence]] of lower-level facts about the world, similar to how a clock's ability to tell time is a logical consequence of its clockwork and structure, or a hurricane being a logical consequence of the structures and functions of certain weather patterns. A clock, a hurricane, and the easy problems, are all the sum of their parts (as are most things).<ref name=":0" />

The easy problems relevant to consciousness concern mechanistic analysis of the neural processes that accompany behaviour. Examples of these include how sensory systems work, how sensory data is processed in the brain, how that data influences behaviour or verbal reports, the neural basis of thought and emotion, and so on. They are problems that can be analysed through "structures and functions".<ref name=":0" />

==== Hard problem ====
The hard problem, in contrast, is the problem of ''why'' and ''how'' those processes are accompanied by experience.<ref name="Chalmers" /> It may further include the question of why these processes are accompanied by this or that particular experience, rather than some other kind of experience. In other words, the hard problem is the problem of explaining why certain mechanisms are accompanied by conscious experience.<ref name=":0">{{Cite book|last=Chalmers|first=David|title=The Conscious Mind|publisher=Oxford University Press|year=1996|location=New York|pages=xii–xiii, 95–106, backcover}}</ref> For example, why should neural processing in the brain lead to the felt sensations of, say, feelings of hunger? And why should those neural firings lead to feelings of hunger rather than some other feeling (such as, for example, feelings of thirst)?

Chalmers argues that it is conceivable that the relevant behaviours associated with hunger, or any other feeling, could occur even in the absence of that feeling. This suggests that experience is [[Irreducibility|irreducible]] to physical systems such as the brain. This is the topic of the next section.

==== How the easy and hard problems are related ====
Chalmers believes that the hard problem is irreducible to the easy problems: solving the easy problems will not lead to a solution to the hard problems. This is because the easy problems pertain to the causal structure of the world while the hard problem pertains to consciousness, and facts about consciousness include facts that go beyond mere causal or structural description.<ref name=":2">{{Cite web |title=Hard Problem of Consciousness |url=https://iep.utm.edu/hard-problem-of-conciousness/ |access-date=2024-10-09 |website=Internet Encyclopedia of Philosophy |language=en-US}}</ref>

For example, suppose someone were to stub their foot and yelp. In this scenario, the easy problems are mechanistic explanations that involve the activity of the nervous system and brain and its relation to the environment (such as the propagation of nerve signals from the toe to the brain, the processing of that information and how it leads to yelping, and so on). The hard problem is the question of why these mechanisms are accompanied by ''the feeling of pain'', or why these feelings of pain feel the particular way that they do. Chalmers argues that facts about the neural mechanisms of pain, and pain behaviours, do not lead to facts about conscious experience. Facts about conscious experience are, instead, [[further facts]], not derivable from facts about the brain.<ref name=":0" /><ref name=":2" />[[File:Inverted_qualia_of_colour_strawberry.jpg|thumb|The hard problem is often illustrated by appealing to the logical possibility of inverted visible spectra. If there is no logical contradiction in supposing that one's colour vision could be inverted, it follows that mechanistic explanations of visual processing do not determine facts about what it is like to see colours.|280x280px]] An explanation for all of the relevant physical facts about neural processing would leave unexplained facts about what it is like to feel pain. This is in part because functions and physical structures of any sort could conceivably exist in the absence of experience. Alternatively, they could exist alongside a different set of experiences. For example, it is [[Logical possibility|logically possible]] for a perfect replica of Chalmers to have no experience at all, or for it to have a different set of experiences (such as an inverted visible spectrum, so that the blue-yellow red-green axes of its visual field are flipped).<ref name=":2" />

The same cannot be said about clocks, hurricanes, or other physical things. In those cases, a structural or functional description is a complete description. A perfect replica of a clock is a clock, a perfect replica of a hurricane is a hurricane, and so on. The difference is that physical things are nothing more than their physical constituents. For example, water is nothing more than H<sub>2</sub>O molecules, and understanding everything about H<sub>2</sub>O molecules is to understand everything there is to know about water. But consciousness is not like this. Knowing everything there is to know about the brain, or any physical system, is not to know everything there is to know about consciousness. Consciousness, then, must not be purely physical.<ref name=":0" />

==== Implications for physicalism ====
{{See also|Physicalism}}
[[File:Sturnus vulgaris -Rotterdam, South Holland, Netherlands -flock-8.ogv|thumb|right|A swarm of birds showing high order structure emerging from simpler physical constituents]]

Chalmers's idea contradicts [[physicalism]], sometimes labelled [[materialism]]. This is the view that everything that exists is a physical or material thing, so everything can be reduced to microphysical things. For example, the rings of Saturn are a physical thing because they are nothing more than a complex arrangement of a large number of subatomic particles interacting in a certain way. According to physicalism, everything, including consciousness, can be explained by appeal to its microphysical constituents. Chalmers's ''hard problem'' presents a [[counterexample]] to this view and to other phenomena like swarms of birds, since it suggests that consciousness, like swarms of birds, cannot be reductively explained by appealing to their physical constituents. Thus, if the hard problem is a real problem then physicalism must be false, and if physicalism is true then the hard problem must not be a real problem.{{cn|date=September 2022}}

Though Chalmers rejects physicalism, he is still a [[Naturalism (philosophy)|naturalist]].<ref name=":0" />{{importance inline|date=April 2023}}

[[Christian List]] argues that the existence of first-person perspectives and the inability for physicalism to answer Hellie's vertiginous question is evidence against physicalism, since first-personal facts cannot supervene on physical third-personal facts.<ref>{{cite web |url=https://philpapers.org/rec/LISTFA |title=The first-personal argument against physicalism |last=List |first=Christian |date=2023 |website= |publisher= |access-date=4 March 2025 |quote=}}</ref> List also claims that there exists a "quadrilemma" for metaphysical theories of consciousness, and that for the metaphysical claims of first-person realism, non-solipsism, non-fragmentation, and one-world, at least one of these must be false.<ref>{{cite web |url=https://philarchive.org/rec/LISAQF |title=A quadrilemma for theories of consciousness |last=List |first=Christian |date=2023 |website= |publisher=The Philosophical Quarterly |access-date=4 March 2025 |quote=}}</ref> List has proposed a model he calls the "many-worlds theory of consciousness" in order to reconcile the subjective nature of consciousness without lapsing into solipsism.<ref>{{cite web |url=https://philarchive.org/rec/LISTMT-2 |title=The many-worlds theory of consciousness |last=List |first=Christian |date=2023 |website= |publisher=The Philosophical Quarterly |access-date=4 March 2025 |quote=}}</ref>