Editing Hard problem of consciousness (section)

=== Related concepts ===

==== The mind–body problem ====
{{Main|Mind–body problem}}
The mind–body problem is the problem of how the mind and the body relate. The mind-body problem is more general than the hard problem of consciousness, since it is the problem of discovering how the mind and body relate in general, thereby implicating any theoretical framework that broaches the topic. The hard problem, in contrast, is often construed as a problem uniquely faced by physicalist or materialist theories of mind.

==== "What Is It Like to Be a Bat?" ====
{{Main|What Is It Like to Be a Bat?}}
The philosopher Thomas Nagel posited in his 1974 paper "What Is It Like to Be a Bat?" that experiences are essentially subjective (accessible only to the individual undergoing them—i.e., felt only by the one feeling them), while physical states are essentially objective (accessible to multiple individuals). So he argued we have no idea what it could mean to claim that an essentially subjective state just ''is'' an essentially non-subjective state (i.e., that a felt state is nothing but a functional state). In other words, we have no idea of what reductivism amounts to.<ref name="Bat"/> He believes "every subjective phenomenon is essentially connected with a single point of view, and it seems inevitable that an objective, physical theory will abandon that point of view."<ref name="Bat">{{cite journal|last=Nagel|first=Thomas|author-link=Thomas Nagel|date=October 1974|title=What is it like to be a bat?|journal=[[The Philosophical Review]]|volume=83|issue=4|pages=435–450|doi=10.2307/2183914|jstor=2183914|s2cid=49125889}}</ref>

==== Explanatory gap ====
{{Main|Explanatory gap}}
{{see also|Reductionism}}
In 1983, the philosopher [[Joseph Levine (philosopher)|Joseph Levine]] proposed that there is an ''explanatory gap'' between our understanding of the physical world and our understanding of consciousness.<ref name=Levine1983>Levine, J. 1983. “Materialism and qualia: the explanatory gap”. ''Pacific Philosophical Quarterly'', 64: 354–361.</ref>

Levine's disputes that conscious states are reducible to neuronal or brain states. He uses the example of pain (as an example of a conscious state) and its reduction to the firing of [[Group C nerve fiber|c-fibers]] (a kind of nerve cell). The difficulty is as follows: even if consciousness is physical, it is not clear which physical states correspond to which conscious states. The bridges between the two levels of description will be [[Contingency (philosophy)|contingent]], rather than [[Necessity and sufficiency|necessary]]. This is significant because in most contexts, relating two scientific levels of descriptions (such as physics and chemistry) is done with the assurance of necessary connections between the two theories (for example, chemistry follows with necessity from physics).<ref name="jw-iep">{{cite web|last1=Weisberg|first1=Josh|title=The Hard Problem of Consciousness|url=https://www.iep.utm.edu/hard-con/|website=Internet Encyclopedia of Philosophy}}</ref>

Levine illustrates this with a thought experiment: Suppose that humanity were to encounter an alien species, and suppose it is known that the aliens do not have any c-fiber. Even if one knows this, it is not obvious that the aliens do not feel pain: that would remain an open question. This is because the fact that aliens do not have c-fibers does not entail that they do not feel pain (in other words, feelings of pain do not follow with logical necessity from the firing of c-fibers). Levine thinks such thought experiments demonstrate an explanatory gap between consciousness and the physical world: even if consciousness is reducible to physical things, consciousness cannot be explained in terms of physical things, because the link between physical things and consciousness is a contingent link.<ref name="jw-iep" />

Levine does not think that the explanatory gap means that consciousness is not physical; he is open to the idea that the explanatory gap is only an [[Epistemology|epistemological]] problem for physicalism.<ref name="jw-iep" /> In contrast, Chalmers thinks that the hard problem of consciousness does show that consciousness is not physical.<ref name=":0" />

==== Philosophical zombies ====
{{Main|Philosophical zombie}}
Philosophical zombies are a thought experiment commonly used in discussions of the hard problem.<ref>{{Cite web|last=Seager|first=William|title=Are Zombies Logically Possible?|url=https://www.utsc.utoronto.ca/~seager/zombie.html|access-date=2020-09-03|website=www.utsc.utoronto.ca}}</ref><ref>{{Cite journal|last1=Kaszniak|first1=Alfred W.|last2=Scott|first2=Andrew C.|date=2007|title=Zombie Killer|s2cid=14891432|journal=Association of Scientific Studies of Consciousness}}</ref> They are hypothetical beings physically identical to humans but that lack conscious experience.<ref>{{Cite web|last=Polger|first=Tom|title=Zombies: Entry|url=https://host.uniroma3.it/progetti/kant/field/zombies.htm|access-date=2020-09-03|website=host.uniroma3.it|archive-date=2020-06-15|archive-url=https://web.archive.org/web/20200615155145/http://host.uniroma3.it/progetti/kant/field/zombies.htm|url-status=dead}}</ref> Philosophers such as Chalmers, Joseph Levine, and Francis Kripke take zombies as impossible within the bounds of nature but possible within the bounds of logic.<ref>{{Citation|last=Kirk|first=Robert|title=Zombies|date=2019|url=https://plato.stanford.edu/archives/spr2019/entries/zombies/|encyclopedia=The Stanford Encyclopedia of Philosophy|editor-last=Zalta|editor-first=Edward N.|edition=Spring 2019|publisher=Metaphysics Research Lab, Stanford University|access-date=2020-09-03}}</ref> This would imply that facts about experience are not logically entailed by the "physical" facts. Therefore, consciousness is irreducible. In Chalmers' words, "after God (hypothetically) created the world, he had more work to do."<ref name=":3">[[David Chalmers]] (1996) ''The Conscious Mind: In Search of a Fundamental Theory'', pp. 153–56. Oxford University Press, New York, {{ISBN|0-19-511789-1}} (Pbk.)</ref> Daniel Dennett, a philosopher of mind, criticised the field's use of "the zombie hunch" which he deems an "embarrassment"<ref>Dennett, Daniel (1999), [https://www.nyu.edu/gsas/dept/philo/courses/consciousness/papers/DD-zombie.html "The Zombie Hunch: Extinction of an Intuition?"],{{dead link|date=January 2025}} ''Royal Institute of Philosophy Millennial Lecture''</ref> that ought to "be dropped like a hot potato".<ref name=":1">Dennett, Daniel; commentary on T. Moody, O. Flanagan and T. Polger. "[https://ase.tufts.edu/cogstud/dennett/papers/unzombie.htm The Unimagined Preposterous of Zombies]", ''Journal of Consciousness Studies'' vol. 2, no. 4, 1995, pp. 322–326.</ref>

==== Knowledge argument ====
{{Main|Knowledge argument}}
The knowledge argument, also known as ''Mary's Room'', is another common thought experiment: A hypothetical neuroscientist named Mary has lived her whole life in a black-and-white room and has never seen colour before. She also happens to know everything there is to know about the brain and colour perception.<ref name="Nida-Rümelin2019">{{cite encyclopedia|author1=Martine Nida-Rümelin|author2=Donnchadh O Conaill|title=Qualia: The Knowledge Argument|date=2019|encyclopedia=The Stanford Encyclopedia of Philosophy|editor=Edward N. Zalta|edition=Winter 2019|publisher=Metaphysics Research Lab, Stanford University|url=https://plato.stanford.edu/archives/win2019/entries/qualia-knowledge/|access-date=2020-09-03}}</ref> Chalmers believes<ref name=":3" />{{Page needed|date=September 2020}} that when Mary sees the colour red for the first time, she gains new knowledge — the knowledge of "what red looks like" — which is distinct from, and irreducible to, her prior physical knowledge of the brain or visual system. A stronger form of the knowledge argument<ref name="Nida-Rümelin2019"/> claims not merely that Mary would lack subjective ''knowledge'' of "what red looks like," but that she would lack knowledge of an objective ''fact'' about the world: namely, "what red looks like," a non-physical fact that can be learned only through direct experience (qualia). Others, such as Thomas Nagel, take a "[[physicalism|physicalist]]" position, disagree with the argument in its stronger and/or weaker forms.<ref name="Nida-Rümelin2019"/> For example, [[Thomas Nagel|Nagel]] put forward a "speculative proposal" of devising a language that could "explain to a person blind from birth what it is like to see."<ref name="Bat"/> The knowledge argument implies that such a language could not exist.