Tony Sobrado: There are essentially four ways to address the hard problem of consciousness. The prominent issue is one of combination, how to reconcile the physical brain with subjective experience and sensations - that is the marriage between the physical and the mental. This typically leads to four paths: 

1. It is not an answerable metaphysical question, akin to asking ‘where the laws of physics come from?’ 

2. Property dualism, both the mental and the physical exist and we have to combine the two. This includes areas of emergence (either weak or strong), second order realisability and/or formal causal chains that explain conscious experience. Perhaps, even a full reductionist programme that may occur in the future. For example, a formulation that mimics how H2O = water, and so in the same vein we can have a reductionist chemical computation that states that neural properties = conscious experience. 

3. The problem is due to the fact that physicalism is false. We must reconceptualise physicalism and scientific practice specifically to accommodate conscious experience in the world and this can be done by panpsychism or conscious realism as proposed by Donald Hoffman.

4. The problem is actually due to the fact that consciousness and the mental realm do not actually exist. Frameworks such mental eliminativism, identicalism and illusionism are present here. 

Many cognitive scientists and neuroscientists simply assert that ‘consciousness’ or sensations are merely the product of functionalism, representationalism or flat-out illusionism.  

As one of the world's premier cognitive scientists, please tell me what you understand consciousness to be? And from your perspective what is the hard problem of consciousness and is it a valid problem?

Steven Pinker: The word “consciousness” has at least two meanings. One is access to a pool of information shared by a set of intercommunicating neural processes such as those that control language, recall, planning, and intentional movements. That is, some kinds of information in the brain, like the surfaces in front of you, your daydreams, your plans for the day, your pleasures and pains, are “conscious” in the sense that you can ponder them, discuss them, and let them guide your behavior. Other kinds of consciousness, like the control of your heart rate, the rules that order the words as you speak, and the sequence of muscle contractions that allow you to hold a pencil, are unconscious. They must be in the brain somewhere, because you couldn’t walk, talk and see without them - but they are sealed off from your planning and reasoning circuits, and you can’t report on them. The so-called “easy problem” of consciousness is to distinguish conscious from unconscious mental computation, identify its correlates in the brain, and explain why it evolved.

“Easy” is of course an in-joke; it’s “easy” in the sense that curing cancer or sending someone to Mars is easy. That is, scientists more or less know what to look for, and with enough brainpower and funding, they will probably crack it in this century. It’s hardly a mystery why we experience a world of stable, solid, colored 3-D objects rather than the kaleidoscope of pixels on our retinas, or why we enjoy (and hence seek) food, sex, and bodily integrity while suffering from (and hence avoiding) social isolation and tissue damage: these internal states and the behavior they encourage are obvious Darwinian adaptations. Nor are the computational and neurobiological bases of consciousness necessarily befuddling. Stanislas Dehaene and his collaborators have argued that consciousness functions as a “global workspace” or “blackboard” representation. The blackboard metaphor refers to the way that a diverse set of computational modules (for perception, memory, motivation, language understanding and action planning) can post their results in a common format that all the other modules can “see.” Those modules include, and the fact that they can all access a common pool of currently relevant information (the contents of consciousness) allows us to describe, grasp, or approach what we see, to respond to what other people say or do, and to remember and plan depending on what we want and what we know. (The computations inside each module, in contrast, like the calculation of depth from the two eyes or the sequencing of muscle contractions making up an action, can work off their own proprietary input streams, and they proceed below the level of consciousness, having no need for its synoptic view.) This global workspace, according to one hypothesis, is implemented in the brain as rhythmic, synchronized firing in neural networks that link the prefrontal and parietal cerebral cortexes with each other and with brain areas that feed them perceptual, mnemonic, and motivational signals.

But the other sense of the word “consciousness” is the way it feels like something to have a conscious process going on in one’s head. In other words, first-person present-tense subjective experience (Ned Block suggested that the two senses be distinguished as access consciousness and phenomenal consciousness). Not only does a green thing look different from a red thing, remind us of other green things, and inspire us to say “that’s green” (the easy problem), but it actually looks green - it produces an experience of sheer greenness that isn’t reducible to anything else. The so-called “hard problem” is explaining how subjective experience arises from neural computation. It’s “hard” not because it is a recalcitrant scientific topic but because it is a head-scratching conceptual enigma. It includes brainteasers such as whether my red is the same as your red, what it is like to be a bat, whether there could be zombies (people indistinguishable from you and me but with “no one home” and who is therefore not feeling anything), and if so whether everyone but me is a zombie, whether a perfectly lifelike robot would be conscious, whether I could achieve immortality by uploading my brain’s entire computational contents to the Cloud etc. No one knows what a solution might look like or even whether it is a genuine scientific problem in the first place.

Sometimes, when I see the mischief that the “hard problem” has caused (such as serving as evidence for the existence of God), I am tempted to agree with Dan Dennett that we’d be better off without the term. Contrary to various misunderstandings, the hard problem does not consist in weird physical or paranormal phenomena such as clairvoyance, telepathy, time travel, augury, or action at a distance. It does not call for exotic quantum physics, kitschy energy vibrations, or other New Age flimflam. And it certainly does not implicate an immaterial soul. Everything we know about human consciousness shows that it depends entirely on neural activity.

In the end, I still think that the hard problem is a meaningful conceptual problem, but agree with Dennett that it is not a meaningful scientific problem. It’s a meaningful conceptual problem because I know that I have subjective experience - as Descartes noted, and I know this with greater certainty than I know anything else - have excellent reason to infer that other people and animals have it too, and can coherently formulate a hypothetical scenario (a world of zombies) in which it did not exist. But it’s a dubious scientific problem, because the instant that you say anything about consciousness other than that subjectivity exists - as soon as you ask what makes one aspect of conscious experience different from another, or the circumstance/s in which various conscious experiences arise, or what their effects are in trains of awareness or in behaviour - as soon as you consider any aspect of consciousness that makes a difference to what anyone can observe and theorize about, it’s no longer “the hard problem”. It’s amenable to analysis only via the information that makes a difference to the conscious person’s reports and behavior, thereby making it “easy.” Science is inherently third-person; phenomenal consciousness is by definition first-person. That’s conceptually as fundamental as it gets.

So I agree with philosophers like Thomas Nagel, Rebecca Goldstein, and Colin McGinn who say that it may be futile to hope for a scientific solution at all, precisely because it is a conceptual problem, or, more accurately, a problem with our concepts. As Nagel put it in “What Is It Like to Be a Bat?” there may be “facts which could not ever be represented or comprehended by human beings, even if the species lasted forever - simply because our structure does not permit us to operate with concepts of the requisite type.” Colin McGinn argues that there is a mismatch between our cognitive tools for explaining reality (namely chains of causes and effects, analysis into parts and their interactions, and modeling in mathematical equations) and the nature of the problem of phenomenal consciousness, which is unintuitive and holistic. Our best science tells us that consciousness consists of a global workspace representing our current goals, memories, and surroundings, implemented in synchronized neural firings in fronto-parietal circuitry. But the last piece of the understanding - that it subjectively feels like something to be such circuitry - may have to be stipulated as a fact about reality where explanation stops.

But overall, I’m not completely sure how to shoehorn this view into the distinctions you draw. It’s “dualistic” not in the disreputable substance-sense in which a ghostlike entity hovers in or around the living brain, but only in the innocuous property-sense in which phenomenal consciousness can’t be defined in physical terms; it means something else. The “easy” problem of access-consciousness is reductionist in the ontological sense of water being nothing but H2O or (Goldstein’s example) heat being nothing but molecular motion, though even in these examples, one can’t eliminate the higher-order concepts being reduced, since they figure into the most perspicuous explanations of macroscopic phenomena. I’m not clear enough on what people mean by “physicalism” to say whether it’s inconsistent with the view that phenomenal consciousness exists, or that access-consciousness depends on the flow of information rather than the material substrate (e.g., neural tissue versus silicon). Must a physicalist deny that there is such a thing as information, or numbers, or logic? In any case, whether or not I’m a physicalist, I’m certainly a naturalist, in the sense that I think that consciousness (like everything else) is intelligible via the laws of logic and nature; it doesn’t require any mysterious, intentional, law-defying entity.

Tony Sobrado: Thanks for the broad understanding and contextually diverse conceptual notions of consciousness. The way you have elaborated on consciousness being twofold, one being easy forms of consciousness and the other being a harder form of consciousness is very succinct and useful. Essentially what Ned Block would also term as access consciousness and phenomenal consciousness is also an effective understanding.

Yes, the easy problems of consciousness would be the intercommunicating of neural processes, such as those that control language, recall, planning, and intentional movements and here, as your say, the computational and neurobiological bases of consciousness are not particularly confounding nor are its neural correlates and evolutionary functionalism. But I think it's interesting that you note the hard problem of consciousness as being ‘how subjective experience comes out of a physical brain’. In fact, this is specifically how I describe one of the elements of the hard problem of consciousness, the second element is obviously linked to this first element but can be extended to the following question: Why is that some physical objects like the brain have conscious subjective experience accompanying it whilst others, like a rock, do not. I think these are both apt ways of thinking about the hard problem of consciousness. However, this in itself implies that the physical brain does cause consciousness or at least is responsible for consciousness, putting aside for the minute that causation is a loaded philosophical term in itself, and here I completely agree with you that it does because it’s extremely difficult to dispute this given all the evidence we have from neuroscience.

However, one aspect of the hard problem of consciousness itself, as you have also alluded to, is its actual specific answerability. So in one respect the way David Chalmers frames it - it is by definition not answerable by science or even reducible to a physical brain. So for example taking one remit of the hard problem of consciousness - how the physical brain causes consciousness we've got lots of models including optogenetics which uses causal models to describe and explain how a physical brain causes certain conscious states. We also have second order realizability from Andrew Melnyk in which consciousness and the mental is a higher-level property that is realised in a lower-level physical structural property, the issue with that is obviously whether it is causation, emergence, realisation, ultimate reductionism or a possible combination of all of these elements coming from the lower-level physical structure, the brain, to the higher-level conscious property.

These are all ways of explaining how consciousness arises from, or at least relates to, a physical brain. But David Chalmers may dispute this saying there's no amount of physical realisation or reducibility that can, even in principle, explain consciousness and its relationship to the brain. Now approaching this specifically nuanced aspect of Chalmers's problem - that there's no amount of scientific or physical reductionism, even through the realisation of a higher-level property such as the mental being realised in, and reducible to, a lower-level physical structure like the brain - there are two ways to approach and counteract this:

1. Using the basic premise of interventionist theories of causation and manipulative theories of causation; and here neuroscience is sufficient to demonstrate that the brain causes consciousness, whichever way we're employing the term causation or whichever way we're defining consciousness, by the mere fact that by manipulating and intervening on the physical brain and using control mechanisms we can clearly note that consciousness is coming from a physical brain and your point elsewhere that neuroscientists have long known that consciousness depends on certain frequencies of oscillation in the electroencephalograph (EEG) clearly demonstrates this as well, as does the work of Earl Miller at MIT who proposes that consciousness comes from the brain's electric fields. There's simply too much evidence that consciousness completely depends on the brain: no one survives multiple gunshot wounds to the head and no one has ever observed a conscious mind outside of a physical brain in any rigorous manner. Thus taking the philosophical framework of the interventionist theory and manipulative theories of causation is sufficient to state that the physical brain either causes, is responsible for or gives rise to consciousness.

2. What is more problematic regarding Chalmers, is whether this question of the hard problem is even answerable and this harks back to what you were saying in terms of this being a scientifically answerable question, causal and theoretical modeling for example versus the conceptual problem itself due to phenomenological consciousness as espoused by McGinn. But I build on this further stating the metaphysical problem regarding this un-answerability: Why is it that consciousness is produced by a physical brain? These kinds of problematic questions end up in elements of an infinite regression, you can keep on asking why and so on and some things just stop at brute facts or necessity via logic: Why is it that subjective experience accompanies one physical object in the universe may not be metaphysically answerable akin to asking where the laws of physics come from? Or why is there is something rather than nothing? These things tend to stop at brute facts in terms of necessity.

Moreover, I also find the hard problem quite quaint and unique when applied to consciousness itself. This is because consciousness is so loaded because we humans possess it. So black holes, entropy and singularities are just as equally if not more peculiar but because we're not a black hole we don't think it's something odd but where we do possess consciousness we think ‘that's very odd’ so it may not be answerable and this in itself is an issue - because why is it an issue for consciousness but not black holes and singularities? Why is it that physical matter coalesces and organises itself into biological life but there is no organic life-matter problem (although there used to be via vitalism which is now redundant) but there is somehow one for the mind-body problem? And whilst I am here, I might as well introduce the hard problem of matter!. Why is it that energy is equivalent to matter, why does matter have mass? I think I have labored the point here sufficiently.

In many respects this issue of mysticism around consciousness is one of those hang ups historically from the soul, from an outdated essence of humanity, i.e. what it is to have a mind and soul that is now disconnected from our contemporary world view and definitely out of kilt with scientific practice that demonstrates that the mind is completely dependent on the brain - the rest might be unverifiable metaphysical speculation.

So with that being the case, as you rightly say, consciousness relies completely on the brain, so do you think interventionist theories of causation and manipulative theories of causation like optogenetics are sufficient to state that consciousness is caused by the physical brain and thus requiring any additional explanation is not necessary, basically do we have all we need?

Steven Pinker: Though it's clear, for reasons the two of us review, that consciousness depends entirely on the information-processing activity of the brain, I suspect that the connection (when it comes to the phenomenal, sentence, "hard" sense) can’t be shoehorned into generic conceptual relationships like "causes" and "reduces to," "emergence," and "realization" as they apply to other phenomena like H20 and water or heat and molecular motion. The objective-subjective relationship is a fundamental conceptual distinction and sui generis, not perfectly analogous to familiar relationships among phenomena in science. This is an essential part of McGinn's argument for cognitive incommensurability: familiar relationships like "causation" and "composition" don't seem to match the holistic nature of phenomenal consciousness.

Tony Sobrado: You've touched upon Dennett who's obviously an incredible thinker in this space and you've also quite eloquently elaborated on elements of consciousness but this assumes that consciousness in some capacity actually exists. How do you feel about eliminative materialism and illusionism for example - that phenomenal consciousness doesn't really exist in terms of formal qualia and it's all just representational knowledge, that is there's nothing above and beyond the direct experience itself that outruns the experience itself therefore there is no formal qualia and no phenomenology and thus consciousness doesn't really exist in the capacity that we think it exists and therefore the hard problem of consciousness by definition doesn't exist. This is also borne out by Attention Schema Theory by Michael Graziano at Princeton and many others. Experience exists but do you think that consciousness exists as a formal phenomenological category?

Steven Pinker: Not to get too Clintonesque on you, but it depends on what the meaning of "exists" is. Sentience clearly exists as the concept that we're all puzzling over, and that, as Descartes pointed out, is the most undeniable thing there is. But it may not exist as an empirical happening with the same ontological status as matter, energy, and spacetime. So Dennett may have a point that the so-called hard problem (in its purest form, when leakages into the so-called easy problem are set aside) is not a genuine scientific problem.  But I wouldn't go so far as to say that it's an illusion or doesn't exist at all. Perhaps it exists in the way that abstract entities like information or numbers exist if one is a mathematical realist or Platonist. But even here I suspect that phenomenal subjective experience doesn't precisely match the ontological status of these other entities - it really is sui generis.

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Steven Pinker is a Canadian-American cognitive psychologist, psycholinguist, popular science author, and public intellectual. He is an advocate of evolutionary psychology and the computational theory of mind. Pinker is the Johnstone Family Professor of Psychology at Harvard University. *** Tony Sobrado is a social scientist and freelance writer focusing on philosophy, science, atheism and current affairs.

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