The following statement by Nicholas Humphrey (Psychology, London School of Economics) is one among many answers to the question: What do you believe is true though you cannot prove it?
I believe that human consciousness is a conjuring trick, designed to fool us into thinking we are in the presence of an inexplicable mystery. Who is the conjuror and why is s/he doing it? The conjuror is natural selection, and the purpose has been to bolster human self-confidence and self-importance—so as to increase the value we each place on our own and others' lives.
If this is right, it provides a simple explanation for why we, as scientists or laymen, find the "hard problem" of consciousness just so hard. Nature has meant it to be hard. Indeed "mysterian" philosophers—from Colin McGinn to the Pope—who bow down before the apparent miracle and declare that it's impossible in principle to understand how consciousness could arise in a material brain, are responding exactly as Nature hoped they would, with shock and awe.
Can I prove it? It's difficult to prove any adaptationist account of why humans experience things the way they do. But here there is an added catch. The Catch-22 is that, just to the extent that Nature has succeeded in putting consciousness beyond the reach of rational explanation, she must have undermined the very possibility of showing that this is what she's done.
But nothing's perfect. There may be a loophole. While it may seem—and even be—impossible for us to explain how a brain process could have the quality of consciousness, it may not be at all impossible to explain how a brain process could (be designed to) give rise to the impression of having this quality. (Consider: we could never explain why 2 + 2 = 5, but we might relatively easily be able to explain why someone should be under the illusion that 2 + 2 = 5).
Do I want to prove it? That's a difficult one. If the belief that consciousness is a mystery is a source of human hope, there may be a real danger that exposing the trick could send us all to hell.
Humphrey mentions the 'hard problem.' David Chalmers formulates the 'hard problem' as follows: "Why is all this processing accompanied by an experienced inner life?" (The Conscious Mind, Oxford 1996, p. xii.) Essentially, the 'hard problem' is the qualia problem. To explain it in detail would require a separate post. Humphrey offers us an explanation of why the 'hard problem' is hard. It is hard because nature or natural selection -- Humphrey uses these terms interchangeably above -- meant it to be hard. Her purpose is to "fool us into thinking we are in the presence of an inexplicable mystery." She wants to fool us in order to "bolster human self-confidence and self-importance." How thoughtful of her. Of course, to say that she is fooling us implies that consciousness is not mysterious but just another natural occurrence.
Not only does Nature fool us into thinking that consciousness is mysterious, when it is not, she also makes it impossible for us to see that this is what she has done. But there may be a loophole: it may be possible to "explain how a brain process could be (designed to) give rise to the impression of having this quality," i.e., the quality of consciousness. By 'impression,' Humphrey means illusion as is clear from his arithmetical example. So what he is suggesting is that it may be possible to explain how brain processes could give rise to the illusion that there is consciousness, the illusion that brain processes have the quality of consciousness.
But this 'possibility' is a complete absurdity, a complete impossibility. For it is self-evident that illusions presuppose consciousness: an illusion cannot exist without consciousness. The 'cannot' expresses a very strong impossibility, broadly logical impossibility. The Germans have a nice proverb, Soviel Schein, so viel Sein. "So much seeming, so much being." The point being that you can't have Schein without Sein, seeming without being. It can't be seeming 'all the way down.'
The water espied by a parched hiker might be an illusion (a mirage), but it is impossible that consciousness be an illusion. For wherever there is illusion there is consciousness, and indeed the reality of consciousness, not the illusion of consciousness. If you said that the illusion of consciousness is an illusion for a consciousness that is itself an illusion you would be embarked upon a regress that was both infinite and vicious. Just as the world cannot be turtles all the way down, consciousness cannot be illusion all the way down.
In the case of the mirage one can and must distinguish between the seeming and the being. The being (reality) of the mirage consists of heat waves rising from the desert floor, whereas its seeming (appearance) involves a relation to a conscious being who mis-takes the heat waves for water. But conscious states, as Searle and I have been arguing ad nauseam lo these many years, are such that seeming and being, appearance and reality, coincide. For conscious qualia, esse est percipi. Consciousness cannot be an illusion since no sort of wedge can be driven between its appearance and its reality.
A French philosopher might say that consciousness 'recuperates itself' from every attempt to reduce it to the status of an illusion. The French philosopher would be right -- if interpreted in my more sober
It is also important to note how Humphrey freely helps himself to intentional and teleological language, all the while personifying Nature with a capital 'N.' Nature meant the hard problem to be hard, she had a purpose in fooling us. She fooled us. Etc. This is a typical mistake that many naturalists make. They presuppose the validity of the very categories (intentionality, etc.) that their naturalistic schemes would eliminate. How could they fail to presuppose them? After all, naturalists think about consciousness and other things, and they have a purpose in promoting their (absurd) theories.
There is no problem with using teleological talk as a sort of shorthand, but eventually it has to be cashed out: it has to be translated into 'mechanistic' talk. Eliminativists owe us a translation manual. In the absence of a translation manual, they can be charged with presupposing what they are trying to account for, and what is worse, ascribing meanings and purposes to something that could not possibly have them, namely, Natural Selection personified. What is the point of getting rid of God if you end up importing purposes into Natural Selection personified, or what is worse, into 'selfish' genes?
So Humphrey's statement is bullshit in the sense of being radically incoherent. It is pseudo-theory in the worst sense. One of the tasks of philosophers is to expose such pseudo-theory which, hiding behind scientific jargon (e.g, 'natural selection'), pretends to be scientific when it is only confused.
A central task of philosophy is the exposure of bad philosophy.