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• Personal Growth

January 2003

What is the Nature of consciousness? Is artificial intelligence possible? These are some of the questions that Sir Roger Penrose, author of The Emperor’s New Mind and Shadows of the Mind, attempts to answer in this interview with Anupama Bhattacharya

Though there is an element of questioning the possibility of artificial consciousness, your book The Emperor’s New Mind leaves one with the feeling that machines can never be conscious in human terms. Why do you feel so?

One has to be careful about what one means by a ‘machine’. I interpret ‘machine’ as ‘computer-controlled robot’. My arguments do not rule out the possibility of a man-made ‘device’, which could be conscious. According to the viewpoint that I am expressing, consciousness is indeed the product of physical processes, but these processes cannot be computational. A key point in my discussion is the fact that there are mathematically describable processes that are outside the scope of computation. This is not in dispute. The contentious issue is whether such non-computational processes can actually be achieved by a physical object.

I argue, by use of Gödel’s theorem (Gödel demonstrated that any consistent first-order theory of arithmetic, if equipped with an effective procedure for recognising its own proofs, is incomplete) et al, that a conscious being is actually a ‘physical object’ of this kind. My position is that non-computational physical actions do occur in our universe, though they are not seen in the physical theories that we know about today. I argue—from quite different considerations—that a new physics is needed to span the gap between the quantum physics of the Schrödinger equation (an equation used in quantum mechanics for the wave function of a particle) and the classical physics of Newton, Maxwell and Einstein. My contention is that when we know this new physics, we shall see that it is actually non-computational. Accordingly, I contend that the conscious brain must make crucial use of physical processes that make use of this (presently missing) non-computational physical action. One could imagine a latter-day Frankenstein who actually incorporates this new physics into a kind of device, in which case it might be conscious. But there is no scope for such things within present-day scientific understanding.

What are the aspects of the consciousness that a computer cannot duplicate or ‘feel’?

In my view, a computer is simply not conscious. Consciousness is the result of physical processes that are not computational.

Today, research indicates that most mental states, including those of meditation, Love and what is called spiritual enlightenment, are actually part of the brain’s functions and can be felt through artificial stimulation of certain brain parts. Doesn’t this indicate that the human brain functions like a machine and every emotion can be duplicated through artificial means?

This presupposes that the brain’s functions are just like those of a computer. This, I deny. I feel sure that many of the brain’s processes are indeed things that are computational and could therefore be simulated computationally, but these are unconscious actions. But the brain’s conscious actions are of a quite different nature. I contend, and according to the Orch-OR model that Stuart Hameroff and I are developing, these are dependent upon coherent quantum processes taking place in neuronal microtubules. One must bear in mind the huge difference between those special processes that impinge significantly upon our awareness and those others—the vast majority of brain processes—that do not. Although things like meditation, love, and spiritual Enlightenment may well have important unconscious components, they are also things that strongly depend upon consciousness, so, in my view, they are not things that a ‘machine’ (in the above sense) is capable of. I can make this claim even more strongly for emotional states. The notion of an emotion makes no sense without consciousness, so (according to my position) machines are incapable of emotion.

In The Emperor’s New Mind, you explain how if the molecules in a person’s entire body are replaced by molecules from a brick, or any other object, it wouldn’t really make any difference since it is the pattern of the molecules that make a difference, and not the molecules themselves. Then, theoretically, shouldn’t it be possible to create a human being out of any sentient or non-sentient material?

Not just by copying the ordinary ‘information’ in a brick. One needs to know the complete quantum state, and there is a theorem (the no-cloning theorem) in quantum mechanics that tells us that a quantum state cannot be copied. My arguments require that consciousness is dependent upon (non-local) quantum phenomena, and one cannot apply ordinary classical arguments in this case.

If that is so, then what makes human consciousness special, if at all?

Actually, I don’t say just ‘human consciousness’, since in my view a good many animals are also conscious, so they depend upon non-computational actions also. It is the harnessing of non-computational processes that are indeed ‘out there’ in the physical world that makes us conscious.

In a critique of The Shadows of the Mind, Bernard J. Baars of the Wright Institute argues that the consciousness is not a problem of physics and, as such, cannot be judged or understood in those terms. Do you agree?

Clearly I disagree. Of course I don’t say that we only need to know about physics to answer the issues of consciousness, but I argue that the physics is a necessary ingredient, and we will not be able to answer the deep issues without fundamental developments in physics.

On a completely non-scientific track, do you believe that spiritual practices such as Meditation can help in the expansion of consciousness?

I am not in a position to answer this question, since I do not practise it myself. I can, however, say that I know of great scientists who have benefited from such things. The great quantum physicist John S. Bell did indeed practise Meditation and claimed to benefit from it. And there is no doubting of the importance of his contributions to the deep issues of quantum mechanics.

Quotation: 1

An emotion makes no sense without consciousness, so machines are incapable of emotion

Quotation: 2

We will not be able to answer the deep issues without fundamental developments in physics