A rebuttal to The Emperor's New Mind

(Or: My views on complex systems, strong-AI, the mind-body problem, and souls.)

Penrose's position

In The Emperor's New Mind, Roger Penrose takes the following position. He tries to debunk the ``strong AI'' view that minds are in principle complex algorithms, and that the particular manifistation of that algorithm is unimportant in principle. Penrose argues that the physical embodiment is important for the presence of actual consciousness. He believes there is a level of physical action deeper than quantum mechanics (quantum gravity?) that is essential to the operation of the brain and is a prerequisite for the presence of ``real'' consciousness.

My position

Complex systems and emergent properties

I think that there is a qualitative change that occurs as systems become more complex. (Lenin once said, with respect to the inferior but more numerous tanks that the Soviet military were producing, that ``quantity has a quality all its own''.) Furthermore, these emergent properties are every bit as real as the back of my head (which I've never seen directly) or the number zero.

To see what I mean, imagine visiting Niagara Falls and taking a polaroid photograph of it. Niagara Falls is real, but what is the status of the image on the photographic paper? The image is not Niagara Falls, but there is something unmistakably Niagara Falls-ish about it. Furthermore, each molecule in the photographic paper by itself has nothing to do with Niagara Falls. But taken together, they make a picture of Niagara Falls. The image is an emergent property of the particular arrangement of molecules on the paper. (For more interesting ideas like this, see William Poundstone's The Recursive Universe.)

It has long been accepted in quantum mechanics that the observer cannot be separated from the event he or she (or it) observes. In the same spirit, it takes someone who already knows what Niagara Falls is and/or looks like to recognize the image on the polaroid paper. That is, the image as ``Niagara Falls'' does not ``exist'' on its own. Rather, it takes an interaction between the observer and observed for the concept of Niagara Falls to enter the picture (so to speak...).

It is for these reasons that I think that emergent properties of systems are qualitative in nature, and will always remain highly subjective.

Consciousness and intelligence

Now, lets apply these ideas onto the mind-body problem and the existence of consciousness. I think that the notions of ``intelligence'' and ``consciousness'' are qualitative ones, and therefore not subject to notions of hard proof of existence or absence. That is, until we have a satisfactory algorithmic theory to describe these concepts, there is no point in discussing, to any great precision, their presence or absence. At least, not without keeping in mind that such discussions are intrinsically subjective.

Furthermore, with regards to these concepts, I take the operational point of view that Penrose objects to. That is, we ``test'' for the presence of intelligence or consciousness by the external behaviour of a system, and not by its internal structure (hardware or software).

Incidentally, the Turing test (discussed at length in the introductory chapter of Penrose's book) is an interactive operational subjective test for the presence of intelligence.


I think it is important to emphasize the interactive nature of proof, communication, and recognition. I believe it is a general feature of complex systems, on more than just a trivial level.

I noted earlier how interaction is essential to image recognition. I think it's also important in the determination of intelligence, as the interactive nature of the Turing test shows. Randomized interactive (zero-knowledge) proofs are the basis for some very powerful identification and authorization protocols.

There is something deep here going on here, related to the arrow of time, and other things.


I believe that the ``soul'' and one's identity is the sum total of the emergent properties of one's body. As with the image of Niagara Falls, this soul and aspects of it can be found not only in your own body, but in the body and souls of all who know or are affected by you. Hence the immortal and noncorporal nature of the soul.

For related ideas, learn about the distributed nature of representations in neural networks.


There have been some recent cases in Canada where a parent has killed a retarded child. In no way do I pretend to condone such actions, and I do not intend my ideas on ``testing for'' intelligence or consciousness to be used as the basis of judgement on whether people should live or die.
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