Book Reviews - Roger Penrose

This is a very intriguing, but decidedly confusing book - purportedly a layperson's critique of 'Strong AI' (the notion that consciousness has an algorithmic basis) that for long stretches reads more like a textbook on modern physical theory for postgraduate mathematicians.

Roger Penrose is himself a mathematician, and his first assault on Strong AI involves an appeal to the nature of mathematical insight. Certain mathematical statements, he shows, can be instantly perceived by a human to be true or false, even though there is no algorithmic means of either proving or disproving them. This is all interesting and germane to the book's central concern, the mind-body problem.

However, things start to get a little hairy after the first hundred pages, as the author slowly gets sucked into his home turf of complex equations and arcane geometry. For the next three hundred pages, the non-specialist reader is largely left standing as Penrose dashes through the mathematical nitty-gritty of relativity, complexity theory, quantum theory and quantum gravity, all 'illustrated' with geometrical representations of abstract mathematical concepts that presumably are supposed to help us 'visualise' what he's talking about. Unfortunately Penrose is not good at restraining his own fascination for mathematical detail in the interest of allowing the reader a reasonable chance of grasping broad concepts; the result is a frequent urge to skip pages for fear of losing momentum completely.

The odd thing is that a basic comprehension of Penrose's ideas about consciousness, which are delineated in the final two chapters, calls upon remarkably little of the detailed mathematical exposition to which the bulk of the book is devoted. Introspection, common sense and imaginative projection are Penrose's main tools here, as he lays out his hypothesis that the superposition of quantum possibilities and the (as yet verified) phenomenon of quantum gravity may be what lie behind the mystery of consciousness. Here, finally swapping mathematical certainties for philosophical speculations, his train of thought becomes much easier to follow, and with relief the reader finishes the book, in spite of the trials that have gone before, feeling stimulated, enlightened and even inspired.

One thing I did have trouble reconciling myself with was Penrose's thinking on the nature of time. The essence of this seems to be the notion that nothing fundamentally differentiates time from the spatial dimensions except our perception of it as 'flowing'; that everything that is, was and ever will be somehow exists unchanging in a type of timeless stasis. Penrose denies that this vision negates free will, but I couldn't follow his argument as to why. I can see how a mathematician, awestruck by the intricate beauty of his subject, might come to the view that mathematics literally occupies a perfect realm of its own; but this seems to make appeal to the very mind/body dualism that science has struggled, for the past four centuries, to eradicate - as yet without success.