So what is the Astonishing Hypothesis?
The Astonishing Hypothesis is that "You", your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behaviour of a vast assembly of nerve cells and their associated molecules.This idea is probably less astonishing today than it was in 1994. Since then it has been widely written about and is accepted by many though not all neuroscientists and philosophers. But the main difference between then and now is that mainstream scientists are willing to talk about consciousness; this was not so when Crick was writing, for reasons he explains.
The book has three main parts. Part 1 considers the general nature of consciousness and explains why Crick concentrates on visual awareness. It contains two quite long chapters on some of the complexities of visual psychology and uses visual illusions to exemplify some problems that arise. Part 2 is on neuroanatomy, starting with the neuron and going on to the brain as a whole and the visual system in particular.
The information in the first two parts provides the necessary background for Part 3, which describes various possible experimental approaches to studying visual awareness and concludes with a discussion of some general issues that arise from Crick's suggestions. Much of the experimental work he cites was done on monkeys (though not by Crick, who was entirely a theoretician). This is likely to distress some readers, but we have to remember that sensibilities were different even as recently as the early nineties of the last century.
Throughout, Crick emphasises the complexities and uncertainties that attend this research. But this is not a reason to neglect the role of neuroscience, he insists; he points out the deficiencies he finds in the view of some physicists, mathematicians and philosophers that we can treat the brain as a black box without being concerned about what is going on inside.
Why not look inside the black box and observe how its components behave? It is not sensible to tackle a very difficult problem with one hand tied behind one's back.Part 3 concludes with a "Sunday Morning Service", in which Crick summarises his conclusions and also criticises religion and provides a postscript on free will.
Crick wrote this book nearly a quarter of a century ago so inevitably its treatment of the visual system cannot be taken as an up-to-date account of what we know about this. So does it still repay reading today? Certainly yes, because it affords a remarkable insight into the mind of one of the foremost scientific thinkers of modern times as he contemplates what is probably the most difficult problem in science. In any case, what Crick is concerned with is not so much to establish a theory as to persuade other scientists to take a different approach to the brain.
What Christof Koch [his collaborator] and I are trying to do is to persuade people, and especially those scientists intimately involved with the brain, that now is the time to take the problem of consciousness seriously. We expect that it is our general approach that will be found useful, rather than our detailed suggestions.The one thing that Crick does not do in this book is to tackle what has been called the Hard Problem of consciousness. How does neural activity give rise to qualia—the subjective experience of colour, heat and cold, fear, desire and so on? He is frank about this omission.
The reader … could well complain that I have talked all round the topic of consciousness with more speculation than hard facts, and have avoided what, in the long run, is the most puzzling problem of all. I have said almost nothing about qualia—the redness of red—except to brush it to one side and hope for the best.Crick suggests that the question may ultimately disappear, as did earlier ideas about the Life Force.
The history of science is littered with statements that something was inherently impossible to understand ("we shall never know of what the stars are made"). In many cases time has shown these predictions to be incorrect.