Preface (Full Text)
- The suggestion that I write this book came from Henry Hardy of Oxford University Press. There were two reasons why I found the idea attractive. I was flattered by the thought that I might challenge comparison with "Russell (Bertrand) - The Problems of Philosophy". More important, I am convinced, perhaps because I read the popular books of Eddington, Jeans, Einstein, Haldane, and Wells when I was at school, that the fundamental ideas of science can be explained to anyone willing to make the effort needed to understand them. I am also persuaded that to understand these ideas is one of the most exciting and rewarding experiences one can have.
- I have tried to concentrate on problems rather than on accepted truths, but this at once raises a difficulty. It is impossible to discuss the questions we cannot answer without first answering those that we can. In biology, this means that we cannot think seriously about the major unsolved problems – in particular, the problems of development and of cognition – without first knowing something about molecular genetics and neurophysiology. The deepest knowledge we have acquired so far about living organisms is our knowledge of the molecular nature of heredity. It therefore seemed unavoidable that I explain this knowledge early in the book. There is a risk that this will prove hard going for those who do not know about DNA replication and protein synthesis, and boring for those who do. To the latter, I can only suggest that they skip rather lightly through Chapter 2; I can assure the former that to understand these ideas is worth the effort.
- Much of biology, however, cannot be explained in molecular terms. In the face of this inability, there are two possible attitudes: I am not sure whether they should be seen as two world views, or merely as two different research strategies. One is to argue that the molecular approach has enabled us to understand heredity, and is already beginning to tell us things about how brains work and how organisms develop. What we should do, therefore, is to press on in the same way, making use of the wealth of new techniques of genetic manipulation that are now available. Even if we cannot yet see how such a problem as pattern formation in development will yield to genetic analysis, the experience of the past thirty years assures us that it will.
- The second approach is to argue that wholes have properties that cannot be deduced from a knowledge of their parts. It follows, therefore, that development, behaviour, perception, and so on must be studied directly, and laws appropriate to those levels of organization be sought. It may later be possible to interpret those laws in molecular terms, but they cannot be deduced from molecular biology. After all, we do not expect to deduce the laws of economics from neurophysiology, even though we assume that they are the consequences of individual decisions to buy or sell, and that such decisions are the consequences of neural activities in people's brains.
- I see myself as a neutral in this debate. Most problems are best solved by starting at both ends, and trying to meet in the middle, as I shall explain in more detail when discussing the problems of perception. I have no doubt that the outstanding problems in biology will require such a dual attack: in contemporary jargon, both top down and bottom up. But to be neutral in such controversies is to invite the hatred and contempt of both sides, so I want to say a few words to ward off such hostility.
- First, a word to the molecular biologist. Members of that profession are often hostile to holistic ideas, and they are often justified. We must distinguish carefully between two kinds of holistic approach. The first, which seems to me entirely reasonable, is to assert that there are phenomena at higher levels which are likely to be discovered only by people who work at those levels, even though they are entirely consistent with known physics and chemistry, and may later be accounted for in those terms. A classic example is Mendel's discovery of the laws of heredity, which could not at that time (or ever?) have been deduced from molecular biology, but which have since been explained in those terms. The second, and illegitimate, type of holistic argument is to claim that, because we do not at present understand some phenomenon, there must be some vital force responsible for it. I can remember precisely this argument being used to persuade me that a chemical explanation of heredity was in principle impossible. Of course, there is no way we can be certain that there are not kinds of forces of which we are at present unaware, but our inability to understand something is not evidence of their existence. As it happens, I do not understand how modem sewing-machines work, but this does not lead me to suppose that the laws of topology have been broken: indeed, I feel confident I could find out if someone would let me take one to pieces. Molecular biologists are quite right to disbelieve in the elan vital.
- Holists are, I think, in a weaker position, if only because in recent years progress has been so much faster from the bottom up than from the top down. Yet I do share their conviction that there are laws that can only be discovered by research on whole organisms, and on populations of organisms. Almost all my own work has been done at those levels. What should be the attitude of a biologist working on whole organisms to molecular biology? It is, I think, foolish to argue that we are discovering things that disprove molecular biology. It would be more sensible to say to molecular biologists that here are phenomena that they will one day have to interpret in their terms.
- There is one important area of biology whose problems I have hardly touched on in this book: this is ecology. One of the important theoretical inputs to ecology is the idea of evolution by natural selection, and that I have of course discussed. But there are other ideas in ecology that have more in common with economics than with anything in contemporary biology, and these I have not dealt with. The reason is that these economic ideas are so different from those discussed in the rest of the book that I felt that any attempt to treat them would tend to confuse the picture.
- I have tried, then, to present what seem to me the fundamental ideas of biology, and some of its major unsolved problems. Although, occasionally, I tell something of the history of a subject, I am not trying to contribute to the history of ideas; I do no more than use the past to illuminate the present. Also, I have made no attempt to give references for the statements I make. Detailed references would be of interest only to professionals, who would know most of them anyway. My reason for referring to some scientists by name is merely to show that science is something done by people, and not written on stone. My choice of names to mention is in part arbitrary: it is not an attempt judiciously to apportion credit. I have used notes in the main to introduce additional ideas that seem to me amusing, but which would interrupt the flow of the argument if included in the body of text.
- I am grateful to Henry Hardy for provoking me into attempting the book, and prodding me into finishing it. My colleagues at the University of Sussex have provided the essential background of ideas and argument. Two of them must be mentioned by name. Paul Harvey read the whole manuscript, and made many helpful suggestions. To Brian Goodwin I have not shown a single word, for fear that he would make me rewrite the whole thing. However, those who know us will see that much of the book is-a debate between us, in which he is not allowed to get a word in edgeways.
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