Science and the Stars

M.F. Perutz

  • The Limits of Science by Peter Medawar
    Oxford, 108 pp, £7.50, February 1985, ISBN 0 19 217744 3

Medawar presents an erudite and entertaining account of the limits of science, or mostly the lack of them, as perceived by great thinkers from Francis Bacon to Karl Popper and himself. His arguments are couched in largely epistemological terms which do not arouse my passions, but they stimulated me to think about those limits that affect laymen’s attitudes to science, about the practical limits scientists face in their everyday research, and laymen in their daily lives, and about the limits that affect industrial and public policy.

Medawar argues that science reaches its limits only when we ask ultimate questions of our existence, such as ‘How did everything begin?’ or ‘What are we all here for?’, but many other people’s attitude to science is more affected by its inability to answer the question ‘How should we behave?’ In their view, science has undermined the religious basis of morality and the belief in Heaven and Hell without putting anything in their places. It has given man immense powers over nature without suggesting any ways of improving the nature of man. Many regard these as science’s greatest failings. In his book Chance and Necessity Jacques Monod suggested that scientific truth might become the basis of a new ethics, but he did not spell out how this was to be achieved. Philosophers have shown that science can tell us only what is, and that an ‘ought’ cannot be derived from an ‘is’.

Medawar asks if there is some intrinsic limit to our understanding of the natural world, either cognitive, having to do with our powers of apprehension, or logical, arising out of the very nature of thought. His denial of both kinds of limit may be valid on philosophical grounds, because science has been defined as embracing all those problems that are in principle open to empirical observation and solution, but it is contrary to practical experience. Whatever I did discover I could have discovered years earlier, and many things that I failed to discover I could have discovered if it had not been for my limited powers of apprehension and logical thought, my obtuse blindness to the answers that lay at hand. History shows that even the greatest scientists usually advance in small steps, because the development of new concepts causes them enormous difficulties. For example, in retrospect an experiment on the scattering of alpha-particles from a gold leaf, performed by Geiger and Marsden in Rutherford’s laboratory in Manchester, ‘obviously’ suggested that the mass of the gold atom was concentrated in a tiny nucleus, but so novel and revolutionary was the idea that it took Rutherford more than a year to formulate it. I feel the lack of my own powers of apprehension and logical thought most acutely when I try to think about the evolution of the large biological molecules whose complex structures I have helped to determine, but since an explanation of this would take me deep into chemistry and physics, let me discuss instead some similar riddles that arise when we try to think about the evolution of birds.

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