772 Book Review Supplement Nature Vol. 272 27 April 1978

ness is said to be "the perfect instrument He has a special place in the hearts of for realising adaptability" (but is there Gunning for neurophysiologists because it was Granit really a dependent relationship here: and Svaetichin who, in the late 1930s, would a highly adaptable animal have to developed the techniques for recording be conscious?). reductionism from nerve cells with an extracellular micro­ Granit's "scepticism" about simple electrode: this step alone was revolutionary. evolutionary ideas leads him to the brink Colin Blakemore In the first five chapters, and in the last of a belief that may lose him some of his one, Granit expounds a personal philo­ readers. If natural behaviour is so full of sophy of science: I suspect that his book purpose, he says, natural selection must The Purposive . By Ragnar Granit. will be read mainly for this, rather than have purpose too. He declares himself Pp. 244. (MIT Press: Cambridge, Massa­ for the more straightforward sections on quite satisfied with applying the term chusetts and London, 1977.) $12.50; brain function. Granit is gunning for "purposiveness" to evolution itself. But £8.75. reductionism and is not ashamed to call here his logic is not transparent: un­ himself a teleologist. Physiology, he says, deniable adaptation of each animal to its is "applied teleology", and the teleological environment is surely not evidence for IN this short book Ragnar Granit brings approach is especially valuable in brain some kind of grand design in the together two subjects on which he himself research to predict whether the purpose mechanism for the emergence of species. has worked-the visual system and the of any particular piece of brain machinery To be sure, there is a frustrating motor system-as the basis of a general "would either be well or badly realised by credibility gap between the elegant monograph about brain function and as one or several of a number of alternative examples of selection of simple character­ the vehicle to express an individual hypotheses or models". Purpose, as the istics and the monumental complexity of philosophy. His treatment of these two title of the book implies, is the central the human brain; but most biologists areas is business-like and straightforward, theme of Granit's discussion of the cling to the unifying hypothesis of though even here his style is idio­ scientific method, the nature of under­ "chance and necessity" and are unwilling syncratic and his personal opinions are standing and, especially, the mechanism to admit that it cannot cope with the clearly expressed. of evolution. mystery of mind. Granit surely gives a In his treatment of vision Granit intro­ The brain is undeniably a purposeful clue to this apparently intractable prob­ duces both the concept of "feature­ machine, and the more advanced the lem when he points out that adaptability extraction" by neurones that are highly species the more complex (even devious (a kind of freedom from the constraints selective for certain "trigger features" in in the case of man) the purpose that its of innately coded instructions), not the retinal image, and a seemingly con­ brain can pursue. But the richness of adaptation to a single environment, is trary hypothesis that cells in the visual purpose in animal behaviour leads Granit "the glorious climax of evolution". The cortex are tuned to different spatial fre­ actuany to doubt the adequacy of genetic richness of human behaviour is essen­ quency components in the complex theory to account for the evolutionary tially epigenetic: what we have our genes distribution of retinal illumination, and emergence of purposiveness. He writes: "I to thank for is the generalised capacity to thus may be involved in some sort of am resigned to an attitude of mild seek purpose in our actions, not the primitive Fourier analysis of the spatial scepticism as to the completeness of its impossible feat of specifying everything pattern of light on the retina. Though he coverage of matters requiring explan­ we can do. D declares that the detection of "change, ations". Consciousness is viewed as an contours, and movement" (classical trig­ Colin Blakemore is Royal Society Locke "emergent novelty", the pinnacle of a Research Fellow ar rhe Physiological Labora­ ger features) is an essential part of visual hierarchy of purposiveness. Conscious- tory, Universiry of Cambridge, UK. analysis, he is, nevertheless, enthusiastic about the parsimony of the spatial frequency hypothesis and emerges on the prejudice or sin that we cannot observe side of the frequency freaks rather than Philosophy Nature aright; or (b) we are not perform­ the feature creatures. ing "the scientific method" correctly. The section on the motor system starts Possibility (a) was taken very seriously by with the mechanism of the synapse, the of ignorance the founding fathers of modern science, function of reflexes and the role of many of whom, doctrinary Puritans, muscle spindles in the control of muscle P. B. Medawar believed that after the Fall, human beings length. It continues with the hierarchical lost the innocent perceptiveness that made central control of movement, from the it possible for them to recognise the integrative function of the spinal moto­ The Encyclopaedia of Ignorance. Vol. 2: Truth that Nature was simply waiting to neurone up to the topographical dis­ Life Sciences and Earth Sciences. Edited divulge to those who would observe her tribution and properties of upper moto­ by Ronald Duncan and Miranda Weston­ intently and without preconceived ideas. neurones in the motor cortex, and the Smith. Pp. 433. (Pergamon: Oxford, Certainly this was John Milton's view, for possible function of regions of the 1977.) Paperback £3.50. Hardback com­ whom the purpose of was "To parietal lobe in the building of body bined edition with Vol. I on the Physical repair the ruins of our first parents". image and in the operation of voluntary Sciences £IO. Possibility (b) would carry some weight movement within external space. if the avowal of ignorance were a con­ All this is tackled with authority and IF, as the Philosophy of Induction invites fession of failure by scientists whose past vigour, and with a vitality that anyone us to believe, the sciences begin as great inability to make head or tail of Nature who has had the pleasure of meeting heaps of factual information which are was already evidence enough that they Granit will instantly recognise. Ragnar "processed" according to a programme did not really know or understand the Granit already has his place in the of ratiocination known as "the scientific scientific method-an explanation clearly history of brain research. He was awarded method", then it is difficult to see why we falsified by the fact that the scientists who the Nobel Prize in 1967 (together with should ever be ignorant of anything that are most conscious of their imperfections Hartline and Wald) for his work on the we want to know or understand; if the and of the boundaries of their present retina; but, as Sir John Eccles noted at inductive scheme were true, there could understanding are often the most brilliant the time, he could equally have won it be only two reasons for our being so: and empirically the most successful. Many for his pioneering study of motor control. either (a) our senses are so obfuscated by of the authors of this symposium are

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