Psychoneural Pairs

A.J. Ayer

  • A Theory of Determinism: The Mind, Neuroscience and Life-Hopes by Ted Honderich
    Oxford, 656 pp, £55.00, May 1988, ISBN 0 19 824469 X

The problem first of clarifying and then of answering the questions how far human thoughts and actions are subject to causality and whether this is consistent with their being free is one to which many different approaches have been made throughout the history of philosophy. I doubt if any of them has been the product of such intense research as Professor Honderich has devoted to the construction, the defence and the evaluation of his theory of determinism. Agreement among philosophers, especially on fundamental questions, is difficult to reach, and I shall be arguing against Honderich’s theory at many crucial points. Nevertheless, I think that his readiness to accept even the most startling implications of his views, the patience he displays in examining alternatives to them, his assiduity in setting out and trying to meet a wide range of objections, are all highly creditable to him.

The book, which runs to well over six hundred pages, is divided into three parts, ten chapters and 74 sections. It begins by elaborating a view of causality as a form of necessary connection, and proceeds to develop a hypothesis concerning the ‘nomic correlation’ between a person’s states of consciousness and states of his central nervous system, from which Honderich extracts the concept of a mental item and its neural associate as ‘a psychoneural pair’. A chapter on the causation of these psychoneural pairs, leading to a shorter chapter on the causation of actions, brings the first and most philosophical part of the book to a close.

In the second part Honderich turns to science. Its title is ‘The Truth of the Theory’, which prompts me to say both that I agree with him in taking the theory of determinism to be empirical, and that I regard his marrying philosophy with science as an example of a current trend which is much to be welcomed. This part of the book consists of a very long chapter on Neuroscience and Quantum Theory, followed by a shorter discussion of the topics of prediction and knowledge. Honderich’s acquaintance with the natural sciences, like my own, is only second-hand, but he has been conscientious in seeking out the best sources for his account of contemporary physics and neurology. I shall nevertheless be arguing that he underrates the threat which Quantum Theory poses to the very strong version of determinism which he upholds, and that his belief in the total predictability, not only of all human experience and action, but even of purely physical states and processes, goes far beyond anything that is warranted by the empirical evidence at our disposal.

By now we have reached page 379 and there are still 236 pages to come; followed by 22 pages of references and an index of 25 pages. There are also diagrams which do not enter into the pagination. A lot is being asked of those whom Virginia Woolf addressed collectively as ‘the common reader’, but there will be a reward for their persistence. The third part of the book, which explores the bearing of Honderich’s theory of determinism on our claims to knowledge, our moral judgments, the rationale of reward and punishment and the concept of free will, is the most interesting and the most original.

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