Faith, Hope and Probability

Mary Douglas

  • The Taming of Chance by Ian Hacking
    Cambridge, 264 pp, £27.50, November 1990, ISBN 0 521 38014 6

The author of The Emergence of Probability (1975) has written another formidable book on the history of probability theory. The first described the development in the 17th and 18th centuries of a new way of legitimating knowledge: a mathematical theory of predictability under uncertainty based on observed frequencies of numbers on thrown dice. From its origins in gambling, probability theory began to meet the demand for a reliable form of authority that would release the Renaissance and the Age of Reason from religious claims to control knowledge. When it had seeped from games and mathematics to marine insurance, and thence moved on to produce what Ian Hacking calls an avalanche of numbers in every kind of public concern, established theories of causality were ready to be toppled. As he said in the earlier book, the world was about to become safe for future Galileos. But the change was slow, and not in time to divert Descartes from his project to establish in reason itself an independent arbiter for truth (and, we can add, not in time to save ourselves from a Cartesian world divided radically between primary and secondary qualities).

The present volume takes the 18th-century developments in statistical theory to the end of the 19th century. Now we are so used to thinking statistically that we hardly notice how much we are besieged by politically serviceable numbers, averages and chances. The process Hacking traces has produced a sea change for our culture. It would be good to be able to look forward to a third volume, bringing the same critical clarity to bear upon the uses of probability in present-day politics. But from what he tells us, that is evidently not on the immediate agenda. The Taming of Chance is not offered as a history, though it has a chronological framework and a narrative to unfold. As a book of philosophy it is evidently part of a deep-planned and evolving programme on the legitimation of knowledge. The programme has already included an edited volume on Scientific Revolutions (1981), together with Representing and Intervening: Introductory Topics in the Philosophy of Natural Science (1983) and writings on classification (‘Making up people’, 1986) and on language. The next major work, he tells us, is to be on styles of reasoning.

This volume therefore deals with philosophical issues using the development of statistics as its main illustration. The central issue is induction. He is going to argue, he tells us at the beginning, that a style of reasoning is self-authenticating. The idea sounds innocent enough: a proposition can only be assessed as true or false when there is some style of reasoning that sets the questions and provides ways of answering them. We learn that there is no way of settling the truth of a proposition without an established style of reasoning with its accompanying style of investigation. On closer acquaintance, this idea is far from innocent: we have to recognise that a style of reasoning cannot be either right or wrong, because it makes its own rules for fixing the sense of what it investigates. It is the actual form of the reasoning process.

The laws of nature underlie the causes which science from its beginning sought to uncover. But as the 19th century progressed, causes were put into question by probability analysis. At first, statistics were in the ancillary role – what we would have once called the handmaid of science, but which with proper regard to gender decorum Hacking calls the role of a loyal Victorian valet. At the beginning of the story, statistics serve: they do not dominate the quest for the laws of nature, far less do they replace them. Half-way through, statistics turn out to have laws which seem to rival those of nature. By the end, the laws and causes have been toppled and quantum theory has arrived. We are faced with a world governed by pure chance. Committed as he is to the principle that change comes by a multitude of tiny trickles. Hacking understandably decides to take the long scenic route, citing an avalanche of names of thinkers who contributed to the eventual flood.

Manufacturing numbers

First the readers have to be convinced that an extraordinary change in the manufacture of numbers took place. The pressure to collect figures comes from a new need to bandy them in politics and administration. Evidently, once the resource has been discovered, like transport or electronic communications, every one needs to use it. Much is at stake, so any official number is liable to be disputed, which further stimulates the industry of producing statistics and the work of arguing about what they may mean. Hacking insists that the nation states’ massive reliance on numbers was the necessary precondition for advances in statistical theory. Modern industrial society was the only platform from which the new style of reasoning could have emerged. It is interesting to note that the initial advances in theory so important to science came in response to social problems. This will partly account for the politically-fired metaphysical speculations foisted upon developments in methods. Statistics grew up in the centre of a public storm about whether the universe was a deterministic system of laws, or whether it was the product of the operations of blind chance.

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