The Intelligibility of Nature: How Science Makes Sense of the World

  • Peter Dear
University of Chicago Press: 2006. 242 pp. $27.50 0226139484 | ISBN: 0-226-13948-4

In 1690 the philosopher John Locke imagined a man with “microscopical eyes” many times more acute than the best microscope. Such a man, he conjectured, might grasp the deep “texture and the motion of the minute parts of corporeal things”, but “would be in a quite different world from other people... I doubt, whether he, and the rest of men, could discourse concerning the objects of sight.” We can surmise that the scientific explanations such a person offered might not be intelligible to others.

Isaac Newton (left) and Antoine-Laurent Lavoisier were central to the creation of modern science. Credit: NATIONAL PORTRAIT GALLERY, LONDON/BRIDGEMAN ART LIBRARY

Intelligibility may be difficult to define but it plays a crucial role in the claim of science to offer credible accounts of nature, argues Peter Dear in his elegant book The Intelligibility of Nature, which is richly informed by scholarship in the history of science. Locke's point looks prescient when we consider the development of quantum mechanics from the 1920s. Its successful predictions of experimental phenomena were aligned with the disorienting prospect of an acausal, probabilistic world. Dear argues that by this time, 'instrumentality' — the power to produce and predict effects — had surpassed intelligibility as the main basis of scientific authority. The leitmotif of his book is that science has availed itself of two self-supporting, albeit circular, rationales: its account of the structure and processes of nature is backed by the success of instrumental techniques (such as the use of electron microscopes and DNA profiling); and explanations of why certain techniques work are grounded in intelligible, even if speculative, accounts of the natural world.

In Western culture there is an abiding distinction between understanding nature and doing things with it. This was formulated by Aristotle as episteme versus techne (the Latin equivalents are scientia and ars). Natural philosophy, the discipline responsible for seeking a causal understanding of natural qualities and processes, was classed as scientia, whereas mathematics, which deals with quantities that need not apply to real things, was regarded as a practical craft charged with measurement and computation. As Dear stresses, Isaac Newton's universal law of gravitation — the great scientific achievement of the seventeenth century — was viewed as a mathematical accomplishment. Although highly sophisticated, it was in the same class as utilitarian calculations of the relative movements of the stars and planets involved in almanacs and horoscopes. Moreover, Newton eschewed any account of what gravity was or how it acted at a distance in a vacuum. He did not provide a natural-philosophical explanation of the kind attempted by René Descartes, for example, who sought to understand celestial motion in terms of bodies in a fluid medium using the analogy of straws in the eddy of a river. Such an account was deemed intelligible, even if not demonstratively true. Newton's reluctance meant that his theory lacked intelligibility, even though it possessed striking instrumentality, as judged by the predictive power of the inverse-square law.

In discussing various scientific domains from the seventeenth century to the present, including celestial mechanics, taxonomy, atomism, natural selection, electromagnetism and quantum physics, Dear meditates on this tension within science. He contends that Newton's success and reputation allowed “the conflation of natural philosophy with instrumentality”. Antoine-Laurent Lavoisier reinforced this by insisting that precise measurement of chemical reactions could be a model of scientific method without any commitment to a view about the underlying elementary structure of matter. In contrast, John Dalton's atomic theory was an attempt at traditional natural philosophy. In so far as Lavoisier was triumphant, the criterion of instrumentality began to rival that of intelligibility, the hallmark of natural philosophy. By the nineteenth century, modern science “was born a hybrid of two formerly distinct endeavours”.

In 1833, William Whewell, surprisingly absent from the book, coined the term 'scientist' in opposition to 'artist'. Both the date and the terms of this contrast resonate with Dear's theme. If the dynamic between the two rationales for science was already in play by Newton's day, what was added in the nineteenth century? The dust-jacket suggests one answer, declaring that the investigation of nature “would be carried out by a new kind of person, the scientist”. Although the features of this new persona are not made explicit, there are indications that it was, and remains, a problematic one. For a cosmologist, being a scientist might be a natural-philosophic quest for laws of nature that cannot become intellectual property; for a microbiologist, it is likely to involve a search for techniques that will be patented. Scientists who wish to reflect on their vocation will gain valuable insights from this beautifully contrived book, and all readers will be prompted to think more carefully about the nature and ethos of science.