Extremes of opinion about the status of science are far enough apart to make the middle ground a pretty broad expanse. It is easy to turn away from claims that a special, well-codified scientific method charts a royal road to truth. It is equally easy to see scientific theories as mere stories, steeped in self-interest and sustained by rhetoric alone. Many who think about science for long probably settle somewhere near the view that it is closely akin to other forms of inquiry, albeit with a much more powerful toolkit. And it is hard not to believe that - while fragile, fallible and, even occasionally, fraudulent - for questions that fall within its remit, scientific knowledge is by far the best we are likely to get.
But does this have to remain a working assumption, or can it be put on a more secure basis, a firm epistemological foundation? Susan Haack makes an impressive attempt to do so. She does not succeed completely, but that puts her in pretty good company. And her account of how scientific claims are developed and tested is certainly a rewarding read.
Her starting point is that, in one sense, there is nothing special about science, no distinctive scientific method. All empirical inquiry, whether undertaken by a detective, an investigative journalist, an anthropologist in the field or a physicist in the lab, demands the same epistemic virtues.
Look for evidence as hard as you can, judge carefully what it is worth, and pay scrupulous attention to what it tells you. Then add this evidence to existing experience and use it to reason out your best-informed conjectures.
What makes science and scientists stand out from this more general set of more or less disciplined investigations of the world, she argues, is the large set of "helps to inquiry" that the various sciences have developed - ever-more powerful instrumental aids to observation, experimental routines, models and metaphors. Together, these enable the natural sciences progressively to improve their understanding of the real world underlying the observations.
How this works in practice is then laid out in some detail, first in general, then using examples taken mostly from molecular biology. The level of exposition assumes some acquaintance with the philosophy of science, though on that score I ended up not quite sure who the book is aimed at.
Readers new to the issues will occasionally want a little less technicality; the professional philosopher, I would imagine, will quite often want a good deal more. The legendary intelligent general reader will probably get by well enough, helped by the fact that the book offers, as it maintains, a "common sense" account of science, and by Haack's admirable clarity throughout.
So the book has a good deal of appeal as an exceptionally thoughtful treatment of a very important question. If I have reservations, none of them would deter me from putting it in the hands of anyone with more than a casual interest in how science pulls off its wonderful trick of giving humans a better-informed view of the universe.
The most important reservation is about one of Haack's core claims. Overall she steers a pretty convincing path between two familiar extremes - what she dubs the Old Deferentialists and the New Cynics. With regard to the Old Deferentialists, she emphasises that, if there is a logic of discovery, logic is never enough. A whole range of other considerations, involving judgements of the quality, comprehensiveness and relevance of evidence, come into play, mediated in complex ways by interpretations of the behaviour of instruments and by the interaction of many scientists over time. Her guiding metaphor for the whole process is the gradual working out of an enormous crossword puzzle. You do not need to be as enamoured of this metaphor as the author - and she uses it an awful lot - to see it as a useful starting point for contemplating the intricacies of scientific practice.
She also insists, though, that while judgement may differ when evidence is considered from different points of view, how good the evidence is remains ultimately an objective matter. This claim seems to be analagous to the fundamental realist commitment without which science loses its point: there is a real world and things that are the case about it. But how can we have access to this objective standard of evidence when, in practice, what emerges as good evidence is determined through collective debate by a scientific community? Is there a position outside the community from which we can judge when it departs from proper evaluation of the evidence?
This seems to be what is implied by, for example, her invocation of two people on a hiring committee, one of whom believes in graphology, while the other does not. They will disagree about whether the way the candidate forms his or her letters is relevant to the selection. But, says Haack, whether it is relevant depends on whether it is true that handwriting is an indication of character. Well, yes. But deciding whether that might be true surely depends on other evidence, gathered on other occasions, and on how that is evaluated by the relevant scientific community. I am not clear whether, if you seize this loose end and pull hard, Haack's entire argument unravels to reveal an infinite regress. But it suggests that, just as the anti-relativist can always point to the standard logical problem of upholding the truth of the relativist position - and Haack does so - the relativists still have a case that you cannot appeal to natural facts to settle a dispute about what the natural facts are. How this difficulty is resolved in scientific work is more elusive than the book makes out.
A less important reservation is that, by focusing on the extravagance (her nice term) of a small number of writers in science studies who have taken extreme epistemological positions, she perhaps undervalues what close observation of scientific practice by sympathetic social researchers can provide. One thing it conveys more vividly than her own acute but generally second-hand analysis is the sheer difficulty of forging agreement about standards of evidence and quality of data, let alone about what the data signify.
A final reservation is the breadth of the topics that are treated in the later chapters. The meat of the book comes in the first 150 pages, where she lays out the details of her view of scientific knowledge. There follow brief treatments of social science, science and literature, science and the law, science and religion, and science and progress. The strongest of these subsidiary reflections is on scientific evidence and (US) law, but the other chapters seem in the end rather dispensable. A pity, as the rewards of the main exposition show what she can achieve at greater length.
Jon Turney is editorial director, Penguin Press, and was formerly in the department of science and technology studies, University College London.
Defending Science- Within Reason:: Between Scientism and Cynicism
Author - Susan Haack
Publisher - Prometheus
Pages - 411
Price - £21.00
ISBN - 1 59102 117 0