Raphael Scholl

Naomi Oreskes’s recent book, Why Trust Science?, occupies an underpopulated space: It is interesting to an audience of professional historians or philosophers of science, but it also aims to engage a much larger part of the public. The book is motivated by Oreskes’s work on climate change denialism, and it asks: Why should we trust the pronouncements of scientists?

Oreskes begins by rejecting the view that scientists employ special methods by which they are able to tell what is true. We might think that scientists only hold theories that have been appropriately verified. But no: Philosophers have long argued, for a variety of reasons, that we can never verify theories in the sense of conclusively demonstrating their truth. Or perhaps proper scientific theories must be falsifiable, and must have survived many rigorous attempts at falsification? Again, this famous proposal by Karl Popper did not hold up to scrutiny. Oreskes goes through additional suggestions, and many influential philosophers make an appearance: Comte, Duhem, Hempel, Quine, Kuhn — and of course Feyerabend, who wrote “against method”.

Oreskes argues that scientific method ultimately cannot be what guarantees the trustworthiness of scientific findings. Instead, she suggests that we should look to social aspects of science. For example, we should ask whether the relevant scientific community is diverse, so that many viewpoints are represented. And we should ask whether the community allows critical discussion, so that superior viewpoints have a chance to prevail. In brief, our trust in science ought to rest not on truth-conducive methods, but on a truth-conducive type of social organisation. If an appropriately open, diverse, and critical scientific community reaches a consensus on a question, that consensus can probably be trusted. Since we cannot know for sure what is true, we use consensus as a proxy.

This is an appealing solution to the problem, and I have no doubt that it gets at something important. However, I am not convinced that it can successfully bracket the question of method. Here’s why. For group consensus to be a meaningful proxy for truth, we have to assume that the group can somehow assess whether its methods a truth-tropic, that is, whether they are sensitive to how the world actually is (which is not to say that these methods are required to be infallible). We must also assume that such an assessment of truth-tropism is relevant to the emergence of consensus. Otherwise the consensus might indicate nothing more than that the entire community has convinced itself to use the same, although unreliable, methods. If a community lacks methods that are truth-tropic, or lacks the ability to tell which of its methods are truth-tropic, or does not care, then its consensus doesn’t count for much — even if the community is wonderfully diverse, open, and critical.

Oreskes rightly fears that strong methodological norms could become a straightjacket (she speaks of a “fetish”), such as when we demand randomised, controlled trials in cases where they are neither feasible nor necessary. She discusses, for example, the debates about the effectiveness of dental flossing. Even in the absence of RCTs, she argues, we should not dismiss the abundant mechanistic evidence that flossing is effective against periodontal disease. I agree! However, this does not show that methodological norms are a bad thing to have. It only shows that we should not adopt artificially narrow accounts. The goal of scientific epistemology must be to study the full range of methods that empirical scientists employ, and to learn about their track records as epistemic tools.

To be clear, I think that we should in most cases trust science. I also think that the social organisation of scientific inquiry is important and deserves much more attention from philosophers of science than it has so far received. And, finally, I agree with Oreskes that the existence of a consensus within a scientific community is an important indicator of whether any particular scientific result ought to be trusted. Consensus is an especially important indicator for a general, non-expert public. But as historians and philosophers of science, we have an additional explanatory aim. It is to understand why consensus in a community can be taken as an indication that particular claims are likely to be true. And this requires a debate about the methods by which such claims are assessed, even if we believe that this assessment is a social processs.

(P.S.: I often dabble in the debates about what, if anything, the history of science and the philosophy of science have to learn from each other. Oreskes’s book is interesting in this respect. She clearly self-identifies as a historian of science. But in this book she begins by reviewing philosophical accounts of method, and she returns to this philosophical framing throughout as she discusses episodes from the history of science. I think that this is not at all surprising: If the epistemology of science is our interest, then we are in an area where the history and the philosophy of science naturally intersect.)

(This is a significantly expanded version of my review for NTM Journal of the History of Science, Technology and Medicine, which will appear later this year.)

Jutta Schickore’s About Method focuses on a neglected genre of scientific texts: what she calls the “methods discourse” of experimentalists. She argues that even though the philosophical and historical literature on experimental science is vast, little attention has been paid to what scientists themselves have to say about how to design, evaluate, and report the results of experiments. She acknowledges, of course, that methods discourse may be an unreliable guide to what scientists actually do in experimental practice, but she argues that it nevertheless offers a unique window into scientists’ conceptions of proper experimental procedure.

The book is structured around an extended case study of research on snake venom. This is a felicitous choice. It allows Schickore to connect significant episodes in the history of experimentation ranging from seventeenth-century Europe to the late nineteenth-century United States. We meet Francesco Redi (1626—1697), the Italian physician and naturalist who is now best known for his experiments questioning spontaneous generation. In his treatise on vipers, he insisted on repeating experiments many times in order to show that the “yellow liquor” in vipers’ teeth caused poisoning if it was inserted into wounds, but not if it was swallowed. Two chapters focus on Felice Fontana (1730—1805), who has been lauded as one of the first experimentalists to use adequate controls. Working a century after Redi, Fontana relied on the variation of experimental circumstances to determine which tissues snake venom acts upon. Another century later, the American physician Silas Weir Mitchell (1829—1914), among others, sought to isolate the active components in snake venom. Schickore finally links the research on snake venom to broader nineteenth-century reflections on the nature and limits of experimental inquiry, especially through the widely felt influence of the French physiologist and methodologist Claude Bernard (1813—1878). As we travel along this historical arc, the stability of snake venom as a research problem serves as a backdrop against which we recognize the evolution of experimental methods.

Schickore distinguishes multiple layers of methods discourse. At an extreme level of generality, we find scientists making broad commitments: for example, that experience is the only path to certain knowledge. At the other extreme, we find detailed discussions of particular laboratory procedures: of how precisely an incision was made and poison was deposited. Schickore, however, focuses on an intermediate level: that of methodological strategies and principles, such as the notions that we should conduct comparative experiments, repeat them, and vary their circumstances. Intriguingly, this intermediate level of analysis reveals continuities between researchers and time periods that remain hidden at the level of broad commitments or concrete research practices.

To illustrate, consider the contrast between two nineteenth-century scientists and methodologists, John Herschel and Claude Bernard. Herschel’s broad commitment was to a form of Baconianism, and his experience with experimental practice was in the physical sciences. Bernard, by contrast, could never quite stop kicking Bacon in the shins, as it were, and his practical experience was in physiology. Nevertheless, at the intermediate level of methodological strategies there was much that united the two. Both, for example, were interested in the theory and epistemic force of comparative experimentation. Thus, the middle-level analysis permits us to recognize significant continuities that might otherwise remain hidden.

Scholars have often reinterpreted methodological statements as efforts at positioning and persuasion, but Schickore believes a literal reading is often appropriate. For example, Redi’s emphasis of his many resource-consuming repetitions has been seen as a “political gambit to display the power of the Tuscan court” (32). However, organisms are highly variable, and repeating experiments helps to reveal variations and to discover which findings are reliable. Schickore shows that Redi defended his methodological views on such epistemic grounds. We have read much about the ways in which detailed descriptions of experimental procedures served to establish an experimenter’s credibility. Schickore, by contrast, emphasizes the role of methodological statements in establishing the credibility of the experimental procedures themselves.

About Method highlights the power of Schickore’s approach to integrated history and philosophy of science. She has previously argued that in order to understand current concepts and practices, we must often study how these concepts and practices have come into existence. The case of experimental method is an excellent example. Present-day methodological statements are all about the particulars of experimental processes and rarely discuss underlying methodological principles. There is much that we have simply come to take for granted. To understand the epistemic aims of such practices as comparisons, repetitions, and variations, we must look to a time when these practices were still controversial and needed explicit defense.

In some instances, it would have been welcome to drive the analysis further. For example, I would have liked to see how precisely Redi or Fontana deployed strategies like repetitions or variations of circumstances, and what inferences these strategies enabled. It is one thing to say that repetitions or variations reveal sources of error — but how did this work in concrete cases? Perhaps such an analysis would have seemed to Schickore too much like an attempt to “measure the distance” (9) between historical actors and modern-day conceptions of experimental reasoning. Or perhaps the shift from methods discourse to practice would have meant a loss of focus. In any case, I would have like to read more about the nitty-gritty details of experimental reasoning.

The title of Schickore’s book is a play on Paul Feyerabend’s seminal Against Method, which was published in 1975. It is telling that the method that Feyerabend argued against has very little in common with the methods that Schickore’s historical actors write about. The goal of the snake venom researchers was to isolate suspected causes, and to demonstrate their competence to produce the effects ascribed to them. These researchers worried about targeted interventions and the control of confounding variables, not about the power of falsification and the problems of ad hoc hypotheses. Schickore’s title is thus fitting. Her book is in many ways orthogonal to older debates. It is not a counterweight to Feyerabend’s book: for method, a defense of a philosophical project. It is about method: a description, an analysis, an invitation to a new dialogue.

To conclude, About Method is an excellent book. It not only gives us insights into the long-term development of experimental methods, but also serves as a model of how to conduct studies at the interface of history and philosophy of science.