Why trust science?

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.)