If we accept that the shape and mood of a field of inquiry is largely, or even just somewhat, determined by the specific kinds of evidence needed to have consensually agreed-upon findings or results in that field, it becomes important to study the perhaps peculiar nature of evidence in different domains to appreciate how these distinct domains fit into the greater constellation of intellectual effort.
Mathematics — a realm in which one might think the issue of evidence to be fairly straightforward (you prove a theorem or you don’t) — will, as we shall see, turn out to be not at all clear, and it has its own history of the shaping of types of evidence.
In the fall semester of 2012 I had the pleasure of co-running a seminar course, “The Nature of Evidence,” in the Harvard Law School with Professor Noah Feldman. It was structured as an extended conversation between different practitioners and our students. A number of experts contributed to lectures and discussions. We found it very useful to learn in some specificity from people in different fields, via concrete examples graspable by people outside the field, what evidence consists of in physics, economics, biology, art history, history of science, mathematics and law.
Once one looks with a microscope at the structure of evidence in any of these fields, even though this structure is quite specific to the field, and a moving target, the project of understanding it in a larger context is very much worth doing. While studying concrete examples in different fields, we aimed for a comprehensive view and not merely a fragmented “evidence-in-X, evidence-in-Y, etc.,” with no matrix to tie these bits together.
The following has been loosely adapted from a class handout I put together as preparation for our students — few of them mathematicians — for my own presentation specifically regarding evidence in mathematics.