The source of our difficulties with "conventions in law and science" is related to images. Practice as experienced in the law contrasts with conventions accepted in science. The difficulties in applying science in the law are commonly explained in terms of the differences in conventions, (1) but to some significant extent they are the result of the images by which those differences are identified. By clarifying these differences, we can perhaps leave aside those places where the differences are only apparent and concentrate instead on those where real differences do exist and cause real difficulties.
IMAGES OF SCIENCE
The image of forensic practice described in the Guidelines is no doubt broadly correct. (2) After all, the Guidelines image is related directly to the difficulties experienced in the ordinary work of the courts. But the image of science invoked here is quite otherwise. It is derived from a certain portrait of science as an essentially gentlemanly, honorable pursuit, whose conventions ensure unfailing courtesy and goodwill. Now, that portrait, which is derived from a traditional self-image of science, is also born of experience. But that traditional self-image of science was not the outcome of an empirical social science enquiry. It resulted rather more from an exercise analogous to propaganda that arose largely from what was once eloquently described as "the warfare of science with theology in Christendom." (3) In the opening line of the classic radical analysis of scientific practice, The Structure of Scientific Revolutions, Thomas Kuhn spoke of the "image of science by which we are now possessed." (4) For him, this image was largely a fabrication for which previous generations of historians were responsible. (5)
This is not the place to analyze that image, its history, and its consequences. But it does recall the image of classical Athenian society (democratic, open, and engaged) as portrayed in Pericles' 431 B.C. funeral orations. (6) That Periclean image, too, was rooted in genuine, lived experience and it also served as a source of idealism, both for Pericles' contemporaries and then for those born millennia later. But when taken as an objective description of Athenian society for the purpose of later scholarly analysis, that image was seriously defective and misleading.
This revealing history of an image is relevant here. It can perhaps help sort out some of the difficulties of science in legal settings that have brought us to the discussion addressed in this symposium and that will require adjusting and modernizing the image of science and its conventions. By examining some of the varieties of scientific practice, defined in terms of the function of their products, we can place the forensic practice--its context and functions--as just one among many. Of course, it has its characteristic features and its points of tension and conflict with the others. But by means of such an analysis we can escape from the supposedly unbridgeable chasm between two utterly different sorts of conventions and forms of practice.
A. Varieties of Scientific Experience
This analysis is not intended to be at all definitive or refined. Its goal is only to establish a useful point. The analysis starts with the "iconic" sort of science--pure or basic research. Just to be clear about fundamentals: even this sort of research does not consist of "discovering facts" as if they were the pebbles that Sir Isaac Newton famously imagined himself picking up on the beach. (7) Of course, discovery is there, and indeed is at the core. But the actual work consists of setting and investigating problems, in the form of hypotheses that are more or less formalized, about some aspect of the workings of the world out there under study. Now, what makes this sort of work "pure" is that, in an important sense, its productions do not matter. That …