Bloor, David and MacKenzie, Donald. Letter to the Editor, Nature 387 (5 June 1997), p. 544.


Bloor, David and MacKenzie, Donald. Letter to the Editor, Nature 387 (5 June 1997), p. 544.

Sir - We welcome the tone of Gottfried and Wilson's assessment of what they (not we) call
‘Edinburgh school' sociology of scientific knowledge'. Their eschewal of the ad hominem
attacks that have characterized too much of the ‘Science Wars' debate is refreshing.

Three points of clarification are, however, in order. First, the goal of the sociology of knowledge,
in our view, is the explanation of belief, not its evaluation. ‘Symmetrical' analysis of the
emergence, development and acceptance or rejection of bodies of knowledge does not involve
the (absurd) claim that all beliefs are of equal merit. Rather,'symmetry' implies that current
evaluation of the truth or falsity of beliefs should not bias the empirical study of the processes
through which knowledge develops. For the historian or sociologist studying nineteenth-century
evolutionism, for example, both Darwinism and anti-Darwinism stand equally in need of

Our second point is a simple corollary of the first. Predictive success is, of course, a vital
measure of the merit of bodies of knowledge, and an important cause of their acceptance or
rejection. But later predictive success cannot be appealed to as a cause of earlier acceptance.

Third, we have always held that satisfactory analysis of the development of knowledge must be
multi-causal. Causal input from the real world and psychological and social processes are all
involved. Scientific knowledge is not a collective fantasy devoid of relation to the real world, but
neither is it a simple mirror of reality. The sociology of scientific knowledge stands or falls by
the value of the best, empirical, case-studies of these complex questions. We are glad that these
case studies are attracting the attention, however sceptical, of distinguished natural scientists. We
benefit from their scrutiny; perhaps they may learn something in return.

David Bloor Science Studies Unit,

Donald MacKenzie Department of Sociology, University of Edinburgh, 21 Buccleuch Place,
Edinburgh EH8 9LN, UK