Why should there be such rapid advances in some fields and not in
others? I think the usual explanations that we tend to think of - such
as the tractability of the subject, or the quality or education of the
men drawn into it, or the size of research contracts - are important
but inadequate. I have begun to believe that the primary factor in
scientific advance is an intellectual one. These rapidly moving fields
are fields where a particular method of doing scientific research is
systematically used and taught, an accumulative method of inductive
inference that is so effective that I think it should be given the
name of "strong inference." I believe it is important to examine this
method, its use and history and rationale, and to see whether other
groups and individuals might learn to adopt it profitably in their own
scientific and intellectual work.
In its separate elements, strong inference is just the simple and
old-fashioned method of inductive inference that goes back to Francis
Bacon. The steps are familiar to every college student and are
practiced, off and on, by every scientist. The difference comes in
their systematic application. Strong inference consists of applying
the following steps to every problem in science, formally and
explicitly and regularly:
Devising alternative hypotheses;
Devising a crucial experiment (or several of them), with
alternative possible outcomes, each of which will, as nearly is
possible, exclude one or more of the hypotheses;
Carrying out the experiment so as to get a clean result;
Recycling the procedure, making subhypotheses or sequential
hypotheses to refine the possibilities that remain, and so on.