The Razor

Generations of writers opined vaguely that 'simple hypotheses are more plausible' without giving any logical reason for it. We suggest that this should be turned around: we should say rather that 'more plausible hypotheses tend to be simpler'. An hypothesis that we consider simpler is one that has fewer equally plausible alternatives. (p.606)

Actual scientific practice does not really obey Ockham's razor, either in its previous 'simplicity' form or in our revised 'plausibility' form. As so many of us have deplored, the attractive new hypothesis or model, which accounts for the facts in such a neat, plausible way that you want to believe it at once, is usually pooh-poohed by the official Establishment in favor of some drab, complicated, uninteresting one; or, if necessary, in favor of no alternative at all. The progress of science is carried forward mostly by the few fundamental dissenting innovators, such as Copernicus, Galileo, Newton, Laplace, Darwin, Mendel, Pasteur, Boltzmann, Einstein, Wegener, Jeffreys – all of whom had to undergo this initial rejection and attack. In the cases of Galileo, Laplace, and Darwin, these attacks continued for more than a century after their deaths. This is not because their new hypotheses were faulty – quite the contrary – but because this is part of the sociology of science (and, indeed, of all scholarship). In any field, the Establishment is seldom in pursuit of the truth, because it is composed of those who sincerely believe that they are already in possession of it. Progress is delayed also by another aspect of this. Scholars who failed to heed the teachings of William of Ockham about issues amenable to reason and issues amenable only to faith, were – and still are – doomed to a lifetime of generating nonsense. (p.613) Probability Theory, The Logic of Science, E.T.Jaynes