The Logic of Scientific Discovery《a book review (zt)》

Popper's work (in general) and this book (in particular) have been much admired by non-philosophers who wanted to have something simple and solid to rely on: and much despised and assaulted by other philosophers of science who liked to have something large and static to react against.

Needless to say in a more balanced view the truth is probably neither that Popper is a complete fool nor that he is a completely reliable guide to how science is or should be done.

Perhaps the place to start is with a naive hypothetico-deductive view of science: scientists boldly propose hypotheses (theories of how some part of the world is) carry out objective experiments which reveal new and definite facts and deduce from these observed facts either that the theories were correct or changes to those theories. This seems to be not far from what many intelligent scientists think they are doing; but a philosopher can demolish this scheme in a minute. Experiments are never purely objective -- people have a vested interest in showing they are right and have publishable results. Facts are never certain -- the instruments may be faulty the sample contaminated the environmental conditions uncontrolled etc. Facts do not themselves suggest specific changes to theories; nor is it possible to apply Aristotelian logic (as Stephen Toulmin shows) to deduce theories from facts.

Given that scientists would like something similar to a hypothetico-deductive model what else could they have? Popper suggested that while indeed you couldn't have your theories proven by experimental test you could have them refuted. Science then never actually arrived at certain theoretical knowledge: but it approximated to it as you gradually found theories that were harder and harder to disprove. This too is pretty simplistic retaining the appeal of definite experimental facts and objective experiments (ideas already critiqued above) to ordinary scientists while escaping the obvious nonsense about 'confirming' theories by experiment. One problem is Thomas Kuhn's historical observation that inconvenient new facts hardly ever cause theories to collapse: theorists are quite accustomed to difficulties and usually just tweak their theories to account for the new observations.

Popper is however more cunning than this brief sketch would imply: this book consists of some 250 pages of close argument supported by detailed appendices. Popper continues to maintain that the quantity of testing that a theory has survived somehow establishes a 'degree of corroboration' something that seems to smuggle back in at least a whiff of the old hypothetico-deductive feeling that you can prove a scientific theory. The 'anarchist' philosophers of science like Paul Feyerabend say openly that that is simply nostalgic nonsense: the world just doesn't contain any such certainties. Indeed the Logical Positivist view that real and definite observable facts exist objectively comes under fire - what you observe depends on what you know so when you go birdwatching with an expert observer you (surprise surprise) see a whole lot more than usual. On the other side scientists who should know better like Sir Hermann Bondi feel able to write

"This splendid book ... Popper speaks as a working scientist to the working scientist in a language that time and again comes straight out of one's heart ... Popper faces on every turn the problems against which the scientist runs up and solves them ... in full accordance with the procedure of science." (from the cover blurb)

Popper is of course not a working scientist at all and speaking the language of the heart is an odd attribute for a serious philosopher; but there is no mistaking the warmth that scientists feel for his writings. People do feel that there must be truth out there which is why cultural relativism as in the history-based philosophy of Thomas Kuhn's Structure of Scientific Revolutions (not to mention Feyerabend's scornful rejection of certainty) makes people uncomfortable however amused they are by Kuhn's tales of subjective goings-on in the laboratory.

Popper then is the plain man's philosopher of science -- which after all means 'knowledge'. How do we know things? Indeed can we? Popper resoundingly replies YES and that is what many people want to hear. But is it true? That of course is another matter.

© Ian Alexander 2004