Postscript to The Logic of Scientific Discovery
In Pursuit of Truth: Essays on the Philosophy of Karl Popper on the Occasion of his Eightieth Birthday
Apart from his celebrated writings on the “open society” and its enemies, Karl Popper is chiefly known as a logician of science who has denied that science employs induction, and who has claimed that what demarcates science from nonscience, in particular metaphysics, is that scientists seek the truth by vigorously trying to falsify their theories. This has become one of the most celebrated and controversial views of science to have been put forward during this century. In a previous article, I noted that vigorous objections have been raised to Popper’s view, most recently in the book under review by Anthony O’Hear, and, as we shall see, there are strong reasons for questioning Popper’s thesis.
First, however, a common misunderstanding of Popper’s work should be clarified. His preoccupation with the logic of scientific method and his early association with some members of the Vienna Circle have frequently led readers to link him with logical positivism and a contempt for metaphysics. What is less well known, and perhaps surprising, however, is that Popper has devoted a number of years to outlining a metaphysics of his own, one drawing on evolutionary theory, that depicts the continuity of method between men and other organisms and more generally articulating the place of man and his intellectual products in nature. This vision, he reminds us, is not a scientific theory itself: it is not falsifiable. Popper regards his own “metaphysical” theory and his evolutionary epistemology as “conjectural” in character: while such conjectures are not empirically testable, he claims, they may, like other nontestable and nondemonstrable theories, such as realism and idealism, be helpful to us. Furthermore, they might be arguable.
What is this “vision”? Popper conjectures that “what is true in logic is true in psychology.” Induction is logically invalid, does not “exist” in logic and so no one (and no animal) has ever performed one. All organisms, according to Popper’s phrase, “from the amoeba to Einstein,” are problem solvers who use the method of trial and error. In nature, as Darwin taught, the plural forms of life evolve from a small number of simple forms by virtue of the mechanisms of heredity, variation through mutation, and natural selection. Of course, the lower organisms lack language and cannot formulate their hypotheses and guesses, but even they do something similar to what we do: they carry out “trial” solutions to problems of adaptation and adjustment, and the “errors” in these trials are eliminated by natural selection. As we solve problems of bridge building or scientific explanation, then, so spiders “solve” problems of where to build their webs and bacteria “solve” problems of overcoming antibiotics. Most organisms other than man incorporate the “solutions” to the problems confronted by their predecessors in their very anatomical design; they die off when these solutions are no longer successful.
With man, according to Popper’s “metaphysical” conjecture, things are different. Our invention and use of language creates a new “world,” an “ontologically distinct” realm, which he …