The Cabinetmaker's Apprentice Jeffrey R. Di Leo (bio) When Sir Karl Popper (1902–94) was twenty years old, he became an apprentice to Adalbert Pösch, an old master cabinetmaker in Vienna. A university student at the time, Popper claims that he learned more about the theory of knowledge from this "omniscient master" than from any of his teachers. "For it was my master who taught me not only how very little I knew," wrote Popper in Unending Quest: An Intellectual Autobiography (1976), "but also that any wisdom to which I might ever aspire could consist only in realizing more fully the infinity of my ignorance." Popper worked with this omniscient cabinetmaker for two years, after which he decided that he was "too ignorant and too fallible" to make mahogany writing desks for the rest of his life. So he did social work with neglected children for a year, and then, after five more years mainly spent studying and writing, he became a schoolteacher in 1930. He says that at that point he had no other professional ambitions. Still, after the publication of The Logic of Scientific Discovery in 1935, he started to grow tired of schoolteaching. In this early book, the Austrian-British philosopher famously argued that science should adopt a methodology based on falsifiability because no number of experiments can ever prove a theory, but a reproducible experiment or observation can refute one. However, writes Popper, "non-reproducible single occurrences are of no significance to science." "Thus a few stray basic statements contradicting a theory will hardly induce us to reject it as falsified," he continues. "We shall take it as falsified only if we discover a reproducible effect which refutes the theory." This notion of falsifiability is one that Paul Ricoeur regards as similar to his own conception of "invalidation," wherein the role of falsification is played by the conflict between competing interpretations of the text. "An interpretation," writes Ricoeur in "The Model of the Text" (1971), "must not only be probable, but more probable than another." "There are criteria of relative superiority," he continues, "which may easily be derived from the logic of [End Page 1] subjective probability." According to Ricoeur, it is the falsification of Popper found in The Logic of Scientific Discovery that renders easier this derivation. Two years after the publication of The Logic of Scientific Discovery, Popper gave up schoolteaching and became a professional philosopher. He was thirty-four years old, and said, "I thought that I had now finally solved the problem of how to work on a writing desk and yet be preoccupied with epistemology." In 1960 the former cabinetmaker's apprentice delivered the Annual Philosophical Lecture to the British Academy. Popper surprised and offended some of his colleagues by entitling it "On the Sources of Knowledge and of Ignorance." While the first part of the title, "On the Sources of Knowledge," was regarded as standard fare for an epistemologist at the time, the latter part, concerning the sources "of Ignorance," was not—and raised some philosophical eyebrows. As his friend put it, "Ignorance is something negative: it is the absence of knowledge." "But," he continued, "how on earth can the absence of anything have sources?" Unsure how to respond, Popper said the following: I told him that I hoped to direct attention, through the phrasing of this title, to a number of historically important although unrecorded philosophical doctrines and among them, especially, to a conspiracy theory of ignorance which interprets ignorance not as a mere lack of knowledge but as the work of some mischievous power, the source of impure and evil influences which pervert and poison our minds and instill in us the habit of resistance to knowledge. Thus, for Popper, the sources of ignorance in the British and Continental schools of philosophy often involve conspiracy theory, which although unstated is nonetheless a consequence of their stated philosophical doctrines. As Popper sees it, "the quarrel between the classical empiricism of Bacon, Locke, Berkeley, Hume, and Mill," that is, the British school, and "the classical rationalism or intellectualism of Descartes, Spinoza, and Leibniz," that is, the Continental school, is overstated. Though it is true that "the British school...