Karl Popper’s most significant contributions were in the philosophy of science. Like Hume he questioned the absolute predictability of cause and effect relationships: all that could be inferred from them were degrees of probability. If all science could offer was probabilities, it followed, argued Popper, that induction was inadequate for confirming scientific theories. To replace it he proposed the criterion of falsification. It, unlike Ayer's verificationism, was negative in its application but more logically rigorous: a scientist could have 1,000 instances of his research hypothesis being confirmed, but if one exception was discovered, an exception that was inexplicable, the hypothesis was invalidated. Popper realized that if such a criterion was strictly implemented, much research would be paralyzed, so he cautioned against rigid theoretical adherence (an interesting question for our meeting is, “If the implementation is harmful, doesn’t that reveal a flaw in the theory?).

Popper’s interest in the formulation of scientific outcomes led him to examine its application in the social sciences. His two major works in this area were The Open Society and Its Enemies, and The Poverty of Historicism. The first reviews the role of Plato, Hegel, and Marx in advancing totalitarian philosophies; the second critiques the assumption that history is like a science, its laws (such as historical determinism) progressive and immutable. Such a belief leads to social engineering and the suppression of minority opinions. Within his lifetime Popper witnessed the rise of two dystopias: Nazi Germany and the Soviet Union. The wars, mass executions, and destruction of social institutions convinced him that classical liberalism was the best guarantor of freedom.

The Poverty of Historicism (Routledge Classics edition) is 176 pages and available from amazon.com ($13.39 new, from $7.75 used).

The following resources provide commentary, bibliographies, lecture notes, and videos.

Wikipedia: "Karl Popper", "Historicism", "Falsifiability", "The Poverty of Historicism"

Stanford Encyclopedia of Philosophy: "Karl Popper", "The Problem of Induction"

Internet Encyclopedia of Philosophy: "Karl Popper and Critical Rationalism"

Karl Popper, “Natural Selection and the Emergency of Mind” (delivered at Darwin College, Cambridge, November 8, 1977)

Karl Popper, “Science: Conjectures and Refutations” (originally published under the title “Philosophy of Science: a Personal Report” in British Philosophy in Mid-Century, ed. C. A. Mace, 1957.

Rafe Champion, “Outline of The Poverty of Historicism” and "Reading Guide for The Poverty of Historicism[masked] and 1957"

Peter Singer, “Discovering Karl Popper” The New York Review of Books 21 no. 7 (May 2, 1974)

Mariano Artigas, “The Ethical Roots of Karl Popper's Epistemology” (author is Philosophy professor at the University of Navarra, Spain)

Hanns-Peter Neumann, “Knowledge Between Science, Historicism and Ideology: The Problem of the Historiography of the History of Philosophy” (author is a scholar at the Interdisciplinary Center for European Enlightenment, Martin-Luther-Universität at Halle-Wittenberg)

Noretta Koertge, “The Moral Underpinnings of Popper’s Philosophy” (author is professor in the Dept. Of History and the Philosophy of Science, Indiana University)

David Levy, “Karl Popper: His Philosophy of Politics” Modern Age (Spring 1978): 151-160. (Popper viewed from a conservative, Hobbesian perspective)

Steve Fuller, Kuhn versus Popper: The Struggle for the Soul of Science (Icon Books, 2003). (Contains entire text of 232 page book)

Martin Gardner, “A Skeptical Look at Karl Popper” Skeptical Inquirer 25 no. 4 (2001): 13-14,72; a rejoinder to this article is J. C. Lester's "A Sceptical Look at a 'Skeptical look at Karl Popper'", published on the Libertarian Alliance web site 2010.

William A. Gorton, Karl Popper and the Social Sciences. SUNY Press, 2006. (Contains entire text of 151 page book)

Neurath, M. “Pseudorationalism of Falsification” in Otto Neurath: Philosophical Papers, ed. R. S. Cohen and M. Neurath Reidel, 1983.

Lecture Notes:

“Notes on Popper” by Professor Anne Hiskes, Dept. Of Philosophy, University of Connecticut

“Falsifiability” by Professor Daniel Little, Dept. Of Philosophy, University of Michigan at Dearborn

Youtube video: “Falsifiability. A self-refuting theory?”