It’s an open secret in my discipline: in terms of accurate political predictions (the field’s benchmark for what counts as science), my colleagues have failed spectacularly and wasted colossal amounts of time and money. The most obvious example may be political scientists’ insistence, during the cold war, that the Soviet Union would persist as a nuclear threat to the United States. In 1993, in the journal International Security, for example, the cold war historian John Lewis Gaddis wrote that the demise of the Soviet Union was “of such importance that no approach to the study of international relations claiming both foresight and competence should have failed to see it coming.” And yet, he noted, “None actually did so.” Careers were made, prizes awarded and millions of research dollars distributed to international relations experts, even though Nancy Reagan’s astrologer may have had superior forecasting skills.

Political prognosticators fare just as poorly on domestic politics. In a peer-reviewed journal, the political scientist Morris P. Fiorina wrote that “we seem to have settled into a persistent pattern of divided government” — of Republican presidents and Democratic Congresses. Professor Fiorina’s ideas, which synced nicely with the conventional wisdom at the time, appeared in an article in 1992 — just before the Democrat Bill Clinton’s presidential victory and the Republican 1994 takeover of the House…

These results wouldn’t surprise the guru of the scientific method, Karl Popper, whose 1934 book “The Logic of Scientific Discovery” remains the cornerstone of the scientific method. Yet Mr. Popper himself scoffed at the pretensions of the social sciences: “Long-term prophecies can be derived from scientific conditional predictions only if they apply to systems which can be described as well-isolated, stationary, and recurrent. These systems are very rare in nature; and modern society is not one of them.”