As we’ve discussed on occasion, conditional probability (“Boltzmann statistics,” in physics jargon) is false at the atomic level. (It’s false at the macroscopic level too, but with discrepancies too small to be detected directly most of the time.) Occasionally I’ve speculated on how quantum probability (that is, the laws of uncertainty that hold in the real world) might be applied to social science research.

I’ve made no progress but remain intrigued by the idea.

Chris Zorn told me he recently went to a meeting on applications of non-Kolmogorovian / quantum probability to social & human phenomena. Here’s his paper (with Charles Smith), “Some Quantum-Like Features of Mass Politics in Two-Party Systems,” which begins:

We [Smith and Zorn] expand the substantive terrain of QI’s reach by illuminating a body of political theory that to date has been elaborated in strictly classical language and formalisms but has complex features that seem to merit generalizations of the problem outside the confines of classicality. The line of research, initiated by Fiorina in the 1980s, seeks to understand the origins and nature of party governance in two-party political systems wherein voters cast partisan ballots in two contests, one that determines partisan control of the executive branch and another that determines party control of a legislature. We describe how research in this area evolved in the last two decades in directions that bring it now to the point where further elaboration and study seem natural in the more general formalistic and philosophical environments embraced in QI research. In the process, we find evidence that a restriction of a classical model that has animated work in the field appears violated in a form that leads one naturally to embrace the superposition principle. We then connect classical distinctions between separable and nonseparable preferences that are common in political science to their quantum and quantum-like counterparts in the QI literature, finding special affinity for a recently-introduced understanding of the distinction that provides a passageway into the boundary between fully quantum and fully classical views of the distinction and thereby provides new leverage on existing work germane to the theory.

Oddly enough, their paper is classified under “general physics.” That doesn’t sound right! It’s purely political science, not physics at all. To call it “physics” because it uses probability laws derived by physicists . . . that makes as much sense as labeling almost all of empirical political science as “physics” because linear regression was invented by Gauss and Laplace.