At the beginning of his career he did research on particle physics.
Since the 1970s his research has dealt with the history and philosophy of science, in particular, the role of experiments in physics.
He has done research on the history of experiments on parity violation, CP violation, neutrinos, and a possible fifth force, as well as the Millikan oil drop experiment and the relationship between theory and experiment in research on weak interactions.
As a philosopher, he dealt with the Duhem–Quine thesis, the theory of confirmation using Bayesian statistics, the corrigibility and reliability of experimental results, and the resolution of conflicting observations.
In 2016 he received the Abraham Pais Prize for History of Physics.