Robustness and Explanation

Robustness and explanation are multiply linked. Robustness is crucially connected, as physicist Richard Feynman said, “to fundamental aspects of physical nature.” In his book The Character of Physical Law (1967), Feynman argued that the fundamental principles of nature are remarkable because they are derivable in multiple ways using multiple different assumptions. So in some sense they are almost unavoidable. This he related to a “Babylonian” architecture of theory, in which various elements of theory are multiply connected, redundant, and thus more reliable. For this reason, fundamental physical laws do not depend on any particular assumptions; a fact that he illustrated with two different independent derivations of the inverse-square law of gravitational attraction. The great conservation laws in physics have this character, and much of the progress in nineteenth-century physics progressed through the discovery of the interconvertibility of different forms of energy. The conservation laws are, for this reason, deeply anchored in the explanatory frameworks that we would use even for deciding what is a reasonable explanation and what is not.