 A clarificatory comment: for stylistic reasons, we will continue to shift back-and-forth between speaking of explanations as truths of a certain kind that can be discovered and argued over, versus speaking of them as activities by which those truths are communicated or understood. That distinction, as well as whether explanations are in fact something else (e.g., theories in a model-theoretic sense), will rise to the forefront later, but for now, we will speak loosely.