Explanations in physics commonly appeal to data drawn from different length or time scales, as when a “top-down” macroscopic constraint such as rigidity is used to evade the complexities one would confront in attempting to model the situation in a purely “bottom-up” fashion. Such techniques commonly embody rather complex shifts in explanatory strategy.
This essay embodies a somewhat different range of considerations than I presented at the Pittsburgh PSA session (which was closer in content to my forthcoming “From the Bending of Beams to the Problem of Free Will,” which additionally surveys Leibniz's remarkable anticipations of our topics). I would like to thank all of the participants for their helpful counsel.