THREE RADICAL QUIBBLES WITH THE “PROLEGOMENA…“

From my perspective as a mechanical designer and developer of theory and computation tools for mechanical design, Sacks and Doyle have provided a convincing and overdue challenge to qualitative simulation. SPQR is interesting, but involves a reduction from the expressive power of differential equations. Engineers generally need more rather than less expressive power; I am unaware of any successful applications of qualitative simulation in mechanical design. “Prolegomena . . .” explains why in clear and wellsupported terms. Sacks and Doyle rightly restrict themselves to conclusions for which they have evidence; having been asked for my opinion, I feel no such constraint. The following sections argue that Sacks and Doyle are in three ways too conservative. First, they seek only to reform qualitative physics, but no purely qualitative automated physics can be of much value to mechanical designers. Second, they underestimate the extent to which computational capabilities are a potential source of new mathematics. Finally, they do not go far enough in calling for a fusion between A1 and non-A1 fields.