Why Alan Musgrave should become an essentialist

Abstract

It was at a conference at La Trobe University in Melbourne that I heard John Fox characterise Alan Musgrave as a lap-dog realist. This was in response to a paper by Musgrave in which he insisted that the realism he defended was of a quite modest kind, and not warranting the label of mad dog realist which was pinned on him at Virginia State Polytechnic in 1986 and which has since stuck. There are unsolved problems in Musgraves version of realism which a realist should be able to solve and which I believe can be solved by adding to it an element of essentialism. A version of the latter position has been clearly articulated and defended recently by Brian Ellis (2001). However, I believe Elliss position is too strong and can be weakened in various ways without destroying its main thrust. I aim to persuade Alan Musgrave to become a lap dog, rather than mad dog, essentialist and thereby become twice as modest as he already is. There are two problems for which Musgrave has no adequate solution, as he himself acknowledges. One concerns an adequate grounding for the intuitive distinction between scientific deductions that are explanatory and those that are not. (The deduction of the range of a projectile from Galileos laws of motion plus initial conditions explains why the projectile has that range, but the deduction of the height of a cliff from those laws plus the time of fall of a stone from top to bottom does not explain why the cliff has that height.) The other is a need for an account of physical necessity that will serve to ground the distinction between scientific laws and true, but only accidentally true, generalisations. Essentialism, the idea that things necessarily behave in the ways that they do on account of the kinds of thing that they are, can solve both problems straightforwardly. Musgrave raises the possibility of an essentialist solution to problems with realism only to dismiss it. However, the account of essentialism that he dismisses is unduly unsympathetic. There is a version which is immune to his criticism and which, I argue, is just what he needs to strengthen the weak points in his realism. © 2006 Springer.