In Defence of the Letter of Fictionalism

Abstract

In his article [5] Gideon Rosen puts forward an account of modal discourse which suggests how one can translate such discourse into possible world discourse without any untoward ontological commitments.As David Lewis has amply demonstrated, translation of modal discourse into possible world discourse has many advantages, but the problem is to see how to obtain these advantages without attracting the 'incredulous stare', or more bluntly, without being regarded as a raving lunatic.Rosen suggests how.Specifically his suggestion is the following.Let P be any modal sentence and PL its translation into Lewisean counterpart theory.Then, Rosen suggests, the correct translation of P into possible world discourse is not PL but rather 'According to the Lewisean hypothesis of a plurality of worlds, PL', that is, 'According to the fiction that there is a plurality of worlds, PL.Thus, according to Rosen [5], the modal fictionalist (as he entitles the proponent of this position) should endorse the following translation schema for modal propositions (where '(PW)' abbreviates 'the Lewisean hypothesis of a plurality of worlds'):(1) P if and only if according to (PW), PL. However, Rosen [6] brings forward an objection to this proposal (also brought forward by Brock [1]). In [4]Peter Menzies and Philip Pettit endorse this objection, but suggest that it is decisive only against the letter of the Rosen proposal in [5], i.e. the 'simple prefixing strategy' encapsulated in schema (1).The spirit of modal fictionalism can, however, be retained, they suggest, by suitable modification of (1).The aim of this paper is to show that Menzies and Pettit are being unnecessarily concessive.The objection of Rosen [6] and Brock [1] is unsound, and so the letter and not just the spirit of Rosen's original modal fictionalism can be retainedat least, that is, it can be retained unless there are any other objections to it.