[From 2005; several typos corrected, July 20, 2018]
It has proven difficult to provide a unified semantics for the French subjunctive (the difficulty applies more generally to Romance, but we concentrate on French). In this preliminary note, we suggest that this is because the French subjunctive is a semantic default, to be used just in case the indicative would have triggered a presupposition failure (a similar idea was explored for Italian by Portner 1997; see also Siegel 2004). Thus the environments in which the subjunctive appears do not form a natural class, although they are the complement of a natural class. Once this is established, a large part of the question becomes: what is the semantic contribution of the indicative? Modifying minimally the analysis of Stalnaker 1975 (which was concerned with English), we suggest that the indicative triggers a presupposition on the value of a world term, of the form w{CS(x', t', w')}, indicating that the world denoted by w lies in the Context Set of individual x' at time t' in world w' (x', t', and w' may be left free -if the context provides them with a salient value- or they may be bound). This derives indirectly the intuition, found both in traditional grammar and in recent research (e.g. Farkas 2003), that the indicative marks an assertive act on somebody's part, though this person need not be the speaker. We also discuss an extension of this theory to the German Konjunktiv I, which we analyze in essence as a reportive indicative, in line with the intuitions -though not with the implementation- of Fabricius-Hansen & Saebø 2004. If correct, the theory we sketch makes it possible to analyze mood by analogy with person and tense as introducing a presupposition on the value of word-denoting terms, and in particular on world-denoting variables.