Possible Worlds Without Extra Universes (2026)

This opening episode asks what a possible world is supposed to be. Robert Stalnaker’s answer is realist enough to support modal semantics, but modest enough not to populate reality with Lewis-style concrete rival universes. 1 The payoff is a deliberately coarse-grained conception of propositions: a proposition is identified, for present purposes, by the ways things could be in which it is true. 2

The lecture follows Stalnaker’s 1976 paper from its contrast with extreme realism, through the distinction between a way things might have been and a world that instantiates that way, to the pressure this puts on theories of propositions. 1 It closes by showing why this metaphysical starting point matters for the next subjects in the series: assertion, context sets, and the management of common ground.

The primary text is Robert C. Stalnaker’s “Possible Worlds,” published in Noûs 10 in 1976, pp. 65–75. 1 The episode’s contrast between concrete-world realism and abstractionist approaches follows Christopher Menzel’s overview in the Stanford Encyclopedia of Philosophy. 2 Stalnaker’s publication list provides the chronology for the later works that the series will reach, including Inquiry and Context and Content. 3