Frank Plumpton Ramsey, who died in 1930 at the age of 26, was “an extraordinary scholarly phenomenon,” according to his editors, Nicholas Rescher and Ulrich Majer. He was appointed Cambridge University Lecturer in Mathematics at the age of 22. According to Cheryl Misak, among many accomplishments in the few short years of his career “he managed to figure out how to measure partial belief and hence lay the groundwork for decision theory and Bayesian statistics.” Misak’s book, Cambridge Pragmatism, from Peirce and James to Ramsey and Wittgenstein, describes how Ramsey took up several pragmatic insights and expanded upon them in On Truth, a book manuscript that was unfinished when he died.

Chapter 5, Judgment and Time, “develops some very general considerations about events in time.” Ramsey argues that Einstein’s theory that time is not absolute, but is instead relative to an observer’s position in space-time, has implications for the definition of “event.” The common view of event, which Ramsey calls the “substance theory”, considers the world to comprise a collection of enduring substances liable to change, and defines an event as an important change in the quality or relations of substances. Ramsey argues that the “substance theory” posits substances and absolute time among the ultimate constituents of the world, a position that flatly contradicts Einstein’s theory of relativity. The problem the substance theory poses for “event” is that it confounds two distinct concepts, which can be distinguished if a relative theory of time is adopted and events defined as “regions or volumes of space-time … are taken to be the ultimate constituents of the world.”

Ramsey illustrates the problem with the example of an eclipse, which the “substance theory” considers an event. Ramsey argues that an eclipse is instead a fact about relations among three events:

• the space-time occupied by the sun;
• the space-time occupied by earth in its orbit around the sun; and
• the space-time occupied by the moon in its orbit around the earth.

He proposes to call such facts about events “occurrences” to distinguish them from the space-time events that are the ultimate constituents of the world.