Abstract

Over the past century, there has been considerable debate over whether and how anything changes with respect to existence. Most A‐theorists of time (presentists, growing block theorists, and branch theorists) think things come to exist or cease to exist. B‐theorists of time (four‐dimensionalists, in particular) think objects do not change with respect to existence. In my Compass article, I outline a serious difficulty that A‐theorists face in trying to reason about temporary existents. The most straightforward logics for time and existence entail that nothing exists merely temporarily. The problem arises from a set of theorems of the simplest temporal logic – the converse Barcan formulas. But attempts to fix the logic to get rid of the Barcan formulas pressure A‐theorists to abandon an intuitive and widespread assumption about existence. I survey the logical and metaphysical options for solving the problem.