Abstract
It is well known that in _Principia Mathematica_ Russell offers a theory of definite descriptions and holds that ‘existence’ is not a property. It is less well known that in “On Denoting” he discusses the version of Anselm’s ontological argument for God formulated by Descartes, accepting the premiss “Existence is a perfection” and assessing the argument as valid but question-begging. This is different from his later comments in _A History of Western Philosophy_ which find the argument invalid. Indeed, given the sanctions of _Principia_, one might have thought he would find the argument logically ungrammatical. This paper shows how Russell might formulate and evaluate Anselm’s ontological argument and the version offered by Descartes in a way that avoids the conflict.1.