Hanna, Robert.  "The Nature of Creativity in Whitehead's Metaphysics."  Philosophy Research Archives 9 (1983): 109-76.

Abstract

Whitehead's categoreal scheme in "Process and Reality" is so constructed that the several basic notions presuppose one another; despite this, there is good reason to consider "creativity" to be more ultimate than the others.  But just how it is that creativity can be a metaphysical ultimate is not initially clear.  For Whitehead's various characterizations of creativity are confused and seemingly conflicting; moreover, and most importantly, creativity comes into conflict with the ontological principle.  An analysis of the relation between creativity and the ontological principle reveals a radical turn in philosophic thought: the conception of a metaphysical ultimate which is "ontologically neutral."  [Abstract from The Philosopher's Index]