Logic Colloquium 2024


Andrzej Indrzejczak

University of Łódź

Talks at this conference:

  Monday, 14:40, J222

Do theories of definite descriptions support Anselm’s God?

We examine the relationship between the ontological argument, in its original version provided by Anselm in Proslogion II, and theories of definite desriptions. Anselm’s ontological arguments, and its later variants proposed by such eminent philosophers as Descartes or Leibniz, still belong to the most discussed themes in the field of philosophy and theology. An advent of interest in these arguments in XXth century, among logicians and analytical philosophers, has thrown a new light on their structure and value. The prevailing approach to their formalisation is based on the application of modal logic, as in the works of Malcolm [3], Hartshorne [2], or Plantinga [6]. However, it seems that at least in the case of the version of the ontological argument formulated in Proslogion II, the crucial elements are contained in the description of God provided by Anselm. Therefore, following Barnes [1] or Oppenheimer and Zalta [4,5], we take as our basic assumption that the proper analysis of the Anselm’s argument should use some logic of definite descriptions. In fact, several theories of definite descriptions were developed and the problem is: which of them is the most suitable tool for its formalisation and evaluation.


  1. J. Barnes, The Ontological Argument, London: Macmillan 1972.
  2. C. Hartshorne, Anselm’s Discovery, LaSalle, IL: Open Court 1965.
  3. N. Malcolm, Anselm’s Ontological Arguments, The PhilosophicalReview 69: 41–62 1960.
  4. P. E. Oppenheimer and E. N. Zalta, On the Logic of the Ontological Argument,Philosophical Perspectives, 5: 509-529, 1991.
  5. P. E. Oppenheimer and E. N. Zalta, A Computationally-Discovered Simplification of the Ontological Argument, Australasian Journal of Philosophy, 89: 333-349, 2011.
  6. A. Plantinga, The Nature of Necessity, Oxford: Oxford UniversityPress 1974.