The question of God’s existence has challenged philosophers and theologians for centuries. Among the many approaches to proving divine existence, ontological arguments are unique—they rely not on empirical evidence, but on pure reason. At the heart of these arguments lies the concept of God as “a being than which none greater can be conceived.” This article reexamines the contributions and critiques surrounding ontological arguments, from Anselm of Canterbury to Alvin Plantinga, and explores their lasting impact on Christian apologetics.
Perfect Being Theology: A Historical Foundation
The ontological argument emerged from perfect being theology, which begins with the definition of God as the greatest conceivable being. Early echoes of this notion appear in Seneca and Augustine, but the most influential formulation comes from Anselm of Canterbury in his Proslogion (1078), where he claims that even the atheist must conceive of God in the mind.¹ Since existing in reality is greater than existing solely in thought, Anselm concludes that God must exist.²
Though Anselm’s argument is deductively valid, it faced strong criticism—most famously from Gaunilo, who used the analogy of a “perfect island” to challenge its logic.³ Thomas Aquinas also questioned whether God’s nature could be understood through reason alone, preferring natural theology rooted in God’s observable effects.⁴
Rational Critiques and Philosophical Pushback
David Hume and Immanuel Kant offered powerful critiques of a priori reasoning. Hume argued that existence must be grounded in experience, not imagination.⁵ Kant insisted that existence is not a predicate; to define God into existence is, in his view, philosophically invalid.⁶ These critiques temporarily shelved the ontological argument until it was revived in the 20th century.
Descartes, Leibniz, and Gödel: Refining the Framework
René Descartes advanced the argument by likening God’s existence to the properties of a triangle: just as a triangle necessarily has three sides, a perfect being must possess all perfections—including existence.⁷ Leibniz sought to improve this by demonstrating that the concept of God is logically coherent.⁸ He claimed all divine attributes are compatible and can reside in a single being, countering objections that divine perfection might be self-contradictory.⁹
Kurt Gödel developed a formal modal logic version of the argument, which was later revised by C. Anthony Anderson to resolve logical inconsistencies.¹⁰ His reformulated axioms present God’s existence as a necessary conclusion derived from the coherence of positive properties.¹¹
Norman Malcolm and Alvin Plantinga: Modal Revisions
Norman Malcolm reformulated Anselm’s argument using modal logic. He proposed that God’s existence must be either logically impossible or logically necessary—nothing could prevent an unlimited being from existing.¹²
Alvin Plantinga expanded this with his “possible worlds” approach. If it’s possible that a maximally great being exists in any world, then such a being must exist in every world—including the actual one.¹³ Plantinga’s modal version addresses Kant’s critique by bypassing existence as a mere predicate and grounding divine existence in necessity.
Conclusion: Conceiving God and the Limits of Reason
Ontological arguments offer a compelling intersection of theology and metaphysics. While no single formulation proves God’s existence beyond doubt, the cumulative development—from Anselm through Plantinga—offers a rational defense of faith that challenges both skeptics and believers.
As Michael Palmer summarizes, the crux of the ontological claim is this: if God is the greatest conceivable being, and if nonexistence implies limitation, then God must necessarily exist.¹⁴ If this stretches the human intellect, perhaps it is because the divine cannot be captured by reason alone—but also requires faith, mystery, and revelation.
References
- Douglas Groothuis, Christian Apologetics: A Comprehensive Case for Biblical Faith (Downers Grove, IL: IVP Academic, 2011), 185.
- William Edgar and K. Scott Oliphint, Christian Apologetics Past and Present, vol. 1 (Wheaton, IL: Crossway Books, 2009), 369.
- Yujin Nagasawa, “A New Defence of Anselmian Theism,” The Philosophical Quarterly 58, no. 233 (2008): 593–594.
- Michael Palmer, The Question of God: An Introduction and Sourcebook (London: Routledge, 2001), 4.
- David Hume, Dialogues Concerning Natural Religion, Part I (1776), 149.
- James Van Cleve, Problems from Kant (Oxford: Oxford University Press, 2003), 187–188.
- René Descartes, Meditations on First Philosophy, accessed September 2, 2021, http://www.classicallibrary.org/descartes/meditations/8.htm..
- Graham Oppy, “Ontological Arguments,” Stanford Encyclopedia of Philosophy, February 12, 2016, https://plato.stanford.edu/entries/ontological-arguments/..
- Barry Loewer, “Leibniz and the Ontological Argument,” Rutgers University, accessed October 2, 2021.
- C. Anthony Anderson, “Some Emendations of Gödel’s Ontological Proof,” Faith and Philosophy 7, no. 3 (1990): 291–303.
- Oppy, “Ontological Arguments,” Ibid.
- Norman Malcolm, “Anselm’s Ontological Arguments,” The Philosophical Review 69, no. 1 (1960): 41–46.
- Alvin Plantinga, The Nature of Necessity (Oxford: Clarendon, 1978), chap. 10.
- Palmer, The Question of God, 42.
Bibliography
Anderson, C. Anthony. “Some Emendations of Gödel’s Ontological Proof.” Faith and Philosophy 7, no. 3 (1990): 291–303.
Descartes, René. Meditations on First Philosophy. Accessed September 2, 2021. http://www.classicallibrary.org/descartes/meditations/8.htm..
Edgar, William, and K. Scott Oliphint. Christian Apologetics Past and Present. Vol. 1. Wheaton, IL: Crossway Books, 2009.
Groothuis, Douglas. Christian Apologetics: A Comprehensive Case for Biblical Faith. Downers Grove, IL: IVP Academic, 2011.
Hume, David. Dialogues Concerning Natural Religion. 1776.
Loewer, Barry. “Leibniz and the Ontological Argument.” Rutgers University. Accessed October 2, 2021.
Malcolm, Norman. “Anselm’s Ontological Arguments.” The Philosophical Review 69, no. 1 (1960): 41–46.
Nagasawa, Yujin. “A New Defence of Anselmian Theism.” The Philosophical Quarterly 58, no. 233 (2008): 577–596.
Oppy, Graham. “Ontological Arguments.” Stanford Encyclopedia of Philosophy. February 12, 2016. https://plato.stanford.edu/entries/ontological-arguments/..
Palmer, Michael. The Question of God: An Introduction and Sourcebook. London: Routledge, 2001.
Plantinga, Alvin. The Nature of Necessity. Oxford: Clarendon, 1978.
Van Cleve, James. Problems from Kant. Oxford: Oxford University Press, 2003.
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