Descartes' Fifth Meditation: A Critique of the Ontological Argument

Introduction

In the Fifth Meditation, Descartes turns to consider what kind of certainty he can attain regarding ideas of objects that may exist materially outside the mind. He finds within himself "countless ideas of things which even though they may not exist anywhere outside me still . . . have their own true and immutable natures" (at VII: 64). This leads him to a contemplation of the triangle. The idea of a triangle as an object of thought serves as an analogy in the meditation to support an ontological proof for God's existence. This paper critically discusses that argument and presents counterarguments suggesting that Descartes' ontological position fails. He shows only that an idea of God is possible, not that God actually exists.

The Triangle Analogy and Immutable Essences

Descartes observes that the triangle has an essence that is immutable and eternal, whether or not it exists outside his thought. A triangle and its properties — for example, its shape with three sides whose interior angles necessarily add up to 180 degrees — do not depend on a mind for their essence. He can clearly and distinctly perceive a triangle even without having had sense experience of it. Therefore, it is certainly true, since clear and distinct perception is his criterion of truth. This does not, however, resolve the problem of whether the triangle actually exists outside the mind (realism) or exists purely inside the mind (psychologism). It simply means that a triangle with its essential properties is clearly and distinctly conceivable.

Applying the Analogy to God's Existence

When Descartes applies this same reasoning to the idea of God, he finds that he already has in his mind the idea of a supremely perfect being, perceived clearly and distinctly as a mental object. This clear and distinct idea is, in his view, the true nature or essence of God. It includes that God is singular, always exists, and — most significantly — necessarily exists outside the mind. He thus asserts realism. Descartes makes this argument because "it is quite evident that existence can no more be separated from the essence of God than the fact that its three angles equal two right angles can be separated from the essence of a triangle" (VII: 66). In his view, it is contradictory to think of a supremely perfect being that lacked existence. In other words, one cannot conceive of God as perfect while denying God's existence.

If someone objected that God does not necessarily possess perfection — pointing, for example, to the Greek gods who were almighty but not perfect — Descartes would reply that the idea he holds is of a perfect God, not an imperfect one. Descartes cannot conceive of God without God possessing all perfections: singularity, eternity, and real existence. Yet this response does not truly answer the objection. All it does is reaffirm the particular idea of God that Descartes insists on holding. The word "God" does not necessarily imply a supremely perfect being.

Conclusion

In sum, Descartes assumes realism, but it remains a presupposition, not a conclusion. He does not prove psychologism wrong, or realism right. It is more accurate to say that God's real existence is eternally unproven by this method. Clearly, God is a possible idea — but the idea alone does not establish the reality. Nor does Descartes prove that every person must ever have an idea of God. All he has succeeded in proving is that a concept of God is possible, not that it is necessary. God may yet be only a fiction invented by the mind, even if real effects and emotions are attached to this object. Descartes' ontological argument is best abandoned in favor of a more psychological understanding of the possibility of the idea of God — one that need not imply God's actual existence.

Bibliography

Descartes, René. Meditations on First Philosophy with Selections from the Objections and Replies. Translated by John Cottingham. Cambridge: Cambridge University Press, 1996.