Aquinas' Critique of Anselm's Ontological Argument

Critique of Anselm's Ontological Argument

St. Thomas' Rejection of the Argument

St. Thomas, consistent with his realism, cannot accept an argument like the ontological argument, which derives God's existence from His essence alone.

Formulation of the Ontological Argument (AO)

Indeed, the AO can be formulated as a syllogism whose premises are:

• Major premise: God is perfect.
• Minor premise: Existence is a perfection.
• Conclusion: God exists.

Knowledge of God's Essence

St. John of Damascus would have raised the difficulty about rationally proving God's existence from His essence, because regarding God, we only have negative knowledge ("In God, one only knows what is not"). One cannot prove the existence of a substance that is unknown.

Aquinas' Counter-Argument on Order

Against this, Aquinas argued that knowledge can attain adequacy regarding essence, and existence can be proven because, although in the ordo essendi (ontological order), essence precedes existence (as the cause precedes the effect), in the ordo cognoscendi (epistemological order), existence predates essence. Thus, for the effect, one traces back to the cause that produced it.

Limitations of the Ontological Argument

What is not permissible is to think that an ontological argument, which derives existence from essence itself, can have probative force. Epistemologically, one must first establish that a thing exists before determining what it is ("before saying what a thing is, one must show that this thing exists").

In other words, the human mind cannot have an intuitive knowledge of the divine essence, nor does it have any other means to grasp it directly. This argument is only valid for God Himself, but not for man, who must use his understanding to extract universal agents from particular species.

The Five Ways

The Five Ways demonstrate God's existence from His effects in the world (His Creation) to trace back (quia Demonstratio) to His principles or first causes.

Rejection of Demonstrative Force

The ontological argument is rejected, not because Thomas doubted its truth in itself, but because its demonstrative force is denied. Aquinas' challenge to the AO results from denying its idealistic foundation—the assumption that God's essence is disconnected from phenomena and can derive existence beforehand.

Descartes and Causal Argument

The formulation of this argument appears in Descartes (Discourse on the Method, Part IV, and Meditations III) in an idealistic manner, though expressed under the guise of a "causal" argument.

Materialist Reinterpretation

However, the AO, expressed as "The essence involves existence," can be reinterpreted from materialistic coordinates as follows: any idea or concept must have worldly counterparts; even the most sublime ideas possess them.

By stripping the AO of its absoluteness and inserting it into a positive context, this materialist argument becomes effective and realistic: "Nihil est in intellectu quod prius non fuerit in sensu" (Nothing is in the intellect that was not first in the senses). This requires recognizing a "fulcrum" (support, connection with positive phenomena) for any concept of truth, however extravagant it may seem. In the case of Plotinian essences or evolutionary genera, this fulcrum of truth will be found in the genesis of positive phenomena.