Making my way through deep dark caverns of the Summa preparing for a class I am teaching on the existence of God, I ran across what seems to be St. Anselm’s proof for the existence of God. Though not altogether strange, since Thomas cites many arguments from other thinkers in his work, the proof shows up in a rather odd place, as the second objection in the article on Whether the Existence of God is Self-Evident. Why would St. Anselm’s proof for the existence of God be an objection to Aquinas’ understanding of God existence not being self-evident?
If you are not familiar with St. Anselm’s proof, allow me to give a quick review. The argument is short although hard to wrap your head around. The proof goes somewhat like this:
The teacher asks the fool (non-believer or atheist): “Would you not agree that the idea of God is ‘that-which-nothing-greater-can-be-conceived’?”
Fool responds: “If such a God does exists, I would have to admit that He would have to be ‘that-which-nothing-greater-can-be-conceived’.”
Teacher asks again: “Would it not also be the case that whatever exists in actually and mentally is greater than that which merely exists mentally?”
Fool responds: “I find no quarrel with your statement.”
Teacher asks a third time: “Then, by agreeing to my definition of God and conceiving of it merely in your mind (but not in actuality), would you not be holding yourself in contradiction, since you could conceive of this idea also existing in actuality, making it greater than ‘that-which-nothing-greater-can-be-conceived’ as merely held mentally.”
At this point in the proof, the fool is trapped in contradiction. Having understood the word ‘God’ as ‘that-which-nothing-greater-can-be-conceived’ mentally, it must then follow that ‘God’ as such must also exist in actuality. The key here is that inherent in the definition of God is existence itself. This is the point of contention for most modern analytical critiques of this proof, believing that St. Anselm has defined God into existence, rather than proved His existence. Yet this is the point, since St. Anselm only intended this ‘proof’ as a mental exercise to wrap one’s mind around the true essence of God (His omnipotence). This can only be done through the eyes of faith. Thus, St. Anselm’s dictum: fides quaerens intellectum (Faith Seeking Understanding).
The question then remains, why is Aquinas using this proof as a claim on God’s existence being self-evident. Not citing St. Anselm directly here, St. Thomas seems to be refuting those who use the proof in a different way than was originally intended. Thomas admits in his reply that if the person understands God to mean that-which-nothing-greater-can-be-conceived, it must then follow that God actually exists. It is not the case, however, that all people understand and will admit to God being such.
For St. Thomas a proposition is self-evident when its predicate is included in the essence of the subject as ‘Man is an animal,’ for animal is contained in the essence of man (Summa Ia Q. 1 art. 1). Thus, certain propositions will be self-evident to some, while not to others as with the learned and the un-learned. For example: if one did not know the essence (or definition) of a man, it would not be self-evident that man is an animal. Yet after learning the essence of a man, it would then be self-evident that man is an animal.
In the same way, God’s essence is His existence (predicate is included in the subject), making His existence self-evident, but only to those who through the eyes of faith understand God to be such. It is this understanding of God as ‘that-which-nothing-greater-can-be-conceived’ that the non-believer would deny. This is why in the proof it was essential for the fool to admit to the teacher’s definition of God as such. Moreover, this understanding of God is not held by all, and thus cannot be held as universally self-evident.
God is, then, not self-evident, unless of course one admits through the eyes of faith that God is ‘that-which-nothing-greater-can-be-conceived’. In this case, God must exist, and indeed he does. Aquinas it seems is critiquing the proof here in order to reveal the original understanding of the proof, an understanding that St. Anselm most certainly intended. That is, a proof only through the eyes of the believer. Therefore, we say faith seeks understanding or as St. Augustine says, “I believe so that I may understand.”