The Divine Lamp

Chapter 10 Of the opinion of those who aver that it cannot be demonstrated that there is a God, since this is self-evident. (The arguments presented here will be refuted in chapter 11).

Possibly it will seem to some that it is useless to endeavor to show that there is a God: they say that it is self-evident that God is, so that it is impossible to think the contrary, and thus it cannot be demonstrated that there is a God.  The reasons for this view are as follows.  Those things are said to be self-evident which are known as soon as the terms are known: thus as soon as it is known what is a whole, and what is a part, it is known that the whole is greater than its parts.  Now such is the statement “God is.”  For by this word “God” we understand a thing a greater  than which cannot be thought of: this is what a man conceives in his mind when he hears and understands this word “God”: so that God must already be at least in his mind.  Nor can He be in the mind alone, for that which is both in the mind and in reality is greater than that which is in the mind only.  And the very signification of the word shows that nothing is greater than God.  Wherefore it follows that it is self-evident that God is, since it is made clear from the very signification of the word.

Again.  It is possible to think that there is a thing which cannot be thought not to exist: and such a thing is evidently greater than that which can be thought not to exist.  Therefore if God can be thought not to exist, it follows that something can be thought greater than God: and this is contrary to the signification of the term.  Therefore it remains remains that it is self-evident that God is.

Further.  Those propositions are most evident in which the selfsame thing is predicated of itself, for instance: Man is man; or wherein the predicate is included in the definition of the subject, for instance: Man is an animal.  Now, as we shall show further on (chapt 22), in God alone do we find that His being is His essence, as though the same were the answer to the question, What is He? as to the question, Is He? Accordingly when we say, God is, the predicate is either identified with the subject, or at least is included in the definition of the subject.  And thus it will be self-evident that God is.

Moreover.  Things that are known naturally are self-evident, for it is not by a process of research that they become evident.  Now it is naturally known that God is, since man’s desire tends naturally to God as his last end, as we shall show further on (book 3, chapt 25).  Therefore it is self-evident that God is.

Again.  That whereby all things are known must needs be self-evident.  Now such is God.  For just as the light of the sun is the principle of all visual perception, so the divine light is the principle of all intellectual knowledge, because it is therein that first and foremost intellectual light is to be found.  Therefore it must needs be self-evident that God is, that it is impossible for the mind to think the contrary.