Whether the Existence of God Is Self-Evident?
Objection 1: It seems that the existence of God is self-evident. Now
those things are said to be self-evident to us the knowledge of which
is naturally implanted in us, as we can see in regard to first
principles. But as Damascene says (De Fide Orth. i, 1,3), "the
knowledge of God is naturally implanted in all." Therefore the
existence of God is self-evident.
Obj. 2: Further, those things are said to be self-evident which
are known as soon as the terms are known, which the Philosopher (1
Poster. iii) says is true of the first principles of demonstration.
Thus, when the nature of a whole and of a part is known, it is at once
recognized that every whole is greater than its part. But as soon as
the signification of the word "God" is understood, it is at once seen
that God exists. For by this word is signified that thing than which
nothing greater can be conceived. But that which exists actually and
mentally is greater than that which exists only mentally. Therefore,
since as soon as the word "God" is understood it exists mentally, it
also follows that it exists actually. Therefore the proposition "God
exists" is self-evident.
Obj. 3: Further, the existence of truth is self-evident. For
whoever denies the existence of truth grants that truth does not
exist: and, if truth does not exist, then the proposition "Truth does
not exist" is true: and if there is anything true, there must be
truth. But God is truth itself: "I am the way, the truth, and the
life" (John 14:6) Therefore "God exists" is self-evident.
_On the contrary,_ No one can mentally admit the opposite of what is
self-evident; as the Philosopher (Metaph. iv, lect. vi) states
concerning the first principles of demonstration. But the opposite of
the proposition "God is" can be mentally admitted: "The fool said in
his heart, There is no God" (Ps. 52:1). Therefore, that God exists is
not self-evident.
_I answer that,_ A thing can be self-evident in either of two ways: on
the one hand, self-evident in itself, though not to us; on the other,
self-evident in itself, and to us. A proposition is self-evident
because the predicate is included in the essence of the subject, as
"Man is an animal," for animal is contained in the essence of man. If,
therefore the essence of the predicate and subject be known to all,
the proposition will be self-evident to all; as is clear with regard
to the first principles of demonstration, the terms of which are
common things that no one is ignorant of, such as being and non-being,
whole and part, and such like. If, however, there are some to whom the
essence of the predicate and subject is unknown, the proposition will
be self-evident in itself, but not to those who do not know the
meaning of the predicate and subject of the proposition. Therefore, it
happens, as Boethius says (Hebdom., the title of which is: "Whether
all that is, is good"), "that there are some mental concepts
self-evident only to the learned, as that incorporeal substances are
not in space." Therefore I say that this proposition, "God exists," of
itself is self-evident, for the predicate is the same as the subject,
because God is His own existence as will be hereafter shown (Q. 3,
Art. 4). Now because we do not know the essence of God, the proposition
is not self-evident to us; but needs to be demonstrated by things that
are more known to us, though less known in their nature--namely, by
effects.
Reply Obj. 1: To know that God exists in a general and
confused way is implanted in us by nature, inasmuch as God is man's
beatitude. For man naturally desires happiness, and what is naturally
desired by man must be naturally known to him. This, however, is not
to know absolutely that God exists; just as to know that someone is
approaching is not the same as to know that Peter is approaching, even
though it is Peter who is approaching; for many there are who imagine
that man's perfect good which is happiness, consists in riches, and
others in pleasures, and others in something else.
Reply Obj. 2: Perhaps not everyone who hears this word "God"
understands it to signify something than which nothing greater can be
thought, seeing that some have believed God to be a body. Yet, granted
that everyone understands that by this word "God" is signified
something than which nothing greater can be thought, nevertheless, it
does not therefore follow that he understands that what the word
signifies exists actually, but only that it exists mentally. Nor can
it be argued that it actually exists, unless it be admitted that there
actually exists something than which nothing greater can be thought;
and this precisely is not admitted by those who hold that God does not
exist.
Reply Obj. 3: The existence of truth in general is
self-evident but the existence of a Primal Truth is not self-evident
to us.
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