Saturday, June 20, 2009

Whether God's Existence is Self-Evident

From St. Anselm, Proslogion, Chs. 3-4:

"[T]he fool has said in his heart, there is no God" (Ps 13:1; 52:1)....

Even the fool is convinced that something exists in the understanding, at least, than which nothing greater can be conceived. For, when he hears of this, he understands it. And whatever is understood, exists in the understanding. And assuredly that, than which nothing greater can be conceived, cannot exist in the understanding alone. For, suppose it exists in the understanding alone: then it can be conceived to exist in reality; which is greater.

Therefore, if that, than which nothing greater can be conceived, exists in the understanding alone, the very being, than which nothing greater can be conceived, is one, than which a greater can be conceived. But obviously this is impossible. Hence, there is no doubt that there exists a being, than which nothing greater can be conceived, and it exists both in the understanding and in reality.

And it assuredly exists so truly, that it cannot be conceived not to exist. For, it is possible to conceive of a being which cannot be conceived not to exist; and this is greater than one which can be conceived not to exist. Hence, if that, than which nothing greater can be conceived, can be conceived not to exist, it is not that, than which nothing greater can be conceived. But this is an irreconcilable contradiction. There is, then, so truly a being than which nothing greater can be conceived to exist, that it cannot even be conceived not to exist;. and this being you are, O Lord, our God.

"[D]ixit insipiens in corde suo: non est Deus" (Ps 13:1; 52:1)....

Convincitur ... etiam insipiens esse vel in intellectu aliquid quo nihil maius cogitari potest, quia hoc, cum audit, intelligit, et quidquid intelligitur, in intellectu est.

Et certe id quo maius cogitari nequit, non potest esse in solo intellectu. Si enim vel in solo intellectu est, potest cogitari esse et in re; quod maius est. Si ergo id quo maius cogitari non potest, est in solo intellectu: id ipsum quo maius cogitari non potest, est quo maius cogitari potest. Sed certe hoc esse non potest. Existit ergo procul dubio aliquid quo maius cogitari non valet, et in intellectu et in re.

Quod utique sic vere est, ut nec cogitari possit non esse. Nam potest cogitari esse aliquid, quod non possit cogitari non esse; quod maius est quam quod non esse cogitari potest. Quare si id quo maius nequit cogitari, potest cogitari non esse: id ipsum quo maius cogitari nequit, non est id quo maius cogitari nequit; quod convenire non potest. Sic ergo vere est aliquid quo maius cogitari non potest, ut nec cogitari possit non esse. Et hoc es tu, Domine Deus noster.

From St. Thomas, Summa Theologiae I.2.1c:

Objection 2. Further, those things are said to be self-evident which are known as soon as the terms are known, which the Philosopher (Posterior Analytics I.3) 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.

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 (De Hebdomadibus), "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 (ST I.3.4). 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 to Objection 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.

Praeterea, illa dicuntur esse per se nota, quae statim, cognitis terminis, cognoscuntur, quod philosophus attribuit primis demonstrationis principiis, in I Poster., scito enim quid est totum et quid pars, statim scitur quod omne totum maius est sua parte. Sed intellecto quid significet hoc nomen Deus, statim habetur quod Deus est. Significatur enim hoc nomine id quo maius significari non potest, maius autem est quod est in re et intellectu, quam quod est in intellectu tantum, unde cum, intellecto hoc nomine Deus, statim sit in intellectu, sequitur etiam quod sit in re. Ergo Deum esse est per se notum.

Respondeo dicendum quod contingit aliquid esse per se notum dupliciter, uno modo, secundum se et non quoad nos; alio modo, secundum se et quoad nos. Ex hoc enim aliqua propositio est per se nota, quod praedicatum includitur in ratione subiecti, ut homo est animal, nam animal est de ratione hominis. Si igitur notum sit omnibus de praedicato et de subiecto quid sit, propositio illa erit omnibus per se nota, sicut patet in primis demonstrationum principiis, quorum termini sunt quaedam communia quae nullus ignorat, ut ens et non ens, totum et pars, et similia. Si autem apud aliquos notum non sit de praedicato et subiecto quid sit, propositio quidem quantum in se est, erit per se nota, non tamen apud illos qui praedicatum et subiectum propositionis ignorant. Et ideo contingit, ut dicit Boetius in libro de hebdomadibus, quod quaedam sunt communes animi conceptiones et per se notae, apud sapientes tantum, ut incorporalia in loco non esse. Dico ergo quod haec propositio, Deus est, quantum in se est, per se nota est, quia praedicatum est idem cum subiecto; Deus enim est suum esse, ut infra patebit. Sed quia nos non scimus de Deo quid est, non est nobis per se nota, sed indiget demonstrari per ea quae sunt magis nota quoad nos, et minus nota quoad naturam, scilicet per effectus.

Ad primum ergo dicendum quod cognoscere Deum esse in aliquo communi, sub quadam confusione, est nobis naturaliter insertum, inquantum scilicet Deus est hominis beatitudo, homo enim naturaliter desiderat beatitudinem, et quod naturaliter desideratur ab homine, naturaliter cognoscitur ab eodem. Sed hoc non est simpliciter cognoscere Deum esse; sicut cognoscere venientem, non est cognoscere Petrum, quamvis sit Petrus veniens, multi enim perfectum hominis bonum, quod est beatitudo, existimant divitias; quidam vero voluptates; quidam autem aliquid aliud.

From Garrigou-Lagrange, Reality, Ch. 7:

St. Thomas does not admit that an a priori proof of God's existence can be given. [269] He grants indeed that the proposition, God exists, is in itself evident, and would therefore be self-evident to us if we had a priori face-to-face knowledge of God; then we would see that His essence includes existence, not merely as an object of abstract thought, but as a reality objectively present. [270] But in point of fact we have no such a priori knowledge of God. [271] We must begin with a nominal definition of God, conceiving Him only confusedly, as the first source of all that is real and good in the world. From this abstract knowledge, so far removed from direct intuition of God's essence, we cannot deduce a priori His existence as a concrete fact.

It is true we can know a priori the truth of this proposition: If God exists in fact, then He exists of Himself. But in order to know that He exists in fact, we must begin with existences which we know by sense experience, and then proceed to see if these concrete existences necessitate the actual objective existence of a First Cause, corresponding to our abstract concept, our nominal definition of God. [272].

This position, the position of moderate realism, is intermediary, between the agnosticism of Hume on the one hand, and, on the other, that excessive realism, which in varying degree we find in Parmenides, Plato, and the Neoplatonists, and which in a certain sense reappears in St. Anselm, and later, much accentuated, in Spinoza, in Malebranche and the Ontologists, who believe that they have an intuition and not merely an abstract concept of God's nature.

Saint Thomas n'admet pas qu'on puisse prouver a priori l'existence de Dieu, Ia, q. II, a. I, bien que la proposition Deus est soit per se nota quoad se, ou évidente par elle-même en soi et pour celui qui saurait ce qu'est Dieu : l'Être même subsistant dont l'essence implique l'existence actuelle ou de fait : existentiam non solum signalant aut conceptam, sed exercitam in re extra animam. Mais, dit-il, nous ne savons pas a priori ce qu'est Dieu, nescimus de Deo quid est; nous n'avons d'abord qu'une définition nominale de Dieu, conçu confusément comme cause première du monde, de tout ce qu'il y a de réel et de bon en lui. De cette notion abstraite de Dieu, fort différente de l'intuition immédiate de l'essence divine, nous ne pouvons pas déduire a priori son existence concrète ou de fait.

Nous voyons sans doute a priori, que Dieu existe par soi, s'il existe de fait. Mais pour affirmer qu'il existe de fait (existentia exercita), il faut partir de l'existence de fait des réalités contingentes que notre expérience constate, et voir si elles exigent nécessai rement une cause première qui corresponde réelle ment en dehors de notre esprit à notre notion abstraite ou définition nominale de Dieu. Cf. Ia, q. II, a. I, ad 2um ; et a. 2, ad 2um.

Cette position est celle du réalisme modéré, inter médiaire entre le nominalisme qui conduit à l'agnos ticisme (on le verra chez Hume), et le réalisme excessif de l'intelligence, qui se trouve à des degrés divers chez Parménide, Platon, les néoplatoniciens, qui reparaît en un sens dans l'argument de saint Anselme, plus tard sous une forme très accentuée chez Spinoza, et aussi chez Malebranche et les onto logistes, qui croient avoir une intuition immédiate confuse, et non pas seulement une idée abstraite, de la nature de Dieu.


269 ST I.2.1.

270 Existentiam non solum signatam aut conceptam, sed exercitam in re extra animam.

271 Nescimus de Deo quid est.

272 ST I.2.1 ad 2; 2 ad 2.

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