The principle running through the proofs is that of causality. The result of each line of evidence is the outcome of the application of this principle. The facts of motion, contingency, production, and the like, in the world, call for an explanation; an ultimate explanation of all phenomena is the one point that marks off divine causality from created causes. In secondary causes, we find the immediate, partial reason for a given event, in divine causality, the principle is pushed to its limit and we reach the final reason for all events. This final explanation is the goal of every philosophical system, and rests on the amount of knowledge the phenomena about us can give us of their ultimate cause.
Whether we regard the principle of causality as objective with St. Thomas, or make it subjective as Kant and his followers hold, this much at least is certain: we perceive things, phenomena, that call for an explanation, and there is in man a natural tendency to seek the explanation of things -- these two factors combined lead us to an ultimate ground or reason of appearances. A Conception of God might then be defined, the ultimate explanation of what the individual or conceiver thinks needs explanation. In this sense, we can have no contention with the Conception as such, but if there is disagreement it must be looked for much further back -- in the theory of reality, which depends on the theory of knowledge. And here is where the need of a true theory of knowledge is absolutely necessary. Thus the Agnostic Unknowable God is the result of the doctrine of the Unknowable in general. The Idealistic Conception of God is the logical outcome of the denial of external reality. The Intuitionists go astray in considering God as primo and per se known. Those who say that God is a necessary Postulate, deny the real proving power of His manifestations. The position of Aquinas is based on the principles already discussed -- the consideration of phenomena, material things, lead us to their final explanation. This is illustrated by the arguments advanced for proving God's existence.
Some consider the first four proofs as instances of efficient causality, and the fifth as teleological. Others regard the four kinds of causes utilized -- first and second proofs represent efficient cause, the third, material cause, the fourth, formal cause, and the fifth, final or exemplar cause. Whatever view we take, the result is practically the same for the proving power of the effects. Though efficient causality was not the only or the principal one for the Scholastics, yet as already noted, every cause looks toward efficiency, and hence the effects of each cause give us a knowledge of the cause; and this for our purpose is the important aspect of causality.
We might, as an instance, consider the knowledge we can derive of the nature of the final or exemplar cause from a consideration of its effects. This is the fifth argument that leads to God as Intelligence -- the other arguments, as arguments, present Him as Prime Mover, First Cause, Necessary Being, Perfect Being, respectively. The axiom -- omne agens agit sibi simile -- gets a higher meaning when the agens acts by intelligence. Here enters the idea of a free agent, and unlike an agent that acts with its physical being only and is limited to one determined effect, we have now a variety of effects depending on the choice of the intelligent cause. "The effects proceed from a cause as they preexist in a cause, since omne agens agit sibi simile. But the effects preexist in the cause according to the nature of the cause."{1} Aquinas concludes that the effects of human and divine causality are present to these causes "according to an intelligent nature." The effect agrees with the idea or prototype in the mind of the agent. Here we meet the question of Divine Ideas which are the measure of things, and of which we receive a knowledge from a consideration of their expression in nature.
Ideas or forms in general are distinct or rather different from the existent objects, and can be viewed under a twofold aspect. They may be the principle of knowledge of a thing, and then we have the idea, form, or species as already discussed -- for the thing itself must be known if the idea, according to which the thing is made, is known. They may be the exemplars of the existent things, for the intelligent agent acts only in so far as he has in his mind the idea or model of what he is to produce, and this idea must be a determined, specific one or the result would be fortuitous. In this sense, the idea is causal, it is the plan the agent follows in his operations. There is then an agreement between the idea and the object based on it. "The exemplar forms of the Divine Intellect are productive of the whole object, both matter and form. And hence they embrace not only the nature of the species but also the specific character of the individual -- first, however the nature of the species."{2} All creation, all finite effects, have their originals in the Mind of God; hence by a knowledge of these effects we are led back to a knowledge of their models, and through the models we learn something of the nature of the cause.
These ideas in the Divine Essence constitute God's knowledge of things other than Himself, which are based on these ideas. "Idea does not signify Divine Essence as Divine Essence, but only as it is the likeness or concept of this or that object."{3} And again, "the Essence of God is the idea of things, not indeed as essence, but as it is understood."{4} "Thus God by knowing His essence knows other things, as effects are known through a knowledge of the cause."{5} On the basis of things as having their models in the Divine Mind, on the same principle that effects give us a knowledge of their cause, we rise to a knowledge of God.
"Creatures lead us to a knowledge of God as effects conduct to the cause. Natural reason can know of God only what is proper to Him as the principle or cause of all beings."{6} The manifestations of God are numerous, and must be so, since no creature can be equal to God," though He as "every cause tends to produce His likeness in the effect in so far as the effect can receive it . . . Hence there is required a multiplicity and variety in created things so that a perfect likeness of God, according to His nature, be found in them."{7} Even with effects that are numerous, and that vary in greatness, "we experience daily that there is a defect in our knowledge, for there are many qualities of sensible objects of which we are ignorant, and in many of those qualities which we do apprehend by sense, we do not attain to perfect knowledge. To a much greater extent therefore is human reason insufficient to investigate all that is intelligible about that most excellent, transcendant substance."{8} We are capable however, of attaining a partial knowledge, which though not adequate is true as far as it goes.
There are a few misapprehensions of the view of Aquinas about the nature of the First Cause that ought to be removed before we take up specifically the Quid Sit, or what we can know about the Nature of God. God is a universal, permanent, continuous cause, present in each phenomenon by His actuality, and contributing more to the result of the created secondary activity than the immediate secondary cause.
St. Thomas says that the very unity and simplicity of God is the reason why He can produce many and diverse effects, just as he holds that the soul knows all things precisely because it is none of those things it knows. "The divine power is not limited to one effect; and this comes from its simplicity, for the nearer a power is to unity, the nearer it is to infinity, and can extend itself to more objects."{9} The effects are in proportion to their cause and get their character from their most perfect cause. "Therefore the distinction in objects, in which consists the order of the universe (but the Order of the universe is what is best in all created beings), is not the result of secondary causes but rather the intention of the First Cause."{10} Moreover the First Cause contributes more to the effect than the immediate secondary cause. "Every cause is in some manner the cause of being, either substantial or accidental. But nothing is the cause of being except in so far as it acts in the divine power. Therefore every cause operates through the power of God."{11} "God is more of a principal cause in each action than even the secondary agents."{12} There is, however, true secondary causality. "The causality of inferior effects is not attributed to the divine power in such a way that the causality of the inferior causes is taken away."{13} Nor is the effect to be considered "as due, partly to God and partly to the natural agent; but the whole is from both under a different aspect, as the same whole effect is attributed to the instrument, and also the whole to the principal cause."{14}
This intimate presence of God in all activities will help us to understand the idea of the First Cause in the proofs for God's existence. There are two opinions on this point among those who hold that these proofs demonstrate God's existence. One maintains that the existence of God is proven from the fact that an infinite series of causes is impossible, and hence we must come to a First Cause, God. The other holds that the idea of the First Cause is valid independently of the series, and this, to our mind, is the view of Aquinas, gathered from his general treatment of Causality. It might be called the intensive view. According to it, a thorough consideration and complete explanation of any effect will lead us to a knowledge of the First Cause, and thus we need not go through a series to find God at the end, and then only the First in the series. He is in every activity and can be known as the full explanation of the event. To the mind of St. Thomas, the proofs have efficacy even were there an infinite series, for he gives them as metaphysically demonstrative, and yet he admits the possibility, or rather the non-contradiction of the eternity of the world.{15} The important point to his mind is the understanding of the effect or effects given, for the simple but complete consideration of an effect is sufficient to reach the First Cause.
If this is true, then the objections raised on the score of the impossibility of conceiving an infinite series fall to the ground, for the simple reason that the existence of the First Cause in the view of Aquinas is not bound up with the infinite series. Prof. Huxley maintains, the First Cause is but the first of a series, with a causal character similar to the other members of the series; we can not reach a true First Cause according to him, for the process is one ad infinitum.{16} Nor is God a Cause in the sense of Deism, a transcendant Cause that created the world and now leaves it to itself. God is both transcendant and immanent. If we understand the meaning that Aquinas gives to the First Cause it will not be exact to say, as Caldecott does, that by the first and second proofs, "he (Aquinas) reaches only an initial Cause and does not bring out permanence of operations."{17} Caldecott says, however, that immanence is contained in the remaining arguments. It is but fair to admit that the two proofs as given say nothing of immanence, but their implication takes account of it. The proofs of St. Thomas are briefly stated; to understand their full content we must seek for light in other portions of his works. Any of the proofs carried to its complete expression would not only give us the existence of God, but likewise His nature in so far as we can know it. This close relation between existence and nature is often overlooked, especially by the Agnostic, who arrives at existence and then fails to use the privilege of deduction and analysis at his disposal to learn something of the nature of God. We now propose to utilize our birth-right.
{1} Effectus procedit a causo agente, secundum quod prae. existunt in ea; quia omne agens agit sibi simile. Praeexistunt autem effectus in causa secundum modum causae. Sum. Theol., I, q., 9, a. 4.
{2} Formae exemplares intellectus divinae sunt factivae totius rei, et quantum ad materiam, et quantum ad formam; et ideo respiciunt creaturam non solum quantum ad naturam speciei, sed etiam quantum ad singularitatem individui, per prius tamen quantum ad naturam speciei. Quodl. 8, q. 1, a. 2.
{3} Idea non nominat divinam essentiam, in quantum est essentia, sed in quantum est similitudo vel ratio hujus vel illius rei. Sum. Theol., I, q. 15, a. 2 ad 1.
{4} Essentia Dei est idea rerum, non quidem ut essentia, sed ut est intellecta. De Veri., q. 3, a. 2.
{5} Sic Deus cognoscendo suam essentiam, alia cognoscit, sicut per cognitionem causae coguoscuntur effectus. C.G. l. 1, c. 68.
{6} Creaturae ducunt in Dei cognitionem, sicut effectus in causam. Hoc igitur solum ratione naturali de Deo cognosci potest, quod competere ei necesse est, secundum quod est omnium entium principium. Sum. Theol , I, q. 32, a. 1. Non enim creatura potest esse Deo aequalis . . . Quum enim omne agens intendit suam simulitudinem in effectum inducere, secundum quod effectus capere potest . . . Oportuit igitur esse multiplicitatem et varietatem in rebus creatis, ad hoc, quod inveniretur in eis Dei simiitudo perfecta secundum modum suum. C.G., l. 2, c. 45.
{8} Idem manifeste apparet ex defectu, quem in rebus cognoscendis quotidie experimur. Rerum enim sensibilium plurimas proprietates ignoramus. earumque proprietatum, quas sensu apprehendimus, rationem perfecte in pluribus invenire non possumus. Multo igitur amplius excellentissmae substantiae, transcendentis, omnia intelligibilia humana ratio investigare non sufficit. C.G., l. 1, c. 3.
{9} Virtus divina non limitatur ad unum effectum; et hoc ex ejus simplicitate provenit, quia quanto aliqua virtus est magis unita, tanto magis est infinita et ad plura se potest extendere. C.G., l. 2, c. 42.
{10} Non igitur rerum distinctio, in qua ordo universali (optimum autem in omnibus creatis est ordo universi) consistit, causatur ex causis secundis, sed magis ex intentione primae causae. C.G., l. 2, c. 42.
{11} Omne enim operans est aliquo modo causa essendi, vel secundum esse substantiale vel accidentale; Nihil autem est causa essendi, nisi in quantum agit in virtute divina. Omne igitur operans operatur per virtutem Dei. C.G., l. 3, c. 67.
{12} Deus igitur principalius est causa cujuslibet actionis quam etiam secundae causae agentes. C.G, l. 3, c. 67.
{13} Non ergo causalitas effectuum inferiorum est ita attribuenda divinae virtuti, quod subtrahatur causalitas inferiorum agentium. C.G., l. 3, c. 69.
{14} Non partim a Deo, partim a naturali agente fiat, sed totus ab utroque secundum alium modum; sicut idem effectus totus attribuitur instrumento, et principali agenti etiam totus. C.G, 1 3, c. 70.
{15} Cfr. Sertillanges, Preuve de l'existence de Dieu et 1'eternité du monde. Revue Thomiste, Sept., 1897.
{16} Huxley's Hume, p. 149.
{17} Selections from the Literature of Theism, pp. 24, 26.