On the perfect union of analysis and synthesis in the angelic doctor's method
In this way St. Thomas perfectly observed the rules of method in general, namely, by always beginning from the more known, by proceeding gradually and not jumping to the conclusion. He never reaches the more remote conclusions before the immediate conclusions are known with certainty. Thus the connection between them is clearly perceived, and all the conclusions make up a truly organic body of doctrine.
In like manner he perfectly applied the rules of the analytic method in the order of finding, especially so, in the direct and not accidental division of the complex subject to be considered, until he reaches the transcendental notions and first principles. Thus, after carefully considering the parts, he arrives at a correct judgment of the whole. He likewise most adroitly made use of the analytic method in the inductive and comparative inquiry into the specific difference of a thing so as to discover the distinct real definitions contained in a confused manner in the nominal ones.
With an equal degree of perfection he employed the synthetic method in his doctrine, both in the questions to be proposed and in the manner of solving them. For in proposing the questions he always begins from the more universal and gradually descends to the less universal, from the essence to the properties, from causes to effects. Likewise, in solving the questions he always starts from principles either revealed or directly known, or derived from experience and from the definition of the thing in question; nor does he depart from the certain principles because of the obscurity of the mystery to which these principles lead, as in the case of the questions on grace and free will. Hence we may say that the element of truth contained in the rules of method as formulated by Descartes, was already perfectly known by the Angelic Doctor.
Thus the Theological Summa is a splendid example of this synthetic method in the orderly arrangement of theological knowledge. It first treats of God's existence and His nature, then of His attributes, in the third place of the three Persons, fourthly of God's actions ad extra, and so on for the rest. In this orderly arrangement anyone can see that St. Thomas far surpasses the Master of the Sentences, who treats but incidentally of moral theology, discussing faith, hope, and charity on the occasion of the following question: "Whether Christ had faith, hope, and charity," (37) and treating of sin in general when the question of original sin presents itself.(38)
Finally, and this must especially be noticed, the Angelic Doctor succeeded exceedingly well in combining analysis and synthesis, according as ascendant analysis, which terminates in principles and causes, is the principle of descendant analysis. For analysis, having finished with natural philosophy, in ontology ascends to consider the notions of analogous being, act and potency, as also the universal principles of reason and being, which illumine the whole synthesis of general metaphysics. After this the mind ascends to consider the pure Act, the Supreme Being, which is required in the final analysis, the true notion of which is, as it were, the sun of all synthesis in the universality of its scope, which is knowledge of all beings inasmuch as they are beings.(39)
By no means do we find in the system of St. Thomas this abuse of the a priori method which, as clearly seen in the works of Spinoza, excludes by means of mathematics the consideration of efficient and final causes, and hence leads to rationalism and pantheism, as if all things could be deduced from God's nature in a geometrical way.(40) By way of investigation and analysis St. Thomas ascends by the light of the first principles of reason from sensible things and the most certain facts of experience to the supreme and most universal cause who, since He is infinitely perfect and in no way stands in need of creatures, created all things with absolute freedom.(41) Then by the way of synthesis, the holy Doctor judges of all things by means of a lofty principle. As he himself says: "By way of judgment, from eternal things already known, we judge of temporal things, and according to laws of things eternal we dispose of temporal things." (42) In accordance with this union of analysis and synthesis, presented by the Angelic Doctor, as Father del Prado shows, (43) the supreme truth of Christian philosophy, in which the analytic method, or method of finding in the ascending order, terminates, and which is the principle of the synthetic method of judgment, is this: God is the self-subsisting Being, I am who am. In other words only in God are essence and existence identical .(44) This is the golden key of the whole doctrinal edifice, which is constructed by the Angelic Doctor with such penetration of thought and fixity of principles that, as Leo XIII testified (45) no one surpassed him in this. Avoiding both nominalism, which denies the objectivity of metaphysics, reducing it to logic, and the extreme realism of Plato, which on no just grounds considers the universal to exist formally apart from the thing, St. Thomas admirably distinguished between logic and metaphysics, between logical and real being.(46) He clearly shows that, before our mind considers the question, the essence of any finite being is not its existence, and that hence only in God are essence and existence identical.(47) This is the culminating point of the five proofs for God's existence, the terminus in the ascending order by the method of finding, and it is the principle of judgment from the highest cause by the synthetic method.
For many years the more we have studied this Theological Summa, the more we have seen the beauty of its structure. The expositions and demonstrations are simple and clear, especially if they are compared with the commentaries on the Sentences of Peter Lombard, and superfluous questions are avoided in accordance with the Angelic Doctor's plan as stated in the Prologue. Likewise, repetitions are eliminated, as much as possible, because subjects are always treated in a general way before they receive special consideration, and St. Thomas does not refer his reader to what is to be said later on. In this simplicity and clarity, the Angelic Doctor evidently far surpasses not only his predecessors, but even Scotus and Suarez.
The perfection of this edifice is in great part due to the consummate skill with which he effects the divisions between the treatises or the questions or the articles or the arguments. These divisions, of course, are not extrinsic but intrinsic, arranged in accordance with the formal point of view of the whole to be divided, and effected by means of members that are truly opposites to each other, so that the divisions are adequate, with subordinate subdivisions; yet all is done with discretion and not by descending to the least details. Thus by a gradual process the light of the principles reaches to the ultimate conclusions that are, nevertheless, still universal - for speculative knowledge does not descend to the particular - and thus it is essentially distinct from experience and prudence.
37. Cf. III Sent., d.23.
38. Cf. II Sent., d.35 f
39. See St. Thomas, Com. on Post. Anal., Bk. II, lect. 20; Bk. I, lect. 22 f.; Com. on Metaphysics, Bk. I, lect. 1f; Bk. IX, lect. 5; also Summa theol., IIa IIae, q.9, a.2; Contra Gentes, Bk. I, chaps. 3, 9; Summa theol., la IIae, q. 112, a.5.
40. Cf. Leo Michel, O.P., "Le systeme de Spinoza an point de vue de la logique furmelle" in the Revue Thomiste, January, 1898.
41. Summa theol., Ia, q.19, a. 3.
42. Ibid., q. 79, a. 9.
43. De veritate fundamentali philosophiae christianae (Fribourg, 1911).
44. Summa theol., la, q.3, a.4.
45. Cf. Encyclical Aeterni Patris.
46 Summa theol., Ia, q.85, a.2 ad 2um.
47. Ibid., q.3, a.4