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ABSTRACTION AND METAPHYSICS IN ST. THOMAS' SUMMA

BY PHILIP MERLAN

On reading modern interpretations of St. Thomas' philosophy one fre- quently receives the impression that St. Thomas professed the following doctrine: 1. The active intellect extracts the species intelligibiles from the phantasmata by an act of abstraction. 2. There are three degrees of ab- straction. The first is from the materia signata (individualis) sensibilis, the second is from the materia communis (sensibilis), the third from all matter (including the materia intelligibilis) altogether. 3a. The first degree of ab- straction is applied in physics; 3b. the second in mathematics; 3c. the third in metaphysics.1

Now, it is the purpose of this paper to remind the reader that 3c is not the doctrine to be found in the Summa and to explain the importance of this absence. What the Summa says is: by the third degree of abstraction we grasp such objects as ens, unum, potentia, actus, etc. All these can exist also without any matter (while physicals and mathematicals cannot); by which is meant that they apply also (are present in, are predicable of) im- material substances. They are immaterial only in this sense of the word, or to use a later term, they are immaterial praecisive. But this kind of im- materiality is of course quite different from the immateriality of God, the angels, etc., which, to use a later term, are immaterial positive. Accord- ingly, the Summa stresses that we cannot reach disembodied forms (im- material substances) superior to the soul such as God and the angels, by the method of abstraction. The assertion to the contrary the Summa considers to be an erroneous doctrine of Avempace (Ibn Bagga). The doctrine is erroneous according to St. Thomas because these immaterial substances are neither forms nor universals. Thus they can be reached neither by ab- stractio formae nor by abstractio universalis (I q. 88, art. 2, resp. dic.).

1 Cf. J. Maritain, The Degrees of Knowledge (1937): the third degree of abstrac- tion enables the mind to consider immaterial objects like God, pure spirits, etc., and also substance, quality, act, potency, etc.-all of which belong to the realm of meta- physics (46). See the penetrating criticisms of Maritain in L. M. Regis, " La phi- losophie de la nature," Jtudes et Recherches publiees par le College Dominicain d' Ottawa, Philosophie, Cahier I (1936), 127-158. Maritain's answer in Quatre Essais sur l'esprit dans sa condition charnelle (1939), 240, n. 1, is hardly satisfying either from the historical or from the systematic point of view. In Ri. Gilson, The Philosophy of St. Thomas Aquinas (1929), we read that immaterial substances like angels or God are known only by abstracting the intelligible from the material and sensible (236); we are thus left with the impression that "abstraction " should be taken in its technical sense. True, Gilson later expresses himself without any am- biguity by saying that the incorporeal is known to us only by comparison with the corporeal (256), and by emphasizing that there are no phantasms of intelligible realities, so that no abstraction can take place.

284

ABSTRACTION AND METAPHYSICS IN ST. THOMAS' SUMMA 285

It is true, the Summa emphasizes that the only way leading to even in- adequate knowledge of these immaterial substances starts from objects of sensation. This starting point is common to several ways: one leading to physicals and mathematicals, another to such objects as ens, unum, etc., a third to immaterial substances. But this third way is from the very be- ginning different from the other ways. It is described by St. Thomas in dis- tinction from the way of abstraction in such terms as: per comparationem ad corpora sensibilia or per remotionem (I q. 84, art. 7; q. 88, art. 2, ad sec.); by some kind of similitudines and habitudines ad res materiales (I q. 88, art. 2, ad primum).

In other words, the method of abstraction is applicable to metaphysics only to the extent to which metaphysics treats forms common to material and immaterial substances (transcendentals). As far as metaphysics deals with immaterial substances, it requires a method different from the method of abstraction.

Since the sentence impossibile est intellectum . . . aliquid intelligere . .nisi convertendo se ad phantasmata (I q. 84, art. 7, resp. dic.) is some-

times quoted to prove that abstraction is the only method by which we can know anything above the sensibilia, it should be stressed that this sentence occurs in the topic indicated in the title of q. 84; quomodo anima . . . in- telligat corporalia. The knowledge of immaterial substances is treated ex professo only in q. 88 (title: Quomodo anima humana cognoscat ea quae supra se sunt), and throughout this quaestio the applicability of abstraction to immaterial substances is denied.

If we consider it legitimate to designate metaphysics dealing with im- material substances such as God, angels, etc., as metaphysica specialis, and to designate metaphysics dealing with such things as ens, unum, potentia, actus, as metaphysica generalis, we should say in brief: in his Summa St. Thomas teaches that the method of abstraction is inapplicable to meta- physica specialis. Geoffrey of Fontaines will say later: Secundum statum vitae praesentis non est nisi unus modus intelligendi omnia, sive materialia . . . sive immaterialia . . . scilicet per abstractionem speciei intelligibilis virtute intellectus agentis, mediante phantasmata.3 But this is not what St. Thomas said, and it should not be presented as his doctrine.

2 This is made completely clear in some other presentations of St. Thomas. An older example is K. Werner, Der heilige Thomas von Aquino (1859): abstraction in metaphysics is insufficient, as metaphysics deals not only with the most universal but also with the most real, which must be reached by a method other than that of logical universalization. This other method Werner correctly calls separatio (II, 157, n. 1)-the explanation of this term is given in the body of the present paper. A more recent example: M. L. Habermehl, Die Abstraktionslehre des hi. Thomas von Aquin (1933), 58-60.

3 Quodl. 6, q. 15, in M. Wulf, " L'intellectualisme de Godefroid de Fontaines d'apres le Quodlibet 6, q. 15," Festgabe . . . Clemens Baeumker (1913), 287-296, esp. 294.

286 PHILIP MERLAN

We find the above results fully confirmed when we read St. Thomas' Expositio super Boetium De Trinitate. Commenting on Boethius' tripar- tition of speculative knowledge into physics, mathematics, and theology (metaphysics),4 St. Thomas declares that only physics and mathematics make use of abstraction, the former mainly of abstractio universalis, the latter of abstractio formae. The method used by theology, says St. Thomas, should be called separatio rather than abstractio; separatio being clearly the intellectual method underlying all discursive thinking.5 Again Avempace is quoted as having committed the mistake of assuming that the quiddities of immaterial substances are adequately expressed in the quiddities of sensible things-so that we can abstract them.6 And again one branch of meta- physics only is credited with dealing with ens, substantia, potentia, actus,7 all of which can obviously be reached by abstraction. The method appro- priate to special metaphysics St. Thomas describes in terms of excessus, re- motio, via causalitatis (causa excellens)-and he refers to Pseudo-Dio- nysius.8

All this should have been obvious even before the study of the Expogitio received a new basis in the form of Wyser's edition of parts of the Expositio, based directly on St. Thomas autograph.9 Such a study establishes two

4 Boetius, De Trinitate, ch. 2 (p. 8 in the Loeb Stewart-Rand ed.). I intend to deal with the doctrines of Boethius elsewhere.

5 Expositio super Boet. De Trin., q. 5, art. 3, resp. Even if we prefer to speak of modes rather than degrees of abstraction (see R. Allers, " On Intellectual Opera- tions," The New Scholasticism 26 [1952], 1-36, esp. 26), it still is impossible to interpret separatio as one of three modes of abstraction. But it is equally impossi- ble to recognize fully the complete difference between abstraction and separation, and at the same time to assert that separation is the only method appropriate to metaphysics, as is done by J.-D. Robert, O.P., "La metaphysique, science distincte de toute autre discipline philosophique, selon Saint Thomas d'Aquin," Divus Thomas (Piacenza) 50 (=ser. 3, vol. 24), 1947, 206-222. Precisely to the extent to which transcendentals are the subject matter of metaphysics, the method of abstraction must be applied in metaphysics.

6 Ibid., q. 6, art. 4. On Avempace see the introduction of M. Asin Palacios in his edition of Avempace, El regimen del solitario (1946); E. A. Moody, "Galileo and Avempace," this Journal 12 (1951), 163-193; 375-422. For historical perspec- tive see, e.g., B. Nardi, "Note per una storia del' Averroismo Latino. II. La posizione di Alberto Magno di fronte all' Averroismo," Rivista critica di storia di filosofia, 2, fasc. 3-4 (1947), 197-220, esp. 200 and 216.

7 Expositio super Boet. De Trin., q. 5, art. 4, resp. 8 Ibid., q. 6, art. 2, resp.; cf. St. Thomas, Expositio super Dionysium de div.

nom., c. 7, lectio 4: we know God ex ordine totius universi by applying the methods per ablationem, per excessum, secundum causalitatem omnium.

9 P. Wyser, O.P., Die wissenschaftstheoretischen Quaest. V u. VI. in Boethium De Trinitate des hi. Thomas von Aquin (1948); cf. the important review by B. Decker in Scholastik 20-24 (1944-1949), 415-418. Indeed, the body of this paper was written without any knowledge of Wyser's edition. I am extremely obliged to Dr. Decker (himself preparing an edition of St. Thomas' Boethius commentary) for

ABSTRACTION AND METAPHYSICS IN ST. TfHOMAS' SUMMA 287

facts beyond any doubt. The first is that in the original draft of the key sentence St. Thomas had written patet ergo quod triplex est abstractio, making it clear at the same time that one of these three kinds of abstraction is the forming of negative propositions (precisely what he later called separatio in the strict sense of the word) and only the other two are abstrac- tion (of the form or the universal) in the proper sense of the word; but even so in the final draft he replaced the words triplex abstractio by triplex distinctio, dividing it in separatio (discursive thinking) and abstractio for- mae or abstractio universalis. (q. 5, a. 3, resp.). Thus St. Thomas con- sciously preferred the term triplex distinctio to triplex abstractio precisely to avoid the misunderstanding that he was teaching the doctrine of three degrees of abstraction. The second fact is that in this sentence (. . . ab- tractio a materia sensibili; et haec competit metaphysicae) the word meta- physicae as found e.g. in the Parma edition (v. 17, p. 386) or in Mandonnet (v. 3, p. 113) is a simple misprint, to be replaced by mathematicae. These two facts should destroy any hope of finding the doctrine of the three de- grees of abstraction in the Expositio.

This has been clearly perceived by Geiger.10 The results of his analysis of the Expositio coincide with the results of the present paper with regard to the Summa, and again it is noteworthy that the main body of the present paper was written without any knowledge of Geiger's (cf. n. 9). Now, the correctness of Geiger's interpretation has been contested by Leroy.11 To prove the weakness of Leroy's argument it is sufficient to concentrate on two points. Leroy asks: if there is no doctrine of the three degrees of abstrac- tion in the Expositio, how are we to explain that in all his writings posterior to the Expositio, St. Thomas does teach this very doctrine? The fact established in the present paper that St. Thomas does not teach it in the Summa should provide a sufficient answer to Leroy. This answer would hold quite regardless of the temporal relation between the Expositio and the Summa (or between any other writings of St. Thomas), for the simple reason that the Summa explicitly rejects the doctrine of the three degrees, and such an explicit rejection would outweigh any evidence provided by incidental and non-explicit references which could be interpreted as implying that doc- trine. Secondly, Leroy asserts that the term separatio does not mean any- thing else in St. Thomas but the highest degree of abstractio. However, Leroy quotes no evidence to support this assertion, and it must be empha- sized that according to St. Thomas abstractio is the method by which we "separate " the universal from the particular or the form from the whole

a letter informing me of the wording of the original draft of the decisive passages in St. Thomas' autograph.

10 L. B. Geiger, O.P., "Abstraction et separation d'apres Saint Thomas in de Trinitate q. 5, a. 3," Revue des sciences philosophiques et theologiques 31 (1947), 3-40.

11 M.-V. Leroy, " Le savoir speculatif," Revue Thomiste 48 (1948), 236-339, esp. 328-339.

288 PHILIP MERLAN

which is composed of form and matter, whereas separatio is the method by which we " separate " e.g., a quality from the subject in which it inheres, as when we say " this man is not white." This separation is simply the opera- tion of discursive thinking or, as St. Thomas says, the operation of the intel- lectus componens et dividends, i.e., the operation described, e.g., in his com- mentary to De Interpretatione I, ch. 4 (lectio 3), as the process of forming propositions. The former " separation " should not be called separation at all according to St. Thomas; only the latter is separation in the proper sense of the word. The process of abstraction does not entail propositions, whereas the process of separation does. The two kinds of "separation " (or as we could equally well say, the two kinds of "abstraction ") are succinctly described in the Opusculum XLV (De sensu respectu singularium, et intel- lectu respectu universalium): . . . si ab homine albo separetur albedo hoc modo, quod intellectus intelligat eum non esse album, esset apprehensio falsa. Si autem sic separetur albedo ab homine albo quod apprehendatur homo non apprehensa albedine, non esset apprehensio falsa . . . Sic ergo [i.e., by the second kind of separation] intellectus absque falsitate abstrahit genus a speciebus . . . (Parma ed., vol. 17, p. 118. Cf. in De Anima 1. II, 1. 12, ib., vol. 20, p. 68). To say, as Leroy does, that separation is simply a maximization of abstraction is to contradict clear evidence.

Of course, it may be said that the operations of separatio and abstractio have something in common in that both " divide." Accordingly, St. Thomas sometimes uses the term separatio or abstractio to cover both: separatio in the proper sense of the word, and abstractio. In such cases he may add a word of explanation, e.g., speak of a duplex abstractio (Summa q. 85, art. 1, ad primum; cf. Expositio, loc. cit.) or separatio proprie. Or he may rely on the context (as in the passage from Opusc. XLV quoted above) to make it clear whether he uses the words in their broader or in their strict sense. But it is always clear that there is a radical difference between abstractio and separatio taken in their strict sense.12

There is no way to deny, of course, that in St. Thomas all knowledge is ultimately based on sensory perception. But it is oversimplifying St. Thomas' position to say that abstraction is the only way in which to ascend to immaterial substances. We should simply admit that St. Thomas left unexplained how precisely the non-abstractive ascent takes place, and lim- ited himself to hints like remotio, ablatio, comparatio, similitudo, habitudo (relatio) ad corporalia, excessus, via causalitatis.13 He made it perfectly

12 On some important implications of the question whether truth resides essen- tially in apprehensions of quiddities or in propositions, see, e.g., R. McKeon, "Thomas Aquinas' Doctrine of Knowledge and Its Historical Setting," Speculum 3 (1928), 425-444, esp. 434ff.

13 The ultimate roots of some of these concepts, esp. ablatio and remotio; simili- tudo, habitudo, relatio; excessus, seem to be found in Albinus' Epitome (Didascali- cus), ch. 10 (p. 61 ed. Louis). Albinus describes the different ways towards the knowledge of God by "kat' aphairesin" (ablatio, remotio), "kat' analogian" (similitudo, habitudo, relatio), and "metabasis" based on "en toi timi6i hypero-

ABSTRACTION AND METAPHYSICS IN ST. THOMAS' SUMMA 289

clear, however, that it is such a non-abstractive ascent which is the basis of our (always inadequate) knowledge of immaterial substances. We may even risk saying: abstraction makes it possible to intuit the objects of physics and mathematics, so that they later can be made the terms of our discursive thinking. But there is no intuition of the objects of metaphysica specialis to start with; they become accessible to discursive thinking alone.14

The whole problem is of interest simply as one of correct interpretation of St. Thomas' doctrines. But it has still another aspect. If abstraction cannot be applied to the subject matter of special metaphysics, while it can be applied to the subject matter of general metaphysics, the unicity of meta- physics is threatened. It is very interesting to notice that a Thomist like Sertillanges denies the existence of a metaphysica specialis altogether, as- serting that God, angels, etc., when treated in metaphysics are not treated as such; they are rather treated as being in general. In this way Sertillanges can easily save the method of abstraction for both branches of metaphysics and also establish the unicity of metaphysics.15 But it seems obvious that St. Thomas did not bring about the unicity of metaphysics in the manner of Sertillanges. In his commentary to the An. Post. I, lectio 41, St. Thomas says: The essences (quiddities) of immaterial substances are not the sub- ject matter of speculative sciences (metaphysics being one of them). But Sertillanges writes as if St. Thomas had said: separate (immaterial) sub- stances are not the subject matter of speculative sciences (metaphysics be- ing one of them). But all that St. Thomas ever said was that knowledge of separate substances in metaphysics is not the knowledge of their quiddities.

chen" (excessus). In the same chapter Albinus explains the principle of the so called negative theology (p. 59 ed. Louis); cf. Proclus, Theologia Platonica III 7, p. 131f. ed. Portus. See R. E. Witt, Albinus (1937) 124 and 132f.; H. A. Wolfson, Philo, 2 vols. (1947), II, 73-164. In Albinus the meaning of "aphairesis" is some- what ambiguous. See also H. A. Wolfson, "Albinus and Plotinus on Divine Attri- butes," Harvard Theological Review 45 (1952), 115-130, esp. 117-121; 129f.

14 There is a certain similarity between St. Thomas' criticism of Avempace and a passage in Ibn Khaldoun, Les Prolegomenes, 3 vols. (1863-1868), III, 233, indi- cating a common source. On the relation between abstraction and intuition in St. Thomas see A. Hufnagel, Die intuitive Erkenntnis nach dem hi. Thomas v. Aquin (1932), 49, n. 4.

15 A. D. Sertillanges, " La science et les sciences sp6culatives d'apres St. Thomas d'Aquin," Revue des sciences philosophiques et theologiques 10 (1921), 1-20, esp. 15f. P. J. W6bert, Essai de Metaphysique thomiste (n.d.; 1927?), after having explained the difference between the abstraction of the universal and abstraction of the form, asserts of the latter that it can be either mathematical or metaphysical (51). This assertion is clearly based on the misprint indicated above in the present paper. It would be interesting to check how many misinterpretations of St. Thomas have been caused by the failure to notice this misprint. Generally, one has the impression that in Webert and Sertillanges general metaphysics has simply absorbed special meta- physics. For an older example of a similar interpretation in most succinct form cf. C. Baeumker, Witelo (1908), 276-280.

290 PHILIP MERLAN

And this assertion is simply another aspect of his doctrine that abstraction, i.e., the method leading to the knowledge of quiddities, cannot be applied to special metaphysics.16 By this, however, St. Thomas did not intend to ex- clude special metaphysics from the order of the speculative sciences.

Also a passage of St. Thomas' In De sensu et sensato seems to imply clearly that when St. Thomas by metaphysics meant special metaphysics, he explicitly excluded the necessity of abstraction for the grasping of its objects, because the objects sunt secundum seipsa intelligibilia actu (lectio 1).

All of which, in turn, leads to one of the most persistent problems in the history of metaphysics. Is metaphysics exclusively ontology, i.e., the sci- ence of being as such and its categories, or is it knowledge of supra-empirical reality? Avicenna and Averroes respectively could serve as the medieval representatives of these two points of view-this at least was the way in which Duns Scotus presented them.17 Or is metaphysics both, knowledge of being as such and knowledge of the supra-empirical? This was answered affirmatively by St. Thomas, as it was also by Suarez.18 This leads to the assertion that special and general metaphysics are simply two branches of one metaphysical science. But this assertion never went uncontested." Today it is discussed implicitly by interpreters of Aristotle, who, it seems, defined metaphysics as knowledge of the uppermost, immaterial sphere of being, and, by the same token, as knowledge of the most universal, or being as such (Met. E 1, 1026a23-32). According to Jaeger this is a self-contra- dictory definition, because knowledge of what is universal and common to all things, material and immaterial alike (ontology, general metaphysics) cannot at the same time be knowledge of the immaterial alone (theology, special metaphysics) which is only part of all things and particular. Is Jaeger right? If he is, how can this self-contradiction be explained? 20 We

16 Cf. footnote " e " of the Leonine edition to lectio 31 of the same commentary. Today the note reads almost like an advance refutation of Sertillanges.

17 Duns Scotus, Quaqstiones subtilissimae super II. Met. Arist., 1. 1, q. 1 (VII, 11-40, ed. Vives).

18 On Suarez' treatment of metaphysics see M. Grabmann, Mittelalterliches Geistesleben, 2 vols. (1926), I, 525-560, esp. 546; E. Conze, Der Begriff der Meta- physik bei F.S. (1928), esp. 18-22.

19 Cf. E. Lewalter, Spanisch-jesuitische and deutsch-lutherische Metaphysik (1935), esp. 44ff., and M. Wundt, Die deutsche Schulmetaphysik des 17. Jahr- hunderts (1939), 161-227, esp. 170.

20 Natorp had tried it by treating as spurious the passages in which Aristotle's text describes metaphysics as the knowledge of the supranatural (P. Natorp, "Thema und Disposition der Aristotelischen Metaphysik," Philosophische Monats- hefte 24 [1888], 37-65; 540-574, esp. 51 n. 23, 550, 542). Jaeger does it by apply- ing his developmental method. According to him, Aristotle had originally conceived metaphysics in Platonistic manner as knowledge of the supersensible, but was later moving away from this position to another which would have eventually reduced

ABSTRACTION AND METAPHYSICS IN ST. THOMAS' SUMMA 291

see that these two questions are closely linked to the question concerning the difference between abstractio and separatio in St. Thomas, because this dif- ference results from the different qualities of the objects of general and spe- cial metaphysics. Thus what started as a very specific problem in St. Thomas leads to such comprehensive questions as: What is metaphysics, its subject matter, and its method? What was Aristotle's answer and how are we to interpret it? 21

Scripps College and Claremont Graduate School.

metaphysics to a positive science, dealing with the only kind of reality still acknowl- edged by him, i.e., sensible reality-so that what we now read as Aristotle's defini- tion of metaphysics would show him oscillating between the two points of view which he tried in vain to reconcile (W. Jaeger, Aristotle, 2nd ed. [1948], 216-219). Ivanka may be right in asserting that this dual aspect of metaphysics appears throughout the whole Metaphysics, thus making it very difficult to apply Jaeger's developmental method to the solution of the problem (E. v. Ivanka, "Die Be- handlung der Metaphysik in Jaegers Aristoteles," Scholastik 7 [1932], 1-29). But even if Ivanka is right, the problem still remains. H. Cherniss tried to solve it in his review of Jaeger's book (AJP 56 [1935], 261-271, esp. 265), and tries it again in his Aristotle's Criticism of Plato and the Academy I (1944), by assuming that the contradiction in Aristotle's definition of metaphysics is only an inevitable conse- quence of the more basic contradiction vitiating the whole system of Aristotle, which is to deny and to assert at the same time that the universal is the real: primary reality is supposed to be the principles of particulars, and yet these principles can be real only by satisfying conditions peculiar to particulars (Cherniss, loc. cit., 352; cf. 220, 369-372).

21 On this problem see P. Merlan, Being and Divisions of Being from the Acad- emy to Neoplatonism (in course of publication), ch. VII.