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METAPHYSICAL SEPARATION IN THOMAS AQUINAS

Paul Gerard Horrigan, Ph.D., 2012.

Metaphysics Operates at the Third Degree of Abstraction (Properly Called Separation).

The level of abstraction that metaphysics operates at is not the first level (which concerns the

physical sciences, or physics and the natural sciences), nor at the second level (which concerns

mathematics in the traditional sense of that particular science), but at the third level (properly

called separation, proper to the science of being as being, [ens qua ens], which is metaphysics).1

The three levels of abstraction are described as “degrees of abstraction” in the sense of a

progressive elevation above matter. St. Thomas writes about the three levels in his Commentary

on the Physics of Aristotle, stating: “There are some things whose being depends on matter, and

which cannot even be defined without matter. Other things, while not being able to exist except

in sensible matter, do not include sensible matter in their definition… Lastly, there are things

which do not depend on matter, whether in their being or in our manner of understanding them –

either because they are never found in matter (like God and the other spiritual substances) or

because they are not found in matter always (like substance, act and potency, and being itself).

These realities constitute the subject matter of metaphysics. Mathematics deals with those

realities that depend on matter as to their being but not as regards our manner of understanding

them. Physics deals with realities that depend on matter both as regards their being and as

regards our manner of understanding them.”2

The First Degree of Abstraction. As regards the first degree of abstraction (pertaining to

the physical sciences, or physics and the natural sciences) the intellect abstracts from matter so

1 Studies on the degrees of abstraction and metaphysical separation (separatio) in Aristotle: M. D. PHILIPPE,

Abstraction, addition, séparation dans la philosophie d’Aristote, “Revue Thomiste,” 32 (1948), pp. 461-479.

Studies on the degrees of abstraction and metaphysical separation (separatio) in Aquinas: L. B. GEIGER,

Abstraction et séparation d’après s. Thomas In de Trinitate, q. 5, a. 3, “Revue des sciences philosophiques et

theologiques,” 31 (1947), pp. 3-40 ; M. V. LEROY, Abstractio et separatio d’après un texte controversé de S.

Thomas, “Revue Thomiste,” (1948), pp. 51-53 ; G. VAN RIET, La théorie thomiste de l’abstraction, “Revue

philosophique de Louvain,” 50 (1952), pp. 353-393 ; P. MERLAN, Abstraction and Metaphysics in St. Thomas’

Summa, “Journal of the History of Ideas,” 14 (1953), pp. 284-291 ; F. G. CONNOLLY, Abstraction and Moderate

Realism, “The New Scholasticism,” 27 (1953), pp. 72-90 ; W. H. KANE, Abstraction and the Distinction of

Sciences, “The Thomist,” 17 (1954), pp. 43-68 ; E. D. SIMMONS, In Defense of Total and Formal Abstraction,

“The New Scholasticism,” 29 (1955), pp. 427-440 ; H. RENARD, What is St. Thomas’ Approach to Metaphysics?,

“The New Scholasticism,” 30 (1956), pp. 67-80 ; E. D. SIMMONS, The Three Degrees of Formal Abstraction, “The

Thomist,” 22 (1959), pp. 37-67 ; R. W. SCHMIDT, L’emploi de la séparation en metaphysique, “Revue

Philosophique de Louvain,” 58 (1960), pp. 376-393 ; L. VICENTE, De modis abstractionis iuxta sanctum Thomam,

“Divus Thomas (Piac.),” 1964, pp. 278-299 ; J. L. ESLICK, The Negative Judgment of Separation, “The Modern

Schoolman,” 44 (1966), pp. 35-46 ; J. OWENS, Metaphysical Separation in Aquinas, “Mediaeval Studies,” 34

(1972), pp. 287-306 ; J. F. WIPPEL, Metaphysics and Separatio in Thomas Aquinas, in J. F. Wippel, Metaphysical

Themes in Thomas Aquinas, Catholic University of America Press, Washington, D.C., 1984, pp. 69-104. 2 In I Physic., lect. 1. “Many authors affirm that the three degrees of immateriality represent different degrees of

abstraction. However, in In Boeth de Trin., q. 5, a. 3, St. Thomas says that only the physical and mathematical

degrees of immateriality correspond to different types of abstraction (taking abstraction to mean a mental

separation); metaphysical concepts involve a real separation, in the sense that they are the result of separating from

matter what is really separable or separated from it. At any rate, there is no objection to regarding the third degree of

immateriality as the result of abstraction, provided we do not take abstraction to mean grasping partial aspects of

reality (as is the case with the particular sciences), but rather transcending materiality”(J. J. SANGUINETI, Logic,

Sinag-Tala, Manila, 1992, p. 199).

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far as it is the principle of individuation, therefore, from individual matter (also called signate

matter or materia signata). However, matter is still retained in so far as it is the basis of sensible

qualities. It thus retains sensible or common matter (materia sensibilis vel communis). Regarding

the first level of scientific knowledge which employs the first degree of abstraction, Koren

writes: “On the first level, scientific knowledge ‘terminates in the senses,’ for ‘the properties and

accidents of the thing which are shown by the senses sufficiently express the nature of the thing.

In this case, the judgment of the intellect concerning the truth of the thing must be conformed to

that which the senses reveal about the thing.’3 The science which is concerned with this level of

knowledge is called physical or ‘natural science, i.e., we judge of natural things according as

they are revealed by sense experience…and whoever disregards sense experience with respect to

the realm of nature falls into error.’4 Hence the conclusions of physical sciences must always be

open to verification by sense experience. From this it follows that physical sciences must retain

something which is subject to sense experience; for otherwise no verification by means of the

senses would be possible.

“It is clear, therefore, that scientific knowledge on this level may make abstraction only

from so-called ‘individual matter,’ i.e., from the differences which distinguish this man from that

man, this sample of sodium from that sample of sodium, etc.5 But it must retain the common

‘sensible matter’ which enters into the definition of the things it considers. By sensible matter is

meant matter ‘insofar as it is subject to sensible qualities, such as being hot or cold, hard or soft,

and such like.’6 Common sensible matter refers to those sensible qualities which are found in

individuals insofar as they belong to a certain group or class. That common sensible matter is

retained in physical science should be clear. For questions referring to such matter are

meaningful in physical science. For instance, it makes sense to ask questions about the

temperature, hardness, density, etc. of a physical object.

“Knowledge on this level is said to be on the first degree of abstraction. The intellect

considers such things as water in general, man in general, plants in general, or a certain type of

water, man or plant, etc., without being particularly interested in the individual as such. The

object is always something which can neither exist nor be understood without sensible matter.7

Experimental sciences, such as physics, chemistry, biology, experimental psychology, etc.,

belong to this level of scientific knowledge.”8

The Second Degree of Abstraction. The second degree of abstraction proper to

mathematics in the traditional sense of that particular science abstracts from common sensible

matter, but keeps under consideration the material substance as quantified, which is called

intelligible matter (materia intelligibilis).9 “Intelligible” in this context refers not so much to the

3 In Boethium de Trinitate, q. 7, a. 2. Attention is drawn to the fact that according to St. Thomas scientific

knowledge on this level reaches the nature of the sensible object. 4 Ibid.

5 All scientific knowledge must make some kind of abstraction, because all scientific knowledge is intellectual

knowledge, and all intellectual knowledge is obtained by means of abstraction. 6 Summa Theologiae, I, q. 85, a. 1, ad. 2.

7 In Boethium de Trinitate, q. 5, a. 1. 8 H. J. KOREN, An Introduction to the Science of Metaphysics, B. Herder, St. Louis, 1960, pp. 2-4.

9 For a detailed study of mathematical abstraction, see: Y. R. SIMON, Nature and Process of Mathematical

Abstraction, “The Thomist,” 29 (1965), pp. 117-139.

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intellect as to the imagination, so much so that one could speak here of “imaginable matter,”

which is matter as terminating in and known by the imagination, an internal sense faculty, in

contrast to matter as terminating in and known by the external sense.10

Koren writes: “On the

second level, scientific knowledge ‘terminates in the imagination,’ for ‘when abstraction is made

from the sensible conditions of a thing, there still remains something imaginable; so that with

respect to such objects judgment must be made according to what the imagination shows.’11

This

‘something imaginable’ is quantity, i.e., extension and number, which are abstracted from all

sensible qualities. A simple consideration will make this clear. If a man inquires about the

temperature of a triangle or the softness of number ten, the listener will conclude, no doubt, that

the fellow must have escaped from an asylum, because such questions do not make sense. The

reason why they are meaningless is precisely that quantity abstracts from all sensible qualities.

The study of mathematics belongs to this level of scientific knowledge. ‘In mathematics the

judgment of knowledge must be terminated in the imagination and not in sense experience

because a mathematical judgment exceeds the apprehension of the senses.’12

The lines, figures,

numbers, etc. considered in mathematics are not objects of sense experience but exist only in our

imagination, although it is true that sense-perceptible representations of them on paper or a

blackboard may be used to aid our imagination. Hence verification by sense experience is not

possible with respect to mathematical objects.

“Scientific knowledge on this level is said to be on the second degree of abstraction from

matter. It abstracts not only from individual matter, but also from common sensible matter, and

retains only quantity, which ‘can be understood in a substance before there is understanding of

the sensible qualities by which matter is called sensible; hence according to its proper nature,

quantity does not depend upon sensible matter, but only upon intelligible matter.’13

By

‘intelligibile matter’ is meant ‘substance insofar as it is subject to quantity.’14

Intelligible matter

has to be retained because numbers, dimensions and figures ‘cannot be considered unless the

substance which is their subject is considered.’15

The object of scientific knowledge on this level

‘depends upon (sensible) matter for its existence, but can be understood without it because

sensible matter does not enter into its definition.’16

All mathematical sciences belong to this level

of scientific knowledge.17

”18

The Third Degree of Abstraction (Properly Called Separation). Separation is the proper

level of abstraction in which metaphysics operates, wherein metaphysical notions correspond to

certain aspects of things understood without sensible matter, and which are also encountered in

beings without matter. Such metaphysical notions (i.e., act, potency, substance, accidents,

essence, act of being) are intelligible aspects of beings that sometimes are in matter (for example,

10 Cf. C. DE KONINCK, Abstraction from Matter (II), “Laval Théologique et Philosophique,” 16 (1960), pp. 63-69. 11

In Boethium de Trinitate, q. 6, a. 2. 12 Ibid. 13

In Boethium de Trinitate, q. 5, a. 3. 14

Summa Theologiae, I, q. 85, a. 1, ad. 2. 15

Ibid. The intelligible matter retained on this level is not individual but common, i.e., not this or that material

subject, but a material subject, as St. Thomas explains, ibid. 16 In Boethium de Trinitate, q. 5, a. 1. 17

Regarding the position of modern mathematics, cf. A. VAN MELSEN, The Philosophy of Nature, Duquesne

University Press, Pittsburgh, 1954, p. 97. 18

H. J. KOREN, op. cit., pp. 4-5.

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a rock is composed of act and potency, substance and accidents, and essence and act of being),

but which can also exist separated from physical matter (for example, an angel, also called the

separated substance, which is wholely without matter, has a composition of act and potency,

substance and accidents, and essence and act of being). Even if material beings exist, being does

not necessarily entail being in matter. Koren explains that “On the third level, scientific

knowledge ‘terminates in the intellect,’ for ‘there are things which transcend both that which

falls under the senses and that which falls under the imagination’19

; not that we obtain

knowledge of these things independently from sense experience and imagination, but rather that

‘the judgment of knowledge must not be terminated in either imagination or sensation.’20

On this

level, knowledge abstracts not only from all individual matter, as in experimental sciences, and

from common sensible matter, as in mathematics, but from all matter. Thus we reach the highest

or third degree of abstraction from matter. Scientific knowledge on this level considers ‘either

things which never exist in matter, such as God and angels, or things which in some cases exist

in matter but not in others, such as substance, quality, potency and act, the one and the many, and

things of this sort,’21

or in general ‘separate (i.e., immaterial) substances, and whatever is

common to all beings’22

and therefore most universal. In other words, the object of scientific

knowledge here is ‘wholly independent from matter, both as to its existence and as to its

understanding.’23

Science on this level is called metaphysics.”24

Even though metaphysics operates at the highest degree of abstraction, this does not

mean that it is a science that has nothing to do with reality (as it would deal only with

abstractions, the metaphysician being lost in the ivory tower of his immanent consciousness). In

fact, metaphysics deals pre-eminently with the real, and the metaphysician is, above all, a realist:

“The word ‘separation’ must not,” says H. D. Gardeil, “lead us astray in another direction.

When, in other words, metaphysics is said to be the science of the ‘separate’ or, if one prefers, of

the ‘abstract,’ this does not imply that its object is divorced from real existence but only from the

material conditions of existence. It could not be otherwise. Indeed, we shall see that the object of

metaphysics is eminently real and concrete; so that far from being out of touch with reality, the

metaphysician is in the full sense of the word more a realist than any of his fellows in the

fraternity of scholars and scientists. And this is true whether he considers, under the aspect of

being, the totality of things material and immaterial or whether, sectoring his horizon, he fixes

attention on what is real above all because immaterial above all: pure spirits, that is, and

infinitely above them, God.”25

Separation is an operation performed, not by the first operation of the mind (simple

apprehension), but by the second operation of the mind, that is, judgment; it is a negative

judgment wherein we discover being as being, the subject of metaphysics. John Wippel explains

that, for Aquinas, “separation is the process through which one explicitly acknowledges and

19 In Boethium de Trinitate, q. 6, a. 2. 20

Ibid. 21

In Boethium de Trinitate, q. 5, a. 1. 22

In Boethium de Trinitate, q. 6, a. 1. 23

In Boethium de Trinitate, q. 6, a. 2. The objects considered in metaphysics can be either positively immaterial, as

God, or abstractively immaterial, as bodies, considered insofar as they are beings, substances, possess unity, etc. 24

H. J. KOREN, op.cit., p. 6. 25 H. D. GARDEIL, Introduction to the Philosophy of St. Thomas Aquinas, vol. 4: Metaphysics, B. Herder, St.

Louis, 1967, p. 21.

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asserts that that by reason of which something is recognized as being need not be identified with

that by reason of which it is recognized as enjoying a given kind of being, for instance, material

being, or changing being, or living being. It may be described as a negative judgment in that

through it one denies that that by which something is recognized as being is to be identified with

that by reason of which it is a given kind of being. It may be described as separation because

through this judgment one distinguishes two intelligibilities, and denies that one is to be

identified with or reduced to the other. One distinguishes the intelligibility involved in one’s

understanding of being from all lesser and more restricted intelligibilities. Thus one negates or

eliminates restriction of being to any given kind from one’s understanding of being. One judges

that being, in order to be realized as such, need not be material, or changing, or quantified, or

living, or for that matter, spiritual. Hence one establishes the negatively or neutrally immaterial

character of being, and prepares to focus on being as such or as being rather than on being as

restricted to this or that given kind.

“Through separation one does not deny that beings of this or that kind also fall under

being. On the contrary, by denying that being itself must be limited to any one of its actual or

possible kinds, one opens the way for considering these, including the differences which are

realized in each, within the realm of being, and as being. Even purely material beings can be

studied not only insofar as they are material and changing as in physics, but simply insofar as

they share in being. This kind of study, of course, will not take place in physics, but in

metaphysics, the science of being as being.”26

Explaining the analogical, and not univocal, nature of the term ‘abstraction’ with

reference to the degrees of abstraction, and elucidating upon the third degree of abstraction

(properly called separation), and contrasting the doctrine of separation held by St. Thomas in his

Commentary on Boethius’s De Trinitate from the position held by Cajetan and John of St.

Thomas with their distinction between total abstraction and formal abstraction, Armand Maurer

writes: “The abstraction used by the metaphysician to grasp his subject is properly called

separation: separatio. This is a radically different mode of abstraction from those we have

already discussed, for it is effected through the negative judgment, not through simple

apprehension. We are thus forwarned that the subject of metaphysics will be radically different

in character from those of natural philosophy and mathematics. For judgment is primarily

pointed to the act of existing of things, whereas simple apprehension has to do rather with their

essences or natures. As a result, the subject of metaphysics will have an existential character not

found in those of the other two speculative sciences.27

“Why, however, must the subject of metaphysics be grasped in a negative judgment? To

understand this we must realize that for St. Thomas the subject of this science is universal being

(ens commune), or being as being (ens inquantum ens). It also deals with the transcendental

properties of being, such as goodness and truth, as well as with God, who is the first cause of

26

J. F. WIPPEL, The Metaphysical Thought of Thomas Aquinas: From Finite Being to Uncreated Being, Catholic

University of America Press, Washington, D.C., 2000, pp. 48-49. 27

This is also evident if we remember that for St. Thomas the act of existing (esse) is the supreme value of being,

the actuality of all acts and the perfection of all perfections. (De Potentia, VII, 2, ad 9). Hence metaphysics, which

studies being from the point of view of being, or in other words from the point of view of that which is most perfect

in being, is necessarily existential. See G. B. Phelan, A Note on the Formal Object of Metaphysics, in Essays in

Modern Scholasticism, pp. 47-51; R. J. Henle, Method in Metaphysics, pp. 51-58.

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universal being.28

Now none of these depends on matter and motion for its existence, as do the

objects of natural philosophy and mathematics. Some of them can exist in matter and motion, as

for instance being, goodness, act and potency; but these can also be found apart from matter in

spiritual beings. God, of course, exists absolutely independent of matter and movement. We can

conclude, therefore, that the objects with which the metaphysician is concerned either actually

exist or can exist without matter. And it is this truth which is grasped by him in a negative

judgment in which he denies that being is necessarily bound up with matter and material

conditions. Through a judgment of this sort he grasps being in its pure intelligibility, and

primarily in its value of existence, and forms the metaphysical conception of being as being.29

“From this it should be clear that St. Thomas never envisaged one type of abstraction

common to all the sciences which admits simply of three degrees. As Jacques Maritain has said,

each of the speculative sciences attains its subject by a mode of abstraction which is sui generis

and irreducible to any other. One does not simply continue the others along the same line, as if

mathematical abstraction lays hold of a subject simply more abstract and general than that of

natural philosophy, and metaphysical separation lays hold of one simply more abstract and

general than that of mathematics. In other words, the term ‘abstraction’ does not have a univocal

meaning. It is analogical, signifying activities of the intellect which are essentially diverse from

each other, although proportionately the same. Each of the modes of abstraction is a distinct type

of ‘eidetic visualisation’ – to use an expression of J. Maritain – a distinct way in which the

intellect lays hold of reality. At the same time, each implies a distinct way of distinguishing one

thing from another, or one aspect of a being from another aspect of the same being.30

The

difference between the mode of abstraction pertaining to mathematics and natural philosophy on

the other, is especially marked, for the former is accomplished through negative judgment,

whereas the latter are the work of simple apprehension. It is this difference to which St. Thomas

wishes to draw our attention when, in the present work, he calls the former separation and the

28 See St. Thomas, In Meta. Prooemium, pp. 80-83; In IV Meta. Lect. 1, nos. 529-533. God is therefore not the

subject of metaphysics, but the cause of its subject. He is not contained in being in general (ens commune), but

transcends it. See St. Thomas, Summa Theologiae, I, q. 105, a. 5; I-II, q. 66, a. 5, ad 4. See also J. D. Robert, La

métaphysique, science distincte de toute autre discipline philosophique selon saint Thomas d’Aquin, “Divus

Thomas,” 1947, pp. 206-222. God, however, is the principal object studied in metaphysics and the whole of that

science is ordained to a knowledge of Him. (See below q. 5, a. 1, p. 8, Summa Contra Gentiles, III, 25). That is why

St. Thomas gives as its first name theology or divine science. (See In Meta. Prooemium, p. 83; below q. 5, a. 1, p. 8.

On the other hand, the theology of Sacred Scripture has God for its subject. (See below, q. 5, a. 4, p. 41).

There is no distinction for St. Thomas between a general metaphysics or ontology and philosophical theology.

The theology of the philosophers and the primary philosophy or metaphysics are one and the same science. See J.

Owens, Theodicy, Natural Theology, and Metaphysics, “The Modern Schoolman,” Jan. 1951, pp. 126-137. 29 Every abstraction has a positive as well as a negative aspect. This is true of abstraction through judgment as well

as through simple apprehension. It would seem that the negative judgment of the metaphysician implies an

affirmative judgment in which being, and particularly the act of existing, are grasped in their positive value. For the

role of separation in metaphysics, see J. Maritain, Existence and the Existent, p. 30, note; L. B. Geiger, Abstraction

et séparation d’après s. Thomas, “Revue des sciences phil. et théol., 1947, pp. 24-28. See also St. Thomas, In IV

Meta. lect. 5, no. 593; and below, q. 5, a. 3. 30

Although J. Maritain uses the expression “degrees of abstraction,” he warns us that there is not simply a difference

of degree between these activities of the intellect. See Philosophy of Nature, p. 24; also Existence and the Existent,

pp. 28-30. On this question, see the prudent remark of L. M. Régis in Un livre…La philosophie de la nature.

Quelques apories, “Etudes et Recherches. Philosophie I,” 1936, p. 141, note 3. See also R. Allers, On Intellectual

Operations, “The New Scholasticism,” Jan. 1952, pp. 25-26.

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latter abstraction. Both of these are said to be ways in which the intellect distinguishes, so that

distinction appears as a quasi-genus of which separation and abstraction are diverse modes.

“It is true that in his later writings St. Thomas does not adhere to this terminology. For

example, in his Summa Theologiae he speaks of two modes of abstraction, one through

judgment, the other through apprehension. The term ‘separation’ does not appear.31

But this is

not surprising, since even in his Commentary on the De Trinitate he uses the verb ‘to abstract’ to

designate the act of ‘separating.’32

St. Thomas sometimes uses terms in a wide sense and not

with their precise meaning. But despite this difference of terminology there is no indication that

he abandoned the views expressed in his early work – views which are so closely in accord with

his fundamental philosophical principles.

“It would be erroneous, however, to see no importance whatsoever in his effort at

precision in terminology in his Commentary on the De Trinitate. As he himself says, words are

signs of concepts; and a philosopher’s struggle to make his vocabulary more precise can

generally be taken as an indication that he is doing the same with his thoughts.

“That this is true in the present case is evident from Thomas’ autograph manuscript of his

Commentary on the De Trinitate. A study of the manuscript reveals that he began the Reply to

Question Five, Article Three, several times, and that the final redaction was achieved only after

great effort at precision of thought and terminology.33

“In the first redaction St. Thomas makes no mention of the distinction between

apprehension and judgment: the distinction which later becomes the keystone of his solution. His

thought moves entirely in the order of essence or quiddity and the various ways in which the

intellect becomes assimilated to it. A threefold division is attempted on the basis of the

simultaneity, anteriority and posteriority of essences and their various elements, and again on the

basis of their dependence on, or independence of each other. But no conclusion is reached along

these lines, and he takes up the question again in a second redaction. Here at once he introduces

the fundamental distinction between apprehension and judgment, but it still does not play the

important role assigned to it in the definitive redaction. He speaks of ‘modes of abstraction’

instead of ‘modes of distinguishing’ as in the final writing; and the explanation of the three

modes tends as before to remain on the level of simple apprhension, essences and their elements,

their simultaneity, anteriority and posteriority. Only in the final redaction does he bring out the

crucial importance of judgment and the act of existing (esse) grasped in that act. Only here does

he establish the basic difference between the intellectual operations by which the metaphysician

lays hold of his subject and those by which the natural philosopher and mathematician lay hold

of theirs.

“The direction in which St. Thomas’ mind was moving in these various redactions is

clear. He was progressively realizing the central role of judgment and existence in the solution of

his problem, as well as the eminently existential character of the subject of metaphysics.

31 See: Summa Theologiae, I, q. 85, a. 1, ad 1, 2. 32

See: q. 5, a. 3, p. 27. 33 See the study of these redactions by L. B. Geiger, art. cit. They have been edited by P. A. Uccelli, S. Thomae

Aquinatis in Boetium de Trinitate Expositiones, Rome, 1880, pp. 335-337.

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“In recent years historians of St. Thomas’ philosophy have become more fully conscious

of these aspects of his thought which for a long time remained quite obscured and forgotten.34

Indeed two of his outstanding followers in the sixteenth and seventeenth centuries, Cajetan and

John of St. Thomas, taught a doctrine of abstraction and division of the sciences based on it

which leaves out of consideration the very features St. Thomas took such pains to emphasize: the

role of judgment and existence. They distinguish between ‘total abstraction’ and ‘formal

abstraction.’ What is abstracted in the former is as a universal whole with respect to that from

which it is abstracted; what is abstracted in the latter is as a form of that from which it is

abstracted. All the sciences, they add, use total abstraction, but they are diversified according to

modes of formal abstraction.35

“It is beyond the scope of this Introduction to attempt an adequate study of their doctrine

and an evaluation of it as a faithful continuation of St. Thomas.’ But this at least should be

pointed out: For St. Thomas, abstraction of a whole, although common to all the sciences, is

especially characteristic of natural philosophy, whereas for Cajetan and John of St. Thomas, total

abstraction is used by all the sciences but properly defines none of them. Again, for St. Thomas

abstraction of form is proper to mathematics, while for his two commentators formal abstraction

belongs to all the sciences, which are diversified by its various modes.36

Finally, and most

important of all, these commentators fail to explain the essential role negative judgment plays in

St. Thomas’ metaphysics, and the existential character of its subject. There are grounds to

suspect, therefore, that behind the difference in the terminology of St. Thomas and his

commentators there is a difference of doctrine.37

This much at least is certain: without a direct

contact with the works of St. Thomas, especially with his Commentary on the De Trinitate, it is

impossible to appreciate his authentic teaching.”38

The above passage from Maurer can adequately respond to the pro-Cajetan and pro-John

of St. Thomas position of Edward D. Simmons in two of his articles, namely, his In Defense of

Total and Formal Abstraction published in The New Scholasticism,39

and his The Three Degrees

of Formal Abstraction, published in The Thomist.40

Focusing on the role of judgment in the metaphysical separatio, Joseph Owens notes that

“the subject of metaphysics is not constituted by any abstraction, except the abstraction required

34

Among other works, see E. Gilson, Le Thomisme, pp. 43-81, 123-139; Being and Some Philosophers. J. Maritain,

A Preface to Metaphysics; Existence and the Existent. J. de Finance, Etre et agir dans la philosophie de s. Thomas.

G. B. Phelan, Being and the Metaphysicians, in From an Abundant Spring, pp. 423-447. 35 See: Cajetan, In De Ente et Essentia, Prooemium, q. 1, no. 5, pp. 6, 7; De Nominum Analogia, 5, p. 50; John of St.

Thomas, Ars Logica, II, q. 27, a. 1, pp. 818-830. 36 The terms themselves (“formal abstraction,” “total abstraction”) are not equivalent to St. Thomas’ “abstraction of

a whole” and “abstraction of a form.” Total and formal qualify the act of abstraction; of a whole and of a form

designate the object of the abstraction. 37

See: L. M. Régis, art. cit., pp. 138-140. The opposite view is expressed by J. Maritain, Existence and the Existent,

p. 30, note; also by M. V. Leroy, Le Savoir spéculatif, in Jacques Maritain, son oeuvre philosophique, pp. 328-339. 38

A. MAURER, Introduction, in St. Thomas Aquinas, The Division and Methods of the Sciences: Questions V and

VI of Aquinas’ Commentary on the De Trinitate of Boethius, translated with introduction and notes by A. Maurer,

Pontifical Institute of Mediaeval Studies, Toronto, 1958, pp. xx-xxv. 39

E. D. SIMMONS, In Defense of Total and Formal Abstraction, “The New Scholasticism,” 29 (1955), pp. 427-

440. 40

E. D. SIMMONS, The Three Degrees of Formal Abstraction, “The Thomist,” 22 (1959), pp. 37-67.

9

for the universality of common being. The aspect that characterizes it as the subject of

metaphysics, namely being, is not obtained by the activity of simple apprehension called

abstraction, but through judgment that separates being from not being. ‘Separation’ in this

context is far from just another word for the same notion designated by ‘abstraction.’ It

designates the crucial difference between the way natures are known by the human mind, and the

way being is known.”41

Interpreting Aquinas’s metaphysics of the separatio and showing how q. 5, a. 3 of the

earlier Commentary on Boethius’ De Trinitate with the later I, q. 85, a. 1 of the Summa

Theologiae can be reconciled without compromising the Angelic Doctor’s doctrine on separation

rooted in judgment of existence which is fundamentally different from the abstraction rooted in

simple apprehension, Wippel observes that St. Thomas’ “fullest discussion (of separation)

appears in a relatively early work (Commentary on Boethius’ De Trinitate), and that his clearly

drawn distinction in terminology between abstraction and separation disappears in his later

writings. Does this not suggest that Thomas may have given up his earlier view of separation and

that in the end he fell back upon abstraction in accounting for our discovery of being as being?

“…A lengthy discussion in the Summa Theologiae, I, q. 85, a. 1 might lead one to

conclude that later on in his career Thomas abandoned his earlier views concerning separation.

In replying there to the second objection against his contention that our intellect understands

material and corporeal things by abstraction from phantasms, Thomas again reviews the kinds of

abstraction associated with physics (abstraction from individual sensible matter) and with

mathematics (abstraction of quantity from common sensible matter). Certain things, he

comments, can be abstracted even from common intelligible matter, i.e., from substance insofar

as it is subject to quantity. As illustrations he lists being (ens), the one, potency and act, and other

things of this kind. Such things, he adds, can also exist apart from matter, as happens with

immaterial substances. Given this, one might maintain that Thomas is now appealing only to

abstraction and not to separation in accounting for our knowledge of being as being.42

41

J. OWENS, An Elementary Christian Metaphysics, Bruce, Milwaukee, 1963, p. 370. Explaining the metaphysical

process by which the establishment of the notion of supersible being is reached, which is by means of the judgment

of separation, Owens writes: “Being is known first as sensible. Then, through judgments, every sensible

characteristic is denied to it in its primary instance. In this primary instance real being and all unmixed perfections

still remain after separation from the sensible through these judgments. The primary instance of being is thereby

understood as a real something beyond the whole sensible order. The notion of being is accordingly exhibited as

applicable to both the sensible and the supersensible. The process by which it is so established is called the judgment

of separation. Being, though encountered directly only in sensible things, is submitted to judgments like these: ‘Of

its nature as such, being is not sensible, is not quantitative, is not mobile, is not temporal, though it does have those

features in observable instances.’ No simple process of conceptual abstraction can isolate the supersensible in the

way notions like ‘animal’ and ‘body’ are obtained. Merely leaving out of consideration feature after feature through

conceptual abstraction will not free being from immersion in the sensible. A direct conceptualization either of the

spiritual or of a generic nature really common to both sensible and spiritual does not occur. Only through acts of

judgment may being and substance, experienced as they are in sensible things, be separated from sensible

commitment. Solely as a result of judgment of separation is the notion ‘being that is not sensible, not quantitative,

not mobile, not temporal’ acquired.”(J. OWENS, op. cit., pp. 96-97). 42

Leon. 5.331. Note in particular: “Quaedam vero sunt quae possunt abstrahi etiam a materia intelligibili communi,

sicut ens, unum, potentia et actus, et alia huiusmodi, quae etiam esse possunt absque omni materia, ut patet in

substantiis immaterialibus.”

10

“In reacting to this suggestion, one should not overlook Thomas’s reply to the first

objection in this same article. There he comments that abstraction may take place through the

operation whereby the intellect composes and divides, as when we understand that one thing is

not in another or that it is separated from it. Or abstraction may occur through that operation

whereby the intellect simply understands one thing without understanding anything about

another. This Thomas now describes as simple or absolute consideration, and is what we have

frequently referred to as simple apprehension or as the understanding of indivisibles. As he had

already indicated in his earlier discussion in his Commentary on the De Trinitate (q. 5, a. 3), here

again he notes that falsity will result if one abstracts in the first way, that is, through judgment

(composition and division) things which are not separated in reality. This is not necessarily so,

however, when one does so in the other way, i.e., through simple apprehension.43

“In sum, in this reply to the first objection we find the same doctine as in q. 5, a. 3 of

Thomas’s Commentary on the De Trinitate. It is true that he no longer restricts the term

‘abstraction’ to the process whereby the intellect distinguishes through simple apprehension.

Now he uses it broadly so as to apply it in addition to the process whereby the intellect

distinguishes by judging, that is, to negative judgments. Even so, he clearly continues to

differentiate between these two ways in which the intellect distinguishes. Hence he can and does

assume that we will keep this in mind as we read his reply to the second objection.

“As we have seen, in his reply to that objection Thomas writes that being, unity, potency

and act, etc., can be abstracted from common intelligible matter and that they can also exist apart

from matter. He repeats a criticism of Plato which he had already raised in his Commentary on

the De Trinitate. Plato’s failure to differentiate between these two ways in which the intellect can

abstract (that is, distinguish intellectually) led him to the mistaken view that every thing which

can be abstracted, i.e., distinguished by the intellect, can also be separated in reality.44

Thomas

would have us recall that while this is true of that which the intellect distinguishes through

negative judgment, it does not apply to all things which the intellect distinguishes through simple

apprehension. If the earlier distinction in terminology between abstraction and separation has

now disappeared, the doctrine remains the same. There are two very different ways in which the

intellect can distinguish. It arrives at knowledge of being as being through a judging operation, a

negative judgment, to be sure; and this is not to be reduced to the level of simple

apprehension.45

”46

What was Aquinas’s existential contribution to the metaphysics of the separatio (as

contrasted to the long standing philosophical tradition of essentialism), and how does separation

43 Ibid. See in particular: “Ad primum ergo dicendum quod abstrahere contingit dupliciter. Uno modo, per modum

compositionis et divisionis; sicut cum intelligimus aliquid non esse in alio, vel esse separatum ab eo. Alio modo, per

modum simplicis et absolutae considerationis; sicut cum intelligimus unum, nihil considerando de alio.” 44

Ibid., end of reply to obj. 2: “Et quia Plato non consideravit quod dictum est de duplici modo abstractionis, omnia

quae diximus abstrahi per intellectum, posuit abstracta esse secundum rem.” For a similar criticism in his

Commentary on the De Trinitate see q. 5, a. 3 (Leon. 50.149:287-290). There Thomas also charges Pythagoras with

this same mistake. 45 To repeat a point already made, this becomes clear when one connects Thomas’s discussion in replying to

objection 2 in the text from Summa Theologiae, I, q. 85, a. 1 with his reply to objection 1. Cf. L. Elders, Faith and

Science. An Introduction to St. Thomas’ ‘Expositio in Boethii De Trinitate,’ Rome, 1974, p. 109. 46

J. F. WIPPEL, op. cit., pp. 49-51.

11

rooted in the second operation of the intellect differ from abstraction rooted in the first operation

of the intellect? Owens explains the crucial role of the Angelic Doctor’s teaching on judgment in

the grasping of existence and how this fits in with the separatio needed to do the science of

metaphysics, and how this is fundamentally different from the abstraction based on the first

operation of the intellect, namely, simple apprehension: “What effect will Thomas Aquinas’s

new doctrine of being and cognition have on the traditional problems of separation and

abstraction? It becomes basic in the explanation given them in the commentary on Boethius’ De

Trinitate. It allows the traditional confusion of abstraction with separation to be faced on a

different ground. Since the quiddity or nature is known through a non-synthetic activity of the

intellect, Aquinas (In Boeth. De Trin., v, 3, resp.; ed. Decker, pp. 181.17-186.12) is able to show

that it can be a distinct object of consideration without any separating activity on the part of the

intellect. This, then, is properly abstraction. The synthesizing activity of the intellect, on the

other hand, composes when it grasps being and divides when it asserts non-being. It, therefore, is

properly the mental activity to which separation may be attributed.

“In this way the basis for the distinction between separation and abstraction becomes

clearcut. It is the twofold activity of the human intellect. So: ‘In the operation by which it

composes and divides, it distinguishes one from another by understanding that the one does not

exist in the other’(p. 183.24-26; tr. Maurer, 2nd ed., p. 28). Existence and the kind of intellection

by which existence is known are accordingly the basis upon which the notion of separation, in

the context of the specification of the sciences, rests. Correspondingly nature and the intellectual

activity by which nature is apprehended provide the basis for abstraction properly so called: ‘In

the operation, however, by which it understands what a thing is, it distinguishes one from the

other by knowing what one is without knowing anything of the other, either that it is united to it

or separated from it. So this distinction is not properly called separation, but only the first. It is

correctly called abstraction”(ibid., lines 26-30).

“By abstraction, in consequence upon this doctrine, the objects of all sciences whatsoever

receive their status as knowable. The universal is abstracted from the singular, as required in

common by all the sciences: ‘and this indeed belongs to physics and to all the sciences in

general, because in every science we disregard the accidental and consider what is essential’(p.

186.19-21); tr. Maurer, pp. 31-32). Likewise by abstraction forms may be considered apart from

sensible matter, as with natures taken precisively and with the mathematicals: ‘…the operation

by which the quiddities of things are formed, which is the abstraction of form from sensible

matter; and this belongs to mathematics’(lines 16-18). The mathematicals, accordingly, are

restored to their pristine Aristotelian status of abstractions without being separate. Separation of

the mathematicals as well as of the universals is regarded as Pythagorean and Platonic (lines 21-

24).

“In this existential setting, then, abstraction is something that takes place only in simple

apprehension. It is the apprehension of quiddities or natures. It includes both cognition by way of

universality (called abstraction of a whole) and abstraction of a formal characteristic of a thing

aside from the subject (called abstraction of a part – In Boeth. De Trin., v, 3, resp.; pp. 185.20-

186.12). Through the latter type the mathematicals are isolated. No emphasis, however, is placed

on the crucial difficulties involved in grouping the mathematicals with precisely abstracted

12

quiddities. The one point made here is that both the universals and the mathematicals are the

work of abstraction, and not of separation properly understood.47

“But if this is the case, why are the most universal notions of all, namely being and the

other transcendentals, not included under the work of abstraction?

“The answer emerges from a closer study of the role played by an existence that can be

apprehended only in the synthesis of judgment. The nature known through simple apprehension

abstracts from all being. In consequence a thing can be known as a being only through reference

to what is grasped through judgment. A being is something that is, something that exists. Simple

apprehension can grasp the natures of things in ever widening universality up to the category of

substance. Even here, however, the notion of substance remains corporeal. One has no simple

apprehension of immaterial substance. Substance and body still coincide in the one notion.

“To advance beyond the corporeal, judgment must intervene. One has to take the notion

of substance, as abstracted from sensible things, and judge that the notion is not restricted to the

corporeal order. One does not see this through simple apprehension. Whether by faith or by

reasoning, one learns that God and spiritual souls are incorporeal yet substantial. From these

supersensible things the notion of corporeality has to be removed, while the notion of substance

is retained. This is done by judgment, not by abstraction. One has now a notion of substance that

is incorporeal. The concept of substance has accordingly been extended to the incorporeal

order.48

“The notion of substance as a notion extending to both corporeal and the incorporeal is

therefore not a concept reached by abstraction. It is attained on the basis of the separation that

takes place in the synthesizing and dividing cognition of judgment. No matter how much at first

sight the abstracting process might seem to continue from the specific through the generic grades

into the transcendental, a closer scrutiny shows definitely that the jump into the transcendental

order is more complex. The question is where an object like substance can be found to exist. The

metaphysical study shows that it exists in bodies and also exists in spirits. It is therefore

47

This topic as in the text of St. Thomas is discussed carefully by Robert W. Schmidt, L’emploi de la séparation en

métaphysique, “Revue Philosophique de Louvain,” 58 (1960), pp. 376-393. A survey of preceding literature on the

subject is given ibid., pp. 373-375. A shorter coverage may be found in the late Philip Merlan’s Abstraction and

Metaphysics in St. Thomas’ Summa, “Journal of the History of Ideas,” 14 (1953), pp. 284-291. The topic is touched

upon by A. Moreno, The Nature of Metaphysics, “The Thomist,” 30 (1966), pp. 110-119. It is debated by D. Burrell,

Classification, Mathematics, and Metaphysics, “The Modern Schoolman,” 44 (1966), pp. 13-34; Rejoinder to Dr.

Eslick, ibid., pp. 47-48; and L. J. Eslick, The Negative Judgment of Separation, ibid, pp. 35-46. A penetrating study

of the doctrine of Aquinas at In Boeth. de Trin., v, 3, may be found in L.-B. Geiger, Abstraction et séparation

d’après S. Thomas, “Revue des Sciences Philosophiques et Théologiques,” 31 (1947), pp. 3-40. In practice,

however, ‘abstraction’ is used frequently enough for ‘separation,’ even where according to the foregoing doctrine it

should be denied. The term is in fact ‘an analogue capable of being both affirmed and denied of certain concepts,’ as

noted by J. Cahalan, Analogy and the Disrepute of Metaphysics, “The Thomist,” 34 (1970), p. 422. Subsistent being,

for instance, in its divine reality, may be referred to as esse abstractum: ‘…sicut sola Dei substantia est ipsum esse

abstractum,’ De Subst. Sep., c. 13, Lescoe no. 71. Likewise esse abstractum is used for the Neoplatonic hypostasis,

In Lib. De Causis, prop. 4a, ed. Saffrey, pp. 29-30. Cf. Summa Theologiae, I, q. 40, a. 1, ad 1m; III, q. 17, a. 1c.; and

In Boeth. de Hebd., lect. 2, Calcaterra nos. 24-25. See also In II Metaph., lect. 1, no. 286. 48

See Schmidt, art. cit., pp. 382-383.

13

universal to both orders. It is separate from each of the two orders in the way a universal is

separate from any one of its particulars, and the way curvature is separate from snubness.

“In the case of substance, then, separation is not achieved through a simple inspection of

notions, as it is with the distinctions between the specific and generic grades. Accordingly

substance is not an instance of something separate just ‘in notion.’ It has to fall back on

existence. It is something that can exist both in the material and immaterial spheres. It is

something separate by way of existence, and knowable as separate only through reference to

existence. In the original notion attained through simple apprehension it does not just alone

manifest the wider extension. It has to be characterized in consequence as separate in notion and

existence.

“The same considerations hold for being. The notion of being is that of a thing in

reference to the thing’s existential actuality. The basic concept involved is that of something

sensible, for all cognition originates in sensation. But, like substance, being is shown through

metaphysical investigation to subsist in God and to be immaterial in the spiritual soul. It is

known as transcendent not through abstraction but through the separation that is effected by

judgment. Like substance it is separate in being, since unlike the mathematicals it can exist

immaterially. As separate, it is common being insofar as it extends to angels and spiritual souls

and their accidents. Though the entirely unique primary instance, subsistent existence, cannot

come under common being, the concept of being nevertheless extends to it as to the cause of

common being.49

“Novel and perhaps forced as this understanding of separation in being may seem, when

viewed against the Aristotelian background, it nevertheless parallels exactly the use of

‘transcendent’ in the thirteenth century. ‘Transcendent’ in one accepted meaning signified the

supersensible. It was what transcended sensible cognition. It referred to what was beyond time

and change and matter. It matched the sense in which God and the separate substances were

‘separate in being and notion.’ But ‘transcendent’ also meant things that spread across the

categories and outside them to God who is not in any category. The term included being, unity,

truth, goodness, and other characteristics. For Aquinas these also, and not only God and the

angels, were ‘separate in being and notion.’ The concepts of separation and transcendence

accordingly corresponded with each other in their different uses.

“Can any significant conclusions be drawn from this observation? Basically, sensible

matter is the operative concept. God and the angels transcend the sensible and are separate from

sensible matter in a way the mathematicals do not transcend and are not separate. That way is

real existence apart from matter. The transcendents can really exist without matter, the

mathematicals cannot. But existence is known only through judgment. Correspondingly, being

and the other transcendentals are known through reference to existence, again involving

judgment. They transcend, because they can refer to existence both in sensible matter and apart

from sensible matter. They are separate in being, because though they can have real existence in

49

“…Deus est causa ipsius esse communis…omnia existentia continentur sub ipso esse communi, non autem Deus,

sed magis esse commune continetur sub eius virtute…”(In de Div. Nom., v, 2, nos. 658-660. Cf. “…ens commune,

quod est genus, cuius sunt praedictae substantiae communes et universales causae.” (In Metaph., Proem.).

14

sensible matter they do not require it as do the mathematicals. From both viewpoints the decisive

factor is real existence.

“From the viewpoints of both separation and transcendence, then, existence is intimately

and necessarily involved in any metaphysical notion for Aquinas. The factor of existence is what

enables a concept to be understood in a way that extends beyond the sensible order. Only

through judgment, by which existence is grasped, is a concept freed from restriction to the

sensible. As far as simple apprehension is effective, concepts would always remain in the

sensible order. It is through separation effected by judgment that they transcend sensible nature

and become metaphysical. There need be little wonder that for Aquinas separation is the method

characteristic of, or proper to, metaphysics.”50

50

J. OWENS, Metaphysical Separation in Aquinas, “Mediaeval Studies,” 34 (1972), pp. 300-304.