[Article] Aquinas On Suppositum, Essence & Universals


Seth Kreeger
PhD Candidate
Dominican School of Philosophy and Theology

[online only response to daniel wagner, “the logical terms of sense realism”]

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Having read “The Logical Terms of Sense Realism: A Thomistic-Aristotelian & Phenomenological Defense” I find myself to be quite in agreement with Professor Wagner about the impossibility of nominalism to make sense of the way in which terms are used in everyday life. Nominalism is the position that universals are mere flatus vocis, breaths of the voice, not concepts, and have no foundation in things.[1] Among the other problems it causes, accepting nominalism makes the success and intelligibility of our everyday language – not to mention the successes of the modern sciences – baffling. As Wagner writes, “Nominalism means that, when I predicate ‘honey bee’ of the buzzing being on the flower, and then later of another buzzing being in my window, I am not actually predicating as a result of the fact that I apprehend as ontologically present in both individuals the essential meaning of ‘honey bee.’”[2] This in turn makes the use of terms as they are used in everyday life into an absurdity, because when we:[3]

predicate a meaning of an individual, we do so precisely because we believe that the meaning signifies what the individual is. And without this belief, it will be in principle impossible to predicate the definition at all because a contradiction will follow: one will both have to believe that the definition signifies what the individuals are, and not believe that the definition signifies what the individuals are.

If the nominalist were to accept this contradiction and tried to remain consistent, he would be reduced ad vegetabile, for both the mundane and scientific exercise of language require the very principle the validity of which he has just denied. To such a nominalist one might ask, perhaps somewhat cheekily, “why should I wish to converse with a vegetable?”

While nominalism cannot make sense of the use of language, an Aristotelian–Thomistic metaphysic regarding common essences can and does. In what follows, I will not address the philosophical problems of nominalism.  Rather I intend to draw on some of Aquinas’ texts concerning the reality of common natures, for as Professor Wagner made clear toward the end of his paper, it is precisely the same specific essence common to many particulars that grounds our use of terms in language.[4] While Wagner’s paper drew almost solely on Aristotle, I will attempt to provide the necessary metaphysical groundwork that underlies the use of logical terms in the Categories.

This response serves two purposes. First, it supports the general Aristotelian character of Wagner’s paper, while refining and developing its ontological foundation through an examination of various texts of St. Thomas Aquinas. In particular, Aquinas’ understanding of ‘suppositum’ and its real distinction from nature in material beings, as well the three different modes of being of essence provide real contributions to the solely Aristotelian approach. Second, this Thomistic framework, particularly the different modes of being of essence, will show how predicating the universal of the particular is possible.

1. Suppositum

Aquinas is a realist about universals, yet not a Platonic realist. This latter kind of realism would hold that universal forms exist separate from sensible substances. As we shall see, Aquinas holds that universal concepts have an immediate, or in some cases remote, foundation in reality and so are not mere flatus vocis, nor mental fictions. Because he is a realist, he holds that there really is something ontologically immanent to the various particulars of a species – as a principle of their being – making them all to be the kinds of things they are. This principle is common to many and grounds the predication of second substance of first substance, making it possible to state, e.g., “Plato and Socrates are rational animals.” Without such an ontologically immanent principle it would not be true to state that two entities, honey bees for example, are really the same kind of being. This real ontological principle that is common to many particular members of a various species, making them to be specifically one, though numerically different, can be seen in Aquinas’ distinction between suppositum, or the individual, and the common nature or essence in all material beings.

If I were sitting down with a friend while enjoying a cup of coffee at a coffeeshop, and–seeing that her eyes drift over my shoulder—happened to ask her what she was looking at, she would most likely respond by saying “the waiter over there,” or “that tree,” or “the tall man walking the beautiful German Shepard on the other side of the street.” The waiter, the tree, the tall man and the German Shepard are all instances of primary being, to use Wagner’s translation, or, to use the more traditional language, primary or first substance. They are all complete individuals existing in themselves and not in another, unlike the brown color of the tree, black color of the dog or height of the man. To use somewhat even more technical Thomistic and metaphysical language they are all supposita.[5] Loosely, we can think of a suppositum as an individual being, but more strictly a suppositum is “an individual complete in some nature.”[6] A suppositum is an individual in the genus of substance of which properties can be predicated and is not predicated of anything else. Socrates then is a suppositum, of which “old,” “white,” “wise” or “man” may be predicated.[7] We cannot, however, predicate Socrates of Plato and say, “Plato is Socrates.” J.L.A. West writes “First, ‘supposit’ refers to an individual insofar as it subsists in the genus of substance. Second, ‘supposit’ signifies a substance insofar as it is a thing having some kind of nature.”[8] We see quite clearly then that suppositum has the characteristics of not being in another being, not being predicated of another being and having a particular kind of nature, i.e., it is a particular kind of thing and so it is not a part of another substance like a hand or foot. Aquinas comments in Meta V.10, form is related to matter while essence is related to suppositum, “which is signified as having such an essence.”[9] To further help clarify supposita we might follow Wagner’s lead and say that they have no contraries, admit of no degrees, but while remaining numerically the same they can receive contrary predicates although not at the same time and in the same respect as when Socrates goes from being hot to cold.[10]

Aquinas also held throughout his career that, in material things at least, there is a distinction to be drawn between a suppositum and its nature.[11] This distinction is I think, implicit in Wagner’s paper for he deals with “primary being” at considerable length while he also states that one primary being is related to another of the same type insofar as they possess the same essence which the definition signifies.[12] Furthermore, he takes issue with Ockham’s claim the “man” signifies nothing that is really common to two existing men and the nominalist conclusion that a definition has no ontological foundation in primary beings or substances.[13] From this it is quite obviously gathered that according to Dr. Wagner’s approach there is something ontologically common to many primary beings of the same type. There are two notions we must keep in mind: first, there are primary beings, or as they are otherwise called supposita or first substances, and secondly, a common essence or nature making the predication of secondary substance of the supposita possible. Yet, we cannot say these two realities are completely identical – rather the suppositum or subject possesses a nature. In material beings, our primary focus here, the suppositum has a nature, but we cannot say it is a nature. From this discussion it can be seen that the suppositum and its characteristics are consonant with Aristotle’s treatment of primary substance in the fifth chapter of the Categories and constitute a refinement and development of the Aristotelian doctrine of primary substance. It seems that the only difference between “primary being” and “suppositum” is one of connotation where “suppositum” makes explicit that the individual being exists as the possessor of a particular kind of nature, includes its principles of individuation and is a complete being in itself.[14] Although a detailed discussion of the distinction in connotation between suppositum and first substance would perhaps be helpful for the Thomistic metaphysician I will forgo such a discussion as being incidental to the overall purpose of this response.

1.1. Suppositum in the Summa Theologiae

To help further clarify the nature of suppositum and its relation to essence we shall now turn to some key texts where Aquinas discusses the real distinction between suppositum and nature. In Summa Theologiae I.3.3[15] Aquinas holds that, in material creatures, suppositum and nature really differ, while in God and other immaterial substances they do not.[16] As J.L. West observes, although Aquinas hardly uses the language of “real distinction” he clearly intends a real distinction between suppositum and nature in material beings.[17] If this distinction is merely a distinction of reason then, as Gabriele Galluzzo has pointed out, there is no point drawing a distinction between the suppositum and nature in material creatures and contrasting this distinction with immaterial being who lack such a distinction, for even in immaterial beings a logical distinction between essence and suppositum is admissible.[18] Aquinas states in this article that the essence or nature signifies only what is included in the species, and is that whereby a man is man. Thus “humanity” signifies human natures as that by which man is man. The individualizing characteristics whereby Socrates is distinguished from Plato are not included in the notion of humanity, yet they are included in the individual man. Humanity is taken as the formal part of man in relation to the individualizing matter, while the suppositum is signified as a whole.[19]

If Socrates were Socrates by virtue of that whereby he is a man, then just as there cannot be many of Socrates so there could not be many men. Therefore, that which is a particular man includes more than does humanity. Aquinas concludes from this that humanity and a man cannot be wholly identical. There is, then, a principle common to many men, namely a human essence and something in addition to this – the individualizing characteristics that receive the essence.[20] To draw from Aquinas’ example in ST I.11.3, what makes Socrates a man is communicable to many men, but what makes him Socrates in particular can only be communicated to one man – Socrates.

1.2. Suppositum in De Potentia

We see Aquinas holding the same position in De Potentia 9.1.[21] Aquinas begins by distinguishing two meanings of substance. The first is the individual which is the ultimate subject of predication and singular in the genus of substance. In a second sense he refers to substance as the form or nature of a subject.[22] It is necessary to make the distinction between suppositum and nature for several subjects can have a common nature as for example several men all have the common nature of man. The common nature indicates what a thing is and is signified by the definition, so it is called essence or quiddity. Whatever, therefore, pertains to the common nature is included in the essence. However, this cannot be said of all that is found in the individual substance. What is found in the individual substance, Aquinas continues, is individual matter. The essence is then related to the individual substance as a formal part: “Therefore in things composed of matter and form, the essence is not quite the same as the subject, and wherefor it cannot be predicated of the subject: for it is not said that Socrates is his humanity.”[23] Aquinas then gives the two marks of substance taken as individual, first it subsists and is not in another. Secondly, in virtue of its subsistence it is able to be the foundation for accidents and sustains them. Following this Aquinas identifies substance taken as subject, with subsistence, hypostasis and first substance – all such names refer to the same thing and are only logically distinct. Aquinas concludes, “Essence, however, in material substances is not the same as these, nor is it altogether diverse since it has the essence as a formal part.”[24]

2. Three Modes of Being of Essence

Having seen that there is a real distinction between suppositum and nature or essence in all material beings, we will now turn to a more in-depth consideration of essence.  In De Potentia Aquinas writes:

While to receive terminates in having as its end, there are two ways of receiving and two ways of having. In one way matter has its own form, and a subject an accident, or in fact anything that is had beyond the essence of the haver: in another way the suppositum has a nature, as this man has humanity: for the nature is not beside the essence of the haver, indeed it is his essence, for Socrates is truly that which is a man.[25]

Again, we see Aquinas refer to the suppositum having a nature, just as man has a human nature. We also see Aquinas explicitly identify nature with essence. Nature as Aristotle states in Physics II.1 is an internal, essential principle of motion and rest.[26] Nature is, however, also the essence of a thing, but considered as the source of its proper activities. Nature and essence are only logically distinct, differing only in their connotation. Thus, to be a man is to be composed of matter and a rational soul or form. As Aquinas states in the second chapter of De Ente et Essentia while discussing material substance “essence in composed substances signifies the composition of matter and form.”[27]

If we turn to the third chapter of De Ente et Essentia we find Aquinas examining three different ways in which nature can be considered. In this text Aquinas is using nature without precision signified by the word “man” instead of human nature with precision signified by the word “humanity.” To say that Aquinas is using human nature without precision means simply that he is referring to human nature without prescinding from its individuating characteristics although without directly signifying them. But as Osborne suggests, there is no reason that “humanity” – nature considered with precision – cannot be considered in the same threefold way.[28]

First, nature can be considered absolutely in itself. In this way the nature contains only what belongs to the species itself. Considering human nature in this way it is neither white nor black and the like, nor one nor many.  If human nature absolutely considered were one, then it could never be found in many individuals as in how it is found in Plato and Socrates. Yet, neither can universality belong to the nature absolutely considered for then it would never be one and particular as when it is found in Socrates. In a like manner to be white, black, tall, short and similar accidental properties do not belong to the nature absolutely considered. For example, if to be tall belonged to human nature absolutely considered then there could never be short human beings. Secondly, nature can be considered in this or that thing, namely in the individual, or in the intellect. In individuals, nature has a multiplicity of beings according as it is received into many individuals.

Thus, we distinguish Socrates with his particular human nature that is specifically the same though numerically different, “because everything in him is individuated,” from Plato who is over there with his particular human nature.[29] In another way, when the intellect abstracts the essence or nature from all the particulars, disregarding their individuating principles and accidental differences, it regards the common nature as universal.

From this analysis it follows that the natures of sensible things, do not exist apart from sensible things they are the natures of, save only in the intellect that abstracts them. Aquinas can therefore say that humanity or man does not have being except in this or than man and likewise all other natures have being only in singulars or in the intellect.[30] Because of this, it can be seen how secondary substance can be said of primary substance, for secondary substance only exist by means of primary substance.[31]  As Wagner writes:[32]

The definition of a primary being is attainable through apprehension of the form/species (εἶδος) of each thing, which though in the individual is also separable and in the understanding. Form as such, then, can be taken to provide the basis for second being, along with the basis of the unity of the individuals making up a defined class. Essence as form (εἶδος) extends from primary being to secondary being and is the intelligible unity of both: εἶδος/eidos extends to both οὐσία/ousia taken in its primary sense as the particular individual[s] of sense experience and taken in its secondary sense as essence in the understanding and definition (genus, species, and difference). The identity between primary and secondary being is the principle of form. This allows us to explain the phenomenon of defining, already given to us in common experience.

As to one caveat, Wippel has pointed out, it must be remembered that the essence or nature of a suppositum is not to be identified with the second substance or secondary being of The Categories.[33] Instead essence as it exists in first substances or supposita is a principle of both first and second substance. Wagner concords with this when he quotes Aristotle holding that secondary beings are “the account of the being/essence and the definition”[34] and the “essence from primary being to secondary being … is the intelligible unity of both”[35] Perhaps only Plato would hold that secondary being is the being of and not the account of the essence. In confirmation, Aquinas states explicitly in Metaphysics VII. 2 while commenting on substance:

Whence it is evident that the division of substance put forth here is almost the same as that which is given in the Categories, for by subject here is understood first substance. And what he called the genus and the universal, which seem to pertain to genus and species, are contained under second substances. But, the essence, that is put forth here, is omitted in that work, because it does not fall in the order of the predicaments except as a principle; for it is neither a genus nor a species nor an individual, but is the formal principle of all of these.[36]

It is not all that surprising to find Aquinas commenting that substance taken as essence is omitted from the categories since that work is primarily a logical work.[37] Yet, because essence as it exists in particulars, is a principle of both primary and secondary substance, we can conclude that logic, and particularly the universal terms of logic, flows from the real and our grasp of individual beings, agreeing in species although different numerically. In this way the Categories is seemingly, although properly a logical work, ontologically informed.[38] 

3. The Understanding of the Intellect

In Sententia Libri Metaphysicae I.10, Aquinas comments that Plato’s theory of forms was mistaken because Plato wrongly assumed that the mode of being a thing has in reality, outside the mind that is, must be the same as the mode of being it has when it is known or inside the mind. But, concludes Aquinas, it is not necessary that a form, although the same form that exist both in the mind and in reality, have the same mode of being in the intellect as it does in reality, for everything that is received is received according to the mode of the receiver. Thus, we cannot conclude from the fact that we apprehend forms as universal in the intellect and use abstract terms in speech that universal forms exist outside the intellect. Explaining this point, Aquinas writes:[39]

When our intellect conceives the quiddity of a thing that is subsistent and outside the mind, there is a certain kind of communication of the thing existing in itself, inasmuch as our intellect receives in some way from the exterior thing the form of the latter: and this intelligible form existing in our intellect proceeds in some way from that exterior thing. But, because, the exterior thing differs in nature from the understanding intellect, the form comprehended by the intellect and the form of the subsistent thing differ in their respective beings.

Here Aquinas explicitly holds that it is the same form or nature that exists in various substances and also in the intellect.[40]  The intellect knows insofar as it is moved from potency to act by the acquisition of a form or nature and therefore the form is a principle of knowledge for the intellect but is also a principle of being for the existing substance by making it to be the kind of being that it is. Forms, then, exist in the intellect according to a different mode from the way they exist in primary substances; but what is this mode?  It is the universality that accompanies the nature in the intellect – having been stripped of all individuating characteristics and accidental features.[41] Thus, humanity exists in the individual men, yet when we form a notion of humanity abstracted from all the individuating conditions we possess a universal concept.[42]  Wagner echoes this point when he states “A singular form, species, or essence is capable of two modes of existence, one in the primary being making it to be the kind of thing that it is, and one separated or abstracted in the human intellect.”[43] Aquinas echoes this point in his commentary on De Anima,[44]

The intention of universality is not able to be attributed to a common nature except according to the being it has in the intellect: for only thus is one predicated of many, as it is understood without the principles by which the one is divided into many. Whence it follows that universals insofar as they are universal do not exist except insofar as they are in the soul. But these natures to which the intention of universality accrues are in things. And on account of this that common names signifying these natures are predicated of individuals; but not the names that signify intentions. For Socrates is a man, but is not a species, although man is a species.

From this text we see that the natures do not exist outside the mind qua universal, but the natures that exists in a universal way in the intellect also have being in things. It is in this context that Aquinas’ Sententia Libri Metaphysicae VII text has to be interpreted: essence in the particular is not the universal concept that exists in the mind, although insofar as essence is the principle of the universal, in a loose manner of speaking we can say that universals only have being in the mind or in things.

Considering the concepts themselves, or secondary substances, certain kinds of concepts are known as first intentions. They are concepts of realities.[45] These are not the only concepts we can form, as we can also form concepts of concepts. Yet, all our concepts can be traced back to the mind’s contact with the real as their immediate or mediate foundation. Aquinas holds that reality corresponds to a concept in two different ways.[46] In the first way when we form a concept of a real beings existing outside the mind – forming the universal concept of “man” and “stone.”. These concepts have an immediate foundation in reality. Second, indirectly when a concept is formed following upon the act of the intellect so that “the reality corresponds to the consideration of the intellect mediately – through the medium of the intellect’s concept.”[47] This is to say that when the intellect forms various universal concepts it can then reflect on its own concepts and form a more universal concept. In this way we form notions such as “genus” or “species.” There is nothing in reality that directly corresponds to these concepts. For example, there is nothing in reality corresponding to the notion of “genus” in the way that all the existing men correspond to the concept “man,” but there is something in reality that is the foundation for this mental act of conceiving a genus – for example the sensible natures in both human beings and other animals giving rise to the concept “animality.” These later notions are second intentions, or “concepts of concepts.”[48] Although strictly speaking the object of a second intention is the relation of an object and a concept achieved by directing one’s mental attention to an object as it exists in the mind.[49]

Consequent upon our mood of understanding, which is drawn from sensible objects and the intellect’s ability to consider forms as universal thereby giving the form an intentional existence in the mind, we can make sense of the different ways in which terms are used. Particularly, we can make sense of how different terms are used even if they signify the same res, for the use of words and names follow from the conceptions in the mind.[50] Such is the case with “man” and “humanity.” While both names arise from the same form or nature and so signify the same res, we cannot say “Socrates is humanity,” but we can say “Socrates is a man.” This is because a man has a human essence but is not identical to it and “humanity” signifies human nature but does so abstractly and as a formal part, signifying only that by which man is a man. Precisely because human nature is taken as the formal part in man, i.e. because there is a real distinction between suppositum and nature, we cannot say “Socrates is humanity.” However, the word “man” signifies the same human nature, yet not as a formal part but as a whole. Thus, it signified human nature concretely as something composed of humanity and what has humanity.[51] Therefore “man” signifies human nature without precision, and so it can be said of Socrates as when we say “Socrates is a man” – “man” suppositing personally.[52]

4. Conclusion

Although, perhaps nothing groundbreaking has been put forth in this response and more could be said, especially in response to nominalism from a Thomistic perspective, I have supported the claims made by Professor Wagner. I have done so by drawing on Aquinas rather than Aristotle and showing that the ontological realism regarding essences makes possible the predication of universal concepts of individuals existing in reality without falling into the error of Platonic realism. Furthermore, this ontological realism is the necessary metaphysical foundation for avoiding the contradictions inherent in nominalism. From this we see that St. Thomas and Aristotle are of one mind concerning the reality of common natures. We have also seen that the more uniquely Thomistic distinction between suppositum and nature plays an important role in these considerations. Thus, Aristotle and Aquinas have shown “us that the essential parts of human language and their syntax cannot be conceived except as through a relation to being and reality.”[53]

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References Historically Layered

ARISTOTLE (384-322bc)

c.353-47bc.            Φυσικὴ ἀκρόασις, in the Basic Works of Aristotle, prepared by Richard McKeon, in the English translation by R. P. Hardie and R. K. Gaye, Physics (New York: Random House, 1941): 218-394 (complete).

AQUINAS, Thomas (1225—1274).

[All references to the digital editions of Aquinas’ works stored on Corpus Thomisticum.]

1252/56a.              Scriptum super libros Sententiarum (In Sent.)

1252/56b.             De ente et essentia

1259/65.                 Summa contra Gentiles

1265-66.                Quaestiones disputatae de potentiae Dei

1266-68.                Summa theologiae, prima pars (ST Ia)

1268.                     Sentencia libri De Anima

1269-70.                Summa theologiae, prima secundae (ST Ia-IIae)

1270-71.                Summa theologiae, secunda secundae (ST IIa-IIae)

1270/71.                 Sententia super Metaphysicam (In Metaphysicae)

1272-73.                Summa theologiae, tertia pars (ST IIIa)

DEFERRARI, Roy (1 June 1890—1969 August 24).

1960.            A Latin-English Dictionary of St. Thomas Aquinas (Boston: St. Paul Editions, 1986).

GALLUZO, Gabriele

2004.  “Aquinas on Common Nature and Universals” in Recherces de théologie et philosophie médiévales, 71.1: 131-71.

KEMPLE, Brian (31 May 1986—).

2017.  Ens Primum Cognitum in THomas Aquinas and the Tradition: The Philosophy of Being as First Known (Boston: Brill | Rodopi).

MAURER, Armand (21 January 1915—2008 March 22).

1968.  “Introduction” to Aquinas On Being and Essence, translated by Armand Maurer (Ontario, Canada: PIMS): 12-13.

OSBORNE, Thomas M.

2017.  “Which Essence is Brought into Existence by the Existential Act?” in The Thomist: A Speculative Quarterly Review, 81.4 (October): 471-505.

WAGNER, Daniel

2019.  “The Logical Terms of Sense Realism: A Thomistic-Aristotelian & Phenomenological Defense” in Reality: a journal for philosophical discourse, 1.1.


2007.  “Distinction between Supposit and Nature” in Peter Kwasniewski (ed.), Wisdom’s Apprentice: Thomistic Essays in Honor of Lawrence Dewan, O.P. (Washington, D.C.: CUA Press): 85-106.

WIPPEL, John F. (21 August 1933—).

2000.  The Metaphysical Thought of Thomas Aquinas: From Finite Being to Uncreated Being (Washington, D.C.: CUA Press).

WUELLNER, Bernard, S.J. (c.1905—1997 March 3).

1956.  Dictionary of Scholastic Philosophy (Milwaukee: The Bruce Publishing Company). Republished (Fitzwilliam, NH: Loreto Publications, 2012).

[1] Bernard Wuellner 1956: Dictionary of Scholastic Philosophy, 81.

[2] Daniel Wagner 2019: “The Logical Terms of Sense Realism: A Thomistic-Aristotelian & Phenomenological Defense”, 21.

[3] Ibid, 23.

[4] Ibid, 25.

[5] “Hypostasis” is another word that means essentially the same thing as suppositum, it is merely the Greek equivalent. Although sometimes “hypostasis” is reserved to refer to persons. Wuellner 1956: Dictionary of Scholastic Philosophy, 55. See also, Thomas Aquinas 1265-66: Quaestiones Disputatae de Potentia, (De potentia hereafter) q.9, a.1. For full biographical information concerning the works of St. Thomas please see the bibliography. All translations, unless otherwise indicated, are my own.

[6] J.L.A. West 2007: “Distinction between Supposit and Nature,” 86. Suppositum is defined by Bernard Wuellner as “a substance that is complete in itself and uncommunicated; an ultimate complete subject of its own being.” Wuellner 1956: Dictionary of Scholastic Philosophy, 121. Suppositum is defined in A Latin-English Dictionary of St. Thomas Aquinas as “the individual substance of a certain kind which is the subject of existence and all accidental modifications which constitute the individual.” Roy Deferrari 1960: A Latin-English Dictionary of St. Thomas Aquinas, 1018.

[7] West 2007: “Distinction between Supposit and Nature,” 87.

[8] Ibid, 88.

[9] Thomas Aquinas 1270/1: In metaphysicae lib.5, lec.10. “Sed forma refertur ad materiam, quam facit esse in actu; quidditas autem ad suppositum, quod significatur ut habens talem essentiam.”

[10] Wagner 2019: “The Logical Terms of Sense Realism,” 16.

[11] For a more complete discussion of all the texts in which Aquinas lays out his understanding of suppositum see John Wippel 2000: The Metaphysical Thought of Thomas Aquinas, 239-253.

[12] Wagner 2019: “The Logical Terms of Sense Realism,” 25.

[13] Ibid, 20.

[14] 1265-66: Quaestiones Disputatae de Potentia 9.1 ad 6. Aquinas states that individual matter is included in the meaning of material hypostasis or subsistence.

[15] Thomas Aquinas 1266-68: ST Ia, q.3, a.3.

[16] To say that suppositum and nature differ, or that they are really distinct is to say that the distinction between them is not merely terminological or the same reality viewed under different descriptions like the distinction between man and rational animal. This is not to say that they are physically separable. Wippel has pointed out a change at least in Aquinas’ terminology. In Quodlibet II, q. 2, a. 2 Aquinas begins to talk of immaterial substances, i.e. angels, also possessing a distinction between suppositum and nature. Wippel 2000: The Metaphysical Thought of Thomas Aquinas, 251.

[17] West 2007: “Distinction between Supposit and Nature,” 93.

[18] Gabriele Galluzzo 2004: “Aquinas on Common Nature and Universals”, 139.

[19] See also 1272-73: ST IIIa, q.2, a.2: “If nothing is found to be added to what pertains to the notion of the species, there would be no necessity of having to distinguish the nature from the suppositum of the nature, which is the individual subsisting in that nature, because every individual subsisting in some nature would be altogether the same with its nature. But in certain subsisting things there is found something that does not pertain to the notion of the species, such as accidents and individuating principles, which appears chiefly in those which are composed of matter and form. Hence in such as these the nature and the suppositum according to reality; not as if they were wholly something separate, but because in the suppositum is included the nature of the species, and in addition certain other things beyond the notion of the species. Hence the suppositum is signified as a whole having its nature as its formal part and perfective of it; and consequently in such as are composed of matter and form the nature is not predicated of the suppositum, for we do not say that this man is his humanity. But if there is a thing in which there is nothing beyond its species or nature, as in God, the suppositum and the nature are not distinct according to reality, but only in our way of having to understand, inasmuch it is called ‘nature’ as it is an essence, and a ‘suppositum’ as it is subsisting.” – “Et si quidem his quae ad rationem speciei pertinent nihil aliud adiunctum inveniri posset, nulla necessitas esset distinguendi naturam a supposito naturae, quod est individuum subsistens in natura illa, quia unumquodque individuum subsistens in natura aliqua esset omnino idem cum sua natura. Contingit autem in quibusdam rebus subsistentibus inveniri aliquid quod non pertinet ad rationem speciei, scilicet accidentia et principia individuantia, sicut maxime apparet in his quae sunt ex materia et forma composita. Et ideo in talibus etiam secundum rem differt natura et suppositum, non quasi omnino aliqua separata, sed quia in supposito includitur ipsa natura speciei, et superadduntur quaedam alia quae sunt praeter rationem speciei. Unde suppositum significatur ut totum, habens naturam sicut partem formalem et perfectivam sui. Et propter hoc in compositis ex materia et forma natura non praedicatur de supposito, non enim dicimus quod hic homo sit sua humanitas. Si qua vero res est in qua omnino nihil est aliud praeter rationem speciei vel naturae suae, sicut est in Deo, ibi non est aliud secundum rem suppositum et natura, sed solum secundum rationem intelligendi, quia natura dicitur secundum quod est essentia quaedam; eadem vero dicitur suppositum secundum quod est subsistens.”

[20] There is then a real distinction between suppositum and nature in all material beings. It is, however, of extreme importance to keep in mind that though suppositum an nature are really distinct they cannot exist physically separated from the other, nor is the distinction between them of two res, like between a door and a doorknob. Rather it is a distinction between the individual and that by which the individual is the kind of thing that it is – its essence or nature. West 2007: “Distinction between Supposit and Nature,” 93.

[21] See also 1265-66: De potentia q.7, a.4: “Homo autem qui habet humanitatem, potest aliquid aliud habere quod non sit de ratione humanitatis, sicut albedinem et huiusmodi, quae non insunt humanitati, sed homini. In qualibet autem creatura invenitur differentia habentis et habiti. In creaturis namque compositis invenitur duplex differentia, quia ipsum suppositum sive individuum habet naturam speciei, sicut homo humanitatem, et habet ulterius esse: homo enim nec est humanitas nec esse suum” – “But man, who has humanity, can have something else which is not of the ratio of humanity, such as whiteness and such things like this which are not included in humanity but belong to the man. But in creature a distinction is found a distinction between the one possessing a thing and the thing possessed. For example, in composite creatures there is a twofold distinction; because the supposit or individual has the nature of its species, as a man has humanity, and also has being: for a man is neither humanity nor his own being.”

[22] Interestingly, in this text from Quaestiones Disputatae De Potentia, we see Aquinas offers the same division of substance as he does in Sententia Libri Metaphysicae V.10

[23] 1265-66: De potentia, q.9, a.1, c.: “Et ideo in rebus, ex materia et forma compositis, essentia non est omnino idem quod subiectum; unde non praedicatur de subiecto: non enim dicitur quod Socrates sit una humanitas.”

[24] Ibid: “Essentia vero in substantiis quidem materialibus non est idem cum eis secundum rem, neque penitus diversum, cum se habeat ut pars formalis; in substantiis vero immaterialibus est omnino idem secundum rem, sed differens ratione.”

[25] 1265-66: De potentia, q.2, a.1, ad.2: “Quod cum recipere terminetur ad habere, sicut ad finem; dupliciter dicitur aliquid esse recipiens, sicut dupliciter est, habens. Habet enim uno modo materia formam suam, et subiectum accidens, vel qualitercumque habitum est extra essentiam habentis; habet autem alio modo suppositum naturam, ut hic homo humanitatem; quae quidem non est extra essentiam habentis, immo est eius essentia. Socrates enim est vere id quod homo est.”

[26] Aristotle c.353-47bc.: Physics, 192b 21-23.

[27] Thomas Aquinas 1252/56b: De Ente et Essentia, “nomen essentiae in substantiis compositis significat id quod ex materia et forma compositum est.” We can see from Professor Wagner’s comments that his position although perhaps at first glance is at odds with what Aquinas has to say is actually quite close to Aquinas’ position. He writes, “though Aristotle is clear that matter is an element of the essential subject of a physical being, he nonetheless gives a special role to form as essence in the most proper sense at Physics II.3.” Here Wagner states that matter is essential to a physical being, while Aquinas stresses the primary of substantial form as the principle of actuality within the essence of physical beings.  Wagner 2019: “The Logical Terms of Sense Realism,” 36.

[28] Thomas M. Osborne Jr. 2017: “Which Essence is Brought into Existence by the Existential Act?” 478. For a further discussion of nature taken with and without precision see footnote 56 below.

[29] Thomas Aquinas 1252/56b: De Ente et Essentia: “In Socrate non invenitur communitas aliqua, sed quicquid est in eo est individuatum.” 1265-66: De Potentia q.2, a.1: “human nature is not one in both Socrates and Plato, but the essential notion of humanity is the same in both.”  To make this somewhat more transparent, Aquinas writes in 1259/65: Summa Contra Gentiles lib.1, c..65: “the singular essence is composed of designated matter and individuated form. Therefore, the essence of Socrates is composed of this body and this soul, just as the universal essence of man is composed of soul and body… just as the later principles fall within the definition of man taken universally, so the former principles would be included in the definition of Socrates if he could be defined.” There is therefore a sense in which we can speak of an individual essence or specific essence whereby Socrates is Socrates. Cf. 1259/65: Summa Contra Gentiles lib.2, c.92

[30] Thomas Aquinas 1252/56a: Scriptum super Sententiis lib.3, d.2, q.2, a.3; 1259/65: Summa Contra Gentiles lib.1, c.65; lib.2, c.5; c.75.

[31] 1270/71: In metaphysicae, lib.5, lec.10.  A particular substance differs from universal substance in these three ways, first, a particular substance is not predicated of inferiors, as a universal substance is; second, universal substance subsists except by reason of a particular substance, which subsists in itself and third, universal substance is present in many things, whereas a particular substance is not but is distinct and separate from everything else. “Et quantum ad haec tria differt substantia particularis ab universali. Primo quidem, quia substantia particularis non praedicatur de aliquo inferiori, sicut universalis. Secundo, quia substantia universalis non subsistit nisi ratione singularis quae per se subsistit. Tertio, quia substantia universalis est in multis, non autem singularis, sed est ab omnibus separabilis et distincta.”

[32] Wagner 2019: “The Logical Terms of Sense Realism,” 25.

[33] Wippel 2000: The Metaphysical Thought of Thomas Aquinas, 207.

[34] Wagner 2019: “The Logical Terms of Sense Realism,” 24. Emphasis is mine. Professor Wagner also states that the account signifies the essence. Ibid, 8.

[35] Ibid, 37.

[36] 1270/71: In metaphysicae, lib.7, lec.2, n.6: “Unde patet quod fere eadem est divisio substantiae hic posita, cum illa quae ponitur in praedicamentis. Nam per subiectum intelligitur hic substantia prima. Quod autem dixit genus et universale, quod videtur ad genus et species pertinere, continetur sub substantiis secundis. Hoc autem quod quid erat esse hic ponitur, sed ibi praetermittitur, quia non cadit in praedicamentorum ordine nisi sicut principium. Neque enim est genus neque species neque individuum, sed horum omnium formale principium.”

[37] 1270/71: In metaphysicae, lib.7, lec.13.

[38] Wagner 2019: “The Logical Terms of Sense Realism,” 14.

[39] 1265-66: De Potentia q.2, a.1. “Cum enim alicuius rei extra animam per se subsistentis noster intellectus concipit quidditatem, fit quaedam communicatio rei quae per se existit, prout a re exteriori intellectus noster eius formam aliquo modo recipit; quae quidem forma intelligibilis, in intellectu nostro existens, aliquo modo a re exteriori progreditur. Sed quia res exterior diversa a natura intelligentis est; aliud est esse formae intellectus comprehensae, et rei per se subsistentis.”

[40] See also Osborne 2017: “Which Essence is Brought into Existence by the Existential Act?” 491.

[41] Ibid, 491.

[42] Ibid, 490.

[43] Wagner, “The Logical Terms of Sense Realism,” 26.

[44] Thomas Aquinas 1268: Sentencia libri De Anima lib.2, lec.12: “Sic igitur patet, quod naturae communi non potest attribui intentio universalitatis nisi secundum esse quod habet in intellectu: sic enim solum est unum de multis, prout intelligitur praeter principia, quibus unum in multa dividitur: unde relinquitur, quod universalia, secundum quod sunt universalia, non sunt nisi in anima. Ipsae autem naturae, quibus accidit intentio universalitatis, sunt in rebus. Et propter hoc, nomina communia significantia naturas ipsas, praedicantur de individuis; non autem nomina significantia intentiones. Socrates enim est homo, sed non est species, quamvis homo sit species.” Emphasis is mine.

[45] Armand Maurer 1968: “Introduction” to Aquinas’ 1252/56b: On Being and Essence, 12.

[46] 1265-66: De Potentia q.1, a.1, ad.10.

[47] 1265-66: De Potentia q.1, a.1, ad.10: “Alio modo mediate, quando videlicet aliquid sequitur actum intelligendi, et intellectus reflexus supra ipsum considerat illud. Unde res respondet illi considerationi intellectus mediate, id est mediante intelligentia rei: verbi gratia, intellectus intelligit naturam animalis in homine, in equo, et multis aliis speciebus: ex hoc sequitur quod intelligit eam ut genus. Huic intellectui quo intellectus intelligit genus, non respondet aliqua res extra immediate quae sit genus; sed intelligentiae, ex qua consequitur ista intentio, respondet aliqua res.”

[48] Maurer 1968: “Introduction” to Aquinas’ 1252/56b: On Being and Essence, 13.

[49] Wuellner 1956: Dictionary of Scholastic Philosophy, 63. For a more detailed discussion of second intentions and their relation to first intentions see: Brian Kemple, Ens Primum Cognitum in Thomas Aquinas and the Tradition (Boston: Brill Rodopi, 2017), 58-68.

[50] 1266-68: Summa Theologiae Ia, q.13, a.1.

[51] 1259/65: Summa Contra Gentiles lib.4, c.81

[52] To help clarify this point Osborne (2017: “Which Essence is Brought into Existence by the Existential Act?”, 479) writes, “‘Humanity’ is the human essence taken with precision, and ‘man’ is the same essence taken without precision. We cannot say ‘Socrates is humanity’ but we can say ‘Socrates is a man.’ Essence taken with precision is not a whole in the way that man is, but instead a formal part of this whole.”  Further, Osborne writes (ibid, 481), “The signification of a term is more or less what that term makes known or means, whereas the logical supposit is more or less the reference of a term. Both ‘man’ and ‘humanity’ signify the same thing, but in different ways. For instance, in the Summa theologiae Thomas writes ‘this name ‘man’ signifies humanity in the supposit.’ The difference is that the concrete term ‘man’ can have personal supposition, meaning that it can take the place of an individual, whereas the abstract term ‘humanity’ always indicates an essence or formal part that inheres in such a supposit…. The terms ‘humanity’ and ‘animality’ signify the same essences that the terms ‘man’ and ‘animal’ signify. Nevertheless, they lack personal supposition, since there is no separately existing ‘humanity’ or ‘animality.’”

[53] Wagner, “The Logical Terms of Sense Realism,” 2.


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