Sample course paper

“On Method in Reading the DE ENTE ET ESSENTIA:

An Analysis of the Accounts of Joseph Owens, John Wippel and R. E. Houser”

Tracy Wietecha (2014, based on 2013 course paper)

Abstract: In this paper I explore methodological approaches to Aquinas’ argument for a real distinction between essence and existence in creatures in De Ente et Essentia.  Joseph Owens and John Wippel examine the text through three stages which, they conclude, result in a demonstration for the real distinction.  I contrast this approach with R.E. Houser, who argues that Aquinas’ text, which proceeds dialectically, must be understood within the context of its sources, namely Avicenna’s Metaphysics of the Healing and The Intentions of the Philosophers by al-Ghazali.  I will come to two adjudications: first I will offer an evaluative judgment on Owen’s and Wippel’s disagreement on which stage Aquinas demonstrates a real distinction; second I will offer an evaluative judgment on the nature of the treatise as a whole, suggesting that the methodology of source based contextualism offers another way to read the De Ente.

1. Introduction

Among the many commentators and writers on the real distinction between essence and existence in the thought of Thomas Aquinas, the writings of Joseph Owens and John Wippel are insightful contributions to the discussion worthy of thoughtful consideration and discussion.  Owens and Wippel both argue that Aquinas demonstrates a real distinction between essence and existence in the De Ente et Essentia; they differ, however, on what stage in the argument Aquinas establishes the real distinction.  Here my purpose is to shed new light on the issue by analyzing their views together with another more recent and distinct methodological approach to the question of the real distinction in Aquinas.  R.E. Houser’s 2007 article “The Real Distinction and the Principles of Metaphysics,” studies Aquinas’ text in detail through the sources which influenced the text, namely Avicenna’s Metaphysics of the Healing and The Intentions of the Philosophers by al-Ghazali available to Aquinas in Latin translation.  In this article my purpose is also to come to a twofold adjudication.  First, I will offer an evaluative judgment on Owen’s and Wippel’s disagreement on which stage Aquinas demonstrates a real distinction.  Second, I will offer an evaluative judgment concerning the nature of the treatise as a whole.  I will do this by critical consideration of the methodologies employed by these three thinkers. 

2. Owens and Wippel on the Real Distinction

Aquinas’ argumentation in the De Ente revolves around establishing how simple substances (such as angels), which are not composed of matter and form, possess form and esse without thereby possessing esse as pure act which is to be found only in God.  Aquinas achieves this by first establishing a real distinction or composition between essence and existence in which he is then able to assert potency and act in simple substances.  Wippel outlines the argument for the real distinction in the De Ente into the following three phases, respectively: 

P1: the intellectus essentiae approach

P2: the impossibility of more than one being whose quiddity is its existence

P3: the (apparent) argument for the existence of God

2.1 The First Phase

At P1, Aquinas states that an essence can be understood without knowing whether or not it exists.  Aquinas offers two examples.  One can know the essence of a human person without knowing whether it exists and one can know the essence of a phoenix without knowing whether or not the phoenix actually exists, reasoning commonly denominated as the intellectus essentiae approach or argument.  Existence, then, would seem in all cases to be distinct from essence, unless there is something whose quiddity is its existence.  Owens notes that at P1 Aquinas draws out the two notions of essence and existence.  Essence is known through simple apprehension; existence is known through judgment according to Owens.  Although Aquinas does not state here what kind of a distinction the intellectus essentiae approach establishes, both Owens and Wippel agree that there is only a conceptual distinction at P1.

The intellectus essentiae approach in the De Ente is similar to other texts of Aquinas where he references a real distinction.   In 1 Sent. d.8 q.4 a.2 Aquinas mentions a real distinction between essence and existence while arguing that God is not under a genus.  He explains that in entities or beings under a genus, one is able to think of the entity’s essence without knowing whether or not the entity exists.  Paraphrasing Avicenna, Aquinas explains that for all beings in a genus quiddity is other than its being.  One can think of the quiddity of humanity without knowing whether a human person does indeed exist.  This is because being is accidental to the quiddity humanity.  The being of God, on the other hand, is not accidental to his essence.  God’s quiddity is his existence.  Thus, in this context Aquinas references a real distinction between essence and existence for entities contained within a genus through reasoning which is similar to the example he uses in the intellectus essentiae approach.  A thing’s quiddity does not cause the thing’s existence.  This distinction is not found in God, however, because God’s quiddity is his existence.  God is therefore not under a genus.  As Owens points out, the distinction of essence and existence for things contained within a genus has to be a real distinction found in real entities.  Yet, Aquinas does not explain in this text how he reaches this conclusion. 

Wippel compares 1 Sent. 8.4.2 with De Veritate 27.1.ad.8.  Although the topic under examination in this passage of De Veritate is grace, Wippel points out that Aquinas’ argumentation is philosophical.  Aquinas argues in De Veritate that grace is something positively created.  Objection eight, however, states that since grace is simple and not composed, it cannot be created.  Only things which are under the genus of substance are composed.  Aquinas replies to the objection by explaining that all things which fall under the category of substance contain a real composition of essence and existence.  There must be a real distinction between essence and existence because, if not, then one would be unable to differentiate between the existence of this particular thing with other things that have the same specific quiddity.  Wippel does not believe that Aquinas’ argument for a real distinction in De Veritate relies upon prior knowledge of God’s existence.  Yet, is not the existence of God already in some important way assumed in De Veritate?  Wippel contends that the main line of argumentation in this passage is similar to 1 Sent. 8.4.2.  The main reasoning in both passages, for Wippel, is not the intellectus essentiae argument (which is not present in the De Veritate passage) but rather the reasoning that things which share the same quiddity are distinguished or individuated by their esse.  It seems that Owens would agree with Wippel’s interpretation of these two passages, however, with the exception of concluding to a real distinction prior to knowledge of God’s existence.

2.2 The Second Phase

After the intellectus essentiae approach, Aquinas’ argument in the De Ente moves onto P2 in which he reasons that, if there is a being whose quiddity is its existence, this being could not be multiplied.  Owens notes that in other works where Aquinas references a real distinction, an argument for the existence of God precedes the mention of a real distinction or Aquinas assumes the existence of God.  In the De Ente, however, before making an argument for the existence of God, Aquinas first states that if a being’s quiddity is its existence, this being could not be multiplied.  According to Owens and Wippel Aquinas does not assume that this being (God) exists.  Aquinas then shows that a being whose quiddity is its existence “cannot be but one.”  At the end of P2 both Owens and Wippel agree that Aquinas’ conclusion is positive and not hypothetical.  They disagree, however, on whether or not P2 admits of a real distinction.  Owens does not believe Aquinas reaches a real distinction at P2.  Wippel, however, asserts that P2 admits of a real distinction.

According to Wippel Aquinas’ conclusion at the end of P2 holds whether or not this being (God) actually exists.  Aquinas’ conclusion reaches a factual distinction between essence and existence, which for Wippel is a real distinction.  Owens objects to Wippel’s conclusion, stating that Wippel’s reasoning proceeds from an examination of concepts to the realm of the ontological.  In response, Wippel acknowledges that Aquinas does argue from concepts to a distinction in reality; however, Wippel makes a distinction between two possible ways to argue from concepts to reality.  The first way is to argue from the positive content of a concept to its actuality, as when one reasons from the concept of God as a being which no greater can be thought to God’s real existence.  The second way reasons from the impossibility of a thing to its nonexistence in reality, for example a square circle. Wippel maintains that Aquinas’s argumentation in the De Ente uses the latter method.   As it is impossible for there to be a square circle so it is impossible for there to be more than one being whose quiddity is its existence.  Wippel, therefore, concludes that this account does not fall into the sort of reasoning found, for instance, in Anselm’s argument for God’s existence, which Aquinas clearly rejects. 

Owens also objects to Wippel’s interchangeable use of the terms “factual” and “real” otherness. While Owens does not object to Wippel’s use of the term “factual otherness” at P2 of the argument in the De Ente, Owens states that a factual distinction between essence and existence cannot also be called a real distinction; the terms factual and real are not interchangeable.  The conclusion of a factual distinction still leaves open the question whether this distinction has ontological bearing; thus it has not yet reached a demonstration of real distinction.  In response to Owens, Wippel cites other texts where Aquinas’ argumentation is similar to P2.  One such text is the Summa Contra Gentiles II, ch. 52. 

In Summa Contra Gentiles (SCG) II, ch. 52 Aquinas wants to show that the being of intellectual substances (such as angels) is different from subsistent being.  Aquinas explains that nothing can be added to subsistent being and that it is impossible for there to be more than one being whose quiddity is its existence.  While the argumentation Aquinas employs in the SCG is similar to the argumentation of S2, a major difference remains.  In the context of the SCG Aquinas has already proven the existence of God, as he chose to mention explicitly.  Aquinas states that God as subsisting being has already been established in Book One.  Wippel acknowledges this reference to the existence of God; still, Wippel believes that despite this, the argumentation for a real distinction in the De Ente still holds.  It seems, however, that Owens’ objection still stands.  The distinction made in SCG between existence and essence in creatures seems to be drawn from the fact that God is subsistent being. 

Further, Owens contends that one cannot grasp existence as a real nature, unless one has first proven the existence of God.  Owens’ objection suggests that Wippel’s argument assumes the conception of existence since for Owens one cannot understand existence itself until one has shown that God is subsistent esse.  Wippel, however, believes that Owens’ objection “remains unproven either philosophically or textually.”  Yet, in order to reach the real distinction one would first need to accept Aquinas’ conception of being and thus one would need to, at least implicitly, accept the existence of God.  In this context Aquinas is working within the metaphysical framework of his thinking, which includes his conception of being. 

2.3 The Third Phase

P3 in the De Ente is an argument for the existence of God.  Aquinas writes that there must be a first cause which is the cause of existence of all other things.  This first cause is “existence alone,” God.  The intelligences, such as angels, consist of form and existence and receive their existence from the First Cause, God.   Owens and Wippel agree that Aquinas proves God’s existence at P3; however, their analyses of this phase differ.  For Owens, Aquinas reaches the real distinction at P3.  The real distinction can only be reached after one establishes pure existence as a real nature.  This can only be done through a proof for the existence of God.  Owens believes that Aquinas’ argumentation moves from formal causality (P2) to efficient causality (P3).  Establishing being as a real nature (in God, whose quiddity is his existence) shows that being in all other entities is participated being.  Participated being cannot have the status of a nature and thus there must be a real distinction between essence and existence in created entities. 

For Wippel P3 is an application of the conclusion Aquinas already reached at P2.  Using the real distinction between essence and existence, Aquinas argues for the existence of God.  Since everything that exists (save one unique being who may or may not exist yet at P2) possesses existence which is other than its quiddity, these created beings must receive their existence from outside of themselves.  Thus, there must be a cause of existence for all these beings whose existence and essence are distinct.  The cause of this existence is God.  If the real distinction is established at P2, then why does Aquinas provide P3?  Wippel asserts that Thomas includes a proof for God’s existence at P3 in order to complete his account on how separate intelligences (such as angels) have form and esse without thereby being pure act.  The proof of God’s existence, then, shows that there is potency and act in the intelligences and not matter and form.  An angel’s form is in metaphysical potency to its existence which it receives from God. 

Despite the fact that Owens and Wippel disagree on what phase in the De Ente’s argument Aquinas reaches a real distinction, they are both in agreement that the De Ente is a philosophical treatise in which Aquinas reaches a real distinction between essence and existence through demonstration.  If we grant for the moment that Aquinas does indeed demonstrate a real distinction, then which account offers the better interpretation?  Wippel’s account draws out a truth about the experience of being creatures which Owen’s account does not address.  In arguing for a real distinction at P2, Wippel’s account points in a subtle manner to the human experience of the finitude of creatures.  Since creatures are possible existents and thus do not have to exist, it would therefore seem that they must receive their existence from something else.  Further, the plurality of beings, which share the same essence, suggests a real distinction of essence and existence.  As Wippel explains in his response to Owens, the real distinction between essence and existence is based upon the impossibility of there being more than one being whose essence is its existence.  If there were two such beings, these beings would need to be distinguished from each other in some manner.  As Aquinas shows, one could not distinguish two such beings without thereby adding something to subsistent existence, and that is impossible.  Thus, if it is impossible for there to be more than one being whose quiddity is its nature, then the plurality of creatures who share the same essence must therefore have two real and ontologically distinct principles, essence and existence.   

Does Wippel, though, assume in his account a distinctive understanding about the nature of existence (esse)?  If Wippel’s account does indeed assume the nature of existence as Owens asserts, this assumption is present only because it is already present within Aquinas’ text.  The analysis that Aquinas presents from the start of the De Ente proceeds from Aquinas’ conception of being.  The question Aquinas is seeking to answer is how angels can have form and esse without thereby having pure being, pure act of existence.  Aquinas is already working within his conception of being in this context.  Under Aquinas’ system, then, it is impossible for there to be more than one being whose quiddity is its existence.  It is because this being (God) exists that all other beings must be composed of existence and essence.  In this way, the limitation of beings points to a real distinction.  Yet, perhaps the tension can be redirected through a new approach to the age old question of the real distinction, an approach taken by R.E. Houser.

3. Houser on the Real Distinction

R.E. Houser’s more recent article “The Real Distinction and the Principles of Metaphysics,” approaches Aquinas’ argumentation in the De Ente through an analysis of a similar argument found in Avicenna’s The Metaphysics of The Healing.  Houser seeks to trace the sources Aquinas uses in the De Ente and thus approach the text through a method one may call source based contexualism.  That is, an approach to the text which analyzes the text through the sources the original author used in order better to grasp the intention of the author and, further, the structure of the argument within the text.  Houser traces two sources Aquinas uses in the De Ente: Avicenna and al-Ghazali. 

3.1 Avicenna

Avicenna begins Met. 1.5 by stating three primary notions: existent, thing and necessary which “are impressed in the soul in a primary way.”  The primary notions form the basic principles of metaphysics.  One cannot use arguments to establish the primary notions without thereby falling into a circular argument; rather the primary notions allow one to make propositions.   In speaking of existence and thing, Avicenna draws out a conceptual distinction between the two terms.  He writes, “[Moreover] we say: The meaning of ‘existence’ and the meaning of ‘thing’ conceived in the soul are two meanings.”  Houser indicates that by the end of this chapter Avicenna establishes a conceptual distinction between essence and existence. 

In Met. 1.6-7 Avicenna lays out two metaphysical hypotheses by which he will argue dialectically for a real distinction between quiddity (essence) and a thing’s existence.  Houser notes that Avicenna speaks about being in a qualitative manner and thus Avicenna brings forth two kinds of existence: necessary existence and possible existence.  These two kinds of existence form two metaphysical hypotheses.  Houser describes these two hypotheses as: 1) “Necessary existence is ontologically simple, existence alone” and 2) “All possible existences are ontologically composite, made up of existence and quiddity.”  From these two hypotheses Avicenna establishes a real distinction dialectically at Met. 1.7, stating that all beings save the necessary existent are composites of quiddity and existence.  Here Avicenna uses an analysis of necessity and possibility in order to reach a real distinction.  A necessary existent can only be one; it is unique.  The necessary existent is therefore simple and thus not composed.  On the other hand, a possible existent does not have to exist and it thus receives its existence from another.  Avicenna will expound upon this by offering arguments in support of the composition of possible existents. 

Houser outlines six theses Avicenna uses in his argumentation for a real distinction, arguments which are both analytical and dialectical.  As Houser focuses upon the theses in Avicenna that Aquinas also uses, we shall here focus our attention on theses two, five and six, which can be outlined as follows:

T2: “Existence possible in itself does have a cause.”

T5: “…it is impossible that the existence of necessary existence be composed, from

multiplicity.”

T6: “…it is impossible that the true nature of necessary existence is shared in any way at all.  And from this it follows that necessary existence is not relative, changing, many, and does not share its proper existence.”

Avicenna argues for T2 in Met. 1.6 with an argument Houser terms the sufficiency argument and clarifies the argument with an infinite regress argument.  T5 and T6 are argued in Met. 1.7 with an argument Houser terms as the predicables argument.  These arguments are dialectical, showing how acceptance of a real distinction helps to save the unity of God for Avicenna who wholly accepts the Islamic doctrine of Tawhīd that God is one. 

In Met. 1.6 Avicenna argues that a possible existent is brought into existence by a cause and further that this cause must be a cause which is outside of the possible existent.  Avicenna then reaches a distinction of essence and existence by employing the “sufficiency argument,” according to Houser.  Avicenna asks whether or not a thing’s quiddity or essence is able to cause that thing to exist.  If a quiddity were able to bring a thing into existence, then this thing’s quiddity would be necessary.  This thing would then be a necessary existent.  On the other hand, if a thing’s quiddity is not sufficient to bring that thing into existence then this thing must receive its existence from something else.  Thus, there must be a cause of existence for things whose being is contingent.  Houser explains that quiddity and existence are two intrinsic principles within the actual being of a thing.  Existence makes a thing or being actually exist and yet does not add anything to the quiddity itself.  Existence then is distinct from essence and is also real.  In addition to the sufficiency argument, Houser notes that Avicenna also uses the “infinite regress argument” in order to refine his claim in support of T2.  The infinite regress argument maintains that the cause of existence must also cause necessity within the existent.  Otherwise there would be an infinite regress in the number of causes. 

In Met. 1.7 Avicenna employs the “predicables argument” to argue for the unity of God, in support of T5 and T6.  If there were more than one necessary existence, then these two necessary existents would need to be distinguished in some manner.  Using the five predicables of Aristotle Avicenna shows the impossibility of multiplicity in a necessary existent.  Houser again points out that this argument is dialectical; it shows how a real distinction “saves” the unity of God, Divine Tawhīd.

3.2 Another Approach to the De Ente

Comparing the principles and methodology of Avicenna with Aquinas, Houser does not analyze the De Ente through the three phases outlined by Wippel but rather re-organizes the text into four steps asserting that Aquinas’ argumentation, like Avicenna’s argumentation, is dialectical.  The four steps can be labeled as follows, with the arguments from Avicenna that Aquinas draws upon in parentheses:

S1: Essence and existence is distinct in creatures (sufficiency argument)

S2: Essence and existence in God is one (predicables argument)

S3: Existence of angels is caused by a cause of existence (infinite regress and predicables argument)

S4: Potentiality in angels (Aquinas’ own argument)

The four steps center not upon a demonstration for a real distinction but rather how a real distinction upholds potentiality in angels and thereby reduces the risk of either ascribing some sort of matter to angels or equating the being of angels with the being of God. 

S1 in Houser’s analysis is the same as P1 in Wippel’s outline of Aquinas’ argumentation in the De Ente.  Houser, however, points out that the reasoning in the intellectus essentiae argument is not original to Aquinas.  Rather, Aquinas’ arguments can be traced back to Avicenna and also to al-Ghazali.  Aquinas’ intellectus essentiae argument follows Avicenna; the main difference between the two is a reference to understanding (intellectus) in Aquinas.  In order to support his claim that one is able to understand an essence without knowing whether or not it exists, Aquinas borrows from al-Ghazali’s Logica Algazelis where al-Ghazali offers an explanation between the difference of understanding essential universals and non-essential universals.  In fact, Aquinas uses the same examples found in al-Ghazali, the example of understanding the essence of a man or a phoenix without necessarily knowing whether it exists or not.  Al-Ghazali explains that when one understands an essence, one must also understand what is essential to the essence but one does not need to understand what is accidental to the essence.  For Owens, Aquinas’ point in the intellectus essentiae is the accidental character of being in creatures.  While one can grant this point at S1 or P1, this argument comes not from Aquinas himself but from al-Ghazali.

Given the structure of the argument and considering the sources Aquinas draws from, Houser concludes that Aquinas’ line of reasoning at S1 is dialectical.  Aquinas breaks up al-Ghazali’s one step inference into two steps.  Houser shows this by structuring Aquinas’ reasoning in the form of a syllogism.   Houser explains that this has led many twentieth-century commentators to believe that Aquinas’ two step inference is demonstrative because it is structured as a syllogism.  As Aquinas’ argument begins with understanding or knowing a difference between essence and existence and proceeds to the reality of their composition, the argument cannot prove this through demonstration.  The argument proceeds dialectically. 

In S2 Aquinas explores how an explanation of essence and existence as identical in God preserves the unity of God.  Unlike Owens and Wippel, Houser asserts that the existence of God is assumed in the context of the De Ente.  At S2 Aquinas argues that subsistent existence cannot be multiplied.  The first two of Aquinas’ three reasons derive from Avicenna’s predicables argument.   Subsistent existence cannot be contained within a genus for then there would need to be a specific difference upon which to separate the two existents.  Avicenna also argues that necessary existence is not contained within a genus.  Second, a principle of individuation, such as matter, would cause subsistent existence to no longer be subsistent.  Avicenna also states this in Met. 1.7.  Aquinas’ reasoning, like Avicenna’s reasoning, is dialectical.  It shows how a description of God’s quiddity as his existence preserves God as the one God. 

In S3 Aquinas uses Avicenna’s predicables argument and infinite regress argument to show that there must be a cause of existence for all creatures, including intellectual substances, such as angels.  This step begins with Aquinas moving from the unity of essence and existence in God (S2) to arguing for a cause of existence in creatures since their essence is other than their existence. Using a reductio argument Aquinas first shows why existence cannot be a property of essence.  If existence were a property of essence then the essence would have to cause itself into existence which could not be possible given the nature of possible existents.  Therefore the cause of existence for creatures must be an efficient cause (God) which is outside of the entity itself.  Existence then for creatures is an “accidental property;” Aquinas thus uses Avicenna’s reasoning at Met. 1.7.  Aquinas also uses Avicenna’s infinite regress argument from Met. 1.6 to locate the cause of existence to a first cause (God) in order to point out that there is not an infinite regress of causes for an entity’s existence.  The real distinction is already assumed in Aquinas’ reasoning since it is part of Aquinas’ two metaphysical hypotheses.  Houser again stresses that Aquinas offers dialectical arguments in support of the two hypotheses in order to show the advantages of accepting the hypotheses.  The hypotheses explain potency in angels without ascribing hylomorphism to angels.

The last step, S4, highlights the focal point in the De Ente which Houser observes has often been forgotten or neglected in the writings of twentieth century commentators – potentiality in angels.  Aquinas explains that while the intelligences have potency and act, they do not have matter and form.  The essence of the intelligences is in potency to their existence, which is received from God.   Houser asserts that Aquinas’ whole task in the De Ente is to prevent assigning some sort of hylomorphism to angels.  Unlike human beings, potency in angels comes from the form and not matter.  God is the cause of existence in angels.  Potency in angels preserves the difference between God who is pure act and angels who are intellectual substances.  Aquinas reaches this conclusion by using his two metaphysical hypotheses to convince his readers that upholding essence and existence as really distinct in creatures and essence and existence as identical in God preserves God’s unity and, further, illustrates how there is potentiality in angels. 

4. Methodology

Given the above analyses offered by Owens, Wippel and Houser, one can see two different methodologies at work.  Houser approaches Aquinas’ text in the De Ente by studying the text from the perspective of the sources which influenced the text.  This way of approaching the text was referred to earlier as source based contextualism.  This methodology studies a text within the context of the sources used to produce the text.  The structure and argumentation of the text is thus not studied in isolation from the sources behind the text.  Houser presents Aquinas’ text in light of the sources, the texts of Avicenna’s Metaphysics and the work of al-Ghazali.  In his article, Houser shows that the arguments utilized in Aquinas’ text are not original to Aquinas.  The arguments bear a clear and evident similarity to those Avicenna uses in the first book of Avicenna’s Metaphysics.  This similarity, Houser notes, is no mere coincidence.  Avicenna begins with two metaphysical hypotheses and then proceeds dialectically to show a real distinction between essence and existence.  Aquinas uses these same two hypotheses and argues dialectically in support of these hypotheses.  Further, Houser is able to show not only the influence of Avicenna upon Aquinas’ text but also show where Aquinas makes al-Ghazali’s one step induction into two steps. 

The description offered above of source based contextualism most likely does not sound like a newly founded methodological approach.  This approach has been used throughout the history of philosophy.  It therefore describes how philosophers have conducted their philosophical research for centuries.  Despite this, however, source based contextualism has not always been the method employed by Aquinas’ commentators.  Houser, employing source based contextualism, reveals the similarities between Avicenna and Aquinas, and, therefore, one can assert, offers an interpretation of Aquinas’ text which is closer to the intentions of Aquinas himself.  The analyses of Owens and Wippel show the complexity of the texts of Aquinas, but careful consideration of the sources Aquinas himself was using in forming his views as we find in the article by Houser permits a perspective that enhances our ability to reveal the reasoning of Aquinas in the De Ente.  

Notes

1 For the sake of clarity, we will define the terms ‘real’ and ‘distinction.’ Aquinas seldom used the term

‘distinction’ (distinctio, distinguere ), perhaps using the term only once in his writings. As Owens points out the

word ‘distinguish’ can arouse similarities with Descartes who was in search of “clear and distinct ideas.” These

connotations with the thought of Descartes may imply that the word ‘distinguish’ refers to two separate conceptual

ideas or two conceptual objects, as the mind is completely different from the body in the dualism of Descartes. The

word ‘distinction’ as used in this discussion, however, does not refer to two separate things or ideas that are grasped

within a concept. Distinction, rather, refers to a kind of difference or diversity between two “things” in a broad

sense of the term, in this case essence and existence. We are, therefore, using the word distinction broadly in our

discussion here to mean two ontological principles, essence and existence. The word real as used here does not refer

to a thing, res , nor does it mean something which is like or similar to a thing. Further, the word real cannot be

understood in contrast to something which has merely mental being. Where Aquinas often refers to real being and

mental being, oftentimes, real being is being which exists in the world while mental being exists only within one’s

mind. To say that there is a real distinction between essence and existence is not to speak of essence and existence

as possessing real being (esse ) in the world in contrast to mental being. Rather, here the term ‘real’ is also being

used in a broad sense to speak of the distinction or composition of existence and essence in things as a composition

that is not only conceptual (since one can think of the essence of a phoenix without knowing whether or not it exists,

to use an example of Aquinas) but to refer to something additional to a mere conceptual distinction, an actual

ontological composition of two distinct principles, essence and existence. For Joseph Owens, the term real refers to

“the thing’s being” as “caused by something else and ultimately shown to be subsistent being.” Owens argues that

the term real does not do justice to the type of distinction we are referring to: “In the course of the same argument

[in De Ente et Essentia ], then, the distinction between a thing and its being is presented at one stage as conceptual

and at another as real. ‘Real,’ therefore, is not the correct word to use in approaching the problem. The term should

be wide enough to describe both conceptual and real distinction, as well as to cover the distinction between a thing

and its cognitional being.” See Owens, Aquinas on Being and Thing , (New York: Niagara University Press, 1981),

6.

2 The real distinction between essence and existence is a distinction between what a thing is (quid est ) and whether a

thing is (an est ). The term essence refers to the definition of a thing (essentia) . Essence therefore refers to the

nature of a thing, such as the nature of a cat or catness. For our purposes here, the word essence will be used

synonymously with quiddity since Avicenna uses the latter term. One reaches the essence of a thing through simple

apprehension which takes place through abstraction. One abstracts from the percept its intelligible content and

forms a concept. According to Aquinas, this is the natural way that the intellect transitions from singulars to

universals. Owens writes, “What the thing is, is known through conceptualization and is expressed in concepts. This

nature or essence or quiddity is, in the noetic of Aquinas, identical with the individual thing as known in

nonprecisive abstraction. It is but the thing itself abstracted nonprecisively from the individuating traits.” See

Owens, “Aquinas on Being and Thing,” 8. Owens explains in his article, “The Accidental and Essential Character of

Being,” that essence has a twofold sense in Aquinas: abstraction without precision and abstraction with precision.

Owens, “The Accidental and Essential Character of Being,” 31: “In this sense, to speak of a distinction between an

essence and being is the same as to speak of a distinction between a thing and its being. Essence so taken includes

implicitly everything that is in the thing itself, even the individual designation.” Abstraction without precision refers

to the thing itself, even the individual. In this sense, one can say that a cat is its essence. Abstraction with precision,

on the other hand, includes an abstraction from the individual designation which is left aside from consideration. In

the latter sense, one can say that a cat has an essence. In our discussion of a real distinction between essence and

existence, we use essence in the former sense, as abstraction without precision. In contrast to essence, one reaches

existence through judgment, not simple apprehension. Although the term existence (esse ) is an equivocal term

which can refer both to the subject of being and the act of being, Aquinas limits his usage of esse  to the latter, the act

of being (actus essendi ). The concept of being is not formed by abstraction but rather by a judgment of separation.

First one makes the judgment “This is.” The “is” is then separated out from the particular subject and condensed

into a noun, that which is . This “is,” however, is always connected with some determinate this or that. Thus, when

speaking of a being that which  refers to the essence of the being while “is” refers to the act of being or the act of

existence. For a fuller discussion on the terms essence and existence in Thomas Aquinas, see Joseph Owens’s

article, “The Accidental and Essential Character of Being,” Mediaeval Studies  (20) 1958): 1-40. For a more detailed

account of abstraction see Joseph Owens, Cognition: An Epistemological Approach , (Texas: The Center for

Thomistic Studies, 1992): 139-186.

Wietecha 17

3 Cf. C. Fabro, La nozione metafisica di partecipazione , 2nd ed. (Turin, 1950), 218-219. J. Bobik, Aquinas on Being

and Essence  (Notre Dame, IN, 1965), 162-70. A. Maurer, St. Thomas Aquinas, On Being and Essence  (Toronto,

1968), 21ff. L. Sweeney, “Existence/Essence in Thomas Aquinas’ Early Writings,” Proceedings of the American

Catholic Philosophical Association  37 (1963): 97-131. See also John Wippel, Metaphysical Themes in Thomas

Aquinas  no. 1 (Washington, D.C.: The Catholic University of America, 2007), 134.

4 For Wippel’s layout of the three stages, see John Wippel, “Aquinas’ Route to the Real Distinction: A Note on De

ente et essentia ,” Thomist , no. 43.2 (April 1, 1979): 279-295.

5 Owens compares the conceptual distinction Aquinas reaches at stage one in the De Ente  with the conceptual

distinction Aquinas makes between animal and rational. In 1 Sent.  d. 8 Aquinas explains in what manner being is

accidental and thus not part of the quiddity of a thing: “Being is not an accident to God. It seems that neither is

<being an accident> to any creature, since nothing is more essential to a thing than its own being. To this

<objection> one ought to say that here whatever is involved in the understanding of a thing is said to be an accident,

e.g. rational is said to be accidental to animal, and in this fashion being is accidental to any created quiddity, since it

is not <part> of the concept of the quiddity itself; for humanity can be understood and it can still be doubted whether

a human has being.” English translation taken from E.M. Macierowski, trans., Thomas Aquinas’s Earliest Treatment

of the Divine Essence: Scriptum super libros Sententiarum, Book I, Distinction 8  (Binghamton, NY: Binghamton

University Press, 1998), 73. The Latin text reads (209): “((Esse non est accidens Deo.)) Videtur quod nec alicui

creaturae, cum nihil sit essentialius rei quam suum esse. Ad quod dicendum, quod accidens dicitur hic quod non est

de intellectu alicujus, sicut rationale dicitur animali accidere; et ita cuilibet quidditati creatae accidit esse, quia non

est de intellectu ipsius quidditatis; potest enim intelligi humanitas, et tamen dubitari, utrum homo habeat esse.” Latin

translation in Macierowski taken from Thomas Aquinas, Scriptum Super Libros Sententiarum Magistri Petri

Lombardi Episcopi Parisiensis , Tomus 1, ed. R.P. Mandonnet, OP, (Paris: Parisiis, Sumptibus P. Lethielleux, 1929).

Being is not accidental in God but being is accidental in creatures. Being is accidental in creatures in the sense that

rational is accidental to animal. An animal, such as a cat, is not rational whereas a human person is rational. Since

rational is not included in the notion of animal under necessity, rational is accidental to animal. The distinction

between rational and animal is conceptual. In a similar way, the distinction at stage one of the De Ente  is

conceptual. It merely shows that being is not contained with the notion of essence. Joseph Owens, “Quiddity and

Real Distinction,” Mediaeval Studies  27 (1965), 13. Owens compares the distinction Thomas makes in 1 Sent . 8.4.2

with the distinction Thomas makes between universal and particular in 1 Sent.  13.1.3. In the latter Thomas

establishes a conceptual distinction between universal essence and particular essence. Wippel points out that

Owens’ comparison of the conceptual distinction in the intellectus essentiae  approach with the conceptual

distinction between animal and rational does not mean that these two distinctions are on the same level as each

other. While the distinction between rational and animal is conceptual, it does not move onto a real distinction as

with the distinction between essence and existence. See Wippel, Metaphysical Themes in Thomas Aquinas , 121-122.

6 Aquinas writes (Macierowski, 99), “The third, subtler reason is that of Avicenna <in his> Metaphysics , Treatis V,

cap. 4 and Treatise IX, chap. 1: Everything that is in a genus has a quiddity different from being, e.g. man.” The

Latin reads (98), “Tertia ratio subtilor est Avicennae, tract. V Metaph ., cap. IV, et tract. IX, cap. I. Omne quod est in

genere, habet quidditatem differentem ab esse, sicut homo.” Sweeny points out that although Aquinas references

Avicenna’s Metaphysics 5.1 and 9.1 in this passage, it is difficult to find this exact argument in Avicenna. Sweeny

points to a possible place in Avicenna’s Metaphysics  8.4 which seems to come closest to Aquinas’ statement.

Sweeny, 110, n. 21. See Avicenna, The Metaphysics of the Healing , trans. Michael E. Marmura, (Provo, UT:

Brigham Young University Press, 2005), Met.  8.4.14: “The First also has no genus. This is because the First has no

quiddity. That which has no quiddity has no genus, since genus is spoken of in answer to the question, “What is it?”

and [moreover] genus in one respect is a part of a thing; and it has been ascertained that the First is not a

composite.” Avicenna Latinus, Liber de Philosophia Prima sive scientia divina  V-X, ed. S. Van Riet, Louvain,

1980: 402.61-64: “Primus etiam non habet genus; primus enim non habet quidditatem, sed quod non habet

quidditatem, non habet genus; genus enim respondetur ad interrogationem per quid est; genus etiam aliquo modo

pars est rei; certificam est autem quod primus non est compositus.”

7 Macierowski, 99: “Everything that is in a genus has a quiddity different from being, e.g. man; for being in act is

not owed to humanity precisely as humanity; for humanity can be thought of and it is still possible for it to be

unknown whether some man is. The reason for this is that the common <feature> that is predicated of the <things>

that are in the genus predicates the quiddity, since genus and species are predicated quidditatively… In God,

however, His being is His quiddity: for otherwise <His being> would be accidental to the quiddity, and so It would

be acquired by it from another and it would not have being through its own essence.” The Latin text reads: “Omne

quod est in genere, habet quidditatem differentem ab esse, sicut homo; humanitati enim ex hoc quod est humanitas,

Wietecha 18

non debetur esse in actu; potest enim cogitari humanitas et tamen ignorari an aliquis homo sit. Et ratio hujus est,

quia commune, quod praedicatur de his quae sunt in genere, praedicat quidditatem, cum genus et species

praedicentur in eo quod quid est. Illi autem quidditati non debetur esse nisi per hoc quod suscepta est in hoc vel in

illo. Et ideo quidditas generis vel speciei non communicatur secundum unum esse omnibus, sed solum secundum

unam rationem commune. Unde constat quod esse suum non est quidditas sua. In Deo autem esse suum est

quidditas sua: aliter enim accideret quidditati, et ita esset acquisitum sibi ab alio, et non haberet esse per essentiam

suam.”

8 Joseph Owens, “Aquinas’ Distinction at De Ente et Essentia  4.119-123,” Mediaeval Studies  48 (1986), 268.

9 De Veritate  27.1.ad8. “Everything that is in the genus of substance is composite with a real composition, because

whatever is in the category of substance is subsistent in its own existence, and its own act of existing must be

distinct from the thing itself; otherwise it could not be distinct in existence from the other things with which it agrees

in the formal character of its quiddity; for such agreement is required in all things that are directly in a category.

Consequently everything that is directly in the category of substance is composed at least from being and what is

(Trans. Mod.).” English translation taken from Dominican House of Studies Priory of the Immaculate Conception,

St. Thomas Aquinas’ Works in English, http://dhspriory.org/thomas/QDdeVer27.htm  (accessed Nov. 20, 2013).

The Latin text reads: “Ad octavum dicendum quod omne quod est in genere substantiae est compositum reali

compositione eo quod id quod est in praedicamento substantiae est in suo esse subsistens, et oportet quod esse suum

sit aliud quam ipsum; alias non posset differre secundum esse ab aliis cum quibus convenit in ratione suae quiditatis,

quod requiritur in omnibus quae sunt directe in praedicamento; et ideo omne quod est directe in praedicamento

substantiae, compositum est saltim ex esse et quod est.” Sancti Thomae de Aquino Opera Omnia , Iussu Leonis XIII,

Tomus XXII 792a221-331.

10 In De Veritate , Aquinas does not begin by offering an argument for the existence of God as he does in the

Summa; he also does not refer to God as a being who may or may not exist. In Question Two of De Veritate ,

Aquinas discusses God’s knowledge. In this context, Aquinas treats various questions on the knowledge of God

under the assumption that God does in fact exist. Wippel compares 1 Sent.  8.4.2 with De Veritate  27.1.ad.8 in order

to show Aquinas’ reasoning for a real distinction. A real distinction explains how creatures with the same quiddity

are differentiated, that is, by their esse. While this comparison can be granted, Wippel’s assertion that this passage

of De Veritate  also supports his argument that the existence of God does not need to be proved or assumed prior to

establishing a real distinction does not stand. Aquinas does not offer an argument for the existence of God because

he already assumes the existence of God in this text. This is clear by what comes before Q. 27.

11 Wippel, Metaphysical Themes in Thomas Aquinas , 136: “Since the substantial esse of individual members of such

a class is not shared in common with other members of that same class, and since their quidditative content in some

way is, Thomas concludes to otherness of essence and esse in all such beings.”

12 Aquinas lists three ways something can be multiplied. The first way is an addition of some difference; yet, this

cannot apply to existence because then existence would consist of existence plus some other difference. Second,

something can be multiplied through a form received in different matter. This also cannot apply to existence

because then it would include existence plus matter. The third way states a being can have something in one of two

ways, either in itself or by participation. Aquinas gives the example of separated heat and participated heat. De Ente

et Essentia , cap. 4, 376b103-377a121. “Unless perhaps there is a reality whose quiddity is its being. This reality,

moreover, must be unique and primary; because something can be multiplied only [I] by adding a difference (as a

generic nature is multiplied in species), [2] by the reception of a form in different parts of matter (as a specific

nature is multiplied in different individuals), [3] by the distinction between what is separate and what is received in

something (for example, if there were a separated heat,' by the fact of its separation it would be distinct from heat

that is not separated). Now, granted that there is a reality that is pure being, so that being itself is subsistent, this

being would not receive the addition of a difference, because then it would not be being alone but being with the

addition of a form. Much less would it receive the addition of matter, because then it would not be subsistent, but

material, being. It follows that there can be only one reality that is identical with its being.” All English translations

of De Ente et Essentia  are from St. Thomas Aquinas, On Being and Essence , Trans. Armand Maurer, (Toronto,

Canada : Pontifical Institute of Mediaeval Studies, 1968), 55. The Latin text reads: “Nisi forte sit aliqua res cuius

quiditas sit ipsum suum esse, et hec res non potest esse nisi una et prima : quia impossibile est ut fiat plurifìcatio

alicuius nisi per additionem alicuius di.&erentie, sicut multiplicatur natura generis in species; uel per hoc quod

forma recipitur in diuersis materiis, sicut multiplicatur natura specie in diuersis indiuiduis; uel per hoc quod unum

est absolutum et aliud in aliquo receptum, sicut si esset quidam calor separatus esset alius a calore non separato ex

ipsa sua separatione. Si autem ponatur aliqua res que sit esse tantum ita ut ipsum esse sit subsistens, hoc esse non

recipiet additionem differentie, quia iam non esset esse tantum sed esse et preter hoc forma aliqua; et multo minus

Wietecha 19

reciperet additionem materie, quia iam esset esse non subsistens sed materiale. Vnde relinquitur quod talis res que sit

suum esse non potest esse nisi una.” All Latin texts of De Ente  are from Sancti Thomae de Aquino Opera Ominia .,

De Ente et Essentia , Iussu Leonis XIII P.M. edita, Tomus XLIII, Editori di San Tommaso, (Santa Sabina, Roma,

1976).

13 Wippel, “Aquinas’s Route to the Real Distinction,” 291: “If it is impossible for there to be more than one being

whose essence is its esse, then it follows that in all other beings essence and existence are not identical. And this

follows whether or not that single exception has already been assumed or proven to exist, or whether it is simply

regarded as possibility.” It is important to note the difference here between Wippel and Owens. Wippel maintains

that a real distinction between essence and existence can be demonstrated prior to proving the existence of God.

Owens, on the other hand, argues that a real distinction cam only be demonstrated after either proving the existence

of God or assuming the existence of God as ipsum esse per se subsistens .

14 Owens, “Stages and Distinction in De Ente,” 120.

15 Wippel, Metaphysical Themes in Thomas Aquinas , 125: “In replying to this, two different situations should be

distinguished: one, wherein one reasons from the content of a positive content to its realization in actuality, as for

instance, from one’s understanding of God as that than which no greater can be thought to his real and extramental

existence; another, where one reasons from the impossibility of something (based on the incompatibility or

contradictory character of the notes it would involve) to its nonexistence in reality – for instance, from the

incompatibility of combining squareness with circle to the conclusion that such cannot and therefore does not obtain

in reality.”

16 This reasoning is from Avicenna, Met.  1.6.8 and Met.  1.7.1-14. See Avicenna Latinus, Liber de Philosophia Prima

sive scientia divina  I-IV, ed. S. Van Riet, Louvain, 1977: 46.78-84 and 49-55. (Hereafter cited as Lat.).

17 Summa Contra Gentiles , II ch. 52: “ For, if being is subsisting, nothing besides this act itself is added to it.

Because, even in things whose being is not subsistent, that which is in the existing thing in addition to its being is

indeed united to the thing, but is not one with the thing’s being, except by accident, so far as the thing is one subject

having being and that which is other than being. Thus it is clear that in Socrates, beside his substantial being, there is

white, which, indeed, is other than his substantial being; for to be Socrates and to be white are not the same except

by accident. If, then, being is not in a subject, there will remain no way in which that which is other than being can

be united to it. Now, being, as being, cannot be diverse; but it can be diversified by something besides itself; thus,

the being of a stone is other than that of a man. Hence, that which is subsisting being can be one only. Now, we have

shown in Book I that God is His own subsisting being. Hence, nothing beside Him can be its own being. Of

necessity, therefore, in every substance beside Him the substance itself is other than its being.”

The Latin text reads (par. 1274), “Si enim esse est subsistens, nihil praeter ipsum esse ei adiungitur. Quia etian in

his quorum esse non est subsistens, quod inest existenti praeter esse eius, est quidem existenti unitum, non autem est

unum cum esse eius, nisi per accidens, inquantum est unum subiectum habens esse et id quod est praeter esse: sicut

patet quod Socrati, praeter suum esse substantiale, inest album, quod quidem diversum est ab eius esse substantiali;

non enim idem est esse Socratem et esse album, nisi per accidens. Si igitur non sit esse in aliquot subiecto, non

remanebit aliquis modus quo possit ei uniri illud quod est praeter esse. Esse autem, inquantum est esse, non potest

esse diversum: potest autem diversificari per aliquid quod est praeter esse; sicut esse lapidis est aliud ab esse

hominis. Illud ergo quod est esse subsistens, non potest esse nisi unum tantum. Ostensum est (lib. I, cap. 22) autem

quod Deus est suum esse subsistens. Nihil igitur aliud praeter ipsum potest esse. Oportet igitur in omni substantia

quae est praeter ipsum, esse aliud ipsam substantiam et esse eius.” Latin translation taken from S. Thomae

Aquinatis, Liber de Veritate Catholicae Fidei contra errors Infidelium , Vol. II, Marietti (Romae, 1961).

18 Wippel, Metaphysical Themes in Thomas Aquinas , n. 54, 129. Wippel writes, “Apart from the appeal to his

earlier demonstration of God’s existence (implicit appeal) and to God’s identity with his esse  (explicit appeal), the

logic here is the same as in stage two of the De ente  argument. If valid, the argument should also hold here even

without appeal to prior knowledge of God’s existence; for it too rests upon the impossibility of there being more

than one esse subsistens. ”

19 Ibid., 124.

20 Aquinas is working within his conception of being as actus essendi . In this context then, he speaks of a real

distinction between essence and existence in creatures in contrast to God who is ipsum esse per se subsistens.  Thus,

Aquinas’ argument for a real distinction is an argument steeped in his metaphysical framework, including how

Aquinas conceives of being. Other thinkers, such as al-Farabi for instance, have a different conception of being.One

can thus argue, as Owens does, that one would first need to prove the existence of God as a nature before arguing for

a real distinction in creatures; otherwise, one would be assuming the nature of being, the nature of existence itself. I

Wietecha 20

concede that one would need to accept Aquinas’ conception of being and, at least implicitly, accept the existence of

God. An argument for a real distinction between essence and existence in creatures can be offered only within the

larger framework of Aquinas’ metaphysical commitments, which includes his conception of being. When one

accepts the notion of existence as pure act, it will then provide a foundation for speaking of a real distinction in

creatures. Thus, Aquinas’ argument for a real distinction is an argument that only makes sense given the context of

his conception of being. For a discussion on the different conceptions of being found in such thinkers as al-Farabi,

Avicenna and Aristotle see Stephen Menn, “Avicenna’s Metaphysics” in Interpreting Avicenna: Critical Essays , ed.

Peter Adamson, (UK: Cambridge University Press, 2013).

21 De Ente et Essentia , Maurer 56-57 : “And because everything that exists through another is reduced to that which

exists through itself as to its first cause, there must be a reality that is the cause of being for all other things, because

it is pure being. If this were not so, we would go on to infinity in causes, for everything that is not pure being has a

cause of its being, as has been said. It is evident, then, that an intelligence is form and being, and that it holds its

being from the first being, which is being in all its purity; and this is the first cause, or God.” The Latin reads (cap. 4,

377a137-146), “Et quia omne quod est per aliud reducitur ad id quod est per se sicut ad causam primam, oportet

quod sit aliqua res que sit causa essendi omnibus rebus eo quod ipsa est esse tantum ; alias iretur in infinitum in

causis, cum omnis res que non est esse tantum habeat causam sui esse, ut dictum est. Patet ergo quod intelligentia est

forma et esse, et quod esse habet a primo ente quod est esse tantum, et hoc est causa prima que Deus est.”

22 This reasoning is from Avicenna, Met.  1.7.14, 38 (Lat: 55.53-55).

23 R.E. Houser, “The Real Distinction and the Principles of Metaphysics: Avicenna and Aquinas,” Laudemus viros

gloriosos: Essays in Honor of Armand Maurer, CSB  (Indiana: University of Notre Dame Press, 2007).

24 This term was coined by Marquette University graduate student Nathan Blackerby and has been adopted by the

Aquinas and ‘the Arabs’ International Working Group  for description of its methodology.

25 Avicenna, Met.  1.5.1, 22 (Lat: 31.2-32.5).

26 Ibid., Met.  1.5.6, 23 (Lat: 33.36-34.42). Avicenna uses synonyms to describe these notions. For example, he

defines a thing as “that about which it is valid [to give] an informative statement.” Although defining a thing as

“that which” is using a synonym for thing in the definition, Avicenna points out that such words still aim at or

indicate what a thing is.

27 Ibid., Met.  1.5.8, 24 (Lat: 34.50-54).

28 A necessary existent exists in and of itself, needing no outside cause to bring it into existence. It cannot be a

composite since that would add multiplicity to the existent and thus potency. A possible existent, on the other hand,

comes into existence through another, that is, through a cause. This cause must be outside of the possible existent.

If not, then the possible existent would be able to bring itself into existence or be a cause of its own existence, thus

ceasing to be a possible existent and becoming a necessary existent.

29 See Houser, 80.

30 Avicenna, Met.  1.7.14, 38 (Lat: 54.44-55.55). The entire passage reads, “As regards the possible existent, from

this its specific property has become evident – namely, that it necessarily needs some other thing to render it existing

in actuality. Whatever is a possible existent is always, considered in itself, a possible existent; but it may happen

that its existence becomes necessary through another. This may either occur to it always, or else its necessary

existence through another may not be permanent – occurring, rather, at one time and not another. This [latter] must

have matter that precedes its existence in time, as we will clarify. That whose existence is always necessitated by

another is also not simple in its true nature. [This is] because what belongs to it [when] considered in itself is other

than what belongs to it from another. It attains its haecceity in existence from both together. For this reason,

nothing other than the Necessary Existent, considered in Himself, is stripped of associating with what is in

potentiality and [what is within the realm of ] possibility. He is the single existent, [every] other [being] a composite

[dual].”

31 For all six theses, see Houser, 83-84. See also Avicenna, Met. 1.6-7 (Lat: 43.7-55.55).

32 Avicenna, Met.  1.6.2, 30 (Lat: 43.14-15).

33 See Houser, 83-84. Avicenna, Met.  1.6.2, 30 (Lat: 43.14-15). Necessary existence is being contrasted to

necessitated existence; the latter referred to of God.

34 Ibid. Avicenna, Met . 1.6.2, 30 (Lat: 43.15-17).

35 The term Tawhīd  refers to the monotheistic belief of Islam that God is one. God is unique. He has no equal, no

son; nothing is begotten of God. D. Gimaret, "Tawḥī d," Encyclopedia of Islam , 2nd ed., ed. P. Bearman, Th.

Bianquis, C.E. Bosworth, E. van Donzel, W.P. Heinrichs. Brill Online, 2014. Reference. Marquette University.

http://0-referenceworks.brillonline.com.libus.csd.mu.edu/entries/encyclopaedia-of-islam-2/tawhid-SIM_7454

(accessed Feb. 9, 2014).

Wietecha 21

36 For Aristotle there are two questions regarding a thing: what it is and whether it is. Aristotle did not question

whether or not these two could be separated through a real distinction.

37 Houser, 85. Houser sums up Avicenna’s argument as follows: “…creatures are caused because their existence is

acquired, and their existence is acquired because their quiddities are insufficient to entail existence, and those

quiddities are insufficient because quiddity is really other than existence.”

38 Ibid., 86: Houser writes,“…the quiddity is not a pre-existing entity but an intrinsic principle within a creature that

comes into being through this cause; and what is introduced is existence…Existence must change the quiddity from

possible to actual without adding anything to its nature. What is added, therefore, can be nothing in the quidditative

order, yet must be real.”

39 P1 and P2 are similar to Avicenna’s sufficiency argument: “If [on the other hand] the existence of its quiddity is

not sufficient [for specifying the possible with existence] – [the latter] being, rather, something whose existence is

added to it – then its existence would be necessarily due to some other thing.” Met.  1.6.5, 31 (Lat: 45.52-55).

40 The Logica Algazelis  is a Latin translation of al-Ghazali’s free translation which included added examples from

Avicenna’s Persian work Danesh-Nameh . See Janssens, J.,“Le Dânesh-Nâmeh d’Ibn Sînâ: Un text à

revoir?” Bulletin de philosophie médiévale  28 (1986): 163–77.

41 See Houser, 94-96. Al-Ghazali, “Logica Algazelis ,” 247.15-19, as noted by Houser.

42 Houser, 96.

43 De Ente et Essentia , cap. 4. The syllogism, as Houser lays out, can be shown, respectively: (See Houser, 96-97)

P1 : “Whatever does not come from understanding essence or quiddity comes from outside it and produces a

composition with essence, because no essence can be understood without those things that are parts of the

essence.”

P2 : “Now every essence or quiddity can be understood without understanding anything about its existence,

for I can understand what is a human or phoenix and yet not know whether it has existence in reality.”

C : “Therefore, it is clear that existence is other than essence.”

44 Houser, 97: “But this deduction is not a demonstration, because the inference runs from knowing essences to the

reality of essences. No necessary inference is to be had here, a fact Avicenna, al-Ghazali, and Aquinas knew very

well. By breaking al-Ghazali’s one-step inductive inference into two, however, Aquinas seems to have opened the

door for some of his twentieth-century followers to think that the second, deductive inference purports to be

demonstrative, simply because it is a syllogism. But this is to confuse deductive form with demonstrative content.”

45 De Ente et Essentia , Trans. Maurer, 55-56: “Now, granted that there is a reality that is pure being, so that being

itself is subsistent, this being would not receive the addition of a difference, because then it would not be being

alone but being with the addition of a form. Much less would it receive the addition of matter, because then it would

not be subsistent, but material, being.” The Latin text (cap. 4 377a113-119) reads, “Si autem ponatur aliqua res que

sit esse tantum, ita ut ipsum esse sit subsistens, hoc esse non recipiet additionem differentiae, quia iam non esset

esse tantum, sed esse et preter hoc forma aliqua; et multo minus reciperet additionem materiae, quia iam esset esse

non subsistens sed materiale.”

46 Houser, 98-99.

47 De Ente et Essentia , Trans. Maurer, 56 : “It follows that there can be only one reality that is identical with its

being. In everything else, then, its being must be other than its quiddity, nature, or form. That is why the being of the

intelligences must be in addition to their form; as has been said, an intelligence is form and being.” The Latin text

(cap. 4, 377a119-124) reads, “Vnde relinquitur quod talis res que sit suum esse non potest esse nisi una ; unde

oportet quod in qualibet alia re preter eam aliud sit esse suum et aliud quidditas uel natura seu forma sua ; unde

oportet quod in intelligentiis sit esse preter formam, et ideo dictum est quod intelligentia est forma et esse.”

48 Houser, 100-101. “Our empirical ability to know what something is without knowing that it exists is a sign  that

there is a composition of essence and existence in all other beings, that is, in all creatures; it does not demonstrate

this truth. . . All these conclusions are only as good as Aquinas’ initial assumptions. Indeed, it is to help his

confreres accept those initial assumptions – the two great hypotheses he had “spoiled” from the metaphysics of

Avicenna – that Br. Thomas argues in the way he does.”

49 De Ente et Essentia , Trans. Maurer, 57 : “Everything that receives something from another is potential with regard

to what it receives, and what is received in it is its actuality. The quiddity or form, therefore, which is the

intelligence, must be potential with regard to the being it receives from God, and this being is received as an

actuality. Thus potency and act are found in the intelligences, but not form and matter, except in an equivocal

sense.” The Latin text (cap. 4, 377a147-b154) reads, “Omne autem quod recipit aliquid ab alio est in potentia

respectu illius, et hoc quod receptum est in eo est actus eius; ergo oportet quod ipsa quiditas uel forma que est

Wietecha 22

intelligentia sit in potentia respectu esse quod a Deo recipit, et illud esse receptum est per modum actus. Et ita

inuenitur potentia et actus in intelligentiis, non tamen forma et materia nisi equiuoce.”

50 After analyzing the four steps of argumentation in the De Ente , Houser points out other places within the writings

of Aquinas where he makes a similar argument. Houser examines two places within the second book of the

Commentary on the Sentences . Although his analysis is brief, Houser identifies the first three steps in 2 Sent .

d.1.1.1. and all four steps in Aquinas’ argument for potency in angels in 2 Sent . d. 3.1.1. See Houser, 101-102.

51 In Posterior Analytics  Aristotle defines demonstration as “a scientific deduction” by which “we understand

something.” Demonstrations, which often take the form of a syllogism, proceed deductively from premises to a

conclusion. The premises used in a demonstration must be true and primary. They also must be known prior to the

conclusion and serve as causes of the conclusion. A demonstration, therefore, provides what Aristotle would call

scientific knowledge for it “proceeds from necessities.” Aristotle contrasts demonstration with another form of

argumentation known as dialectical argumentation. A dialectical argument does not necessarily differ from a

demonstration in its logical form; they, rather, differ on the nature of their premises. The premises in a dialectical

argument are not premises that are true and primary but premises which are accepted as true. Houser, in contrast to

Owens and Wippel, argues that Aquinas’ argumentation in the De Ente  is dialectical because it proceeds from

Aquinas’ two metaphysical hypotheses. These hypotheses are simply accepted. Aquinas then provides arguments

in support of the hypotheses in order to offer reasons why one should accept these hypotheses. As we have seen,

Houser shows that these two metaphysical hypotheses help to “save” the unity of God and potency in angels.

Cf. Aristotle, Posterior Analytics , trans. Jonathan Barnes, (Oxford: Clarendon Press, 1993), I.2-I.3.

52 Houser also points out the differences between Avicenna and Aquinas. Although both argue dialectically,

Avicenna’s argumentation is analytic whereas Aquinas’ argumentation is synthetic.

Bibliography

Al-Ghazali. “Logica Algazelis, Introduction and Critical Text.” Ed. C.H. Lohr. Traditio 21,

1965.

Aquinas, Thomas. On Being and Essence. Trans. Armand Maurer. Toronto, Canada: Pontifical

Institute of Mediaeval Studies, 1968.

-------. De Veritate. Dominican House of Studies Priory of the Immaculate Conception. Q. 21-29

Trans. Robert Schmidt. Thomas Aquinas’ Works in English.

http://www.dhspriory.org/thomas/QDdeVer.htm (accessed Nov. 20, 2013).

-------. Liber de Veritate Catholicae Fidei contra errors Infidelium. Vol. II. Marietti. Romae:

1961.

-------. Sancti Thomae de Aquino Opera Omnia. Iussu Leonis XIII P.M. Edita.

-------. Scriptum Super Libros Sententiarum Magistri Petri Lombardi Episcopi Parisiensis,

Tomus 1, ed. R.P. Mandonnet, OP, (Paris: Parisiis, Sumptibus P. Lethielleux, 1929).

-------. Summa Contra Gentiles. Dominican House of Studies Priory of the Immaculate

Conception. Trans. James F. Anderson. Thomas Aquinas’ Works in English.

http://dhspriory.org/thomas/ContraGentiles2.htm#52 (accessed Nov. 20, 2013).

Aristotle. Posterior Analytics. Trans. Jonathan Barnes. Oxford: Clarendon Press, 1994.

Wietecha 23

Avicenna. Avicenna Latinus: Liber de Philosophia Prima sive Scientia Divina I-IV. S. Van Riet.

Peeters, 1977.

-------. Avicenna Latinus: Liber de Philosophia Prima sive Scientia Divina V-X. S. Van Riet.

Peeters, 1980.

-------. The Metaphysics of The Healing. Trans. Michael E. Marmura. Provo, UT: Brigham

Young University Press, 2005.

Houser, R.E. “The Real Distinction and the Principles of Metaphysics: Avicenna and Aquinas.”

Laudemus viros gloriosos: Essays in Honor of Armand Maurer, CSB. (Indiana:

University of Notre Dame Press, 2007).

Macierowski, E.M. Trans. Thomas Aquinas’s Earliest Treatment of the Divine Essence:

Scriptum super libros Sententiarum, Book I, Distinction 8. Thomas Aquinas.

Binghamton, NY: Binghamton University Press, 1998.

Gimaret, D. "Tawḥīd." Encyclopedia of Islam, 2nd ed. Ed. P. Bearman, Th. Bianquis, C.E.

Bosworth, E. van Donzel, W.P. Heinrichs. Brill Online, 2014. Reference. Marquette

University.

http://0-referenceworks.brillonline.com.libus.csd.mu.edu/entries/encyclopaedia-of-islam-

2/tawhid-SIM_7454 (accessed Feb. 9, 2014).

Janssens, J. “Le Dânesh-Nâmeh d’Ibn Sînâ: Un text à revoir?” Bulletin de philosophie

médiévale 28 (1986): 163–77.

Owens, Joseph. “Aquinas’ Distinction at De Ente et Essentia 4.119-123.” Mediaeval Studies 48

(1986): 264-87.

-------. Aquinas on Being and Thing. New York: Niagara University Press, 1981.

-------. Cognition: An Epistemological Inquiry. Texas: The Center for Thomistic Studies, 1992.

-------. “Quiddity and Real Distinction in St. Thomas Aquinas.” Mediaeval Studies 27 (1965): 1-

22.

-------. “Stages and Distinction in De Ente: A Rejoiner.” The Thomist 45 (1981): 99-123.

-------. “The Accidental and Essential Character of Being.” Mediaeval Studies 20 (1958): 1-40.

Sweeney, Leo. “Existence/Essence in Thomas Aquinas’ Early Writings. Proceedings of the

American Catholic Philosophical Association 37 (1963): 97-131.

Wietecha 24

Wippel, John. “Aquinas’ Route to the Real Distinction: A Note on De ente et essentia.” The

Thomist 43,2 (1979): 279-295.

-------. Metaphysical Themes in Thomas Aquinas, no. 1. Washington, D.C., Catholic University

of America Press, 2007.