My aim in this study is to establish where Avicenna (Ibn Sīnā, 980–1037) presents a formal demonstration for the existence of God within the Metaphysics of the Healing (al-Shifāʾ, al-Ilāhiyyāt).Footnote 1 I shall argue that Avicenna only formally demonstrates the existence of God in book VIII of the Ilāhiyyāt. A formal demonstration is distinct from a material demonstration in two important respects. First, for a formal demonstration Avicenna must intend within a particular passage to demonstrate God's existence by a series of ordered propositions, arguments, enthymemes, or syllogisms. Second, and as a necessary corollary to his intention, Avicenna must at least assume he has adequately supplied the relevant arguments that sufficiently support the premises employed within a formal demonstration for God's existence. A material demonstration consists in any variety of the necessary conditions for the proof, but is without the sufficient condition of being ordered to the end of demonstrating God's existence. For example, simply developing an argument that shows the notion “necessary existence in itself” cannot be caused is not sufficient to generate a formal demonstration for God's existence, or even for the existence of a first cause that is necessary existence in itself. There are many reasons for proving such contentions, and one would undoubtedly use similar arguments if one were presenting a formal demonstration for God's existence, but the cross-pollination of rational strategies or patterns of argumentation do not produce the same conclusions. Material arguments could be fortified and contextualized appropriately to become formal demonstrations, and perhaps the author does this in other passages, but we cannot infer that similar premises and arguments in one context necessarily provide us with formally the same conclusions in a very different context. As we will see, the failure to consider the intentions of Avicenna within a particular context has led many scholars to misinterpret where Avicenna has presented a formal demonstration for the existence of God in the Ilāhiyyāt.
Those familiar with the scholarship on Thomas Aquinas will recognize a similar set of exegetical confusions have arisen for those who read into the De ente et essentia IVFootnote 2 or Summa contra gentiles I.15 arguments for God's existence because similar premises are employed elsewhere in formal demonstrations for God's existence, like in the third way of the Summa theologiae, to take the latter case.Footnote 3 I suggest, but will not investigate here, that a similar transposition of a material to a formal demonstration might be found in Avicenna, from Ilāhiyyāt I.6–7 to the Kitāb al-Najāt, Ilāhiyyāt, II.12, as well as in other earlier and later works.Footnote 4 It should also go without saying that just because later authors like al-Ghazālī, Maimonides, Averroes, Thomas Aquinas, Henry of Ghent, and Duns Scotus may have taken such materials from Avicenna for their own formal demonstrations, or criticisms thereof, we cannot necessarily read their interpretations back into Avicenna.
I shall argue that the formal demonstration for the existence of a first cause that is identified with God is found only in the Ilāhiyyāt VIII.1–3, and that the substance of the dense and numerous arguments about the necessary existence in itself found in Ilāhiyyāt I.6–7 constitute, at best, nothing more than a material demonstration. In other words, Avicenna has very different intentions in I.6–7, which this paper will attempt to make transparent in structure, though not in detail.
1. LEGIONS OF INTERPRETATIONS OF AVICENNA'S ARGUMENTS FOR GOD'S EXISTENCE
A brief examination of the wild variety of opinions on where and what kind of demonstrations for God's existence are attributed to the Ilāhiyyāt, makes clear how controversial this problem is in contemporary scholarship on Avicenna. No one seems to dispute that book eight presents a formal demonstration for God's existence, and since we do not wish to be the first among the assemblage of the undiscerning, we will follow suit. Disagreement resides around those controversial passages in Ilāhiyyāt I.6–7 where Avicenna distinguishes and analyzes at length the properties that belong to possible and necessary existence. This same battery of materials is also deployed in Avicenna's Najāt to initiate what appears to most scholars to be a genuine formal demonstration. So what is the difference between the two? The diversity of both historical and recent interpretations on the significance of these passages is legion.
It has been argued by some that this passage from Ilāhiyyāt I.6–7 is merely a sort of conceptual consideration or dialectical investigation into the properties that belong to the notions necessary existence in itself and possible existence in itself. Consequently, such interpreters rule out the thesis that there is formal demonstration to be found in this text from Ilāhiyyāt I.6–7.Footnote 5 A larger contingent has held that Ilāhiyyāt I.6–7 does in fact present a cosmological style formal demonstration or, at least, it provides some of the premises to a formal demonstration that is scattered throughout the whole of the Ilāhiyyāt.Footnote 6 Some have been inventive enough to contend that this is an ontological or proto-Anselmian styled a priori formal demonstration. A few outliers, not satisfied with making a decision one way or the other, have even contended it is either a genuine cosmological formal demonstration, which has notes proper to the bouquet of ontological arguments, or that what we have here is simultaneously both a cosmological and ontological formal demonstration for God's existence.Footnote 7
Clearly enough the first problem that confronts us has little to do with Avicenna's text, but with this tangled web of contemporary interpretations. What do each of these interpretations mean by terms like cosmological, ontological, a priori, and a posteriori? Some scholars seem to employ these terms in the conventional ways found in contemporary philosophy of religion, yet others seem to use them in entirely idiosyncratic ways. Avicenna of course never used any of these terms, and since it would be beyond the scope of this paper to categorize and evaluate all the arguments laid out by each of these interpretations, I will stay close to the terminology of Avicenna who thinks in terms of demonstrations that and why (burhān inna and burhān lima, respectively). My arguments aim to show that many of these contemporary debates about different kinds of arguments for God's existence in Ilāhiyyāt I.6–7 completely miss the point, because, as I shall demonstrate, there is no formal argument for God's existence in this passage. It will be shown that Avicenna's analysis of necessary and possible existence in Ilāhiyyāt I.6–7 could not be a formal demonstration for God's existence since these chapters are oriented towards providing us with insights into the proper first principles of metaphysics.Footnote 8 These principles will then be employed throughout Avicenna's metaphysical investigations concerning this science's objects of inquiry, one of the last being the formal demonstration of God's existence in Ilāhiyyāt VIII.1–3.
2. THE SUBJECT OF AVICENNA'S METAPHYSICAL SCIENCE
Before looking at the disputed texts themselves we must first address the context of these passages, and their place within Avicenna's innovative organization of the Aristotelian science of metaphysics. Observing the systematic order of Avicenna's approach to philosophical problems can often be as insightful as what he has to say about these problems themselves. This will especially prove to be true for the problems considered in this paper.
We will begin our exegetical investigation with the opening chapters of the Ilāhiyyāt where Avicenna establishes the subject and objects of inquiry sought in his metaphysical science. Since Aristotle's doctrine of a demonstrative science plays a central controlling role in his Ilāhiyyāt,Footnote 9 it is not surprising that he introduces metaphysics by first considering the subject (mawḍūʿ) of the science. What is required at the start of any science, however, is more than just its subject; we also need principles (mabādiʾ) that are admitted (musallama), foundations upon which we can derive vis-à-vis our subject that third feature of every Aristotelian science, namely, its demonstrated conclusions or proper attributes, that is, the objects of inquiry (maṭālib) or things which are sought after (ashyāʾ hiya al-maṭlūba).Footnote 10
But what is the subject of Avicenna's metaphysical science? This is the central question of the early chapters of book one. Within these chapters Avicenna will consider three alternatives for the subject of metaphysics: is it an ontology, aitiology, or theology? Many misinterpretations of Avicenna's analysis of necessary and possible existence in Ilāhiyyāt I.6–7 fail to consider the significance of his account of the subject of metaphysics in Ilāhiyyāt I.1–4. Avicenna's treatment of necessary and possible existence follows his presentation of the subject of metaphysics; however, the analysis of necessary and possible existence is also distinct from the objects of inquiry sought by the science of metaphysics; these objects of inquiry begin with substance in Ilāhiyyāt II. We must observe closely Avicenna's division of metaphysics into its subject (Ilāhiyyāt I.1–4), principles (Ilāhiyyāt I.5–8), and objects of inquiry (Ilāhiyyāt II-X). The key for unlocking our problem will be found in properly understanding the unity of topics addressed in the first book of the Ilāhiyyāt.
Aristotelian philosophers are at odds about the subject of metaphysics. If Avicenna were to take God as the subject of metaphysics, that is, if Aristotelian first philosophy were principally a divine science, because it took God as its initial point of departure, then nothing would make more sense than to begin metaphysics with demonstrations that prove God exists. Whether or not this is the proper Aristotelian procedure does not concern us, for it certainly is not the approach of Avicenna.
In Ilāhiyyāt I.1–2 we quickly learn that this science of metaphysics is the only science that presents demonstrations for the existence of God,Footnote 11 that God's existence “is neither self-evident, nor something one despairs of demonstrating” for, as Avicenna tells us, “there is a proof for” God's existence.Footnote 12 But since no science demonstrates the existence of its own subject, and God's existence must be demonstrated, and the science of metaphysics alone can demonstrate it, then we must conclude that the study of God's existence and attributes cannot be identified with the subject of metaphysics.Footnote 13 After a number of additional arguments in chapter one, Avicenna draws the further conclusion that neither God nor the ultimate four causes are the subject of metaphysics; rather, they are among its objects of inquiry.Footnote 14 In short, the aitiological and theological investigations of metaphysics are not identified with the subject of first philosophy but with the objects of inquiry the science will ultimately investigate. The conclusions of Ilāhiyyāt I.1 make it perfectly clear: the primary subject of metaphysics cannot be God or the ultimate causes, since the existence of both must be demonstrated later, along with the many other objects of inquiry proper to metaphysics.Footnote 15Ilāhiyyāt I.2–3 establishes that the subject of metaphysics is being inasmuch as it is being and clarifies further the distinction between the subject of metaphysics and its objects of inquiry, that is, those things sought in this science as quasi-species and quasi-accidents of being.Footnote 16
Given these early contentions about the subject of metaphysics and its objects of inquiry in Ilāhiyyāt I.1–3, it would be unusual, to say the least, for Avicenna to provide us with a formal demonstration for God's existence in Ilāhiyyāt I.6–7. Avicenna has just identified, not God, but being qua being as the subject of metaphysics, and he has identified the demonstrations for God's existence among the ultimate objects of inquiry. Up to this point in his metaphysics Avicenna has not given any indication that he intends immediately to present a formal demonstration for the existence of God in Ilāhiyyāt I.6–7 prior to addressing the other objects of inquiry proper to metaphysics. Rather, Avicenna has given us every reason to think that arguments for God's existence will not be addressed until the last books of the Ilāhiyyāt.Footnote 17
3. THE SCIENTIFIC ORDER OF THE ILĀHIYYĀT
In Ilāhiyyāt I.4, Avicenna sets forth the general order of his metaphysical science, that is, all the topics to be treated from this chapter to the end of the Ilāhiyyāt. The significance of this scientific order should be central to any interpretation concerning where Avicenna's formally demonstrates the existence of God, for it is here in I.4 that he explicitly states what philosophical topics he intends to treat and where he intends to treat them.
Avicenna begins this table of contents in I.4 with the topics to be addressed in the next chapter of book I, that is, Ilāhiyyāt I.5. He says we must begin with a consideration of being and thing and their relation to the categories. Following the treatment of being and thing Avicenna promises to investigate necessary and possible existence, and the distinction between truth and falsity, which corresponds to the topics addressed in Ilāhiyyāt I.6–7 and I.8, respectively.Footnote 18 This exhausts the contents of topics taken up in Ilāhiyyāt I and there is no reference to any proofs for God's existence up to this point in Avicenna's table of contents.
Avicenna spends the rest of Ilāhiyyāt I.4 surveying the long list of objects of inquiry to be addressed in the other nine books of the Ilāhiyyāt, which consists in the quasi-species of being, namely, substance (II) and accidents (III), as well as the many quasi-properties of being like the prior and posterior (IV), universals and particulars (V), causality (VI), and the one and many and beliefs about various pseudo-ultimate causes (VII).Footnote 19 Only after this series of objects of inquiry, which summarizes the contents of the Ilāhiyyāt from books I–VII, does Avicenna state that his metaphysical science will finally reach the highest object sought. In short, “We will prove the existence of the First Principle and show that He is one, truth, omnipotent and all other divine attributes.”Footnote 20 And this is precisely what he does in Ilāhiyyāt VIII. Nowhere else in this summary of topics from Ilāhiyyāt I.4 does Avicenna even hint that he might intend to demonstrate the existence of God prior to Ilāhiyyāt VIII.
Hence, it should be clear that Avicenna's own explicit intentions in Ilāhiyyāt I.4 present a serious problem for those interpretations that contend that Ilāhiyyāt I.6–7 includes a formal demonstrations for God's existence. Avicenna has just spent four chapters declaring that God is neither the subject nor among the principles of metaphysics – the problems Avicenna addresses in Ilāhiyyāt I.1–8 – but God's existence is among the ultimate ends of his metaphysical science. Not only is the demonstration of God's existence among the many objects of inquiry, the actual demonstration itself, according to Avicenna, will follow nearly the whole sundry of objects of inquiry addressed in his metaphysics. Further, the statements made here in Ilāhiyyāt I.4 about Ilāhiyyāt I.5–7 suggest that the inquiry into necessary and possible existence is intended to be nothing more than an investigation of these notions, along with the relation of being and thing to the categories. In short, Avicenna gives us no reason to think he intends to present a demonstration for God's existence in the first book of his Ilāhiyyāt, and all interpretations to the contrary must deal with the fact that their view directly contradicts Avicenna's numerous explicit statements and completely ignores the scientific order of Avicenna's metaphysical science.
4. AVICENNA'S METAPHYSICAL FIRST PRINCIPLES
Let us turn to a closer analysis of the remaining chapters of book one so as to make clearer Avicenna's intentions in Ilāhiyyāt I.5–8. As we have seen, the first four chapters of book one are dedicated to distinguishing the subject of metaphysics from its many objects of inquiry. But Avicenna has not yet discussed that third element which he noted in chapter one also belongs to every demonstrative science. Every science has “something which is a subject; things that are searched after; and principles, [universally] admitted, from which demonstrations are constructed.”Footnote 21 Where are the metaphysical principles he promised us? This is the task of the final four chapters of book one. According to Aristotle principles are admitted at the outset of any science; they are divided into proper and common principles, and proper principles subdivide into notions and hypotheses. Common principles are those axioms adopted by every science but are properly treated in the universal science of metaphysics, for example, that there is no middle between affirmation and negation, which Avicenna introduces after a brief analysis of the nature of truth in the final chapter of the first book. Avicenna appropriated this division of first principles into his own account of the two noetic acts of conceptualization (taṣawwur) and assent (taṣdīq). Concepts and assents are either primary, or acquired through other concepts and assents that are more fundamental. The ultimate primary concepts and assents in any science provide the principles of conceptualization (mabādiʾ al-taṣawwur) and the principles of assent (mabādiʾ al-taṣdīq).Footnote 22 Accordingly, a science will employ both the principles of assent common to all sciences, as well as the primary principles of conceptualization and assent that are proper to its own subject.
Not only does Avicenna bring to his Aristotelian metaphysics a precise account of the threefold division of scientific first principles into primary notions of conceptualization and primary hypotheses and axioms of assent, but he also does so by integrating three of Aristotle's four senses of being into this threefold division of the first principles of metaphysics. Throughout the Metaphysics Aristotle distinguishes the various senses of being into being per accidens, being per se, which is analogically found in all ten categories, being as divided into act and potency, and being as the truth of propositions.Footnote 23 Avicenna synthesizes his own novel appropriation of Aristotle's fourfold division of being into the threefold division of the first principles of metaphysics. This appropriation is made particularly clear in Ilāhiyyāt I.4's announcement of the topics to be addressed in Ilāhiyyāt I.5–8.
We must, in this art, know the state of the relation of thing and being to the categories – the state of nonexistence, the state of necessity (that is, necessary existence and its conditions), and the state of possibility and its true nature (and this is in itself the theoretical investigation of potentiality and actuality). [We must also] examine the state of what is in itself and what is accidental; the true and the false […].Footnote 24
Here Avicenna subtly represents his own version of Aristotle's four senses of being. Let us begin with Avicenna's integration of Aristotle's doctrine into the primary notions treated in Ilāhiyyāt I.5.
One of the four senses of being for Aristotle involved a comparison of being to the categories. Aristotle argued that both being and one are primary notions that pervade all of the categories of being per se and cannot be contained by any one genus.Footnote 25 In Ilāhiyyāt I.5 Avicenna correlates the sense of being that transcends all the categories with the primary notions of metaphysics, that is, the first principles as primary notions. Avicenna goes beyond Aristotle and extends this attribution of primacy and transcendence to the metaphysical notions thing and the necessary. This is seen most clearly in the opening lines of Ilāhiyyāt I.5, where we are told that:
[The] notions of “being,” “thing,” and “necessary” are impressed in the soul in a primary way. This impression does not require better known things to bring it about. [This is similar] to what obtains in the domain of assent, where there are primary principles found to be true in themselves, causing [in turn] assent to the truths of other [propositions].Footnote 26
Just as there are first principles that involve assent, like primary hypotheses and axioms, so also there are first principles in the realm of notions conceived. “Similarly, in conceptual matters, there are things which are principles for conceptualization that are conceived in themselves.”Footnote 27 These primary notions or first principles of conceptualization transcend the limitations of the ten genera of the categories for they are the “things that have the highest claim to be conceived in themselves {and} are those common to all entities – like, ‘being,’ ‘thing,’ ‘one,’ and others.”Footnote 28 In short, Avicenna's treatment of primary notions in Ilāhiyyāt I.5 is both able to extend Aristotle's sense of being to thing and the necessary, as well as incorporate these primary notions into the first division of proper principles found in his metaphysical science.
A similar correlation and innovation occurs in his treatment of primary hypotheses and axioms in Ilāhiyyāt I.6–7 and Ilāhiyyāt I.8, respectively. We have just seen that Avicenna affirms there are first principles in both the domain of conceptualization and assent. The first principles of assent proper to the science of metaphysics pertain to the properties of necessary and possible existence. These hypotheses of assent are established in the course of Ilāhiyyāt I.6–7. In these chapters Avicenna modulates Aristotle's sense of being as act and potency by subordinating the priority of this Aristotelian division to what Avicenna takes to be the more fundamental modal disjunctive sense of being as necessary or possible. As quoted above, Avicenna tells us that the modal division between necessary and possible existence “is in itself the theoretical investigation of potentiality and actuality.”Footnote 29 This theoretical investigation will establish the primary hypotheses of assent that belong to metaphysics, such as, possible existences are composite and caused, as well as, necessary existence in itself is uncaused, one, simple, and peerless.
Finally in Ilāhiyyāt I.8 Avicenna connects Aristotle's sense of being as the truth of propositions with his defense of the axiom that there is no middle between affirmation and negation, a universal truth common to all propositions. Avicenna's metaphysical examination of axioms or principles common to all sciences is set within his division of ontological and epistemological truth. Aristotle's sense of being as the truth of propositions is developed within Avicenna's brief account of epistemological truths. The first among epistemological truths can be found in the axiom that is the first principle of demonstration. Avicenna then supports the whole hierarchy of epistemological truths within the hierarchical edifice of ontological truths, which ultimately depend upon the first truth that is necessary existence in itself.Footnote 30
More could be said about Avicenna's correlation of the three kinds of scientific first principles with Aristotle's senses of being, but only the second kind of proper principles is essential to the interpretation of Ilāhiyyāt I.6–7. In order to defuse the common theological misinterpretations of I.6–7, we must begin with Avicenna's analysis of the necessary as primary notion in I.5, before turning to his presentation of the primary hypotheses of metaphysics in I.6–7.
5. THE NECESSARY AS A PRIMARY METAPHYSICAL NOTION
It is characteristic of the proper principles of metaphysics, the universal science of being, to be like axioms in a number of respects. Axioms are the common principles that are always present and utilized in all our assents, so much so that we often do not notice their ubiquitous deployment. This point is reiterated in the opening remarks of Ilāhiyyāt I.5. There are two kinds of proper principles, those in the order of conceptualization and those in the order of assent. Said otherwise, there are principles that are notions and principles that are hypotheses or axioms. We would do well to observe Avicenna's distinction, and to keep these two acts of the intellect in view for what follows in his treatment of first principles.
As we have seen above, the notions that are impressed in our soul in a primary and per se way are being (mawjūd), thing (shayʾ), and necessary (ḍarūrī/wājib). These notions are the principal notions by which we conceive all other meanings, they are common to all other notional meanings, can be said of any other notion, and they cannot be apprehended or defined through other notions since all other meanings include these notions in their definitions. Any attempt to define these primary notions or to demonstrate them will involve one in countless confusions or circularity.Footnote 31
So how do we become aware of them if they are always present but not always noticed? The substance of Ilāhiyyāt I.5 consists in Avicenna's endeavor to awaken our minds to the metaphysical meanings being, thing, and necessary by way of various signs. Avicenna uses signs which are more known to us in order to make the metaphysically more known in itself manifest. He begins by introducing the reader to a number of signs and names that direct our attention to this metaphysical trio. His use of less common meanings or definitions, synonyms, and various dialectical arguments all aim to prepare us to go beyond that threshold of vagueness just prior to intellectual insight. We do not have the space to explicate Avicenna's use of signs, synonyms, and dialectical arguments that concern the notions being and thing, so we will turn to the end of Ilāhiyyāt I.5 where he treats the primary notion the necessary.Footnote 32
Avicenna commences with a few remarks on the difficulties that the ancients had with defining the nature of the necessary.Footnote 33 As a modal notion, any definition proposed for the necessary seems to involve the possible and the impossible as much as their own definitions involve the necessary. All attempts to distinguish which modality is prior by way of definition results in endless circularity. To escape circularity Avicenna tells us we must make use of a sign (ʿalāma) in order to distinguish the necessary (al-wājib), the possible (al-mumkin), and the impossible (al-mumtaniʿ) since they cannot be known and distinguished by way of definition (ḥadd).
What is this sign? Drawing upon an insight from the Second Teacher, al-Fārābī, Avicenna reveals to us that the necessary is first because it points to the “invariance of existence” (taʾakkud al-wujūd).Footnote 34 Existence, that is, established existence (wujūd ithbātī),Footnote 35 is known through itself and is better known than nonexistence. In fact, nonexistence is always, in some way or another, known through existence, as Aristotle noted long ago in Metaphysics Γ 2. Now, in a manner of speaking, the impossible and the possible signify complete or relative modes of nonexistence, respectively. Accordingly, inasmuch as the possible has existence it is known through the necessary, for its dependence on the necessary – which is the invariance or assurance of its existence – is also proportionately equivalent to its existential knowability. In short, the invariance of existence is the proper meaning of the necessary, and the impossible and possible are known through the necessary.
After providing us with this insight into the existential and cognitive priority of the necessary among modalities, Avicenna digresses from the point at hand. This new insight allows him to clear up some problems with a particular view on the resurrection held by some Mutakallimūn.Footnote 36 In bringing such recondite matters to a close, Avicenna also signals that he is finished with these conceptual matters concerning primary notions, and that he is moving on to the realm of principles within the domain of assent. The difficulty is, Avicenna has just started his treatment of the necessary. Compared to his treatment of thing and being, the primary notion necessary seems to be getting short shrift. This new insight into the necessary as the invariance of existence, however, takes us beyond the absolute consideration of notions in themselves and forces our discussion of priority within modalities to oscillate between notions and the assents that affirm existence. In short, without looking to established existence there is no way to indicate which modality is prior.
6. THE GOAL OF ILĀHIYYĀT I.6–7: THE PROPERTIES OF NECESSARY AND POSSIBLE EXISTENCE
Ilāhiyyāt I.6–7 returns to Avicenna's treatment of the necessary and possible. From the very beginning of these two chapters Avicenna tells us that there are properties (khawāṣṣ) for both necessary existence and possible existence that we must now establish. We can be certain that establishing these properties is the central goal of both chapters six and seven, since chapter seven explicitly draws to a close with a conclusion that affirms and recapitulates the properties of necessary and possible existence that were first introduced in the opening paragraphs of chapter six.Footnote 37 It is also important to note that neither of these two chapters mentions anything about presenting a formal demonstration for the existence of God. Rather, their aims are continuous with where the previous chapter left off, that is, with an attempt to dispose us towards insights and assents into the primary notions and hypotheses related to the necessary, respectively, just as Avicenna said he would do in Ilāhiyyāt I.4.
Avicenna continues to make good on his promise by addressing the existential significance of these modal notions. Now among those entities that enter into existence we find, he contends, a twofold division in the intellect. Note well that we are dealing with ways of intellectually considering entities that exist. The existence of the entities under consideration is either taken for granted or, more likely, hypothetical, but Avicenna is certainly not attempting to present a formal demonstration that establishes the existence of such entities. So what is the point? Avicenna's goal is to consider and establish an exhaustive division of all the beings that could exist, that is, he intends to establish the properties that belong to necessary and possible existence.
Avicenna's account proceeds as follows. Some entities, when we consider them in themselves their existence will not be necessary, yet their existence is not impossible. This is because we are dealing with entities that were supposed to enter into existence; these things then belong to the realm of possibility. In contrast to these possible existences, the existence of other entities considered in themselves is necessary.Footnote 38 Notice that this twofold division requires an initial intellectual affirmation of existence – it is either assumed or hypothetical – and then a reflexive intellectual consideration of those entities that enter existence. To include existence, is to affirm existence as established.Footnote 39 In short, Avicenna is bringing us into the realm of assent, and so we need to be attentive to the properties he will affirm (or deny) of necessary existence and possible existence that constitute the first principles of assent proper to metaphysics. What properties can we affirm regarding necessary existence and that modal notion known through necessary existence, namely, possible existence?
Avicenna spends the next two chapters establishing a series of primary assents concerning the properties that truly belong to necessary existence and possible existence. For example, the necessary existence in itself has no cause, that which is possible existence in itself has a cause and is composite, necessary existence has no equivalent and is not dependent on another, necessary existence is neither composite nor many, but is one.Footnote 40 How are these primary hypotheses of assent established? Not by demonstrations, but by deductive dialectical arguments. Axioms, like the principle of contradiction, cannot be demonstrated, but they can be taught and defended by formally deductive dialectical arguments that show denying an axiom will result in a contradiction or absurdity. These deductive arguments do not demonstrate the truth of axioms; they merely show that the denial of their truth entails falsity. Similarly, Avicenna establishes the reasonableness of assenting to these primary metaphysical hypotheses concerning the properties of necessary and possible existence by showing that their denial results in impossibilities, contradictions, and absurdities. Most of Avicenna's arguments in I.6–7 consist in formally valid modus tollens deductive arguments. These are negative arguments that do not demonstrate the hypotheses are true, but that their denial is false. We do not have the space to explicate fully all of Avicenna's numerous arguments in defense of his primary hypotheses,Footnote 41 or to show the way in which this account of the properties of possible and necessary existence transitions into I.8's treatment of truth and axioms.Footnote 42 Instead, let us briefly survey some of the arguments Avicenna marshals in defense of these primary hypotheses.
The first hypothesis established in Ilāhiyyāt I.6 is that necessary existence in itself is not caused.Footnote 43 Avicenna presents two reductio ad absurdum arguments that show the proposition “necessary existence in itself is caused” is false. The arguments begin with a denial of the hypothesis that necessary existence in itself is uncaused. If necessary existence in itself is caused, then necessary existence in itself is not necessary existence in itself. But this is a contradiction, and so it is false that necessary existence in itself is caused. So we should assent to the hypothesis that necessary existence in itself is not caused.
Whether there exists an uncaused necessary existence in itself is not the point here. Avicenna aims to show us that it is impossible to hold as true the proposition “necessary existence in itself is caused,” so we should intelligently assent to the proposition: “necessary existence in itself is not caused.” Again, Ilāhiyyāt I.6 does not present any philosophical demonstration that there exists a necessary existence in itself that is not caused. Avicenna just wants us to grant that it would be absurd to deny this primary proposition, which is why it is a fundamental principle of metaphysics. Whether this uncaused necessary existence in itself exists is an entirely different question, and it is neither posed nor answered in Ilāhiyyāt I.6–7.
The next hypothesis established in Ilāhiyyāt I.6 is that any possible existence in itself is caused.Footnote 44 Avicenna again employs two modus tollens arguments to show that it is impossible and absurd to deny that possible existence in itself is caused. The first argument is from the insufficiency of the possible existence's quiddity to establish its existence or nonexistence. Avicenna concludes that all possible existences in themselves must have a cause for their existence; this existential cause is other than the quiddity of the possible existence considered in itself.
The second argument goes one step further and establishes that this existential cause must necessarily cause this possible existence in itself to be necessary existence through another. Avicenna contends that a denial of the identification of the cause of necessity with the existential cause would entail an infinite regress. Avicenna concedes that he has not yet established that an infinite regress is impossible, but what is of note is that he introduces the infinite regress here in Ilāhiyyāt I.6, not to show that there must exist some necessary existence in itself, but to show that if possible existences are not rendered necessary existence through another, then they cannot exist at all. If there is an infinite regress, then
the existence of the possible … would not have been specified by [the cause of its existence]. As such, its existence would not have been realized. This is impossible, not only because this leads to an infinity of causes … but because no determination has been arrived at through which its existence is specified, when it has been supposed to be an existent. Hence, it has been shown to be true that whatever is possible in its existence does not exist unless rendered necessary with respect to its cause.Footnote 45
Notice that these arguments do not establish that possible existences must have some cause that is an uncaused necessary existence in itself. Rather, Avicenna's arguments aims to show first, that possible existences in themselves are caused because their quiddities are existentially insufficient for their own existence, and second, that their existential cause renders them a necessary existence through another.
The third and final hypothesis established in Ilāhiyyāt I.6 shows that it is false to contend that necessary existence in itself could have an equivalent, that is, that there could be more than one uncaused necessary existence in itself.Footnote 46 The arguments given here are very complex, and once again, Avicenna aims to show that a denial of this hypothesis entails a number of contradictions and impossibilities.
Ilāhiyyāt I.7 continues where I.6 left off, and attempts to establish the hypothesis that necessary existence must be one, which occupies the whole chapter up to Avicenna's recapitulation of Ilāhiyyāt I.6–7 at the very end of I.7. Once more Avicenna uses a series of arguments that end in contradictions, falsity, and impossibilities, none of which conclude with the existence of God. He does not demonstrate that necessary existence in itself is one, but shows us that it is absurd to deny it. Therefore, we should accept the hypothesis that necessary existence is:
one in [its] entirety (not as species are [subsumed] under genus) and one in number (not as individuals [subsumed] under species). Rather, it is a meaning, the explication of whose term belongs only to it; and its existence is not shared by any other. We will clarify this further in another place. These are the specific properties which necessary existence is exclusively endowed.Footnote 47
This brings us to the specific properties of possible existence that are established in Ilāhiyyāt I.6–7. First, “that it necessarily needs some other thing to render it an existent in actuality. Whatever is a possible existence is always, considered in itself, a possible existence; but it may happen that its existence becomes necessary through another.”Footnote 48 We have already seen that, for Avicenna, the quiddities of possible existences in themselves are existentially neutral, since their quiddities are insufficient to render them existents in actuality. This is why possible existence in itself is only rendered necessary existence through another. Second, and in contrast to the unity and simplicity of necessary existence in itself, all possible existences must be composed.
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 essence in existence from both together. For this reason, nothing other than necessary existence, considered in itself, is stripped of associating with what is in potentiality and [what is within the realm of] possibility. It is the odd, and [every] other composite, even.Footnote 49
It should be clear by now that Avicenna's intention in Ilāhiyyāt I.6–7 was to establish the properties of necessary and possible existence, not to demonstrate formally that God exists. The final recapitulation of I.6–7 draws the two chapters to a close by presenting the hypotheses or principles of assent proper to metaphysics, namely, that necessary existence in itself is one and simple, and that all possible existences in themselves are composed of quiddity and their existential necessity, which is received from another. None of these argument found in Ilāhiyyāt I.6–7 conclude with a statement like, “therefore, the necessary existence in itself exists, and this is God.” Furthermore, with respect to the hypotheses Avicenna does intend to establish, none of the arguments he uses actually demonstrate the truth of these hypotheses; instead, they merely refute their denial. Why does Avicenna argue in this way? Because these are the kinds of arguments used to establish, not demonstrative conclusions, but to defend first principles of assent, that is, the sort of knowledge that cannot be demonstrated by any prior knowledge because it is the foundation for all demonstrative knowledge.Footnote 50 The truth of these metaphysical hypotheses, such as necessary existence in itself is not caused, are not demonstrated, yet Avicenna's deductive arguments in defense of these primary hypotheses seek to help his readers understand the reasonableness of assenting to the truth these first principles of assent proper to metaphysics.
To summarize: thus far it has been shown that Avicenna's explicit goal in Ilāhiyyāt I.6–7 was not to demonstrate the existence of God, but to establish the properties that belong to possible and necessary existence. By now this much should be obvious. But in addition to our non-theological interpretation of the goal of I.6–7, I have also argued for a complementary and corroborating thesis that places I.6–7 within the scientific order of Avicenna's metaphysics. While my interpretation is easily verified by Avicenna's own words, it nevertheless only shows that it is so, it does not explain why he treats the properties of possible and necessary existence in I.6–7, in the argumentative fashion that he does, right in the middle of his overt treatment of metaphysical first principles as notions in I.5 and axioms in I.8, and all the while completely omitting any explicit mention of those metaphysical first principles that are known as hypotheses, which he himself, following Aristotle, acknowledged as among the kinds of first principles. I have contended that the most reasonable explanation of these additional facts is admirably handled by the thesis that Avicenna's account of the properties of necessary and possible existence in I.6–7 do in fact provide him with his metaphysical first principles as hypotheses, which should be treated in between his account of primary notions and axioms. Furthermore, it is also reasonable to understand Ilāhiyyāt I.6–7 as presenting the hypotheses of metaphysics, since first principles of assent can only be defended dialectically, and would consist in primary propositions that affirm basic properties of simple notions such as we find in the hypothesis that the necessary existence in itself is uncaused. Still, an extended defense of this contention merits a study of its own.Footnote 51
In the next section of this paper I shall further defend this study's interpretation of I.6–7 by pointing out four features of these arguments from Ilāhiyyāt I.6–7 that would be very peculiar and problematic if Avicenna did intend to use these arguments to demonstrate God's existence. These four features, however, do not present any problems for my interpretation of I.6–7, since I reject that there is any kind of demonstration for God's existence in these chapters. The problems with our interlocutors’ interpretations will be further amplified by showing that these four features do not create any tensions in Ilāhiyyāt VIII, where Avicenna does explicitly intend to demonstrate God's existence.
7. FOUR PROBLEMS FOR INTERPRETING I.6–7 AS FORMALLY DEMONSTRATING GOD'S EXISTENCE
First, formal demonstrations for the existence of God do not include within their premises that God exists, since this is the conclusion sought by the proof. Avicenna, however, begins Ilāhiyyāt I.6 with the assertion that the intellect is able to distinguish two different ways in which entities exist: as necessary or possible in themselves. And as we have seen, this twofold affirmation of existence is the point of departure for the rest of the two chapters. The affirmation of existence – whether real or hypothetical – is itself a further development on the previous chapter's point that the necessary is the primary modal notion because it indicates the invariance of existence.Footnote 52 In Ilāhiyyāt I.6 Avicenna is simply taking another step forward in his analysis of first principles by revealing for us two ways of existing by necessity: necessary existence in itself and necessary existence through another, which is possible existence in itself.
Second, if this is a formal cosmological demonstration it should begin by showing us that all possible existences are caused, and in the ultimate analysis are caused by the necessary existence in itself. But Avicenna does just the opposite. In I.6, he first shows us that necessary existence through itself does not have a cause, and then he shows us that possible existences must have causes. We should recall, that this is also the order Avicenna said he would follow at the outset in I.4, and that neither in I.6 nor in the beginning of I.4 does he even mention the prospect of demonstrating God's existence.
Third, one would expect Avicenna to eliminate the possibility of an infinite regress of caused possible existences that are necessary through another so as to terminate the causal series with that being which is an uncaused necessary existence in itself. But again, Avicenna does not do this here in I.6–7. Instead he is concerned with showing us that the possible existence has a property, such that its existential necessity is caused by another. The contradictory he argues would be impossible, yet not because an infinite regress of causes is impossible, but because no realization of existence would then be achieved for possible existences when their existence was already supposed to be realized. In short, Avicenna shows us that the actual existence of an entity that is possible existence in itself, requires that this possible existence be necessary existence through another, but he does not use this last point to show that there ultimately must be some being that is necessary existence in itself and is causally responsible for all things that are possible existence in themselves. Significantly, Avicenna never states in I.6–7 whether or not there is any causal connection between the necessary existence in itself and the multiplicity of possible existences in themselves. How could this be a formal demonstration for the existence of God when Avicenna does not even attempt to establish a causal relationship between possible existences and the necessary existence in itself? In fact, Avicenna does not make this connection explicit until the summary of points that immediately follow his formal demonstration of God's existence in VIII.3, wherein he also clarifies the notion of “creation.”Footnote 53
Fourth, what Avicenna says here in I.6 about the possibility of an infinite regress is also interesting, and for two reasons. First, Avicenna introduces the problem of an infinite regress to show, not that there must be a first cause that is necessary existence in itself, but in the context of showing that possible existences are caused by another. Second, he notes that we cannot appeal to the impossibility of an infinite regress because this “is still open to doubt in this place.”Footnote 54 In other words, Avicenna does not yet think he has established that an infinite regress is impossible, and furthermore, that book I.6–7 is not the place where he will show us why an infinite regress is impossible.Footnote 55
These four objections merely highlight problematic structural features for any interpretations that hold there is a formal demonstration for God's existence to be found in the arguments from I.6–7. Nevertheless, I think that a more thorough analysis of the arguments themselves, such as R. E. Houser has done, only further corroborates this paper's thesis.Footnote 56
8. AVICENNA'S FORMAL DEMONSTRATION FOR GOD'S EXISTENCE IN VIII.1–3
One might still attempt to try and resolve these difficulties by saying Avicenna was unaware or has a different idea about how to conduct a proper demonstration of God's existence. But as we will see this is not the case, for all these problematic features disappear when we turn to the place where Avicenna does formally demonstrate God's existence. Avicenna begins the eighth book of his metaphysics as follows.
Now that we have arrived at this stage in our book, it behooves us to conclude it with [the question] of the knowledge of the First Principle of all existence – whether He exists, whether He is one (having no companion in His rank, and no equal) – and to indicate His rank in existence, the ordering of the existents and their ranks below Him, and the state of return to Him, [in all this] seeking His help.Footnote 57
Faced with Avicenna's own words in this very clear passage, we should note two obvious problems with our interlocutors’ theological interpretation of I.6–7. First, whenever Avicenna does demonstrate the existence of God, like in al-Risāla al-ʿArshiyya, Ilāhiyyāt VIII, and in Najāt II.12, he explicitly declares it, and sometimes he even solemnly invokes divine assistance. However, such explicit statements of his intentions are not found anywhere in I.6–7 and would even be inconsistent with what he had just announced in I.4 in his summary of topics to be treated within his metaphysical science. Second, why does Avicenna think he needs to demonstrate God's existence twice, once in book one, and again in book eight, but yet also seems to be unaware that he has already demonstrated God's existence in I.6–7? This latter question, of course, rests upon an unreasonable assumption, as Avicenna clearly thinks the first time his metaphysical science arrives at its distinctively theological stage is in Ilāhiyyāt VIII. And there is no reason to think Avicenna has already provided a formal demonstration for God's existence up to this point.
We do not have the space to outline Avicenna's actual argument for the existence of God in Ilāhiyyāt VIII; nevertheless, before we return to our four problematical features we should note one final problem for some interpretations of the Ilāhiyyāt. Contrary to a number of interpretations, I agree with those who hold that in the Ilāhiyyāt there are no formal demonstrations for God's existence that involve arguments from possibility and that conclude to a necessary existence through itself. Rather, the only formal demonstrations to be found are those in Ilāhiyyāt VIII, and they seek to do what was not accomplished in Aristotle's Metaphysics, namely, unify all four causes into some one or more ultimate cause(s). Avicenna unites his aitiological inquiry into the ultimate causes and the theological inquiry into the divine cause by showing us that all four causes terminate in some first cause of a finite causal series, and that the First Efficient Cause is the cause of the existence for each of the respective first causes.Footnote 58 As Davidson and Bertolacci have both pointed out, unlike the Najāt, there is no formal demonstration for God's existence in the Ilāhiyyāt that is based solely on the distinction between possibility and necessity.Footnote 59
In the first of the four problematic features introduced above, we noted that if I.6–7 contained an argument for the existence of a being that is necessary existence in itself, it would beg the question, for the whole argument in I.6 begins by assuming – either really or hypothetically – the existence of a being that is necessary existence in itself. In contrast to I.6–7, Ilāhiyyāt VIII.1–3 does not assume the existence of a being that is necessary existence in itself, but endeavors to demonstrate its existence as an uncaused efficient cause. Further, instead of beginning with the uncaused necessary existence in itself as I.6 does – which was the second of the four problematic features mentioned above – Avicenna begins Ilāhiyyāt VIII.1–3 with effects and their per se causes, which then ultimately brings him to the existence of the uncaused necessary existence through itself. In short, the first two problematic features completely disappear in Ilāhiyyāt VIII.1–3.
As for the third and fourth problematic features, we do not need to appeal to what Avicenna does, as we can look to his own words.
The first thing we ought to do in this is to show that the causes are in all respects finite, that in each of their classes there is a first principle, that the Principle of all of them is one, that He differs from all [other] beings, that He alone is necessary existence, and that in the case of every [other] being, the beginning of its existence is from Him.Footnote 60
Evidently Avicenna does appreciate the importance of establishing the impossibility of an infinite regress, in fact, he says it is the first thing that must be done. But to get this demonstration off the ground Avicenna notes that another premise is needed, namely, “that the cause of a thing's existence coexists with it, it is [something] that has been previously presented and ascertained for you.”Footnote 61 This is significant because Avicenna's sophisticated treatment of the principle of causality in terms of the coexistence of per se causes was not addressed until Ilāhiyyāt IV.1 and VI.2. Here are two crucial elements in Avicenna's formal demonstration for God's existence that he explicitly says were not available in book I.Footnote 62 This final point reveals that the last two problematic features from I.6–7 have been addressed by the time we get to the place where Avicenna explicitly intended to demonstrate God's existence. By the close of the first book of the Ilāhiyyāt, Avicenna had not yet introduced the additional doctrines that were required for showing the impossibility of an infinite regress. But since these doctrines were established prior to Ilāhiyyāt VIII, Avicenna can proceed right away in VIII.1–3 to show that there cannot be an infinite regress of possible existences that were efficiency caused by another, unless we terminate in an uncaused first efficient cause of existence that is necessary existence through itself.
9. CONCLUSION
For a paper entitled “Where does Avicenna demonstrate the existence of God?” I have done very little to show where Avicenna does and more to show where Avicenna does not formally demonstrate the existence of God. In order to show that there is not a formal demonstration for the existence of God in Ilāhiyyāt I.6–7, I provided an alternative interpretation of this text that makes clear Avicenna's true intention in I.6–7. This interpretation revealed what was false in the assumptions of those who hold I.6–7 contains a formal demonstration for the existence of God.Footnote 63 Let us conclude with three overarching contentions that this essay has employed to undermine any interpretations that take Ilāhiyyāt I.6–7 to contain a formal demonstration for God's existence.
First, all theological interpretations of Ilāhiyyāt I.6–7 fail because they are completely inconsistent with the scientific structure of Avicenna's metaphysics whose subject is being qua being; whose primary principles of conceptualization are being, thing, necessary; whose fundamental proper principles of assent are “that necessary existence through itself is uncaused, one, and simple,” and “that necessary existence through another is composite and caused;” and whose ultimate object of inquiry – which follows Ilāhiyyāt II–VII's account of the quasi-species and quasi-properties of being – is the demonstration of God's existence and attributes in Ilāhiyyāt VIII. In short, the essential problem with many alternative interpretations is that they confuse Avicenna's treatment of metaphysical principles with a demonstration of metaphysics’ ultimate object of inquiry; a confusion that is in some respects similar to the mistake of those who regard God as the subject of metaphysics, when God is, for Avicenna, among its ultimate objects of inquiry.
Second, theological interpretations of Ilāhiyyāt I.6–7 disregard many of Avicenna's explicit intentions, which clearly indicate where God's existence will be demonstrated, as well as what principles and premises this formal demonstration requires, and where they are established within his metaphysical science. Third, not only do such interpretations render unintelligible both the overt goals that we find clearly stated at the beginning and end of I.6–7 along with these chapters’ intrinsic relationship to I.5 and I.8, but they also fail to address adequately the four problematic features found in the arguments from I.6–7 and the resolution of these tensions in VIII.1–3. Furthermore, it was shown that if the passage in I.6–7 is not intended by Avicenna to present a formal demonstration for God's existence, then these four problematic features of the arguments in I.6–7 disappear.
In conclusion, I recognize that many of the arguments given by Avicenna do have the appearance of being either a cosmological or ontological argument when they are read outside their context. But when they are understood within their proper epistemic framework as elements in his Aristotelian demonstrative science, these problems vanish. Without any unified principle which reveals the scientific order of Avicenna's metaphysics, many readers remain vulnerable to these and other misinterpretations, which all seem to run against Avicenna's own expressed intentions. Placing the Ilāhiyyāt within its Aristotelian scientific framework makes clear the problems involved in any interpretations which contend that Avicenna demonstrates the existence of the necessary existence at the beginning of his metaphysical science and yet does so again towards the end of his metaphysical science.Footnote 64
Avicenna's Healing prescribes an Aristotelian dosage of four measures from the diverse studies of logic, natural philosophy, mathematics, and metaphysics. The final treatment of his metaphysical science concludes with its ultimate object of inquiry, namely, theological being. Like any inoculation, it must be administered in the proper order. Confusions and misunderstandings occur when we fail to observe the scientific order prescribed by the Vizier himself. In this study I have tried to follow his many pointers and directives with respect to the demonstration of God's existence within his conception of metaphysics as an Aristotelian science. I hope it has been shown that one can learn a lot from Avicenna by observing what he does and where he does it, rather than trying to prescribe for him how he should have affected his philosophical cure.
Acknowledgment
An earlier version of this paper was presented at the Aquinas and ‘the Arabs’ International Working Group, “Philosophy in the Abrahamic Traditions” Co-Sponsored by Société Internationale pour l’Étude de la Philosophie Médiévale, Satellite Session at the American Catholic Philosophical Association 85th Annual Meeting, St. Louis University, St. Louis, MO, October 28–30, 2011. I would like to thank Jon McGinnis, Thérèse-Anne Druart, Richard Taylor, and Jörg Tellkamp for their comments, and especially the detailed feedback from Edward Macierowski that I received on this paper at the ACPA conference. David Twetten generously provided numerous comments and corrections on an earlier draft. Finally, I must thank my dissertation director, R. E. Houser, whose work on Aquinas and Avicenna inspired this study.
