Augustine and Ibn Sina on Souls in the Afterlife

Gareth Matthews. Philosophy. Volume 89, Issue 3. July 2014.

Richard Sorabji, in his book, Self: Ancient and Modern Insights about Individuality, Life, and Death, points out many similarities between what Ibn Sina says about self-knowledge and what Augustine says in his De trinitate, Book 10, about the mind’s knowledge of itself. These similarities, according to Sorabji, cannot have been the result of any direct influence Augustine had on Ibn Sina since Ibn Sina had no access to any of Augustine’s writings. Sorabji surmises that it may instead be the result, or at least partly the result, of both thinkers having read, and been influenced by, some earlier philosopher, perhaps a Neo-Platonist. ‘Gilson noticed the general similarity between Augustine’s use of the Cogito here and Avicenna’s (Ibn Sina’s) Flying Man’, Sorabji writes,

… and appears to suggest as common sources Plotinus and Proclus, but this cannot have been his intention [Sorabji adds, with characteristic generosity] since Proclus is too late to have influenced Augustine. If there is a common source [he adds], I think it is likely to be Porphyry.

Sorabji has quite a bit to say about the similarities between Augustine and Ibn Sina on self-knowledge. One very important similarity is that they both use a claim about self-knowledge to underwrite an argument for soul/body, or mind/body dualism. I am going to discuss their arguments in a moment. However, Sorabji also points out what is apparently an important difference between Ibn Sina and Augustine. The soul/body dualism that self-knowledge underwrites for each philosopher presents a challenge for Ibn Sina that seems not to have concerned Augustine. That challenge concerns the individuation of souls in the afterlife. According to Sorabji, Ibn Sina thinks he must account for how it is that separated souls are individuated in the afterlife and he is not sure how to do this. In fact, in one important passage, Sorabji suggests, he presents no fewer than six different suggestions for how separated human souls are individuated, but is unable to settle on any one of them. By contrast, Augustine, again, according to Sorabji, is ambivalent about whether it would even be good to survive bodily death by existing as a separated soul; perhaps it would be better for the righteous human soul in the afterlife to merge with God. Being ambivalent about whether it would even be good to survive as a separated soul, Augustine is therefore not motivated to figure out the metaphysics of separated-soul individuation.

Sorabji attributes Augustine’s ambivalence on these matters to his having read Plotinus. Here is a Plotinus-like question Sorabji thinks Augustine asks himself: ‘Might not our individuality ideally be merged in the divine Intellect, from which indeed our souls ultimately derived, and did we not lose our true identity by separating out from it?’ Sorabji adds that Augustine ‘felt torn’ ‘between an intense sense of individuality and an aspiration for a less individual life after death.’

Later in his book Sorabji returns to this theme. He writes:

Augustine, who was inspired by Plotinus, was [like him] torn in two directions in his Confessions, between on the one hand love of his mother as in individual and hopes that his unnamed dead friend will remember him, and on the other hand aspiration towards a heaven in which there is not genetic relationship and no memory.

Before I take up this alleged difference between Augustine and Ibn Sina on soul individuation in the afterlife, I want to discuss the similarity that Sorabji and others have found between the accounts of self-knowledge in Augustine and Ibn Sina and how these two thinkers thought self-knowledge supports soul-body, or mind/body, dualism.

Augustinian Dualism

Here is the kernel of Sorabji’s account of Augustine on self-knowledge:

In on the Trinity 10.10.14 Augustine produces some of his many versions of the Cogito argument that Descartes was much later to offer in his Second Meditation. First, doubt [about one’s existence] is impossible, because if you doubt, then you are alive, think, understand, judge, want to resolve the doubt, know your ignorance, are cautious, and so you cannot rightly doubt the existence of these mental operations. ([De trinitate] 10.10.14): Augustine makes the basis of the argument even clearer than Descartes does, and in more than one way. He is not appealing to the supposed infallibility of introspection, of which we are all the more suspicious in the wake of Freud. Instead, he is looking for those conditions that would have to be fulfilled if any doubt is to be entertained at all. If there is doubt, there is life, thought, understanding, desire, and he adds, judgment, self-awareness and caution.

So far, on Sorabji’s telling, Augustine has offered each of us a way of establishing for our individual selves, that we exist and also live, remember, understand, will, think, know, and make judgments. Then, Sorabji goes on to say, Augustine makes a second use of the Cogito. It is an argument for mind/body dualism. Sorabji summarizes it this way:

The incorrect, but crucial, principle is offered that a thing can only rightly be said to be known if its essence is known. So the soul knows with certainty not only the operations listed in the Cogito argument above, but also its own essence. But it has no certainty whether it is air, fire, or any other body, or bodily thing. So it is none of these ([De trinitate] 10.10.16)

Here is the actual Augustinian passage:

T1. …the mind knows itself, even when it seeks itself, as we have already shown. But we can in no way rightly say that anything is known while its essence (substantia) is unknown. Wherefore, since the mind knows itself, it knows its own essence (substantia). But it is certain about itself as is clearly shown from what we have already said. But it is by no means certain whether it is air, or fire, or a body, or anything of a body. It is, therefore none of these things.

Somewhat regimented, Augustine’s argument seems to be something like this:

Argument A1:

(1) The mind knows itself with certainty.

(2) If x knows y with certainty, then x knows the essence of y [with certainty]. Therefore,

(3) The mind knows the essence of itself with certainty.

(4) The mind does not know with certainty whether it is air or fire or a body, or anything bodily.


(5) The mind is not air or fire or a body, or anything bodily.


(6) The mind is something immaterial.

This argument, as it stands, is not formally valid. Adding this premise after (3) would help it approach validity:

(3.5) If x knows y with certainty and x does not know whether y is z, then y is not essentially z.

But then (5) should be changed to this:

(5*) The mind is not essentially air or fire or a body, or anything bodily.

And then the more general conclusion would be,

(6*) The mind is not essentially anything material.

I myself think that Augustine has a better argument for dualism than what he offers in T1. Sorabji quotes the better argument, but, surprisingly, he does not discuss it. It focuses on the ways in which various kinds of thing can be present to the mind. Physical objects, Augustine thinks, are present to the mind by either the mediation of sense perception or else the mediation of mental representations. Crucially, the mind is primarily present to itself without any mediation at all. Augustine seems to be thinking of the mind (mens) here as the conscious mind, or what people talk about today simply as consciousness. To an approximation, the mind is fully present to itself; that is, consciousness is fully present to itself. But the brain is not, even to an approximation, fully present to itself. Nor is anything material fully present to itself. So the mind is not the brain, nor anything else material. I’ll return to this argument later on.

Ibn Sina on Self-Knowledge

So what does Ibn Sina say about self-knowledge and why does Sorabji think it is similar to what Augustine has to say?

Sorabji concentrates his discussion of Ibn Sina on Ibn Sina’s famous thought experiment, “the Flying Man.” Although Ibn Sina presents this thought experiment in several different passages, Sorabji takes the following passage as definitive of it:

The Flying Man

T2. The inquiry leads us to concern ourselves with grasping the quiddity (mâhiyya) of this thing that is called ‘soul’. We must here indicate a way to affirm the existence (wujûd), Latin, esse) of our soul with an affirmation that may serve as an admonition and a reminder. This will be a pertinent indication for one who has the ability to observe the truth by himself, without needing to be instructed or rebuked, or averted from errors.

We say that one of us must imagine (yatawahhamu, Latin, putare) himself as if he were created all at once and as a whole, but with his sight covered so that he cannot see anything external, and created falling through the air or a vacuum, but falling in such a way that he encounters no air resistance nor anything else that would allow him to have any sensation, and with his limbs separated from one another so that they do not meet or touch. Then consider whether he will affirm the existence of his essence [or of himself, dhâtihi, Latin essentia]. For he will not have any doubt in affirming existence for his essence, yet he will not along with this affirm [the existence of] the extremities of his limbs, nor his innards, his heart, his brain, or anything external to him. Instead, he will affirm [the existence of] his essence, without affirming that it has length, breadth, or depth. Nor, if in that state he were able to imagine [yatakhayyalu, Latin imaginari] there to be a hand or other body part, would he imagine (yatakhayyalu, Latin,imaginary) that it was a part of himself (dhâtihi] or a condition for his essence (dhâtihi, Latin, essentia).

You know what is affirmed is different from what is not affirmed. And what is grasped immediately [literally, ‘what is near at hand’] is different from hat is not grasped. Therefore the essence (dhât, Latinessentia) whose existence is affirmed [by the Flying Man] is proper to him, insofar as it is his self (‘ayn), not his body or his limbs, which he does not affirm. Thus he is admonished and has a way of being awake to the existence of his soul as something distinct from the body and immaterial, and he knows and is aware of it [sc. his soul].

I take Ibn Sina’s argument here to be something like the following:

Argument A2:

(1) The Flying Man knows that he exists.

(2) If x knows that y exists, then x knows the essence of y.


(3) The Flying Man knows his essence.

(4) The Flying Man does not know that he has a body.

(5) If (3) and (4), then having a body does not belong to the essence of the Flying Man.


(6) Having a body does not belong to the essence of the Flying Man.

(7) If (7), then the Flying Man is essentially incorporeal.


(8) The Flying Man is essentially incorporeal.

(9) If (9), then the Flying Man is essentially an incorporeal soul.


(10) (9) The Flying Man is essentially an incorporeal soul.

The further implication is, of course, that if the Flying Man is essentially an incorporeal soul, then you and I and all other human beings are essentially immaterial souls as well.

The Individuation of Souls

The Flying Man passage above, T2, includes this crucial conclusion:

T3. Therefore the essence (dhât, Latin essentia) whose existence is affirmed [by the Flying Man] is proper to him, insofar as it is his self (‘ayn), not his body or his limbs, which he does not affirm.

This passage, translated in this way, suggests that the Flying Man has an individual essence, that is, an essence that not only guarantees his humanity but also his individuality. Moreover, since, implicitly, any of us might be a Flying Man, each of us human beings also has an individuating essence. Since Ibn Sina seems to have found it difficult to say what individuates separated souls, that is, souls after one’s bodily death, it must have been difficult for him to decide what an individuating essence for each of us might be. Thus separated souls pose a problem more starkly that, nevertheless, should be a problem for the Flying Man, too, even though, ex hypothesi, the Flying Man is not, or at least, not yet, a soul separated from his body.

Here is the passage in which Ibn Sina tries out, according to Sorabji, six different suggestions as to what might individuate separated souls:

T4. But doubtless there is something by which the soul is made individual, but it is not the impression of soul on matter, because we have already destroyed that. Rather it is some of the effects, and some of the virtues, and something from the accidental spiritual attributes, or a composite from those things, although we do not know it. But after it comes to be individual on its own, it is impossible that it should be a numerically different soul, and that the two souls should be [or have?] one essence. We have said much to deny that elsewhere. But we will demonstrate that since the soul is created with a creation, involving some combination, it is possible (1) that after it there should be created some affect in rational actions and in rational passions by the combination of which its action differs from similar action in another soul, and (2) that the acquired affect that is called intellect in actuality should be so defined in one soul that that soul differs from another through that affect, and (3) that because it falls to it to perceive its own individual essence, it has some affect from what it perceives that is unique to itself and possessed by no other. It is also possible (4) that there arise in the soul from its bodily virtues a unique affect that depends on moral affects, or the moral affects themselves, or (5) that there are yet other properties there hidden from us that accompany souls when they are created and after they have been created, and differentiate them, like the individual traits of bodily forms that accompany them, and (6) that souls exist in such and such a way, but are individuated in the properties on account of which bodies have or have not been created, whether we know those dispositions or some of them, or not.

A first thing to say about T4 is that it concerns the metaphysics, not the epistemology, of soul individuation. That is, the problem Ibn Sina is addressing is what makes Jacob’s soul to be Jacob’s soul, rather than, say, the soul of Esau. The problem is not how Jacob recognizes that his soul is, indeed, his own soul. Thus Ibn Sina says of the proper essence of each of us that we have it, ‘although we do not know it’.

Apparently the Flying Man thought experiment applies to separated souls as well as to souls conjoined with bodies. This consideration should help us understand T3. Even if Ibn Sina thinks that the Flying Man can affirm his own individual essence, it will not be by using his knowledge of his essence as a criterion for determining which particular being he is. But how could it really be that the Flying Man is able to affirm his own individual essence without having a criterion and using that criterion to determine which being he is?

In trying to come up with a solution to this last problem we may be helped by a passage in Augustine I sketched earlier. In the continuation of De trinitate 10.10.16 Augustine tells us, as I have already explained, that there are three ways in which an individual thing may be present to the mind. First, a physical object, such as a tree, may be present to the mind through sense-perception, as when one actually sees the tree. Second, a physical object may be present to the mind by one’s calling up a mental image, for example either a memory image of the individual tree, or perhaps a fictitious image, such as my mind might fabricate when you tell me about a tree I have never actually seen. Third, an individual thing may be present to the mind by being that mind. ‘Nothing’, Augustine writes, ‘is more present [to the mind] than the mind itself’. This means that, according to Augustine, the mind is non-representationally present to itself. It has no need of, nor any use for, a way of picking out itself by distinguishing itself from other individual things.

Ibn Sina also speaks, in The Healing and in the Book of Discussions of the soul as being present to itself. Perhaps it is his view that the Flying Man, like Augustine’s ‘mind’ (mens), can infallibly identify his own individual soul without needing or even using a representation of himself or, let alone a criterion for picking himself out.

If all this works out, as Ibn Sina needs it to, the next question is this: What underlies, not the epistemology of the Flying Man’s self-recognition, but the metaphysics of his soul’s individuation, especially when it is separated from the body. This is the question Ibn Sina seems to be addressing in T4.

By Sorabji’s count, Ibn Sina in T4 presents no fewer than six distinct alternatives to explain the soul’s individuation in the afterlife. But syntactically there seem to be only three possibilities mentioned. The first possibility is (1) and (2) and (3). The second possibility is (4). And the third possibility is (5) and (6). With each of these possibilities it seems that individuation arises from the soul’s acquisition of some affect that the soul did not initially have. One wants to protest that if one’s soul were not an individual from the very beginning, ab initio, then it would not become an individual by the acquisition of some affect or other. Indeed, Ibn Sina says, in T4, ‘after it comes to be individual on its own, it is impossible that it should be a numerically different soul, and that the two souls should be one essence.’ So it is unclear what work the three (or six, on Sorabji’s count) alternatives are supposed to be doing.

In any case, it seems to be true that Ibn Sina was puzzled about the individuation of souls in the afterlife—not, I repeat, about how each soul could identify itself as the distinct being that it is, but rather about what would actually make it a distinct individual. How does this compare with Augustine?

Augustine as Christian Neo-Platonist

There is good reason to think that, when Augustine became a Christian, he did not immediately become what he himself would later have considered an orthodox Christian. Thus, it is not clear that he immediately accepted the full doctrine of the Trinity, and, with it, the idea that both Jesus Christ and the Holy Spirit are each God, although, of course he later came to give eloquent expression to that idea in his De trinitate.

In any case, the young Augustine was certainly attracted to the Plotinian idea that individual souls can, after their separation from the body at death, merge with the Divine Intellect. However, in later life he took much more seriously the idea of the bodily resurrection. No doubt influenced by his close study of St. Paul’s letter to the Romans, Augustine took on the Pauline notion that the blessed will enjoy a resurrection of their own individual earthly bodies, even though those bodies will then be transformed into spiritual bodies. Here is part of what Augustine says in his City of God, Book 13, about those resurrected bodies:

T5. A human being [homo] will then be not earthly but heavenly—not because the body will not be that very body which was made of earth, but because by its heavenly endowment it will be a fit inhabitant of heaven, and this not by losing its nature, but by changing its quality.

The ‘qualitative’ change that Augustine here speaks of is actually quite a drastic change, yet Augustine seems to think of what he calls, following St. Paul, the ‘spiritual body’ that the blessed will receive in heaven as a spiritualization of the individual earthly body, where spiritualization is understood as a transmogrification that, at least for those who die in adulthood, preserves the shape, size, and anatomical and even physiological structure of the original body. Thus, in the last book of the City of God Augustine asks such questions as these:

(i) What size bodies will resurrected persons receive who died, not in adulthood, but in infancy?

Answer: The size of the bodies they would have had if they had lived to adulthood.

(ii) What teeth will persons have who either died in infancy or for some other reason failed to develop a full adult set of teeth?

Answer: The full set of teeth they would have had, if their teeth had been able to develop naturally.

What would it be to get back the very same body one had in earthly life, so that it could then be spiritualized? In a way Augustine is very explicit about this, and, in a way, he is hardly explicit at all. On the explicit side he says things like this

T6. Let it never be said that the Almighty Creator, in his purpose of raising up bodies and restoring them to life, is unable to recall all the substance which beasts or fire have consumed, or which has crumbled to dust or ashes, or has been dissolved in water or gone with the winds. Let it never be said that there is any recess or hidden place in nature where anything, though removed from our perceptions, can hide from the knowledge or escape the power of the Creator of all.

Augustine is vague about which particles God must reassemble at the resurrection—just the particles that belonged to one’s body at the moment of death, or also some particles before one was wasted by, perhaps, a very long illness, or simply by the natural replacement of one’s bodily cells.

A Human Life: The Simple Picture

Here is a simple picture of a human life, according to late Augustine. A man and a woman have intercourse and conceive a child. At conception there is a human corporeal seed, with a program of development (ratio seminalis , De genesi ad litteram 9.17.32). At 40 or 90 days, depending on gender, it receives a human soul. The now ensouled body develops according to its ratio, but is perhaps thwarted in this respect or that so that it does not achieve, for example, a ‘normal’ height, or a full set of adult teeth. Let’s call this person ‘Lee’.

At death Lee’s soul is separated from Lee’s body. But Lee’s soul retains a longing to return to the very same body:

T7. Thus the souls of the departed saints are not affected by the death which dismisses them from their bodies, because their flesh rests in hope, no matter what indignities it receives after sensation is gone. For they do not desire that their bodies be forgotten, as Plato thinks fit, but rather, because they remember what has been promised by Him who deceives no man, and who gave them security for the safe keeping even of the hairs of their head, they, with a longing patience [desiderabiliter et patientier] await in hope the resurrection of their bodies, in which they have suffered many hardships and are now to suffer never again. For if they did not ‘hate their own flesh’, when it, with its native infirmity opposed their will, and had to be constrained by the spiritual law, how much more shall they love it, when it shall even itself have become spiritual!

It is important that what Lee’s soul longs for, in its disembodied state, is the very same body Lee had in mortal life, not a replica of Lee’s mortal body, or something indistinguishable from it, but the very same body. It will be given to Lee’s soul, Augustine tells us, by God’s miraculous action in collecting particles that once constituted Lee’s body. Only after it has been reconstituted will it be transformed into a spiritual body. The spiritual body Lee receives in the resurrection will be superior to Lee’s earthly body in many ways. If the earthly body was abnormal in any way, that abnormality will be corrected. Although Lee’s spiritual body will have the same gender as the one Lee had in earthly life, there will be no lust in heaven and the gendered organs will have no specifically sexual or reproductive function.

It is important to understand that the account of soul individuation implicit in this story is a metaphysical account, rather than an epistemological account. Thus there may be no way for Lee to determine, except by God’s own assurance: The resurrection body I now have is the very same body I had in my earthly life. Nevertheless, God has the power and the knowledge to make this the case.

An Augustinian Account of Soul Individuation

So what about the individuation of human souls, according to this Simple Picture? Although Augustine does not explicitly say this, it seems that the soul given to Lee at either 40 or 90 days gestation is individuated by the body to which it is attached. It remains individuated throughout Lee’s earthly life, it seems, by the rule, one living human body, one human soul. At death and before resurrection it is individuated, it seems, by its longing for the particular body it used to ensoul. That longing is not merely for re-ensoulment. Nor is it a longing for a replica body, let alone for an improved body very much like the body Lee had in mortal life. At the resurrection the resurrection God miraculously gives Lee’s soul the reassembled original body and then transforms it into a spiritual body.

This Simple Picture, as I have painted it, thus includes an implicit Theory of Soul Individuation. I say the theory is implicit, because Augustine does not, so far as I can tell, address explicitly the metaphysical question of soul individuation. Yet implicitly, particularly in his discussions of the resurrection, and most especially in his imputation of a desire of the separated soul for the resurrection of its very own earthly body, he seems to be responding to a need to say something about what makes Lee in the resurrection to be Lee, and not some other person, say, Lee’s identical twin.

In extrapolating an Augustinian account of the individuation of separated souls I want to insist that a soul’s desire to get its very own body back is a de re desire with respect to a particular body, that the soul get that very body back, not just a de dicto desire to receive a body under some description that might be satisfied by two or more bodies. God, in his omnipotence, can assure that the body Lee’s soul gets is the individual body Lee’s soul longed for, and not merely a perfectly matched facsimile.


I began this paper with Richard Sorabji’s claims of similarity and difference between Augustine and Ibn Sina. According to Sorabji, Augustine and Ibn Sina present rather similar accounts of the human soul’s knowledge of itself. Moreover, according to him, they base their argument for soul-body or mind-body dualism in a similar way on their claims about the soul’s knowledge of itself. So much for the similarities.

Augustine and Ibn Sina differ, according to Sorabji, in their attitudes toward the soul’s afterlife. Whereas Ibn Sina considers it philosophically important, but also philosophically frustrating, to explain how human souls can be said to be individuated in the afterlife, Augustine, Sorabji tells us, is of two minds as to whether an individuated afterlife would even be preferable to having one’s soul merge with the Divine Intellect.

I have left Sorabji’s claim of similarity largely unchallenged. What I have taken issue with is Sorabji’s claim that Augustine was ambivalent about wanting an individuated existence in the afterlife. I have pointed out that the later Augustine, as opposed to the early, Neoplatonic Augustine, was as much interested in a well-individuated afterlife as Ibn Sina. However, for Augustine the individuality of a human soul in the afterlife includes each soul’s desire to be given back its very own earthly body. The blessed, according to Augustine, will indeed be given back their earthly bodies in the resurrection, although those earthly bodies will be immediately transformed into spiritual ones.

Augustine, unlike Ibn Sina, seems not to have been caught up with the philosophical challenge of explaining how souls are individuated in the afterlife. However, his insistence that each soul desires to get its own earthly body back offers a way of supplying a criterion of individuation for souls in the afterlife. So I end with this intriguing irony: Whereas Ibn Sina wanted to be able to supply a satisfying account of the individuation of souls in the afterlife that he was apparently not able to provide, Augustine, though seemingly not especially interested in supplying any such an account, nevertheless attributed to separated souls a desire to return to their very own bodies, which suggests a way of developing such an account.

Would Ibn Sina have been attracted to such an account? I am not sure, since it requires longing for one’s previous body to individuate one’s soul. It was certainly important to Ibn Sina to show that the nature of the soul is independent of anything bodily. I suspect that he would have wanted the individuation of the soul to be equally independent.

I should point out, however, that Ibn Sina’s fourth suggestion in T4 (in Sorabji’s numbering) might be thought somewhat similar to my Neo-Augustinian criterion. This is Ibn Sina’s suggestion #4:

T4*. It is also possible that there arise in the soul from its bodily virtues a unique affect [or perhaps, distinctive desire, Latin: affectionem proprian] that depends on moral affects [or moral desires, quae pendeat ex affectionibus moralibus]…

Would Ibn Sina have counted the separated soul’s longing for its very own earthly body as the ‘unique affect’, or ‘distinctive desire’ that arises from the soul’s ‘bodily virtues’ he talks about in T4? I am somewhat skeptical, but perhaps unduly so. If my skepticism can be overridden, then a way of filling out one of Ibn Sina’s suggestions for soul-individuation in the afterlife would make it fit the criterion of soul individuation I have reconstructed from Augustine.