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Medieval psychological texts include extensive discussions about the ability to cognise various things which are parts of the cognising subject itself. Awareness of oneself as a subject of thought was not, however, commonly distinguished from other kinds of self-awareness. In this way, the general approach to philosophical questions concerning self-cognition is different from the modern one – as are the contexts in which these questions were asked. Still, medieval philosophy contains interesting material about self-cognition. It should be mentioned that although there is no Latin equivalent to the noun ‘self,’ medievals employed various grammatical structures to discuss these matters. For instance, the pronoun ipse and the reflexive pronoun se (se cognoscere for self-knowledge, se apprehendere for self-apprehension, etc.) were much used. Also, the Latin terms conscientia and conscientia sui were used in ways similar to the contemporary English ‘consciousness’ and ‘self-consciousness,’ though this was not very common.

Medieval discussions continue the ancient Neoplatonic-Stoic tradition, which also incorporated Aristotelian ideas. This tradition was taken over and developed further by Arabic thinkers, whose influence on medieval Latin discussions of self-cognition was significant. The opposition between Ibn Sina (Avicenna) and Ibn Rushd (Averroes) became especially important. Avicenna emphasises the direct presence of everything in the soul to the soul itself. By contrast, Averroes thinks that human cognitive capacities are primarily suitable for cognising material reality, and consequently, that the soul cannot be a direct object of cognition. Another important source in medieval Latin discussions on self-cognition was Augustine, whose texts (in particular, De trinitate) were widely used. Augustine and Avicenna approached self-cognition through a threefold division that became standard in thirteenth-century discussions. The three objects of knowledge they defined were the essence of the soul, the acts of the soul, and the dispositions (habitus) of the soul.

Medieval authors generally assumed – and often explicitly pointed out – that no one can be in doubt about the existence of one’s own soul. Yet it was a matter of disagreement whether, from this indubitable knowledge, anything follows concerning the essence of one’s soul or its separability from the body. In the Latin Middle Ages, the topic is occasionally connected to Avicenna’s well-known ‘floating man’ thought experiment, which supposedly shows that one can directly perceive one’s own existence without any reliable perception of the body, and that therefore one must conceive of oneself as an incorporeal soul (1). Avicenna’s idea can be understood in relation to the Neoplatonic notion of the intellect’s ability to turn toward itself, which also influenced Latin thinkers directly, especially through Liber de causis (2).

Thinkers in the Augustinian tradition also thought that the soul’s incorporeality could be directly inferred from the immediate awareness of oneself which is unlike any awareness of corporeal things. In thirteenth-century European universities, this Augustinian-Avicennian conception was defended and developed by Franciscan thinkers, who gave it a more epistemological twist (3). It was also challenged by an appeal to the Aristotelian conception of self-cognition, which was understood in light of Averroes’s interpretation. According to the medieval understanding of the Aristotelian view, the essence of the soul cannot be immediately experienced, and even knowledge of the existence of one’s own soul results from perceiving acts of the soul rather than its essence. Thus, Thomas Aquinas argued that knowledge of the incorporeality of the soul does not result from immediate perception, but from scientific study (4).

It was generally agreed that we perceive the acts of our own soul. When seeing a stone, say, we normally perceive seeing and not only the stone. There were, however, disagreements about how this second-order perception ought to be understood, and whether it is separable from the first-order seeing (5). Towards the fourteenth century, it became increasingly acknowledged (on the basis of some Augustinian examples) that there are non-conscious cognitive acts, which are not accompanied by and do not include any second-order perception (6).

The knowledge of the dispositions of one’s own soul was often discussed with an eye to a particular problem of knowing one’s own faith. Augustine argued in his De trinitate that one has indubitable consciousness of one’s own faith. Medieval Aristotelian thinkers, such as Thomas Aquinas, argued that knowledge of the dispositions of the soul comes through perceiving the acts of the soul, since dispositions are not directly perceivable (7).

In addition to these explicitly recognised topics of discussion, two further issues were often addressed in a less systematic way, and usually in connection with each other: first, the experiential unity of the soul (or the lack thereof), and second, the experience of the things in the soul as one’s own. The latter was dealt with especially in relation to the so-called Averroist one-mind doctrine, according to which all humans share the same intellectual soul and are individuals only in relation to the body (and thereby the animal soul, too).

According to Aquinas, Plato thought that human beings have several souls. This is a position Avicenna had argued against through reference to an experiential unity in action-related cognitive operations, apparently referring even to the souls of the lower animals. On this issue, the positions taken do not follow the typically important distinction between the Aristotelian and Augustinian-Avicennian approaches. The mainstream solution to this problem was to accept some kind of experiential unity, although it was not taken as self-evident. One of the problems was locating the faculty that experiences this unity somewhere in the psychological system (8).

From the viewpoint of the Averroist one-mind doctrine, it becomes problematic to claim that one experiences intellectual acts as individually one’s own. Thus, Aquinas argues against the so-called Latin Averroists that, since everyone experiences that one has individually one’s own intellectual acts, one has one’s own intellectual soul. Defenders of a radically Averroist approach in this issue were few in the Latin Middle Ages. Nevertheless, it was not generally accepted that experience alone reveals the subject of intellectual acts. For example, William of Ockham thought that in experiencing an intellectual act one does not experience oneself as the subject of the act (9).

A further topic which emerged from time to time in various contexts was the awareness one has of one’s own body as a part of oneself. Medieval philosophers generally adhered to the idea that the body is a genuine part of one’s self, especially as the Christian doctrine of the resurrection of the body emphasises the embodied nature of human existence. A distinctive feature of some of the thirteenth-century discussions was that the scope of the sense of touch was extended so as to include perception of one’s own body under it (10).

1 ‘Floating Man’ Thought Experiment

a. We say: one of us must imagine himself as though created all at once and perfect but with his sight veiled from observing external things, and as though created falling in the air or in the void so that he would not encounter air resistance, which he would have to sense, and with his limbs separated from each other so that they neither meet nor touch. He must then reflect upon whether he would affirm the existence of his essence.

He would not hesitate to affirm his essence existing, but he would not thereby affirm any of his limbs, any of his internal organs, whether heart or brain, or any of the external things. Rather, he would be affirming his essence without affirming for it length, breadth or depth. And if in this state he were able to imagine a hand or some other limb, he would not imagine it as part of his essence or a condition for its existence.

Now, you know that what is affirmed is other than what is not affirmed and what is close is other than what is not close to him. Hence the essence whose existence he has affirmed is special to him in that it is he himself, other than his body and limbs that were affirmed. Thus, he who is attentive has the means to be awakened to the existence of soul as something other than the body – indeed, not a body at all – and to be acquainted with and aware of it. (Avicenna, De anima, Arabic text, ed. Rahman, I.1, 16, trans. Jari Kaukua; Latin text, ed. van Riet, 36–37)

Avicenna’s so-called ‘floating man’ thought experiment has often been compared to Descartes’s cogito ergo sum. Avicenna’s intention, however, is not to prove the existence of the immaterial soul. Instead, the idea is to show how one can bring oneself to see the independence of the soul from the body. See also De anima V.7, 162–163 (Latin); Avicenna, Ishārāt, 119; Pseudo-Aristotle, Theologia VIII, 144–163. Avicenna’s thought experiment was not often cited in Latin discussions. See, however, William of Auvergne, De anima II.13; John of la Rochelle, Summa de anima I.5 (51); Matthew of Aquasparta, Quaestiones disputatae de cognitione 5 (295, 312); Vital du Four, Octo quaestiones disputatae 4.1 (242). See Hasse 2000, 80–92; Kaukua and Kukkonen 2007; Kaukua 2007; Sorabji 2006.

2 Neoplatonic Return of the Mind onto Itself Understood as Self-Knowledge

a. I may withdraw with my soul, put my body aside and become as if I were a naked substance without a body, so that I enter myself, return to it apart from other things. And so I am knowledge, what knows and what is known all together, and I see in myself such beauty, splendour and brightness that I remain marvelling and perplexed at it, so that I know that I am one of the parts of the sublime, surpassing, divine world, possessing active life.

When I am certain of that, I ascend by myself from that world to the divine world and become as if placed in and connected to it, so that I am above the entire intellectual world, and I see as if I were standing in that sublime and divine position. And there I see such light and splendour that tongues cannot describe nor ears exhaust it. When that light and splendour overwhelms me and I do not have the strength to endure it, I descend from the intellect to thought and reflection. When I have come the world of thought and reflection, thought veils that light and splendour from me, and I remain wondering how I have fallen from that lofty and divine place and come to the place of thought, my soul having once been able to leave its body behind, to return to itself and to ascend to the intellectual world and then to the divine world, until it came to the place of the splendour and light, which is the cause of all light and splendour. What a wonder how I have seen my soul filled with light, although it was still in the state of being in the body, not leaving it. (Anonymous, Uthūlūjiyā Aristātālīs, ed. Badawī I, 22; trans. Jari Kaukua; Pseudo-Aristotle, Theologia I, 21–27 (225))

b. Every knower that knows itself returns completely to itself. That is, knowledge is nothing but [intellectual] action. Thus, when the knower knows itself, it returns through its knowledge to itself. Since this is so, the knower and the known are one thing, since the knower’s knowledge of itself is from it and to it: it is from it because it is the knower, and to it because it is the known. (Anonymous, Kitāb al-īdāh fī al-khayr al-mahd li Aristūtālīs 14, 16 ed. Badawī; trans. Jari Kaukua; Liber de causis XIV (XV))

In the Neoplatonic tradition, meditative retracement of the soul onto itself was a way of elevating oneself from the corporeal world to higher realms. In the mystical tradition, consciousness of God was often sought in consciousness of the higher parts of one’s soul. Some Arabic thinkers discussed in this context the so-called Theology of Aristotle which derived from Plotinus’ Enneads IV-VI (a). See Adamson 2002. Another Neoplatonic conception pertaining to self-cognition is discussed in Liber de causis, a twelfth-century Latin translation of an anonymous Arabic treatise which was based on Proclus’s Elements of Theology. Self-cognition pertains to the essence of the subject, the knower and the known are one and the same thing, and self-cognition is achieved by a reflexive turning toward one’s own essence (b). See also Augustine, De trinitate VIII.6; IX.3–5, 11–12; X; XII.12; XIV.5–6; XV.12; Avicenna, Taclīqāt 160–161; Anselm of Canterbury, Monologion 33. For discussion, see Cary 2000.

3 Franciscan Thinkers on the Soul’s Direct Apprehension of Its Essence

a. Some things are so certain to us that with regard to them there is no probability of error. Augustine says, in De civitate Dei XI.24 [nowadays 26]: ‘We are, and know that we are, and we love our existence and our knowledge of it, and in these three we are not troubled by any error resembling the truth. For we do not perceive these things by any of the external senses, as we perceive external objects … but without any phantasms of delusive imagination, I am quite certain that I am and that I know and love it. In respect of these truths, I fear none of the arguments of the Academicians when they say, What if you are mistaken? For if I am mistaken, yet I am.’ (Matthew of Aquasparta, Quaestiones disputatae de fide 1 (45–46))

b. I say that we can speak in two ways about cognition of the mind itself and the dispositions it has: in one way as for the origin or beginning of the cognition or the knowledge, and in another way as for the completion of the knowledge. Concerning the origin or beginning of the knowledge or the cognition, I say without doubt that the soul cannot look at itself or at the dispositions that exist in it, nor can the first cognitive act be about itself or about things that are in itself. […] But when [the mind] has been actualised by a species that is abstracted from phantasms […] it is called to itself by a kind of spiritual turning that is almost fully disengaged from the exterior things, and it can discern and look at itself and at the things that are inside itself by a direct gaze. In this way it cognises itself and dispositions within itself, not only by reasoning but by intuition and inspection – in such a way that it can direct intellectual contemplation to itself and things in itself, as to an object. (Matthew of Aquasparta, Quaestiones disputatae de cognitione 5 (304))

c. The infallible certainty of one’s own existence indicates this [namely, that cognition does not require phantasms], for a human being infallibly knows that he exists and lives in such a way that he cannot doubt it. But if a human being did not know that he exists and lives otherwise than through phantasms, a doubt concerning these could arise – and with good reason, since phantasms could not represent these things directly and uniformly, but only indirectly and dissimilarly; and they could not do this per se and primarily, but only by a manifold of comparison and reasoning. This is why the proponents of this position say that we arrive at the cognition of our own minds and our intellectual faculties by [cognising] their acts, and at cognition of the acts by cognising objects. For we conjecture by reasoning that the acts by which we cognise objects are derived from some faculty and substance, and they are in some subject. So, in this way we discover that we have some faculty from which the acts are derived. However, if someone were to examine this manner [of cognising one’s own mind] very closely, he would find out not only that some uncertainty may occur in it, but also that by this way we could never be sure that we exist, live, and understand. For although we would be certain that these acts are derived from some faculty and are in some subject, how could we know from this that we are the subject and that the faculty is ours? (Peter John Olivi, Impugnatio quorundam articulorum Arnaldi Galliardi 19 (459))

Medieval thinkers often defended the certainty of one’s own existence by referring to Augustine. For instance, Matthew of Aquasparta quotes Augustine’s De civitate Dei verbatim when he argues that the knowledge of our own existence is not susceptible to skeptical arguments, for the fact that we err suffices to prove that we exist (a). Another commonly quoted passage is De trininitate X.10.16. Franciscan authors put Augustine’s Neoplatonic view against the Aristotelian conception of self-cognition (see (4) below), and argue that the soul is capable of cognising itself directly in such a way that it need not apprehend external things in order to be able to cognise itself. Various views sharing this general starting point were presented. For example, Aquasparta argues that although the soul is incapable of apprehending itself as its first cognitive act (cf. Avicenna’s ‘floating man’, (1a) above) it can become capable of apprehending itself directly by intuition and inspection (b). Peter Olivi criticises Aristotelian position by pointing out that if the mind could cognise itself only by reasoning the existence of the mind from the existence of mental acts, we could never be sure that the acts we experience belong to us. By contrast, the experience of mental acts as one’s own proves that the mind must cognise itself directly (c). In another place he argues that there are two distinct ways in which the soul knows itself: by a direct apprehension of itself, and by a rational investigation. He identifies the latter with the Aristotelian view and argues that it is possible only if the soul already cognises itself directly. Instead of using a visual metaphor, Olivi describes the direct experiential self-cognition as ‘quasi-tactual’ (Quaestiones in secundum librum Sententiarum 76 (III, 146–148); Toivanen 2013). See also Roger Marston, Quaestiones disputatae De anima, q. 1. According to Marston, the intellect forms a species of itself and of its habits after having multiple experiences of its own acts. Afterwards it can be conscious of itself by mediation of this species. See Putallaz 1991b.

4 Aristotelian Views on Indirect Apprehension of the Intellectual Soul

a. Everything is cognisable insofar as it is actual … This is clear in the case of sensible things because sight does not perceive things which are potentially coloured but only things that are actually coloured. Similarly, it is clear that, insofar as the intellect cognises material things, it cognises only those which are actual … Human intellect is only a potential being in the genus of intelligible beings, as prime matter is in the genus of sensible things; this is why it is called ‘possible [intellect]’. Thus, considered in its essence, the intellect is a potentiality of understanding. This is why it has in itself a power to understand but not to be understood, except insofar as it is actualised … However, because in this life our intellect naturally looks upon material and sensible things, as has been said above, it understands itself insofar as it is actualised by species that are abstracted from sensible things by the light of the agent intellect, which is the actuality of intelligibles and, by means of intelligibles, of the possible intellect. Therefore, our intellect knows itself by its actuality and not by its essence. This happens in two ways: in the first place, particularly, as when Socrates or Plato perceives that he has an intellectual soul by perceiving that he understands; in the second place, universally, as when we consider the nature of the human mind from the actuality of the intellect … There is a difference between these two kinds of cognition. Namely, the presence of the mind, which is the principle of the act from which the mind perceives itself, is sufficient for having the first kind of cognition. This is why it is said that the mind cognises itself by its presence. However, the presence of the mind is not sufficient for having the second kind of cognition of the mind, which requires a careful and subtle investigation. (Thomas Aquinas, Summa theologiae I.87.1)

b. Everybody agrees that the human intellect can understand itself, as has been shown immediately above. But it is uncertain how the intellect does this. Therefore I will posit some conclusions about this matter. First, the intellect does not understand itself by its essence … because in that case it would always chiefly understand itself, without any discursive reasoning, and it would not understand anything before it understands itself, like the divine intellect. And we experience that this is false … The second conclusion is that the human intellect does not understand itself before it understands something else. Rather, it has to understand something else first before it understands itself, because it is not capable of understanding itself or anything else without the co-operation of the senses … For we experience that in order to understand, we need an act of sensation (either from the external or from the internal senses), and for this reason we do not understand anything when we sleep deeply without dreaming … The third conclusion is that even ordinary people and old women understand the intellect easily, since they very easily form the general concepts by which we have the names ‘being’, ‘thing’, ‘one’, ‘substance’, etc. Yet all beings, and by consequence also the human intellect, are understood indifferently by these concepts and by any of these. In another way, an old woman understands her intellect because she experiences and judges that she knows and believes that no dog is a horse … Since she cannot know these universals otherwise than by her intellect, she cognises that she is not only a body, as she knows and believes in this way, but a composite of the body and the intellect. Thus, by cognising herself as knowing this and as a composite of the body and the intellect, she cognises both the body and the intellect, although in a confused and indistinct way … I pose, therefore, the fifth conclusion: Without discursive reasoning you cannot understand the human intellect by a concept that is proper to it, that is, by a concept that does not supposit for anything else than the intellect, but by discursive reasoning you can do this … It is clear that the intellect cannot be conceived of by a concept that is proper to it without discursive reasoning, because it has been said in the second conclusion that the intellect cannot understand itself first but it has to understand sensible things first. As the intellect knows these sensible things because [it has] their proper representations, it is clear that the intellect understands itself only by discursive reasoning, as when we experience in ourselves such operations which we judge to exist only from this kind of power. (John Buridan, Quaestiones in De anima III.9 (92–96))

Accounting for intellectual self-understanding is a complex issue within the context of the Aristotelian theory of the possible and the active intellect. Clearly, it does not come about through the general model of abstraction of the intelligible form from matter. Following Averroes’s interpretation, Aquinas argues that the human intellectual soul is capable of understanding all sensible things, and as such, it must have a potentiality to become like every other thing. Thus, it is not actual before it actually understands something external to itself, and in this way it is comparable to prime matter. As it is not possible to cognise something that is purely potential, direct self-cognition is impossible. The soul knows itself only by its acts, and thus it arrives at cognition of itself only indirectly (a). John Buridan takes the same approach, but points out that as a result of discursive reasoning we can form a proper notion of the soul by which the soul can be known (b). See also Averroes, Commentarium magnum in Aristotelis De anima III.4 (426–436); Thomas Aquinas, Quaestiones disputatae de veritate 1.9 and 10.8; William of Auvergne, De anima III.12; Thomas Sutton, Quodlibet I.14 and II.14; Thomas Sutton, Quaestiones ordinariae, q. 22; Godfrey of Fontaines, Quodlibet VII.9; Vital de Four, Octo quaestiones disputatae de cognitione 4 (232–252); Francisco Suárez, Commentaria una cum quaestionibus in libros Aristotelis De anima 14.5. Sutton analyses not only the reasons why the intellect cannot directly know itself (it is purely passive in itself), but also why it cannot know the essence of the soul (the nature of the intellect is to turn towards phantasms: in itself the soul is knowable but the intellect as a knowing subject cannot achieve direct knowledge of it). By contrast, Godfrey of Fontaines thinks that the intellect is also knowable in itself, but in this life the lack of a phantasm representing it prevents its direct self-knowledge. See Pasnau 2002a; Putallaz 1991a.

5 Apprehending the Acts of the Soul

a. If this perception that we see took place through some other sense than vision, it would happen that that sense would comprehend doubly. For it would comprehend that vision comprehends, and it would comprehend the colour which vision comprehends. For it is impossible that it would comprehend vision to comprehend a colour without itself also comprehending the colour … And if we also posited the existence of these two powers, namely that the sense which comprehends that we see is different from that which sees, what happened with the first sense also happens with this sense. For it is necessary that it also has a double comprehension, namely the comprehension of its first subject which perceives and the comprehension that it comprehends. And also, if we posit two powers, the same happens with the third one that happened with the second, and so on to infinity, which is impossible. Therefore it is necessary for us to posit that the same power comprehends both, namely its first subject, which also comprehends that it comprehends. And because it is necessary to stop the infinite regress, it is better to do this at the first level, and to posit that we comprehend colour and that we comprehend also that we comprehend it. (Averroes, Commentarium magnum in Aristotelis De anima III.2 (337–338))

b. There are two ways in which the soul experiences a thing, since a thing may be experienced as an object, and a thing may be experienced as a living subject experiences its own act. For otherwise an infinity would arise, since if one’s own acts are only experienced as objects, it follows that there is another act whose object it is, and it is experienced. Thus, [it is experienced] as an act and not as an object, and the claim has been [proved], or [it is experienced] as an object of another act, and thus into infinity. (Walter Chatton, Reportatio et Lectura super Sententias, prologus 2.5 (121))

c. But if it is held that the reflex act is to be distinguished from the direct act, then I say that the seeing of the stone is seen by another vision. [The regress] nevertheless eventually stops at some seeing that is not naturally seen by a distinct seeing, although it could be seen if it there was no impediment. And I concede an infinite regress with a divine potency. But naturally speaking there will be some seeing that cannot be seen. This is so because our intellect is a limited power which is thus capable of only a certain number of seeings and no more. I do not know, however, at which seeing the regress stops. Perhaps it stops at the second seeing, because perhaps it cannot be seen naturally. (William of Ockham, Quodlibeta septem I.14 (OTh 9, 79–80))

d. In reflexive acts there can be an infinite regress. This is evident because the intellect can first understand a stone to exist, then it can understand that it understands the stone to exist, then it can understand that it understands the understanding by which it understands the stone to exist, and so forth. It is evident also because these spoken propositions differ from each other: a stone exists, I understand the stone to exist, I understand that I understand the stone to exist, I understand myself understanding to understand the stone to exist, etc. They differ because they correspond to mental propositions which are distinct in the mind. And just as in such spoken propositions there can be an infinite regress, so also in mental ones. (Anonymous, Quaestiones in De anima, ed. Patar, III.11 (463))

Averroes argues that awareness of seeing must be based on the visual sense itself. If some other perceptual power perceived the seeing, it would have to have visual powers as well. Furthermore, if there is a second power involved, its awareness would have to be perceived by a third power, and so on to infinity. Averroes has in mind a higher order sensation model of consciousness. He concludes that adding powers will not help with the infinite regress and thus visual awareness must be involved already in the visual experience itself, leaving the infinite regress essentially unsolved (a). Walter Chatton argues that an act of the soul does not have to be apprehended by a second-order act in order for the subject to experience the act. His argument is based on the idea that if an act of the soul should be apprehended by a second-order act, an infinite regress would follow. This is avoided by the distinction between perceiving an object and experiencing a mental act (b). Ockham rejects this view, allowing that a first-order act of the soul is experienced only if it is cognised by a second-order act, but claiming that the regress does not have to continue ad infinitum. Rather, at some level (fairly low in the chain) the higher-order act does not need to be experienced. Ockham appears to think that we are incapable of experiencing the experience that we see. Rather, we just experience that we see (c). The anonymous author (John Buridan?) follows Ockham in requiring that mental acts need to be objects of second-order mental acts in order to be experienced, but he simply states that the regress can be infinite (d). See also Augustine, De trinitate XV.12.21–22; Avicenna, Ishārāt (120); Thomas Aquinas, Quaestiones disputatae de veritate 10.10; Thomas Aquinas, Summa theologiae I.78.4 and 87.3; Thomas Aquinas, Scriptum super libros Sententiarum I.1.2.1, ad 2; I.10.1.5, ad 2; Peter John Olivi, Quaestiones in secundum librum Sententiarum 79 (III, 158–169); Peter John, Impugnatio quorundam articulorum Arnaldi Galliardi 19; Vital de Four, Octo quaestiones disputatae de cognitione 4 (232–252); John Duns Scotus, Ordinatio IV.45.3, nn. 4, 6, 7, 20; William of Ockham, Quodlibeta septem II.12 (OTh 9, 165–167); William of Ockham, Scriptum in librum primum Sententiarum. Ordinatio, prologus 1.6 (OTh 1, 65–69); Francisco Suárez, Commentaria una cum quaestionibus in libros Aristotelis De anima 6.4. See Martin 2007; Yrjönsuuri 2007.

6 Non-conscious Cognitive Acts

a. Augustine’s De trinitate has an example of such response at the end of XI, 8, where he says that he has often read and not known what he read or heard because of some distraction from the acts of another potency, although there was no incompatibility with those acts. Thus also a person intent on seeing does not perceive hearing anything even when he does hear, although there is no incompatibility between acts of seeing and hearing. (William of Ockham, Quodlibeta septem I.14 (OTh 9, 81))

b. I say that when the following is posited in the mind – ‘I think’ – it is possible that it does not appear to the mind that the case is as the proposition signifies, although the case then is as it signifies. […] Nevertheless, even if this is posited, the mind cannot help but apprehend its own thinking. Even this, however, will not make the mind certain that it thinks, nor does it make the mind see that it thinks, if the intentional act corresponding to the words ‘I think’ is not intuitive. In that case it would be impossible that it would not appear to the mind that it thinks. (Adam Wodeham, Lectura Secunda in librum primum Sententiarum, prologus 6.14 (166–167))

c. I add that this act, which is called ‘remembering’, is not immediately about some past thing, but only about some act which was in the remembering subject itself as a human act … For I only remember the fact that you were sitting because I remember that I saw or knew that you were sitting. Thus, even though I know, for instance, that I was born, and that the world was created, still I do not remember either of these, since I am not aware of any act of my own in the past which was about this or that. (John Duns Scotus, Ordinatio IV.45.3 [4])

Augustine’s De trinitate XI.8.15 contains influential observations concerning the fact that people do not always consciously apprehend everything in their surroundings. William of Ockham accounts for Augustine’s observation by appealing to the need for a second-order act which makes the object of first-order act appear to the subject. Even though an act of seeing and an act of hearing may take place simultaneously, the subject is conscious only of the act about which she has a second-order cognition (a). This differs from the Aristotelian principle that all mental acts are also perceived. Adam Wodeham’s thought experiment assumes that an abstract proposition, ‘I think,’ is the only thought in the mind. It can appear to be false (when it does not express any direct perceptual awareness of a thought). It cannot, however, appear not to be a thought. Thus, it verifies itself and cannot really be false (b). Wodeham’s discussion grows into a detailed account of how thoughts are present in the mind. See also Adam Wodeham, Lectura Secunda in librum primum Sententiarum, Prol. q. 2 § 9–16 (50–64). Scotus assumes that in order to be able to recall an earlier mental act, one has to be immediately aware of it when it occurs, and this takes place by an intuitive second-order act (c). See Knuuttila 2006, 261–262; Wolter and McCord Adams 1993. For related discussions, see also Augustine, De trinitate XI.8.15 and William of Ockham, Reportatio IV.14 (OTh 7, 278–317). Scotus’s idea is criticised by Walter Chatton who thinks that all mental acts are consciously experienced when they take place, without a second-order act (see (5b) above, and Reportatio et Lectura super Sententias: Collatio ad Librum Primum et Prologus, prol. 2.5.80–104 (121)). The anonymous author of Quaestiones in De anima (John Buridan?) criticises both Chatton and Scotus. According to him, it is possible to remember an earlier thought even if there was no actual awareness of that thought when it occurred (ed. Patar, III.11 (465)).

7 Perceiving the Dispositions of the Soul

a. And we know differently faith itself, which anyone sees to be in his heart if he believes and not to be if he does not believe. […] He [who believes] has most certain knowledge of it, and conscience proclaims it. We are told to believe, because we cannot see that which we are told to believe, but we do see the faith in us when it is in us. For things absent we have faith present, and for things outside we have faith inside, and for things not seen we see faith. (Augustine, De trinitate XIII.1.3)

b. A disposition is a kind of a middle between a pure potency and a pure act. It has already been said that everything is cognised insofar as it is actual. Therefore insofar as a disposition falls short of being a pure act, it falls short of being cognisable by itself, and it is necessary that it is cognised only from its act, either when someone perceives that he has a disposition by perceiving that he produces an act that is proper to the disposition, or when someone inquires into the nature and essence of the disposition by considering the act. The first kind of cognition of the disposition arises from the presence of the disposition, because the very fact of its presence causes the act whereby it is perceived. The second kind of cognition of the disposition takes place by a studious inquiry, as above has been said about the mind. (Thomas Aquinas, Summa theologiae I.87.2)

Augustine thinks that the soul is capable of apprehending its dispositions (such as faith) directly, because nothing is more present to the soul than the soul itself (a). Drawing from Aristotelian conception of self-cognition, Aquinas argues that the soul is incapable of apprehending its own dispositions. The existence of dispositions can be reasoned out by apprehending the acts that are related to those dispositions (b). See also Thomas Aquinas, Quaestiones disputatae de veritate 10.9; Vital de Four, Octo quaestiones disputatae de cognitione 4 (232–252).

8 Experiencing the Unity of the Soul

a. Moreover, we say ‘since we perceived such and such, we became angry,’ and this is a true statement. So that which perceives and that which becomes angry is one and the same. […] So perhaps the truth is that what we mean when we say ‘we perceived and became angry’ is that something in us perceived and something became angry. But the point of someone saying ‘we perceived and became angry’ is not that this is in two parts of us, but rather that something to which perception transmitted this intention (al-ma’nā) happened to become angry. Now either this statement is deceptive in this sense, or the truth is that what perceives and what becomes angry is one and the same thing. But this statement is clearly true. Then, that to which perception transmits what it perceives is that which becomes angry. Its being in this state, even if it were a body, does not belong to it insofar as it is body. Thus, it belongs to it insofar as it possesses a faculty by which it is capable of combining these two things. This faculty is not natural, so it must be a soul. (Avicenna, Kitāb al-najāt II.6, 228–229, ed. Fakhry; trans. Jari Kaukua)

b. I apprehend by my reason myself seeing and sensing just as I apprehend myself understanding and willing – in such a way that I apprehend and sense by my reason that it is the same who sees and understands, namely me. This sensation would be false unless these acts truly were from the same subject which is called ‘I’. (Peter John Olivi, Quaestiones in secundum librum Sententiarum 59 (II, 540))

Avicenna explains the experience of the unity between various acts of the soul by appealing to the soul itself: all the acts of the soul are apprehended as belonging to the same subject because they are acts of one and the same soul (a). Another solution was to attribute the unifying function to one of the faculties of the soul in such a way that one faculty apprehends the acts of other faculties and provides experiential unity. Thus, e.g., Peter John Olivi attributes the unifying function to the highest faculty of the soul, which apprehends all the acts of the lower faculties as belonging to the same subject as the highest faculty itself belongs (b). See also Avicenna, De anima V.7 (158–159); Peter John Olivi, Quaestiones in secundum librum Sententiarum 37 (I, 659); 51 (II, 122); 54 (II, 241); 58 (II, 464); 74 (III, 126).

9 Experiencing Cognitive Acts as One’s Own

a. You will say, ‘I experience and perceive myself to understand.’ I say that this is false. Rather, the intellect, which is united to you naturally as the mover and regulator of your body, has this experience, just like the separate intellect experiences the objects of understanding to be in it. If you say, ‘I experience myself to understand as an aggregate of the body and the intellect,’ this is also false. Rather, the intellect which needs your body as an object has this experience, and it communicates the experience to the aggregate in the aforesaid way. (Anonymous, Quaestiones in De anima, ed. Giele, II.4)

b. But if someone wants to say that the intellectual soul is not a form of the body, he must figure out a way in which this action of understanding is the action of this particular human being, because everyone experiences that it is himself who understands. (Thomas Aquinas, Summa theologiae I.76.1)

c. I say that it is possible to evidently prove that there is not numerically one intellect in everyone, because it is not possible that the same simultaneuosly knows and is ignorant of the same thing, loves and hates the same thing, enjoys and suffers the same thing, assents to and dissents from the same thing, and so on. But the intellect in one person knows something and the intellect in another person is ignorant of the thing by its dispositional ignorance; the will in one person loves a thing and the will in another hates it; and so on. All these cases are clear through experience. Thus, it is impossible that there is one intellect in two such people. (William of Ockham, Quodlibeta septem I.11 (OTh 9, 67))

d. I say that if one understands by ‘intellectual soul’ an immaterial and incorruptible form which is whole in the whole body and whole in each part, it is not possible to know evidently, neither by reason nor by experience, that such a form exists in us, or that intellection proper to such a substance exists in us, or that such a soul is the form of the body … Following natural reason it was granted that we experience in us intellection, which is an act of a corruptible form of the body … But we do not experience that intellection which is the proper operation of an immaterial substance … And perhaps if we did experience such intellection to exist in us, we could not conclude more than that its subject is in us as a mover, but not as a form. (William of Ockham, Quodlibeta septem I.10 (OTh 9, 63–65))

e. We experience that we are those who understand. Thus, my understanding is a vital operation of mine just like seeing and so forth. Therefore the principle of this understanding is a true form and a soul of mine. The antecedent is clear from experience. The consequent is evident because … if the principle of understanding is not my form but some spiritual substance which is accidentally united to me, the one who understands is the spiritual substance and not me at all because to understand is to produce an [act of] understanding and receive it vitally … This is confirmed, for we experience that an act of understanding is ours just as an act of seeing. Therefore, it proceeds from an intrinsic principle. But seeing proceeds from a true informing form. The intellect cannot even comprehend how could seeing be a true vital act of mine and how could I see by it unless I myself produce it by an intrinsic form. Therefore the same goes for understanding. (Francisco Suárez, Commentaria una cum quaestionibus in libros Aristotelis De anima 2.4)

The discussion concerning the experience of the acts of the soul as one’s own was related to the so-called one-mind doctrine, connected to Averroes. The anonymous Latin Averroist (an arts master, c. 1270) argued that the experience of being individually the subject of one’s intellectual acts is false, because thoughts belong to an intellect that is separate from individual human beings (a). By contrast, Thomas Aquinas believed that thoughts are subjectively and correctly experienced as individually one’s own (b), which seems to be the majority view represented also by Francisco Suárez (e). See Black 1993b. Some thinkers – Ockham for instance – rejected the argument from experiencing cognitive acts as one’s own. He admits that we can infer from the fact that people disagree intellectually that individual human beings have their own intellects. Note, however, that the experience Ockham refers to is from the third person perspective (c). According to him, the one-mind doctrine cannot be disproved by appealing to our experience of intellectual acts. This is because we do not experience in ourselves the acts which are proper to an immaterial substance; even if we did, there would not necessarily be anything subjective in them (d). See also Averroes, Commentarium magnum in Aristotelis De anima III.5; Thomas Aquinas, De unitate intellectus, 3; William of Baglione, Utrum in omnibus hominibus sit intellectus unus numero, 43; Anonymous (John Buridan?), Quaestiones De anima, ed. Patar, III.7 (441–442). Siger of Brabant, who defended Averroist metaphysics of the soul, held a more moderate view than the anonymous master. According to Siger, we perceive as our own those operations of the separate intellect which take place in us. See Quaestiones in tertium De anima 4 (14). The experience of cognitive acts as one’s own was sometimes used as a proof that the soul must be capable of directly cognising itself (see 3c above).

10 Awareness of One’s Own Body

a. I notice in my body the movements by which things related to its growth come about. But these movements never help me to make those distinctions [involved in thinking], nor are able to do any such thing … Furthermore, I perceive that my body possesses senses, whose movements are spontaneously coordinated to the control of the body. I see with the eyes, hear with the ears, smell with the nostrils, taste with the palate and touch with the hands. But tell me, which of these would you say is able to do that [thinking and distinguishing]? (Aelred of Rievaulx, Dialogus de anima I, 25 (692))

b. You may ask why the soul desires more one than another, since there is no preference of one over another due to their uniformity. The answer is that it desires [its own body] because of the union and connection which it had to it. This becomes clear from the following. The rational soul differs from angels and is akin to other souls because it is a soul, and this is why it has an inclination toward a body. Because it is rational, it has an inclination toward a human body. Because it is noble, it has an inclination toward a nobly organised body. And it has an inclination toward a certain body rather than toward another due to the connection which it had to it … The soul is united to the substance of the flesh which it vivified earlier with such an affection that it is not satisfied unless it receives the same flesh, wherever it is hidden. Thus, it is clear that the soul has an orientation and desire by which it is ordained to the same body, however much it might be conformed to others. (Bonaventura, Commentaria in quatuor libros sententiarum IV.43.5)

c. The proper object of the sense of touch is the interior condition of its own organ. (Peter John Olivi, Quaestiones in secundum librum Sententiarum 61 (II, 578))

d. The object of the sense of touch is the whole group of features in which the appropriate or inappropriate constitution of the body of the animal may consist. And if you wish to specify this to the human sense of touch, the object of the human sense of touch is the whole group of features in which the constitution of the human body may be perfected or forsaken. (Quaestiones in secundum librum Sententiarum 61 (II, 585))

e. The things mentioned are perceived by the senses, and often without any first or second quality. Thus, when I write this, there is a pain in my neck. There is something sufficiently sensible in this, but I cannot perceive in it any other first or second sensible quality of the kind discussed above but the pain. Also, what would be the first or second quality which is perceived in coitus, apart from the joining of the fitting with the fitting which is pleasure. (Pietro d’Abano, Conciliator differentiarum philosophorum et precipue medicorum 77 (117vb))

Awareness of the body is rarely related to self-consciousness in medieval discussions, although it was taken for granted that the body is an important part of the self. The idea that man is a soul in exclusion of the body was called ‘Plato’s view’ and it was deemed to be false (see e.g., Thomas Aquinas, Summa theologiae I.76.1). The soul was generally taken to be embodied in a rather deep manner, especially in respect to the sensory functions shared with other animals, whose souls were thought to be inseparable from their bodies. Thus, to defend the immortality of the soul, Aelred of Rievaulx argued that there is something incorporeal in the soul, listing the embodied functions of the soul and then asking if any of them might be of any help in intellectual thinking (a). According to Christian faith, resurrection on Judgement Day involves humans as embodied beings and not as mere souls. This doctrine raises philosophical problems concerning the identity of the resurrected body. For discussion, see Bynum 1995. Bonaventura’s solution to this distinctively medieval problem is that the body to which the soul is united is the same body, and that the soul somehow recognises its own body and desires the union with the same body to which it was united when the human being was alive. Thus, the soul has some sense of owning its body (b). The soul’s apprehension of the body was addressed also in discussions concerning the unity and the scope of the sense of touch. Olivi argues, in opposition to the Aristotelian view, that the proper object of the sense of touch is the whole body (c, d). In medical writings, bodily pain and pleasure are also addressed as modes of self-perception (e). See Yrjönsuuri 2006, 2008a.