Aristotle’s Philosophy of Mind

Abstract

In an attempt to reject Cartesian Dualism, some philosophers and scientists of the late twentieth century proposed a return to the ancient position that Descartes had opposed, i.e., Aristotle’s psychological hylomorphism, which applied to living beings the ontological thesis, according to which every substance is a compound of matter (hyle) and form (morphe). In this perspective, the soul is actual possession of the body’s capacity to perform a series of life functions. Therefore, according to Aristotle, soul and body are reciprocally interdependent aspects of the living being, so that we must consider the former as an enmattered form, and the latter as an enformed or ensouled matter. This means that, for Aristotle, all the functions of the soul, even the highest ones like thought, are essentially connected with the body, since they ultimately require sensations. This paper illustrates and supports this doctrine in detail, especially in relation to the cognitive processes of the human mind.

1 Introduction

In his works of psychology and especially in De Anima (On the Soul), Aristotle, in the light of his own hylomorphism, conceived the soul (psyche) as the complex of the capacities of the living body to carry out the activities that are essential to it: those of both vegetative nature (for example, nutrition, digestion, and reproduction) and mental nature (for example, perception and memory). Aristotle’s psychological hylomorphism undoubtedly still attracts great interest: in fact, it can be considered a valid alternative to the two dominant philosophical orientations regarding the “mind–body problem”, i.e., dualism (ontological or conceptual) and monism (materialist or idealist). For this reason, it has fully entered the contemporary scholarly debate.¹

On the other hand, perhaps precisely because of its originality and complexity, this doctrine has so far evaded a univocal classification: from time to time, Aristotle has been considered a “dualist”, a “materialist”, neither, and a “happy medium” between the two.² Some scholars have considered him the precursor of contemporary solutions, for example “the first functionalist”³ or “the first cognitivist”,⁴ while others have questioned the “credibility” of his philosophy of mind.⁵

My purpose is here to synthetically reconstruct Aristotle’s perspective on the basis of his most significant texts. I will try to show, firstly, how Aristotle’s psychological hylomorphism establishes an indissoluble unity of soul (psyche) and body (soma) with reference to all psychophysical processes, from the most elementary to the highest. Secondly, I will demonstrate that, in this way, Aristotle’s doctrine may actually serve as a powerful theoretical weapon against what I would call the “Cartesian misunderstanding”, which consists of postulating two distinct and separable dimensions of the living being: body and soul.⁶ At the same time, I will try to dispel the interpretative errors that have arisen around Aristotle’s philosophy of mind.

Schematically, we can say that the most representative positions of the current debate on Aristotle’s philosophy of mind are “materialism”, “spiritualism”, and the so-called “double-aspect theory”.⁷ By materialism, we mean the thesis according to which matter is at the origin of both physical and psychic phenomena: in this perspective, the psychophysical activities of the living being are properly physiological processes affecting certain body organs. This position is opposed by the supporters of spiritualism: they define the psychophysical activities of the living as purely cognitive processes (“spiritual changes”) that do not involve any physiological process (“material change”), except “accidentally”.⁸ The double-aspect theory constitutes, so to speak, a compromise between materialism and spiritualism: according to it, the psychophysical activities of the living are cognitive functions (formal aspect) that are “realized in” or “come about” certain physiological processes (material aspect).

These interpretations miss the essence of Aristotle’s position for a simple reason: despite their mutual differences, materialism, spiritualism and the double-aspect theory share the same basic assumption. As a matter of fact, they presuppose that, in the psychophysical activities of the living, it is possible to distinguish a purely psychic (formal) component and a purely somatic or physiological (material) one. This distinction is explicit in the double-aspect theory, but it is presupposed also by the supporters of materialism and spiritualism. Indeed, if they did not recognize a conceptual distinction between what is psychic and what is physical, they could not question the nature of the relationship between these components. This “post-Cartesian” assumption has originated the modern mind–body problem. However, Aristotle’s hylomorphism does not recognize such a distinction and, thus, can provide a unitary and coherent reconstruction of man’s psychophysical processes.

According to Aristotle, the soul (form) and the body (matter) are inseparable and mutually interdependent components of the living compound: it is impossible to speak either of the soul, except as a “material (or embodied) form”, or of the body, except as “informed (or animated) substrate”. This position emerges clearly in De Anima from the “outline of the soul”, which constitutes the principle for the subsequent deduction of each of the soul’s specific faculties. Using the methods of division and induction, Aristotle formulated two notions of the soul that are complementary to each other: the soul is defined in the first place (a) as “substance in the sense of being the form and the first actuality of a natural body potentially possessing life; and such will be any body which possesses organ”⁹; then (b) as “that whereby we live and perceive and think in the primary sense”,¹⁰ that is, as the principle and first cause of the faculties of the living.

From both these notions, it follows that the reference to the body is an integral part of the definition of the soul and, vice versa, the reference to the soul is an integral part of the definition of the body. Maintaining that the soul is “the form and the first actuality of a body which possesses organs” (first definition) means in fact admitting that the soul is not simply form, but is the form of a body of a certain type, and that the body, in turn, is not simply matter, but a matter of a certain type, i.e., a matter which is “appropriate” for the soul. Additionally, defining the soul as “that whereby we live and perceive and think in the primary sense” (second definition) means admitting the unity of the soul with the body, because the subject of these activities is not only the soul, but the living being understood as composed of soul and body.¹¹

The soul, therefore, forms an inseparable unity with the body.¹² Aristotle compares this unity to that formed by wax with its impression¹³:

So one need no more ask whether body and soul are one than whether the wax and the impression it receives are one, or in general whether the matter of each thing is the same as that of which it is the matter [scil. the form].¹⁴

In this passage, the psychophysical unity that is proper to the living seems to constitute a special case of the hylomorphic unity that characterizes sensible substances in general (natural and non-natural). The use of artificial objects (artefacta) to exemplify the relationship between the form (soul) and the matter (body) of the living being in Aristotle is not unusual.¹⁵ However, this does not mean that the hylomorphic unity of an artificial entity is of the same kind as the psychophysical unity of a natural and living being.¹⁶ For Aristotle, in fact, while the form of a natural entity is immanent, the form of an artificial object is imposed from outside, i.e., by the man,¹⁷ so it can be realized in different kinds of matter characterized by certain “functional properties”.¹⁸ Instead, the form of a living being cannot be realized in a matter that is not the organic body: consequently, its unity with it is not contingent (like the hylomorphic unity of an artificial entity) but essential.¹⁹

2 The Affections of the Soul

Let us now consider what implications Aristotle’s thesis of the inseparable union of the soul with the body has in the analysis of psychic processes or operations. Aristotle indicated as pathos, “affection”, all that the soul or, better, the being animated because of the possession of the soul, “suffers” or “performs”.²⁰ Among the affections of the soul, he listed not only passions (pathe in the strict sense of the word, or pathemata), such as anger and fear,²¹ but also all the characteristic activities (“any function or affection”) of the soul as perceiving and thinking.²²

The possibility that some affections may belong exclusively to the soul and not to the body is for Aristotle a considerable difficulty (aporia), which may impact the very definition of the soul.²³ However, “it is evident” (phainetai) that most affections of the soul also involve the body.²⁴ Indeed, Aristotle went so far as to suppose, in general terms, that “all the affections of the soul are common and shared (koina) by that which contains the soul”.²⁵

This is particularly evident, in his opinion, if we consider a specific sub-class of affections of the soul, passions: “anger, gentleness, fear, pity, courage and joy, as well as loving and hating”.²⁶ In fact, passions attest beyond all doubt that all affections of the soul are “associated with the body”.²⁷ Experience itself shows that they involve “simultaneously” (hama) body and soul, “for when they appear the body is also affected”²⁸:

There is good evidence for this. Sometimes no irritation or fear is expressed, though the provocations are strong and obvious; and conversely, small and obscure causes produce movement, when the body is disposed to anger, and when it is in angry mood. And here is a still more obvious proof. There are times when men show all the symptoms of fear without any cause of fear being present.²⁹

The argument expounded here consists of two proofs, of which the first (“There is good […] angry mood”) is divided into two experiences, while the second (“And here is a still more obvious […] being present”) consists of only one experience. The three experiences taken as a whole confirm that a certain “state” of the body is essential for the living to be “moved”, for example, to irritation, fear or anger.³⁰

The reason why, in the first experience, “no irritation or fear is expressed”, despite the presence of “provocations [which] are strong and obvious”, and therefore should lead to anger or fear, is the absence of a physical condition that is relevant or appropriate for these passions. This demonstrates that a certain physical state is the necessary condition for a determined psychophysical affection. With the second experience, Aristotle shows that a certain physical state constitutes the condition that is not only necessary, but also sufficient for the living to experience a certain passion: the subject “is moved” to anger, despite the fact that the stimuli are “small and obscure”, because his body is in the right state for this condition (“when the body is disposed to anger, and when it is in angry mood”). But we find “a still more obvious proof” that the physical state is also a sufficient condition in the third case, in which the living experiences fear despite the absence of a stimulus to fear.³¹ Consequently, a given condition of the body constitutes in itself the sufficient requisite for the pathos of fear.

Aristotle’s examples thus prove, empirically, that a certain bodily condition is an essential condition for a certain psychophysical affection to take place. According to some interpreters,³² this would mean that a relationship of “non-symmetrical covariation” exists between psychic states and physical states, such as for the former to “supervene” over the latter.³³ However, this thesis assumes that, in psychophysical affections, it is possible to distinguish a purely psychic (formal) component and a purely physical (material) component, of which the latter would constitute the “physical basis” for the occurrence of the former. Nevertheless, this distinction into “pure” components is not admissible in Aristotle’s psychological hylomorphism. For Aristotle, indeed, it is precisely because of the inseparable unity of form and matter in the living being that a certain state of the body constitutes the necessary and sufficient condition for a certain affection of the soul. In fact, the physical states that are relevant to passions, in so far as they are affections of an essentially informed or animated matter (the living body), cannot be considered “purely” physical, because, as they involve the body, they also simultaneously involve its form, the soul. In this sense, the states of the body are also, and essentially, states of the soul.

In order to express the unity of form and matter in psychophysical affections, Aristotle used a significant expression: he called them logoi enyloi, “enmattered forms”.³⁴ By qualifying the affections of the soul as enmattered (or embodied) forms, he was able to clarify the reason why they also involve the body: it is their very form that is “enmattered”, i.e., “not separable” from a given matter, at the level of both existence and definition.³⁵ Thus, for example, anger is defined as “a certain movement (kinesis tis), roused by such a cause, with such an end in view”; this movement involves “such a body”, i.e., the living body, or a part or faculty of it.³⁶

The fact that here Aristotle did not ask at all what kind of relationship exists between a psychic state and a bodily one is particularly interesting. For Aristotle, this problem did not exist. After ascertaining that the affections of the soul involve the body at the same time (hama), he limited himself to establishing their indivisible unity: the psychophysical affections are precisely “enmattered forms”, that is, forms that include in their essence and definition the reference to a matter of a certain type, an essentially informed matter.

The implications of this position are of great importance also at the different levels of cognitive activity of living beings, and particularly of man.

3 Perception

Aristotle describes perception (to aisthanesthai) as the exercise of a faculty, the perceptive one, that essentially involves bodily organs: the sense organs. This exercise is aimed at the discrimination of sensory differences and is produced by the contact of the sensible object with the sense organ through a medium. In this way, the sense organ receives the sensible qualities “without the matter”.³⁷ In recent decades, some interpreters have launched a debate on Aristotle’s analysis of perception, in which the main exegetical positions on his philosophy of mind in general have emerged: “materialism”, the “double-aspect theory” and “spiritualism”.

i) According to materialists, perception for Aristotle is a physiological process in which the sense organ takes on, in act, the sensible qualities of an object: for example, when we perceive the red colour, the sensorium of sight (i.e., our eyes) literally turns red.³⁸

ii) Conversely, supporters of the double-aspect theory identify in perception a material aspect (the physiological process) and a formal aspect (the cognitive act): perception would then consist in a cognitive function that “is realized in” or “comes on” a material process.³⁹

iii) Finally, according to spiritualists, perception for Aristotle is a “spiritual” change (cognitive or intentional), which consists of the “pure transition of forms”; when, in the perception, material changes are produced, these would be only “accidental events” with respect to the act of awareness which is perception.⁴⁰

However, these three interpretative positions appear unsatisfactory. In fact, perception for Aristotle is neither (i) a physiological process only, nor (iii) only a cognitive act, nor (ii) the “sum” of the two. Instead, it is an indissolubly psychophysical phenomenon, just like anger and all other affections. A clear evidence for the fact that perceiving must not be considered as a purely cognitive or “spiritual” activity (according to thesis iii) is Aristotle’s description of the “movements” (kineseis) to which the sense organs are subjected according to their material characters. At the same time, perceiving is described as a process which is essentially directed to the realization of an end, that is, as a “completion” (teleiosis). Therefore, the perceptive faculty is, like every pathos of the living, an “enmattered form” and, accordingly, essentially psychophysical.

4 Imagination

Aristotle’s analysis of phantasia is even more interesting. Since phantasia acts as a “bridge” between sensory knowledge and the activity of thought, it allows us to understand, in the light of the principle of psychophysical indissolubility, the higher functions of the human mind also. Recently, the exact definition of the notion of phantasia according to Aristotle has been the object of a heated debate that has engaged a large group of scholars, starting with Malcom Schofield.⁴¹ Schematically, we may say that the central meaning of the term phantasia is: “that by virtue of which x appears or presents itself to y as z”, where x is the object of a perception either in act or that has already occurred, y the perceiving subject, and z the perceptive appearance or the mental picture.⁴² If x is the object of an actual perception, phantasia is characterized as “perceptive” (“appearance”), whereas, if x is the object of a perception that has already occurred, it is qualified as “post-perceptive” (“imagination” or conservation of what has been perceived, in the form of mental pictures).

Just like perception, so also phantasia “seems to be a certain movement (kinesis tis)”⁴³: it is in fact defined by Aristotle as “the movement produced by the perception in act”.⁴⁴ The “perception in act”, that is, the act of perceiving, consists, as we have seen, in the completion of the psychophysical faculty of perception: it results from the contact that the sensible being establishes with the sensorium through a medium, for the purpose of discrimination of the sensible. According to Aristotle, this “movement” continues to be exercised for a certain time in the sense organs, even when the perception is no longer in act.⁴⁵ For example, if, after staring at the sun or another luminous object, we close our eyes and keep our look in the direction of the object, this “appears (…) first of all in its own proper colour; then it changes to red, and then to purple, until it fades to black and disappears”.⁴⁶

But sensory impressions are not yet mental pictures, phantasmata: they are fixed in mental pictures only after they have been transmitted to the heart, which is the “central sensorium”, as the principle of perception and place of organization of perceptive data.⁴⁷ There, they leave a kind of “imprint” or “likeness” (typos): this constitutes for Aristotle the true mental picture, the phantasma.⁴⁸ Therefore, while the sensory impression represents the immediate effect of the perception in act, the mental picture is the result of a subsequent operation: for this reason, it is not bound to the presence of an external sense object that acts on the sensorium. In this way, it is “similar” to the sensory impression from which it derives, but with an important difference: it is “without the matter”.⁴⁹

Significantly, Aristotle described the movement derived from the perception in act that leads to the formation of phantasmata with the same image he used to illustrate the original movement of perception, the seal imprinted in wax⁵⁰: “the stimulus produced impresses a sort of likeness of the percept, just as when men seal with signet rings”.⁵¹ The use of the same image to explain, on the one hand, the reception of sensible forms by the sense organs and, on the other, the fixing of sensory impressions in the central sensorium, is justified by the fact that for Aristotle the two “movements” are “similar”: “[a] movement may be caused by actual sensation, and this movement must be similar to the sensation”.⁵² Post-perceptive phantasia, or imagination in the strict sense of the word, is what makes the phantasmata available to operations of different complexity, from the forming of oneiric images to the establishment of memories and concepts. With the latter, we come to talk about the thought and the conditions that make it possible.

5 The Soul Does Not Think Without Images

In the third book of De Anima, Aristotle underlined the close connection between phantasia and thought (nous). He explained that the activity of thought is not possible without imagination⁵³ and that concepts do not exist without images.⁵⁴ Conversely, phantasia itself is sometimes considered as “some sort of thinking process (noesis)”.⁵⁵

The correlation between phantasia and thought appears, first of all, in the activities of phantasia themselves, some of which lie at the boundary between perceiving and thinking. In fact, perceptive phantasia is what allows the subject to interpret the sensory data at his disposal and to have a unitary vision of the sensible object as characterized in a certain way. In particular, it intervenes when the sensory data are incomplete or unclear, because, according to Aristotle, “[we do not say] ‘I imagine that it is a man’ when our sense is functioning accurately with regard to its object, but only when we do not perceive distinctly”.⁵⁶ This simultaneous and “collaborative” activity of perception and imagination makes cognitive operations such as the identification and recognition of a sensible object possible. In fact, the sensory data received from perception can be “completed” through sensory impressions preserved by the imagination and, in this way, be “interpreted” by the subject.

For its part, post-perceptive phantasia or imagination makes phantasmata available to various operations. Among the cognitive operations in which mental pictures are involved, memory, which Aristotle considers a form of imagination, is particularly important. How does it work? In memory, the phantasma is considered not “in itself”, but “in relation to something else”, that is, in relation to the past moment in which the object of the memory-image was perceived.

In order to illustrate the relationship between the mental picture considered “in itself” and the mental picture considered “in relation to something else”, Aristotle used the analogy of painting. As the painted figure in a painting can be considered for itself, that is, as a figure, or can refer to something else, that is, to the object of which it is a “portrait” (eikon), so the mental picture (phantasma) can be considered in itself, as a mental picture, or can refer to something else and be considered “as a likeness [and] an aid to memory”.⁵⁷ The mnemonic picture, therefore, refers to the experience that originated it. Conversely, when the mental picture is considered for itself, we do not say that we “remember” it, but that we “have it present” (theorein) or “think” (noein). In this case, it is not a reminiscence, but an object of contemplation (theorema) or a thought (noema):

In so far as we consider it in itself, it is an object of contemplation (theorema) or a mental picture (phantasma), but in so far as we consider it in relation to something else, e.g., as a likeness (eikon), it is also an aid to memory (mnemoneuma). Hence when the stimulus of it is operative, if the soul perceives the impression as independent, it appears to occur as a thought (noema), or a mental picture.⁵⁸

Mental pictures can be subjected to a subsequent noetic operation that leads to the formation of concepts:

We have already dealt with imagination in the treatise On the Soul. It is impossible even to think without a mental picture. The same affection is involved in thinking as in drawing a diagram; for in this case although we make no use of the fact that the magnitude of a triangle is a finite quantity, yet we draw it as having a finite magnitude. In the same way the man who is thinking, though he may not be thinking of a finite magnitude, still puts a finite magnitude before his eyes, though he does not think of it as such. And even if the nature of the object is quantitative, but indeterminate, he still puts before him a finite magnitude, although he thinks of it as merely quantitative.⁵⁹

Thus, we come to the decisive thesis of the necessary involvement of mental pictures in the activity of thought:

Since apparently nothing has a separate existence, except sensible magnitudes, the objects of thought—both the so-called abstractions of mathematics and all states (hexeis) and affections (pathe) of sensible things—reside in the sensible forms. And for this reason (…) no one could ever learn or understand anything without the exercise of perception (…).⁶⁰

Aristotle means that the intelligible are potentially in the sensible forms that are received by the senses and preserved by the imagination. This is the case not only of the mathematical objects, which are the result of the abstraction (aphairesis) of the sensible characters from natural bodies, but also of “all states (hexeis) and affections (pathe) of sensible things” (432a6),⁶¹ which are the result of a process of generalization starting from single perceptions, i.e., the epagoghe or “induction”.

Consequently, it would be impossible either “to learn” or “to understand” anything without perception, which is the basis of imagination and, therefore, of thought (432a7-8). Aristotle reiterated this principle in his Second Analytics, where he argued that perception is a necessary condition for the episteme, i.e., knowledge “in the proper sense”, or demonstrative knowledge: “if some perceptive capacity is lacking, it is necessary that it lacks also some kind of scientific knowledge “.⁶²

6 Conclusions

Summarizing the results of the survey conducted so far, we can state that Aristotle proposed a coherent and highly original philosophy of mind, whose main features are the following:

• (1) Thought constitutes an “emerging” capacity. This means that it is a complex capacity of the human being understood as a whole and, more precisely, a capacity emerging from the interaction of multiple structures and psychophysical processes.

• (2) All the affections (pathe) of the living being are essentially and indissolubly psychophysical. A psychophysical condition, such as perception or imagination, can not only not exist, but even be defined (and therefore understood) without referring to its two conditions, the formal and the material.

• (3) The thesis of the indissolubly psychophysical character of all the “common” affections of the living originates from the application of the general principles of hylomorphism to the living: the soul is not simply “form”, but the form of a body of a certain type. For its part, the body is not simply “matter”, but a matter of a certain type, an essentially animated matter.⁶³

This crucial point allows us to identify the “anti-Cartesian” relevance of Aristotle’s philosophy of mind. Aristotle’s hylomorphism, applied to living beings and particularly to human beings, is definitely outside the classifications that originated in the modern age,⁶⁴ and deserves to be rediscovered as a coherent and plausible alternative to the theories dominating in the current debate on the mind–body problem.