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4 September 2021 (c) Richard C. Taylor
Human Knowing in Aristotle
Lecture for class on 9 September 2021
Aristotle, with Alexander and Themistius
Aristotle: On scientific knowledge and the conditions for scientific demonstration, see Posterior Analytics 1.1-4. Mure: http://classics.mit.edu/Aristotle/posterior.1.i.html
“We suppose ourselves to possess unqualified scientific knowledge of a thing, as opposed to knowing it in the accidental way in which the sophist knows, when we think that we know the cause on which the fact depends, as the cause of that fact and of no other, and, further, that the fact could not be other than it is. Now that scientific knowing is something of this sort is evident-witness both those who falsely claim it and those who actually possess it, since the former merely imagine themselves to be, while the latter are also actually, in the condition described. Consequently the proper object of unqualified scientific knowledge is something which cannot be other than it is. . . . .” (1.2)
“What I now assert is that at all events we do know by demonstration. By demonstration I mean a syllogism productive of scientific knowledge, a syllogism, that is, the grasp of which is eo ipso such knowledge. Assuming then that my thesis as to the nature of scientific knowing is correct, the premisses of demonstrated knowledge must be true, primary, immediate, better known than and prior to the conclusion, which is further related to them as effect to cause. Unless these conditions are satisfied, the basic truths will not be ‘appropriate’ to the conclusion. Syllogism there may indeed be without these conditions, but such syllogism, not being productive of scientific knowledge, will not be demonstration. The premisses must be true: for that which is non-existent cannot be known-we cannot know, e.g. that the diagonal of a square is commensurate with its side. The premisses must be primary and indemonstrable; otherwise they will require demonstration in order to be known, since to have knowledge, if it be not accidental knowledge, of things which are demonstrable, means precisely to have a demonstration of them. The premisses must be the causes of the conclusion, better known than it, and prior to it; its causes, since we possess scientific knowledge of a thing only when we know its cause; prior, in order to be causes; antecedently known, this antecedent knowledge being not our mere understanding of the meaning, but knowledge of the fact as well. Now ‘prior’ and ‘better known’ are ambiguous terms, for there is a difference between what is prior and better known in the order of being and what is prior and better known to man. I mean that objects nearer to sense are prior and better known to man; objects without qualification prior and better known are those further from sense. . . . .” (1.2)
“Since the object of pure scientific knowledge cannot be other than it is, the truth obtained by demonstrative knowledge will be necessary. And since demonstrative knowledge is only present when we have a demonstration, it follows that demonstration is an inference from necessary premisses.” (1.4)
Posterior Analytics, 2.19 Mure: http://classics.mit.edu/Aristotle/posterior.2.ii.html
“As regards syllogism and demonstration, the definition of, and the conditions required to produce each of them, are now clear, and with that also the definition of, and the conditions required to produce, demonstrative knowledge, since it is the same as demonstration. As to the basic premisses, how they become known and what is the developed state of knowledge of them is made clear by raising some preliminary problems.
We have already said that scientific knowledge through demonstration is impossible unless a man knows the primary immediate premisses. But there are questions which might be raised in respect of the apprehension of these immediate premisses: one might not only ask whether it is of the same kind as the apprehension of the conclusions, but also whether there is or is not scientific knowledge of both; or scientific knowledge of the latter, and of the former a different kind of knowledge; and, further, whether the developed states of knowledge are not innate but come to be in us, or are innate but at first unnoticed. Now it is strange if we possess them from birth; for it means that we possess apprehensions more accurate than demonstration and fail to notice them. If on the other hand we acquire them and do not previously possess them, how could we apprehend and learn without a basis of pre-existent knowledge? For that is impossible, as we used to find in the case of demonstration. So it emerges that neither can we possess them from birth, nor can they come to be in us if we are without knowledge of them to the extent of having no such developed state at all. Therefore we must possess a capacity of some sort, but not such as to rank higher in accuracy than these developed states. And this at least is an obvious characteristic of all animals, for they possess a congenital discriminative capacity which is called sense-perception. But though sense-perception is innate in all animals, in some the sense-impression comes to persist, in others it does not. So animals in which this persistence does not come to be have either no knowledge at all outside the act of perceiving, or no knowledge of objects of which no impression persists; animals in which it does come into being have perception and can continue to retain the sense-impression in the soul: and when such persistence is frequently repeated a further distinction at once arises between those which out of the persistence of such sense-impressions develop a power of systematizing them and those which do not. So out of sense-perception comes to be what we call memory, and out of frequently repeated memories of the same thing develops experience; for a number of memories constitute a single experience. From experience again-i.e. from the universal now stabilized in its entirety within the soul, the one beside the many which is a single identity within them all-originate the skill of the craftsman and the knowledge of the man of science, skill in the sphere of coming to be and science in the sphere of being.
We conclude that these states of knowledge are neither innate in a determinate form, nor developed from other higher states of knowledge, but from sense-perception. It is like a rout in battle stopped by first one man making a stand and then another, until the original formation has been restored. The soul is so constituted as to be capable of this process.
Let us now restate the account given already, though with insufficient clearness. When one of a number of logically indiscriminable particulars has made a stand, the earliest universal is present in the soul: for though the act of sense-perception is of the particular, its content is universal-is man, for example, not the man Callias. A fresh stand is made among these rudimentary universals, and the process does not cease until the indivisible concepts, the true universals, are established: e.g. such and such a species of animal is a step towards the genus animal, which by the same process is a step towards a further generalization.
Thus it is clear that we must get to know the primary premisses by induction; for the method by which even sense-perception implants the universal is inductive. Now of the thinking states by which we grasp truth, some are unfailingly true, others admit of error-opinion, for instance, and calculation, whereas scientific knowing and intuition are always true: further, no other kind of thought except intuition is more accurate than scientific knowledge, whereas primary premisses are more knowable than demonstrations, and all scientific knowledge is discursive. From these considerations it follows that there will be no scientific knowledge of the primary premisses, and since except intuition nothing can be truer than scientific knowledge, it will be intuition that apprehends the primary premisses-a result which also follows from the fact that demonstration cannot be the originative source of demonstration, nor, consequently, scientific knowledge of scientific knowledge. If, therefore, it is the only other kind of true thinking except scientific knowing, intuition will be the originative source of scientific knowledge. And the originative source of science grasps the original basic premiss, while science as a whole is similarly related as originative source to the whole body of fact.”
Aristotle, De Anima, Book 1: http://classics.mit.edu/Aristotle/soul.1.i.html
The case of mind is different; it seems to be an independent substance implanted within the soul and to be incapable of being destroyed. If it could be destroyed at all, it would be under the blunting influence of old age. What really happens in respect of mind in old age is, however, exactly parallel to what happens in the case of the sense organs; if the old man could recover the proper kind of eye, he would see just as well as the young man. The incapacity of old age is due to an affection not of the soul but of its vehicle, as occurs in drunkenness or disease. Thus it is that in old age the activity of mind or intellectual apprehension declines only through the decay of some other inward part; mind itself is impassible. Thinking, loving, and hating are affections not of mind, but of that which has mind, so far as it has it. That is why, when this vehicle decays, memory and love cease; they were activities not of mind, but of the composite which has perished; mind is, no doubt, something more divine and impassible. That the soul cannot be moved is therefore clear from what we have said, and if it cannot be moved at all, manifestly it cannot be moved by itself.
De Anima Book 2.2: http://classics.mit.edu/Aristotle/soul.2.ii.html
We have no evidence as yet about mind or the power to think; it seems to be a widely different kind of soul, differing as what is eternal from what is perishable; it alone is capable of existence in isolation from all other psychic powers.
De Anima Book 3.4: http://classics.mit.edu/Aristotle/soul.3.iii.html
Turning now to the part of the soul with which the soul knows and thinks (whether this is separable from the others in definition only, or spatially as well) we have to inquire (1) what differentiates this part, and (2) how thinking can take place.
If thinking is like perceiving, it must be either a process in which the soul is acted upon by what is capable of being thought, or a process different from but analogous to that. The thinking part of the soul must therefore be, while impassible, capable of receiving the form of an object; that is, must be potentially identical in character with its object without being the object. Mind must be related to what is thinkable, as sense is to what is sensible.
Therefore, since everything is a possible object of thought, mind in order, as Anaxagoras says, to dominate, that is, to know, must be pure from all admixture; for the co-presence of what is alien to its nature is a hindrance and a block: it follows that it too, like the sensitive part, can have no nature of its own, other than that of having a certain capacity. Thus that in the soul which is called mind (by mind I mean that whereby the soul thinks and judges) is, before it thinks, not actually any real thing. For this reason it cannot reasonably be regarded as blended with the body: if so, it would acquire some quality, e.g. warmth or cold, or even have an organ like the sensitive faculty: as it is, it has none. It was a good idea to call the soul ‘the place of forms’, though (1) this description holds only of the intellective soul, and (2) even this is the forms only potentially, not actually.
Observation of the sense-organs and their employment reveals a distinction between the impassibility of the sensitive and that of the intellective faculty. After strong stimulation of a sense we are less able to exercise it than before, as e.g. in the case of a loud sound we cannot hear easily immediately after, or in the case of a bright colour or a powerful odour we cannot see or smell, but in the case of mind thought about an object that is highly intelligible renders it more and not less able afterwards to think objects that are less intelligible: the reason is that while the faculty of sensation is dependent upon the body, mind is separable from it.
Once the mind has become each set of its possible objects, as a man of science has, when this phrase is used of one who is actually a man of science (this happens when he is now able to exercise the power on his own initiative), its condition is still one of potentiality, but in a different sense from the potentiality which preceded the acquisition of knowledge by learning or discovery: the mind too is then able to think itself. . . . .
[I]t is by means of the sensitive faculty that we discriminate the hot and the cold, i.e. the factors which combined in a certain ratio constitute flesh: the essential character of flesh is apprehended by something different either wholly separate from the sensitive faculty or related to it as a bent line to the same line when it has been straightened out.
De Anima 3.5
Since in every class of things, as in nature as a whole, we find two factors involved, (1) a matter which is potentially all the particulars included in the class, (2) a cause which is productive in the sense that it makes them all (the latter standing to the former, as e.g. an art to its material), these distinct elements must likewise be found within the soul (en tē psyche)
And in fact mind as we have described it is what it is what it is by virtue of becoming all things, while there is another which is what it is by virtue of making all things: this is a sort of positive state like light; for in a sense light makes potential colours into actual colours.
Mind in this sense of it is separable, impassible, unmixed, since it is in its essential nature activity (for always the active is superior to the passive factor, the originating force to the matter which it forms).
Actual knowledge is identical with its object: in the individual, potential knowledge is in time prior to actual knowledge, but in the universe as a whole it is not prior even in time. Mind is not at one time knowing and at another not. When mind is set free from its present conditions it appears as just what it is and nothing more: this alone is immortal and eternal (we do not, however, remember its former activity because, while mind in this sense is impassible, mind as passive is destructible), and without it nothing thinks.
Alexander of Aphrodisas on intellect and intellectual abstraction:
Alexander of Aphrodisias. Supplement to On the Soul, R. W. Sharples (tr.) (London: Duckworth, 2004), pp. 28-29:
This [intellect] is what is intelligible in its own nature and is such in actuality; for it is this that produces thinking and leads the material intellect to actuality. This too is itself an intellect; for immaterial form, which alone is intelligible in its own nature, is intellect.
For enmattered forms are made intelligible by the intellect, being intelligible potentially. The intellect separates them from the matter with which they have their being, and itself makes them intelligible in actuality, and each of them, when it is thought, then comes to be intelligible in actuality and intellect; [but] they are not like this previously or by their own nature. For intellect in actuality is nothing other than the form that is being thought, so that each of these things too, that are not intelligible without qualification, becomes intellect, whenever it is thought. As knowledge in actuality is the same as what is knowable in actuality, and / p.29 / as sensation in actuality is the same as the sensible in actuality and the sensible in actuality [is the same] as sensation in actuality, so too intellect in actuality is the same as what is intelligible in actuality, and what is intelligible in actuality [is the same] as intellect in actuality. For intellect, apprehending the form of the thing that is thought and separating it from the matter, both makes it intelligible in actuality and itself comes to be intellect in actuality.
Alexander of Aphrodisias. Supplement to On the Soul, R. W. Sharples (tr.) (London: Duckworth, 2004), p. 36:
Moreover, its producing is prior and [part of] its substance. First it produces by abstraction [something] intelligible, and then in this way it apprehends some one of these things which it thinks and defines as a this-something. Even if it separates and apprehends at the same time, nevertheless the separating is conceptually prior; for this is what it is for it to be able to apprehend the form. We say that fire is productive in the highest degree, because it consumes all matter that it gets hold of and provides [it as] nourishment for itself; and yet, in that it is nourished it is affected. In the same way we must consider that the intellect that is in us is productive; for it itself makes intelligible the things that are not intelligible in actuality. For nothing is intelligible other than the intellect that is in actuality and in itself. And the things that are made intelligible by what thinks them, and the activities of this, [are] also themselves intellect when they are thought. So, if intellect did not exist, nothing would be intelligible, neither what is naturally [so] – for it itself was alone of this sort – nor what is brought about by this; for if it did not exist, it would not produce.
Themistius, Paraphrase of the De Anima
In his Paraphrase of the De Anima of Aristotle, the Greek commentator Themistius provides his own detailed account of the reasoning of Aristotle in De Anima 3.5, a key text in the discussion of intellectual abstraction. As indicated earlier, while Aristotle neither in De Anima 3.4-5 nor elsewhere in that work or others provides a clear account of intellectual abstraction, the Arabic tradition knew the abstractionist accounts of Alexander and read them back into Aristotle. In his Paraphrase of the De Anima Themistius does the same thing, though his account does not conceive of the Agent Intellect as God as had Alexander. Rather, for Themistius the Productive or Agent Intellect “has all the forms all together and presents all of them to itself at the same time” and yet plays a literally intrinsic role in the formation of intelligibles in act in individual human knowers.
According to Themistius the human soul has a potential intellect and an actual intellect. The latter is the potential intellect in a completed state of actuality in which it has knowledge of universals. Yet this “potential intellect must be perfected by some other intellect that is already perfect, i.e. actual, not potential. [This intellect] moves the potential intellect analogously to the craft [moving matter], and it perfects the soul’s natural disposition for thinking, and fully constitutes its hexis ‘And this intellect is separate, unaffected, and unmixed’ (430a17-18).” This separate actual intellect, here the Agent Intellect, “advances the potential intellect, and not only makes it an actual intellect, but also constitutes its potential objects of thought as actual objects of thought. These are the enmattered forms, ie. the universal thoughts assembled from particular objects of perception.” For Themistius what he calls the potential intellect is not an intellect as such (in contrast to Avicenna) but rather it is his denomination of the human soul as containing a collection of images from the external and internal senses. It is a potency which the Agent Intellect takes over to make its collection of thoughts thereby enabling the human soul “able to make transitions, and to combine and divide thoughts.” Here the Agent Intellect, though full with forms, does not emanate from its forms upon the individual’s potential intellect but instead assists the potential intellect in actualizing itself as knower of intelligibles in act, that is, as an intellect in act or actual intellect. Though not stated explicitly, the implication is that the Agent Intellect will not mislead the human potential intellect but rather will function as a positive guide for the human intellect assisting it to a knowledge of forms that corresponds to the eternal forms it possesses in itself.
Themistius, On Aristotle’s On the Soul, tr. Robert B. Todd, Ithaca, NY: Cornell University Press, 1996. Book Three, Ch. 5, p.123.
In this realization of human intellectual knowledge, the potential intellect becomes all things, while the former [productive intellect, scil. the Agent Intellect] produces all things. That is why it is also in our power to think whenever we wish, for is not outside the craft its matter (as [for example] the craft of forging is with bronze, or carpentry with wood), but the productive intellect settles into the whole of the potential intellect, as though the carpenter and the smith did not control their wood and bronze externally but were able to pervade it totally. For this is how the actual intellect too is added to the potential intellect and becomes one with it. For [the compound] consisting of matter and form is one, and also has the two definitions of matter and creativity (démiourgia) by in one way becoming, and in another producing, all things. For in a way it becomes the actual objects [that it thinks] by being active in its thinking; and the one [aspect] of it, in which there is a plurality of its thoughts, resembles matter, the other [sc. its thinking] a craftsman. For it is in its power, when it wishes. to comprehend and structure its thoughts, since it is productive, and thus the founder (arkhégos), of these thoughts.
An Arabic Translation of Themistius Commentary on Aristotle’s De Anima, ed. M. C. Lyons, Oxford & Columbia, South Carolyna, 1973, pp. 179-180.
The corresponding Arabic translation of the Greek has the following (my translation):
The relation of art to matter is [the same as] the relation of the Active Intellect to the intellect in potency. In this way the intellect becomes everything and the intellect knows everything. On the basis of this it comes about for us that we know whenever we wish by the fact that the Agent Intellect is not external to the intellect in potency in the way the art is external to the matter as, for example, the art of the bronze forger is external to the bronze and the carpenter is external to the wood. Rather, the Agent Intellect enters into the intellect in potency entirely, as if one were to imagine the carpenter not only as approaching the wood from outside and the smith [likewise] the bronze but rather he has the power so that it penetrates it completely. For in this way the intellect in act [scil. the Agent Intellect], when united to the intellect in potency becomes one with it, since the composite [of the two] is one. And there are in it two notions, I mean the notion of matter and the notion of art. For in a way it becomes everything and in a way it makes everything. For in a way it comes to be the things themselves by its act according to intelligible forming (taṣawwur) by intellect and there appears from it a thing like a certain matter, I mean as all the intelligibles, and a thing from it like the maker. So this is so for it insofar as it possesses and brings about any intelligible it wishes. For it is the maker (fa‘‘āl) and the commander (qā’id) of the intelligibles.