The Process of Induction

Experience and the Acquisition of Reason in Human Beings

"All animals have an inborn discriminatory capacity, called perception. If perception is present, in some retention of the percept comes about, but in others not. ... When many such things come about, a difference comes about, so that some come to have reason (λόγον) from the retention of such things, and others not. From perception comes memory, and from memory (when it occurs often in connection with the same thing), experience (ἐμπειρία); for memories many in number from a single experience. From experience, or from the whole universal that has come to rest in the soul (the one apart from the many, whatever is one and the same in all those things), there comes a starting-point of art and of knowledge, of art if it deals with coming to be, of knowledge if it deals with being. Thus the states [that grasp the starting-points for demonstration] neither belong in us in a determinate form, nor come about from other states that are more cognitive; but they come about from perception—as in a battle when a rout occurs, if one man makes a stand another does and then another, until a starting-point (ἀρχὴν) is reached. The soul is such as to be capable of undergoing this. ... [So it] is clear that it is necessary to cognize the first things (τὰ πρῶτα) by induction (ἐπαγωγῆι); for perception instills the universal in this way" (Posterior Analytics II.19.99b).

"Animals are by nature born with the power of sensation, and from this some acquire the faculty of memory, whereas others do not. ... The other animals live by impressions and memories, and have but a small share of experience (ἐμπειρίας); but the human race lives also by art and reasoning. It is from memory that men acquire experience, because the numerous memories of the same thing eventually produce the effect of a single experience. Experience seems very similar to science and art, but actually it is through experience that men acquire knowledge and art. ... Art is produced when from many notions (ἐννοημάτων) of experience a single universal (καθόλου) judgment is formed with regard to like objects. To have a judgement that when Callias was suffering from this or that disease this or that benefited him, and similarly with Socrates and various other individuals, is a matter of experience; but to judge that it benefits all persons of a certain form (εἶδος) , considered as a class, who suffer from this or that disease (e.g. the phlegmatic or bilious when suffering from burning fever) is a matter of art" (Metaphysics I.980a).

"It would seem that for practical purposes experience is in no way inferior to art; indeed we see men of experience succeeding more than those who have theory without experience. The reason is a that experience is knowledge of particulars, but art of universals; and actions and the effects produced are all concerned with the particular. For it is not man that the physician cures, except incidentally, but Callias or Socrates or some other person similarly named, who is incidentally a man as well. So if a man has theory without experience, and knows the universal, but does not know the particular contained in it, he will often fail in his treatment; for it is the particular that must be treated.Nevertheless we consider that knowledge and proficiency belong to art rather than to experience, and we assume that artists are wiser than men of mere experience (which implies that in all cases wisdom depends rather upon knowledge); and this is because the former know the cause, whereas the latter do not. For the experienced know (ἴσασι) the fact, but not the wherefore; but the artists know the wherefore and the cause. For the same reason we consider that the master craftsmen in every profession are more estimable and know more and are wiser than the artisans, because they know the reasons of the things which are done; but we think that the artisans, like certain inanimate objects, do things, but without knowing what they are doing (as, for instance, fire burns); only whereas inanimate objects perform all their actions in virtue of a certain natural quality, artisans perform theirs through habit (ἔθος). Thus the master craftsmen are superior in wisdom, not because they can do things, but because they possess a theory and know the causes (Metaphysics I.1.981a).


"There are men that are doctors (ἰατροί), we say, and others that are doctors' assistants; but we call the latter also, to be sure, by the name of doctors. These, whether they be free-born or slaves, acquire their art under the direction of their masters, by observation and practice (ἐμπειρίαν) and not by the study of nature—which is the way in which the free-born doctors have learnt the art themselves and in which they instruct their own disciples" (Plato, Laws IV.720a).
"By nature all men strive for knowledge
(πάντες ἄνθρωποι τοῦ εἰδέναι ὀρέγονται φύσει)"
(Metaphysics I.1.980a).

Human Beings Acquire Reason

Aristotle thought that over time human beings naturally acquire (the kind of cognition he calls) "reason" and that this process is an instance of teleological causation (change for the sake of an end). The end is the existence the unmovable first mover enjoys. In acquiring reason, human existence naturally becomes like the divine existence of the unmovable first mover.

Aristotle works out his understanding of reason in human beings against the background of Plato's Theory of Recollection. As Platonist and Platonic critic, he thinks Plato was right in one way about reason but wrong in another. Aristotle does not think the human soul can exist apart from the body, but he does conceive of reason in terms of the possession of certain concepts and the knowledge that constitutes the possession of these concepts. In this way, Aristotle rejects the ontological thesis but accepts the epistemological thesis in the Theory of Recollection.

The natural process in which human beings acquire reason is what Aristotle calls "induction" (ἐπαγωγή). It begins with perception. Memory comes next. After memory, comes "experience." After experience, comes "reason" and the knowledge that belongs to reason. It follows that reason is not present in human beings from birth. It comes to be present as they mature.

To understand the role the cognition Aristotle calls "experience" plays in the process he calls "induction," consider the knowledge that many children now acquire in a geometry class that the interior angles of triangles sum to two right angles. No experience of looking at or touching particular triangles is part of the proof of this fact about triangles. So the relation of the experience to the knowledge is not evidential. It might be, though, that no human being can have the knowledge without first looking at particular triangles. If so, the relation of the experience to the knowledge is enabling. Looking at particular triangles is part of a process that makes it possible for human beings to know that the interior angles of triangles sum to two right angles.

For Aristotle, the "experience" in induction is part of a causal process. The experience enables a human being to have reason and knowledge that belongs to reason. The experience in induction is not evidence for the knowledge that belongs to reason. Aristotle does not think human beings infer the knowledge by drawing conclusions from this experience. The ability to make inferences and to draw conclusions is an ability human beings possess only once they have the cognition he calls "reason," and the "experience" in induction comes before "reason" and its knowledge.

The Practitioner and Theorist

In the Metaphysics, Aristotle appeals to the practice of medicine for an example to distinguish "experience" (ἐμπειρία) from "art" (τέχνη) and "knowledge" (ἐπιστήμη).

The translations "art" and "knowledge" can be confusing. Both of these cognitive states involve a grasp of the universal whereas "experience" does not. "Art" grasps universals in connection with "coming-to-be." "Knowledge" grasps universals in connection with "being."

The example Aristotle uses to distinguish "experience from "art" and "knowledge" involves the types of medical doctors in ancient medicine, the practitioner and the theorist.

The medical practitioner does not have "art" or "knowledge." He makes the "judgement that when Callias was suffering from this or that disease this or that benefited him, and similarly with Socrates and various other individuals." This judgment is a matter of "experience."

The medical theorist has "art." He makes the judgment "it benefits all persons of a certain type, considered as a class, who suffer from this or that disease (e.g. the phlegmatic or bilious when suffering from burning fever) ." This judgment is a matter of "art".

Experience gives the medical practitioner the ability to make a diagnosis in circumstances in which the layman is more likely to make a mistake, but judgments the practitioner forms in experience are not the same as the judgments the theorist forms in art or knowledge.

Judgments Formed in Experience

Aristotle thinks that "knowledge" (ἐπιστήμη) as an achievement of reason.

In this way, Aristotle's conception of knowledge is similar to the conception of belief Plato has Socrates articulate in the Theaetetus. He explains that to form the belief that something is F, it is necessary to have more than "experience" because a grasp what it is to be F is necessary for the belief.

  "Knowledge (ἐπιστήμη) is not in the sensations, but in the process of reasoning about them; for it is possible, apparently, to apprehend being and truth by reasoning, but not by sensation.
  So it seems, Socrates.
  Then will you call the two by the same name, when there are so great differences between them?
  No, that would certainly not be right.
  What name will you give, then, to the one which includes seeing, hearing, smelling, being cold, and being hot?
  Perceiving. What other name can I give it?
  Collectively you call it, then, perception?
  Of course.
  By which, we say, we are quite unable to apprehend truth, since we cannot apprehend being, either.
  No; certainly not.
  Nor knowledge either, then.
  No.
  Then, Theaetetus, perception and knowledge could never be the same.
  Evidently not, Socrates; and indeed now at last it has been made perfectly clear that knowledge is something different from perception.
  But surely we did not begin our conversation in order to find out what knowledge is not, but what it is. However, we have progressed so far, at least, as not to seek for knowledge in perception at all, but in some function of the soul, whatever name is given to it when it alone and by itself is engaged directly with realities.
  That, Socrates, is, I suppose, called having opinion.
  You suppose rightly, my friend" (Theaetetus 186d).

The cognition in terms of which the the practitioner makes his judgment is a matter of perception and memory. Aristotle describes it as a judgment that results from "habit" (ἔθος). He does say that practitioners "know (ἴσασι) that the thing is so," but here he is talking about the discrimination the practitioner makes in the way it is ordinarily talked about. Because the cognition that characterizes the judgment of the practitioner is a matter of experience as opposed to reason, it follows that this judgment is not "art" (τέχνη) or "knowledge" (ἐπιστήμη).

Further, the judgment of the medical practitioner is a special case of "experience."

The medical practitioner grasps empirical generalizations about diseases and their proper treatments. This grasp is the result of long and careful observation, but "experience" is not always a matter of this kind of observation. Human beings can reliably discriminate human beings from the other things they encounter in their lives. Aristotle does not say so explicitly, but it is natural to suppose that he thinks that "knowledge" (ἐπιστήμη) of what a human being is is not necessary for this ability and that for human beings this ability is a matter of "experience."

Behavior Learned in Experience

In the Metaphysics, Aristotle says that some animals are "sensible" (φρόνιμα). These animals are capable of controlling their behavior by discriminating among things in their environment in ways that benefit themselves, but this behavior is not an exercise of "reason." Humans have both experience and reason, but animals are limited to experience.

"Now animals are by nature born with the power of sensation, and from this some acquire the faculty of memory, whereas others do not. Accordingly the former are more sensible and capable of learning than those which cannot remember. Such as cannot hear sounds (as the bee, and any other similar type of creature) are sensible (φρόνιμα), but cannot learn; those only are capable of learning which possess this sense in addition to the faculty of memory. Thus the other animals live by impressions and memories, and have but a [comparatively] small share of experience; but the human race lives also by art and reasoning" (Metaphysics I.1.980a).





"For that part of the soul is deliberative which is capable of discerning (θεωρητικὸν) a cause (αἰτίας): the for sake of which (ἕνεκα)—which is one of the causes—‘cause’ being something because-of-which. And we say that the for sake of which something is or comes to be is a cause—for instance, the carrying of goods is a cause of walking if it is for the sake of that that a man walks. That is why those who have no goal before them are not in a position to deliberate" (Eudemian Ethics II.10.1226b25).
So, according to Aristotle, there are two ways to engage in purposeful behavior. Some purposeful behavior is a matter of "experience." In human beings, however, because they have reason, some purposeful behavior is a matter of what Aristotle calls "choice" (προαἱρεσις).

"[Choice] is not present in other animals, nor at every time of life, nor in a human being no matter what state he is in; for deliberation is not, either, nor a judgment about the why; a belief about whether something should be done or not may well be present in many, though not through reasoning (λογισμοῦ)" (Eudemian Ethics II.10.1226b21).

We will consider Aristotle's understanding of "choice" (προαἱρεσις) in a subsequent lecture.

Reason Grasps Universals


"[E]xperience is knowledge of particulars, but art is knowledge of universals (ἐμπειρία τῶν καθ᾽ ἕκαστόν ἐστι γνῶσις ἡ δὲ τέχνη τῶν καθόλου)" (Metaphysics I.1.981a; cf. Metaphysics I.1.981a).
For Aristotle, what distinguishes "reason" from "experience" is the grasp of universals. So for Aristotle reason is a more distinctive form of cognition than we might have initially expected given the use of the words 'reason' and 'reasoning' in ordinary English.

The doctor with experience (the medical practitioner) does not have cognition of the universal. He does not grasp the "form" (εἶδος) the doctor with art (the medical theorist) knows is common to the patients who have a certain disease and benefit from a certain treatment. The medical practitioner discriminates or notices the disease in terms of how his patients look. This ability is an exercise of experience. It is a matter of perception and memory, not "reason." The medical practitioner does not conceive of the disease in terms of a universal, such as being phlegmatic or bilious or having a burning fever. Because he does not grasp the universal, he does not understand what the disease is and why the treatment is successful for this disease.

The point is not that the practitioner has less clinical success than the theorist. Aristotle explicitly says otherwise. It is possible for the practitioner to have the experience that allows him to discriminate all and only the patients who have a certain disease that will benefit from a certain treatment. Still, the practitioner does not grasp "the why and the cause." This grasp is an achievement of reason. Without this grasp, there is no "knowledge" (ἐπιστήμη).

Knowledge requires that the knower be in a special position with respect to the proposition he knows. Sometimes this point is expressed by saying that knowledge requires justification, but for Aristotle what one might ordinarily accept as justification in such cases is insufficient. The medical practitioner might be able to point to the past success he has had in treating patients whose disease he identifies in terms of a certain way they all look, but Aristotle thinks that for "knowledge" (ἐπιστήμη) it is necessary to grasp the universal and intelligible features that underlie the sensible and figure in the account of what the disease is and why the treatment is successful.

The Perfection of Reason

The battle metaphor Aristotle uses in II.19 of the Posterior Analytics is not easy to interpret, but it suggests that Aristotle thinks that "reason" does not grasp universals one by one in isolation and therefore that this grasp does not take place without the advent of "knowledge" (ἐπιστήμη) of the necessary connections of consequence and incompatibility between these universals.

"[T]he states [that grasp the starting-points for demonstration] neither belong in us in a determinate form, nor come about from other states that are more cognitive; but they come about from perception—as in a battle when a rout occurs, if one man makes a stand another does and then another, until a starting-point is reached" (Posterior Analytics II.19.100a).

If this is right, then presumably Aristotle also thinks that the reason human beings first acquire is something that can be improved and perfected. A human being first grasps universals in some basic domain and comes to deduce that certain further relations hold and thus in this way extends his knowledge and understanding of the domain. Further, as he becomes familiar with other parts of reality, he can grasp universals in other domains and in this way further perfect his reason.




Perseus Digital Library:

Plato, Phaedo, Theaetetus
Aristotle, Eudemian Ethics, Metaphysics.

Henry George Liddell, Robert Scott, A Greek-English Lexicon:
γνωρίζω, gnōrizō, verb, "gain knowledge of, become acquainted with, discover,"
ἐμπειρία, empeiria, noun, "experience"
ἐννοέω, verb, "reflect upon, consider"
ἐννοηματικός, ennoēmatikos, adjective, "notional"
ἔννοια, noun, "notion, conception"
ἐπαγωγή, (from ἐπᾰ́γω = ἐπι +‎ ἄγω),
καθόλου, (= καθ᾽ ὅλου), katholou, adverb, "on the whole, in general"
λογισμός, logismos , noun, "counting, calculation"
συλλογισμός, syllogismos, noun, "computation, calculation"
τέχνη, technē, noun, "art"

Charlton T. Lewis, Charles Short, A Latin Dictionary:
inductio, noun, "a leading or bringing into, introducing"

Arizona State University Library. Loeb Classical Library:
Aristotle, Posterior Analytics




"To say that it [induction] is somehow a natural process by means of which we arrive at first principles is to exploit Aristotle's generous conception of what is natural and to focus on just one aspect of it. This becomes particularly clear if we keep in mind that on Aristotle's view it also is the case that by nature we are meant to be virtuous and are thus constructed as to naturally be virtuous. Nevertheless, Aristotle also assumes that it takes a great deal of effort on our part to come to know the first principles in general (and thus to become wise), or even just the first principles in some domain. What is needed for this is a great deal of often highly specialized observation and of often highly technical reflections. But this should not obscure the fact that the insight, if it is an insight, does not derive its epistemic status from these observations and reflections which lead up to it. What makes it an insight is not the support it gets from observations or considerations, but that one finally sees in a way which fits how the features in question are related to each other and to other relevant features" (Michael Frede, "Aristotle's Rationalism," 172. Rationality in Greek Thought, edited by Michael Frede and Gisela Striker (Oxford University Press, 1996), 157-173).

"[Aristotle thinks] that organisms have to be understood teleologically, as naturally tending to achieve full development and perfection in their kind, unless handicapped or their development is thwarted. Since we naturally do have reason and since reason functions best, and serves its function best, if we do have the requisite knowledge, he assumes that we must be constructed in such a way as to be able to acquire the knowledge reason needs to function well. And he, too, thinks that he can explain this by assuming that there is a process which leads, on the basis of perception and memory, not only to our having concepts, but to our having concepts which are adequate to the way things essentially are, and which thus provide us with basic knowledge about things, but also with the ability to think and reason about things, properly speaking, instead of, for instance, just having impressions or even generalized impressions of things" (Michael Frede, "Introduction, 14. Rationality in Greek Thought, edited by Michael Frede and Gisela Striker (Oxford University Press, 1996), 1-28).

"On Aristotle's view it does not seem to suffice for thinking that we have a notion of, say, a human being which allows us, by and large, to distinguish successfully between human beings and other things; the notion rather has to be based on a sufficient grasp of what it is to be a human being, of the crucial feature or features of human beings, and of how these features are related to each other and to a whole network of features. ... To grasp what it is to be a human being, on Aristotle's view, is more than just to grasp what human beings have in common; it is to grasp something which figures prominently in the explanation of human beings and their behavior" (Michael Frede, "Aristotle's Rationalism," 164. Rationality in Greek Thought, edited by Michael Frede and Gisela Striker (Oxford University Press, 1996), 157-173).

"Aristotle in [Posterior Analytics] B 19 not only claims that we only come to have reason, only come to be, at least ideally, thus disposed to know first principles, he also explains how this disposition arises out of perception and experiences. ... However obscure, and in their interpretation controversial, the details of his account of how we acquire concepts may be, it is abundantly clear from [Posterior Analytics II.19.]100a12-13 that Aristotle does not envisage that the concepts are acquired one by one in isolation. However we interpret the battle metaphor, it seems clear that he assumes that we begin with a tentative and unstable grasp of the different features, which constantly threatens to collapse until we get a firm grasp on some feature such that, given the way the features are interrelated, our grasp of the whole group solidifies and stabilizes. This is also why Aristotle can assume that having the right concepts is to know first principles. We do not come to acquire these concepts piecemeal, but by a process of mutual adjustment with other related concepts, as a result of which certain elementary relations between features in the end seem evident. Again it is clear that Aristotle, to explain how we first come to grasp universals, does not appeal to some mysterious power of the mind to see directly or intuit features or forms, but to some complex process in the course of which our notions again and again are readjusted until they finally fit into a coherent and appropriately structured system of notions and corresponding beliefs in terms of which we finally can make sense of what know from experience" (Michael Frede, "Aristotle's Rationalism," 171. Rationality in Greek Thought, edited by Michael Frede and Gisela Striker (Oxford University Press, 1996), 157-173).


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