Aristotle on Knowledge
 

 

Recommended Reading

 

Barnes, J. (1982) Aristotle London: OUP

Ackrill, J. L. (1981) Aristotle the Philosopher London: OUP

 

Text of Aristotle

 

                http://classics.mit.edu/Browse/index.html

Mure, G. R. G. Posterior Analytics

Hardie, R. P. Hardie, R. K. Gaye Physics.

Ross, W. D. Metaphysics.

                 

Aristotle

 

384–322 BC. Student of Plato, Teacher of Alexander. Founded Lyceum.

 

Introduction

 

We saw previously that Plato’s theory of knowledge depended upon the existence of a realm of so-called ‘Forms’ which are the enduringly real ‘ideals’ of the things that exist in the mundane realm. These Forms can be thought of as the referents of universal or general terms, and they are required in order to explain how we can recognise that some thing falls under a general term. When we say that some observed thing is a dog, for example, we are recognising that the Form of Dog is somehow inherent in that thing, or that the thing participates in the Form of Dog.

 

Because real knowledge is properly only of ideals, and because the world that we see about us every day is only a poor projection from these Forms and not at all to be trusted to tell us about how things really are, Plato’s stance can be described as idealistic. For him, real knowledge comes from pure contemplation on abstract things, and the evidence of the senses can play very little role in the pursuit of knowledge.

 

Aristotle’s attitude was quite different. He represents the class of philosophers that we might call ‘Realists’, and he puts much more trust in the evidence of the senses. It is from the interpretation of the information to be gained from looking at the world that Truth can be found.

 

Aristotle’s Rejection of the Forms

 

In particular Aristotle was quite dismissive of the whole idea of independently existing Forms. He had several arguments against them, of which the most famous was the so-called ‘Third Man’ argument. Oddly enough, we don’t actually have Aristotle’s argument, but it was apparently[1] a modification of one that Plato himself had put forward in his Parmenides at 132a-b. There Plato says:

 

PARMENIDES: I imagine that the way in which you are led to assume one Form of each kind is as follows: -You see a number of large objects, and when you look at them there seems to you to be one and the same Form (or nature) in them all; hence you conceive of Largeness as one thing. 

SOCRATES: Very true.


PARMENIDES: And if you go on and allow your mind in like manner to embrace in one view the Form of Largeness and of large things which are not the Form, and to compare them, will not another Largeness arise, which will appear to be the source of all these? 

SOCRATES: It would seem so.


PARMENIDES: Then another Form of Largeness now comes into view over and above Largeness and the individuals which share in it; and then another, over and above all these, by virtue of which they will all be large, and so each Form instead of being one will be infinitely multiplied.

 

The Third Man version of this would be the claim that we can recognise a particular man as a man (let’s call him Bob) because he participates in the Form of Man, which we are able to recognise. But we can only recognise the Form of Man as the Form of that particular because it and Bob participate in another Form – call it the Third Man – which we recognise. And we only recognise the Third Man as the Form in which Man, and Bob participate because we recognise a Fourth Man. And we only recognise … Well, you get the idea. The epistemological upshot of all this is that if our ability to recognise men depends upon our becoming acquainted with the necessary Forms, then no such knowledge is possible, for there are an infinite number of Forms with which it is first necessary to become acquainted. And since, as Aristotle would insist, we really do have knowledge of things like Bob being a man, this means that the Forms are not necessary for knowledge; and so one of the justifications for proposing them as independently existing things in the first place is removed.

 

The other problem with the Platonic Forms was that they didn’t seem able to explain change. If something is increasing from small to large, let’s say, then at one point in time it is a copy participating in the Form of the Small and at another point it is participating in the Form of the Large. But Plato gives us no idea of how to think of this change of ‘participations.’ The metaphor just doesn’t help.

 

[1] Aristotle’s book On Ideas where these arguments were elaborated is lost; our knowledge of them is largely from a commentary on his Metaphysics by Alexander of Aphrodisias written in the 2nd-3rd C. BC and including fragments of the peri idewn.

 

Aristotle’s Metaphysics

 

Aristotle does have a role for Forms, but not as independently existing things. For Aristotle the Forms are patterns which make Matter into the things that we find in the ‘real world.’ Matter and Form together constitute Substance, and Substance is that to which we can apply all the useful and informative sorts of predicates (names of properties,) which Aristotle lists as the Categories[1]. A man, for example, is matter arranged in the pattern that is characteristic of a man. The same matter differently arranged might have been a duck or a dog or a daisy or a dish. All of those things are substances: and of all of those things one can enquire about their properties. Take the substance Socrates, for example. We can ask about the categories of quantity (is he short?), quality (is he ugly?), relation (is he younger or older than me?), location (is he at the market?), time (when was he there?), position (was he standing?), habit (was he wearing sandals?), action (was he buying something?), or passion (who was talking to him?).

 

This way of looking at things meant that Aristotle was at least able to talk about changes. When something is changing the change can be understood in a couple of different ways: either the substance of Socrates was taking on different properties, so that formerly standing he is now sitting, or formerly happy he is now sad; or the matter that was the substrate of Socrates is taking on a new pattern, so that formerly a child he is now a man, or formerly alive he is now dead, and so on.[2]

 

To go along with this view of change, Aristotle also had a view of the causes (aitia/aitia) of change. In Physics II.3 he says:

 

In one sense, then, (1) that out of which a thing comes to be and which persists, is called 'cause', e.g. the bronze of the statue, the silver of the bowl, and the genera of which the bronze and the silver are species. [This is now referred to as the Material Cause]

In another sense (2) the form or the archetype, i.e. the statement of the essence, and its genera, are called 'causes' (e.g. of the octave the relation of 2:1, and generally number), and the parts in the definition. [This is now referred to as the Formal Cause]

Again (3) the primary source of the change or coming to rest; e.g. the man who gave advice is a cause, the father is cause of the child, and generally what makes [is the cause] of what is made and what causes change [is the cause] of what is changed. [This is now referred to as the Effective Cause]

Again (4) in the sense of end or 'that for the sake of which' a thing is done, e.g. health is the cause of walking about. ('Why is he walking about?' we say. 'To be healthy' and, having said that, we think we have assigned the cause.) The same is true also of all the intermediate steps which are brought about through the action of something else as means towards the end, e.g. reduction of flesh, purging, drugs, or surgical instruments are means towards health. All these things are 'for the sake of' the end, though they differ from one another in that some are activities, others instruments. [This is now referred to as the Final Cause]

This then perhaps exhausts the number of ways in which the term 'cause' is used.

 

[1] Aristotle is not consistent with his metaphysics any more than Plato is with his. Sometimes matter is said to be the primary substance, and sometimes (Met. 1041) the Form is, and sometimes (Cat. 2a11-14) the compound of the two in normal everyday objects is. For us, none of this really matters.

[2] On the other hand, the permanence of Socrates from moment to moment, or the permanence of the ship of Theseus, is to be explained by supposing that the Form remains unmodified and changing matter is informed by it.

 

Explanations and Scientific Knowledge

 

But perhaps you’re not entirely convinced that all the things that Aristotle is calling causes are really the sorts of things that you’re used to calling causes. You are right to be cautious, because what Aristotle seems to mean by a cause is more like what we would call an explanation. And more than this, Aristotle also has a very definite idea of what an explanation should look like. For Aristotle an explanation is an answer to a question of the form ‘why is S a P?’ where S is the subject of the enquiry and P is a property we see belongs to that subject; for example, ‘why is this statue brown (a brown thing?)’, ‘why is the moon eclipsed (an eclipsed thing?)’, ‘why is the child ugly?’, ‘why go walking?’, and so on.

 

So what sort of thing will give an explanation of the observed fact that S is P? Here Aristotle refers back to his earlier investigations into logic where he showed the validity of such classic arguments as:

 

                                                Socrates is a man

                                                All men are mortal

                                                Socrates is mortal

 

An argument such as this gives us the grounds, the best possible grounds, for believing that Socrates is mortal. It also, in Aristotle’s view, gives us the explanation for Socrates’s mortality. Socrates is mortal because he is a man and all men are mortal. Generalising on this insight, Aristotle claims that arguments of the form:

 

                                                S is M

                                                M is P

                                                S is P

 

provide an explanation for the fact that S is P. Thus we say:

 

                                                Why is S a P? Because S is an M, and any M is a P.

 

Now consider the sorts of things that make sense when we put them into the M position (this is called the middle term of an argument.) Aristotle thinks that all the things that can sensibly be put in there fall into one or another of his four classes of ‘causes.’ For example:  ‘why is this statue brown?’ ‘Because it is bronze, and bronze is brown.’ That is the material cause of the brownness of the statue, and the deduction that it fits into goes thus:

 

                                                The statue is bronze

                                                Bronze is brown

                                                The statue is brown

 

‘Why is the moon eclipsed?)’ ‘Because it is darkened by earth’s shadow, and to be darkened by Earth’s shadow  is to be eclipsed’ That is the formal cause.

 

‘Why is the child ugly?’ ‘Because the father is ugly and ugly fathers have ugly children.’ That is the efficient cause, and possibly the only cause that we would actually think of as a cause

 

 ‘Why go walking?’ ‘Because those who want to be healthy go walking, and we want to be healthy.’ That is the final cause.

 

Aristotle’s view of scientific knowledge (epistēmē/episthmh) was of a collection of such deductions, and we can see the implications of this in certain statements such as that in Post. An. 1.2 where he says:

 

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.

 

The last two conditions are really insisting upon the deductive form of knowledge. If we take the explanation of the brownness of the statue for example, having knowledge about this is being aware of the deduction from its being a statue via the middle term of it being bronze to its being brown. We know that the bronzeness is the cause of that fact and no other because, given the two premises, ‘the statue is bronze’ and ‘bronze is brown’, there is only one statement that follows inevitably to make a valid deduction, that is that ‘the statue is brown.’ And we know that the fact could not be other than it is because the deduction we have come up with in the explanation is a valid deduction, and it is thus impossible for the premises to be true and the conclusion to be false.

 

Aristotle further claimed that there were conditions on the kinds of premises that can play the explanatory role required for scientific knowledge. He says:

 

Assuming then that my thesis as to the nature of scientific knowing is correct, the premises 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. Deduction there may indeed be without these conditions, but such deduction, not being productive of scientific knowledge, will not be demonstration.

 

The point of these criteria is to eliminate trivial or irrelevant deductions that cannot give us scientific knowledge. For example, we don’t want to be able to say that Socrates is a man because Socrates is a man and all men are men. That doesn’t give us knowledge. Scientific knowledge is got only from deductions whose premises reveal the causal nature of the world. Such things are called demonstrations, and demonstration (apodeixis/apodeixis) is how we get scientific knowledge.

 

We can’t look at all these criteria here to see what role they play, but I will make a couple of remarks. In the first place, it’s obvious why the premises have to be true. If they weren’t true then the demonstration might be valid but it would be unsound, and would therefore not give us knowledge. Yes, if all men were animals and all animals were green, then it would follow that all men are green; but of course, we don’t know that men are green because it just isn’t true that all animals are green. And we would have the same failure of knowledge if we had a true conclusion but with false premises. (You might recall that I talked about that sort of thing in the first lecture.)

 

In the second place, when Aristotle says that the premises have to be better known than and prior to the conclusion, he goes on to ‘clarify’ that:

 

… '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. Now the most universal causes are furthest from sense and particular causes are nearest to sense, and they are thus exactly opposed to one another.

 

It’s not much a clarification, I know, but what he seems to be getting at is that some things are known more immediately to us through our senses – like the fact that that particular triangular patch of grass is green – but they are less certainly true, because they are not universally and eternally true. On the other hand some things that are not known immediately through our senses are, nevertheless, more certainly known when they are known – like the fact that a triangle has internal angles summing to 180o – because they are universal and eternal truths that we come to know through reason. The criterion for causes that we’re looking at now seems to be saying that in constructing a chain of premises and conclusions we are trying to climb up the ladder of generalisations, so to speak; that the causes should be more general than the subject and predicate being explained.

 

Intuition and the Foundations of Scientific Knowledge

 

There is, of course, an obvious problem with all of this. Demonstrations are only as sound as the truth of their premises; so how do we determine the truth of the premises, or how do we come to know the premises at all? If we come to know them in the same scientific fashion as we come to know the conclusions, then they will have to be the conclusions of further demonstrations, and those demonstrations will also have premises, which we will then have to question. And so on, apparently, ad infinitum. Eventually we have three options:

 

i.         The chain of premises and conclusions is infinite – and real scientific knowledge is impossible

ii.        The chain of premises and conclusions is circular – and knowledge has no certain foundation

iii.      There is an end to the chain of premises and conclusions at which the premises are knowable through some other means.

 

For reasons which seem good to him, Aristotle is convinced that the last option is the correct one; in which case, from what we saw just previously, at the very top of the chains of demonstrations that constitute the body of scientific knowledge we have our most general concepts which are known non-scientifically. This non-scientific knowledge he thinks arises from our sense perceptions, and he has a fairly clear idea of how this is supposed to happen. In the Posterior Analytics II, 19 he says:

 

Therefore we must possess a capacity of some sort [for getting knowledge without demonstration.] ... 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; or 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. 

…
 
Thus it is clear that we must get to know the primary premises by induction (epagoge/epagwgh); 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 (noûs/nous) are always true: further, no other kind of thought except intuition is more accurate than scientific knowledge, whereas primary premises 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 premises, and since except intuition nothing can be truer than scientific knowledge, it will be intuition that apprehends the primary premises – 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 premise, while science as a whole is similarly related as originative source to the whole body of fact.

 

Investigations

 

At this point we know what scientific knowledge looks like: it is a structure of demonstrations: deductions leading upwards from more general truths to more particular truths, giving the causes of things. And we know that at the bottom of the structure are conceptual truths that are undemonstrated (and ‘unscientific’) which we come to know through intuition based ultimately on our senses.  

 

It only remains to give a brief description of the processes by which that structure can be built on those bases.

 

The first steps of this process are well enough understood and reasonably straightforward.

 

1.        Collect relevant observations of the appearances (phainomena/fainomena) of things.

This is the obvious first step, and it simply expands upon what it is that inspires us to take up science (or philosophy) in the first place: In Metaphysics I, 2 (982b12-15) he remarks that

 

it is owing to their wonder that men both now begin and at first began to philosophize; they wondered originally at the obvious difficulties, then advanced little by little and stated difficulties about the greater matters, e.g. about the phenomena of the moon and those of the sun and of the stars, and about the genesis of the universe.

 

And you will notice that Aristotle has no particular problems with simply relying upon our senses to inform us of how the world really is. He does not think they are infallible and he does think that they must be used cautiously, but he obviously thinks that they are generally reliable since that is their function.

 

2.        Consider the reputable opinions (endoxa/endoxa)

 

In almost all of Aristotle’s works he begins by considering the opinions of those who had gone before, to see what answers they had made to the questions that the phenomena inspire. In the Nicomachean Ethics VIIi 1, (1145b2–7) he says

 

As in other cases, we must set out the appearances and run through all the puzzles regarding them. In this way we must test the credible opinions about these sorts of experiences – ideally, all the credible opinions, but if not all, then most of them, those which are the most important. For if the objections are answered and the credible opinions remain, we shall have an adequate proof.

 

Aristotle clearly thought that if lots of well-informed and sensible and trustworthy people had a certain opinion on a matter, then it was well worth considering it seriously.

 

3.        Apply dialectic

 

It’s unfortunate that we don’t have a consensus any longer on what is supposed to follow: it’s currently a point of much dispute amongst scholars of Aristotle. Surprisingly enough, the evidence of his actual scientific works doesn’t seem to give obvious clues to the details of his method; but one possibility is that he sees the application of the method of dialectic as the appropriate way to sift through the possible answers to the puzzles to arise from consideration of the phenomena. So let’s take that to be the third step. In support of this we can quote from Topics 101a26-b4:

 

Dialectic is useful for philosophical sorts of sciences because when we are able to run through the puzzles on both sides of an issue we more readily perceive what is true and what is false. Furthermore, it is useful for uncovering what is primary among the commitments of a science; for it is impossible to say anything regarding the first principles of a science on the basis of the first principles proper to the very science under discussion, since among all the commitments of a science, the first principles are the primary ones. This comes rather, necessarily, from discussion of the credible beliefs belonging to the science. This is peculiar to dialectic, or is at least most proper to it. For since it is what cross-examines, dialectic contains the way to the first principles of all inquiries.