Locke's account of what knowledge is

'It is evident the mind knows not things immediately, but only by theintervention of the ideas it has of them.' Locke's Essay, Book IV Chapter IV Section 3.

Knowledge is perceiving 'agreements / disagreements' amongst ideas

Knowledge arises from a kind of 'scrutiny' of the 'ideas' in your mind. Locke says the scrutiny is carried out by our 'reason', which he thinks of as a 'faculty' of the mind. (It is consistent with this that he sometimes speaks of the mind as doing the scrutinising.) 'Knowledge,' says Locke, ' ... seems to me to be nothing but the perception of the connexion and agreement, or disagreement and repugnancy, of any of our ideas... Where this perception is, there is knowledge, and where it is not, there, though we may fancy, guess, or believe, yet we always come short of knowledge.' Essay Book IV Ch1 Section 1. An example of 'agreement' is this: 'When we possess ourselves ... of the demonstration that the three angles ofa triagle are equal to two right ones, what do we more but perceive that equality to two right ones does necessarily agree to and is inseparable from the three angles of a triangle? (Ibid, Section 2.)

Locke says there are four different sorts of 'agreement / disagreement' amongst ideas

Locke says there are four different sorts of 'agreement and disagreement' between ideas, of which this example is of just one.

The capacity to perceive that an idea of yours 'agrees with itself' and 'disagrees' with 'all other distinct ideas' is a basic human capacity without which 'there could be no knowledge, no reasoning, no imagination, no distinct thoughts at all' Ibid, Section 4. When you excercise this faculty, you cannot make a mistake: 'a man infallibly knows, as soon as ever he has them in his mind, that the ideas he calls white and round are the very ideas they are, and that they are not other ideas which he calls red or square.'

[This is a foundational capacity indeed. Benson says there is a principle of reason at work here: but he goes on to ask Why should that be the only one? Admit one principle of reason, and you will have to explain why that one is accorded priority in this way. But Locke I think objects to the claim that a principle of reason is involved. 'Men of art' he says 'have reduced this [the perception of two ideas agreeing in identity] into those general rules, What is, is and It is impossible for the same thing to be and not to be ... yet it is certain that the first excercise of this faculty is about particular ideas. You have before you two ideas what makes you certain, and justifies you in being certain, that the two ideas are distinct is your perceiving them directly to be so. No 'maxim or proposition in the world' can make him 'clearer or surer' than he is as a result of this direct perception. Ibid. Section 4.]

If the only way in which two ideas could 'disagree' with each other was in virtue of being distinct ideas, and the only way in which an idea could 'agree' with an idea was by being identical with it, Locke acknowledges that very little knowledge would be possible! You would just know, when you perceived an idea, that it was a distinct idea. But there are other types other types of agreement/disagreement that reason is capable of perceiving, which makes possible a wider range of knowledge. Locke lists as the second type of agreement/disagreement 'relations'. The mind can compare ideas in certain respects and perceive whether or not ideas agree or disagree in those respects, finding out 'the agreement or disagreement they have one with another, in several ways the mind takes of comparing them'.Section 5. Thus, reason can tell you that 'two triangles upon equal bases between two parallels are equal' in virtue of perceiving a relation of equality to obtain between the two ideas. Section 6.

Thirdly, reason is capable of perceiving whether two properties 'belong to the same "subject"'. Our knowledge that gold doesn't burn amounts to our perceiving that resistance to fire is always accompanied by the other properties of gold (if I can put it so). What our reason perceives in this case is that resistance to fire 'is an idea that always accompanies and is joined with that particular sort of yellowness, weight, fusibility, malleableness, and solubility in aqua regia, which make our complex idea signified by the word gold.' Thus, 'the third sort of agreement or disagreement to be found in our idaes, which the perception of the mind is employed about, is co-existence or non-coexistence in the same subject...' Section 6.

Fourthly, reason can perceive whether the thing of which it is scrutinising an idea exists: 'The fourth and last sort [of agreement or disagreement capable of being perceived by reason] is that of actual real existence agreeing to any idea.' Section 7. It is the capacity to perceive this type of agreement that enables reason to tell us that God exists. The idea of God and the idea of actual real existence are seen by reason to agree. Section 7.

But how can consideration of mental entities yield knowledge of any 'non-mental' world?

Locke considers the objection that considering mere mental entities cannot give you any knowledge of the world as it is independently of ideas. [Put here quote from Locke to establish the seriousness of this criticism]

In his reply he returns to his notion of complex ideas. These are made up ultimately of simple ideas, which he believes are 'encountered' or 'experienced' by us, rather than in any way our 'constructs'. Complex ideas, on the other hand, are constructed - and constructed, all of them, by us - with simple ideas as their raw materials.

Leaving the possible exception of ideas of substances for special discussion, he concludes that it is true in a sense that as far as other complex ideas are concerned perceiving their agreements and disagreements can tell us nothing about the non-mental world. Surely, he says, no-one would actually expect scrutiny of things you have made yourself in your own mind - ie complex ideas - to yield unconditional knowledge of the world outside. What the scrutiny can be expected to yield though is hypothetical knowledge of the non-mental world. Suppose for example you have a complex idea of a triangle, and that through scrutiny of this idea you have perceived that it has an 'agreement' with the idea of a figure whose angles are the equivalent of two right angles. Then, should there actually be an object in the real non-mental world that your complex idea of a triangle adequately represents, it will be true of that object that its internal angles sum to two right angles.

It is exactly the same with moral knowledge, Locke tells us: 'if it be true in speculation, i.e. in idea, that murder deserves death, it will also be true in reality of any action that exists conformable to that idea of murder.' Section 8.

Ideas of substances

What of his special case of complex ideas of substances?

We know that according to Locke, once complex ideas have been constructed, reason is in a position to perceive agreements or disagreements between them and other ideas. How are they constructed? We know that Locke says: by the mind, out of simpler ideas - and so ultimately out of ideas that are absolutely simple. This being the case, there arises the question of whether our construction of complex ideas is subject to constraints of any kind.

As far as complex mathematical ideas are concerned the answer is that there is indeed a constraint. The constraint is that only simple ideas that are 'consistent' with each other may be built into a complex. What is meant by 'consistent'? Locke believes that when you have a complex geometrical idea your reason has the capacity to infer from it propositions which must obtain if the complex idea is as it is. Locke thinks that scrutiny of the complex idea of a triangle allows you to infer that the sum of its internal angles will equate with with the sum of two right angles.

'Thus the mind, being willing to know the agreement or disagreement in bigness between the three angles of a triangle and two right ones cannot by an immediate viewand comparing them do it, because the three angles of a triangle cannot be brought at once and be compared with any one or two angles; and so of this the mind has no immediate, no intuitive knowledge. In this case the mind is fain to find out some other angles to which the three angles of a triangle have an equality, and finding those equal to two right ones, comes to know their equality to two right ones.' (Book IV Chapter II Section 2)

In building your complex idea of a triangle you need to bear in mind such inferences as this. And bearing them in mind, you must only include in the complex idea you are constructing ideas that taken together do not allow the inference of two propositions which contradict each other. This is what is meant by their having to be consistent.

(I say 'you' must do this. It is of course your mind which Locke supposes must do this for you - your mind calling in particular on your reason to tell it which ideas can and which ideas cannot coexist within one and the same complex.)

Our ideas of geometrical figures are therefore constructed under the constraint of consistency.

But when it comes to our constructing complex ideas of 'substances', however, Locke thinks we cannot appeal to consistency as our guide. And this for a very interesting and fundamental reason. It is because, as he understands it, our reason does not have the power to perceive what substances must be like if they are to have the properties we can observe them as having.

Why doesn't it have that power? It is because we don't know the real constitution of substances. We don't know, says Locke ' what real constitution it is of substances whereon our simple ideas depend, and what is the cause of the strict union of some of them one with another and the exclusion of others...' Section 172.

So, Locke thinks substances have a corpuscular constitution, and this structure of corpuscules gives rise to various stimuli impinging on our senses. These impingings result in our having a sequence of simple ideas. But because we don't know anything about the corpuscular constitution of a thing we can't understand why these particular impingments, and their consequent simple ideas should be produced by it. If we did what would our knowledge of the the configuation amount to? It would be knowing that such and such a configuration of corpuscles necessarily results in such and such a sequence of simple ideas. Knowledge of 'necessities' such as this would enable us to assemble the simple ideas we have into complex ideas which were coherent - ie which contained only mutually consistent ideas in the sense explained. We would then be able to make our complex ideas of substances by putting together packages of simple ideas which together produced no contradiction.

But we don't have the knowledge of the constitution of substances which would make this possible. So our construction of complex ideas of substances is not constrained in the way that our construction of complex ideas of geometrical figures is.

But there is something that could serve as a constraint in our building of complex ideas of substances: the patterning sometimes displayed by the simple ideas of sense as we encounter them. We could be guided by this. We could put simple ideas together in a way that copied the patterns they display when they are first perceived by us. An example of the patterning simple ideas can display is this. The simple ideas we are referring to when we speak of a thing being hard, malleable, yellow and soluble in aqua vita. The patterning of these simple ideas involved here is such that we legitimately speak of the substance gold having the properties of harness, malleability being yellow and being soluble in aqua vita.

If we give Locke his point that the sequence of simple ideas we experience displays patterning, we must next understand that Locke clearly thinks that there is some reason why when it comes to ideas of substances, we have to let our complex idea building be guided by that patterning.

What is his reason? I think it is that this patterning is some sort of a guide as to what the real constitution of a substance is.

He believes on the one hand that it is the corpuscular constitution of a thing which produces the patterning in the sequence of simple ideas we encounter. But on the other, he believes that we are ignorant of those corpuscular constitutions.

This is why the idea we form of a corporeal object cannot be a reliable reflectionof its essential - corpuscular - nature. We do form ideas of corporeal objects, but they can only be in effect just lists of the properties the objects can be observed to have. From such lists we cannot deduce anything for certain.

Why does Locke think we are and are likely to remain ignorant of the corpuscular constitution of things? He appears to think that corpuscles are simply too small ever to come within empirical reach. If we were in a position to study them directly, he argues, we would be able to work out what properties a thing made up of those corpuscles would necessarily display:' I doubt not but if we could discover the figure, size, texture, and motion of the minute constituent parts of any two bodies, we should know without trial several of their operations one upon another; as we do now the properties of a square or a triangle... [but] ...having no ideas of the particular mechanical affections of the minute parts of bodies that are within our view and reach, we are ignorant of their constitutions, powers, and operations...' Essay, Book IV, Chapter III, Sections 25 and 26.

But if he thinks this, he must be misunderstanding his own position here. His point appears to be, in his terms, that with knowledge of the corpuscles of which a material body is made up our minds would be able to construct a complex idea of it which allowed the deduction of no inconsistency. - And once we had this our reason would be able to discern agreements and disagreements between that idea and others - that is, our reason would be able to arrive at knowledge of that body.

But what this assumes is that our reason can identify 'inconsistencies' between simple ideas. As Hume showed later, observation will never yield knowledge of 'inconsistencies'. From empirical study of corpuscles no knowledge of 'inconsistencies' will flow. At the bottom of Locke's epistemology is the assumption that reason can discern these inconsustencies, a power that the mind can use to build coherent complex ideas, from which knowledge of further necessities may flow. At bottom, Locke is a believer in the power of reason to identify necessities, a power that Hume showed to be chimerical. All ideas come from experience says Locke and on those grounds he is said to be an empiricist. But it is reason's independent power, not in the least derived from experience, to identify necessities that must govern the mind's construction of complex from simple ideas, if there is to be knowledge at all, and on those grounds Locke's deeper commitment is to the power of reason to get at what is really important in the world, namely the necessities to which all its workings are thought by him to be subject.

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The upshot of our ignorance of the corpuscular constitution of things is that We don't know why it produces the particular patterning it does in fact produce: so we can't build a complex idea of a substance by including in the package just those ideas which are 'consistent'. But if we form our complex ideas of substances by putting together the simple ideas which are associated in the patterning, we will form complexes that are some use to us - of greater utility than they would be if consisting of simples 'put together at the pleasure of our thoughts'. (Section 11.)

Locke says:

"Herein, therefore, is founded the reality of our knowledge concerning substances: that all our complex ideas of them must be such, and such only, as are made up of such simple ones as have been discovered to co-exist in nature. And our ideas, being thus true though not perhaps very exact copies, are yet the subjects of real (as far as we have any) knowledge of them ... Whatever ideas we have, the agreement we find they have with others will still be knowledge. If those ideas be abstract, it will be general knowledge. But to make it real concerning substances, the ideas must be taken from the real existence of things. Whatever simple ideas have been found to co-exist in any substance, these we may with confidence join together again, and so make abstract ideas of substances. For whatever have once had an union in nature, may be united again. (Locke's Essay, Bk IV Ch IV, Section 12.)

Reprise

Let me attempt a reprise.

It follows from Locke's understanding of things and their real essences (which he thinks is their corpuscular constitution) that at least we can say this about the patterning shown by simple ideas as we encounter them: that if they are produced by an entity existing in the non-mental world they would be being produced by that entity's constitution.

Ideally, we would build our complex idea of the substance in question using just those simple ideas that together would enable our reason to deduce all the substance's properties. But, lacking knowledge of its constitution, we can't do this - we can't work out which set of simple ideas when packaged together would enable valid inferences to all the substance's properties to be made. The best we can do is to be guided in our packaging by the patterns displayed by the simple ideas as we encounter them.

Locke and scepticism about the non-mental world

What answer does all this give to the question: Does Locke think we can be sure there exists a non-mental world? He thinks we can know God exists, explaining that we can perceive the agreement between the idea of God and 'real existence'. And he gives the following argument for the conclusion that our sense experience guarantees the existence of things outside our minds:

'...[S]imple ideas, which since the mind, as has been shown, can by no means make to itself, must necessarily be the product of things operating on the mind, in a natural way, and producing therein those perceptions which by the Wisdom and Will of our Maker they are ordained and adapted to. From whence it follows, that simple ideas are not fictions of our fancies, but the natural and regular productions of things without us, really operating upon us ... Thus the idea of whiteness, or bitterness, as it is in the mind, exactly answering that power which is in any body to produce it there, has all the real conformity it can or ought to have, with things without us. And this conformity between our simple ideas and the existence of things, is sufficient for real knowledge.' Locke's Essay Book IV Chapter IV Section 4.

Locke and rationalism

It is clear from the forgoing that Locke believes the world to be such that on the basis of some knowledge about it the mind can, through the use of reason, validly obtain knowledge that would otherwise - if reason were not at work - not be there. (This is usually taken to involve the view that there are necessary connections in nature, which reason is in principle capable of grasping...)

Does this make Locke a 'rationalist' - and not an 'empiricist' at all?

One test is this: does he think there is a route to knowledge that bypasses the senses? In a sense he does. There is 'intuitive' knowledge, he thinks, for example the knowledge we have when we encounter a distinct simple idea that it is indeed distinct.

There is also for Locke the power the reason has to see that if a certain complex idea has such and such a constitution, then certain propositions must be true. (From the constitution of the complex idea of a triangle reason can see that its internal angles must sum to two right angles.)

But these operations of reason are operations on ideas which we get through internal or external sense, and Locke is a great pains (in his extended argumentation against the occurrence of 'innate ideas') to argue the point that none of our ideas derives from any other source.

This is the decisive break with Scholasticism. The construal of mental content as representational - adumbrated but not quite achieved by Descartes - allows the Moderns to think of knowledge as of our our own creation, not something entirely forced on us by our living in the world that is independent of us.

[But the question explodes: who on earth believed that ideas were innate? Ideas had onlky just been invented ... Woolhouse says it was those who thought someof our knowledge we were born with. Locke says: we are born with a processor, but the material it works on is all given in experience.]

Probable Opinion

Even when we have formed complex ideas, and have these constructs in our minds as well as the simple ideas we are given by our senses (and which form the building blocks of the ideas we have constructed) - we still don't have knowledge. Knowledge only comes as a result of our minds - using the faculty of reason - scrutinising the ideas we have and noting relationships - Locke's phrase is 'agreements and disagreements' amongst them. So for example our reason may review our idea of a triangle and our idea of a straight line and 'see' that a triangle must have at least one straight line.

Locke thinks that the extent of our knowledge is very restricted. For knowledge of a thing to be possible, the ideas reviewed by reason have to reflect the essential nature of the subject of the knowledge - the nature, Locke assumes, from which all the properties of a thing necessarily flow. Our ideas of mathematical objects are like this - they do reflect their essential natures. But our ideas of corporeal bodies do not. And therefore, thinks Locke, we cannot have any real knowledge about them.

The reason our ideas of corporeal bodies do not reflect their essential nature is that the corpuscles of which they are made up are two small to be studied. There is no mystery for Locke about what the essential nature of corpreal bodies is: it is the their corpuscular constitution. The problem is that as human beings we can't get at it. The corpuscles are much too small. So the ideas we form of a corporeal object can reflect nothing of its essential - corpuscular - nature. We do form ideas of them, but they are just lists of the properties the objects can be observed to have. From such lists we cannot deduce anything for certain.

Nonetheless, we can form some reasonable beliefs about corporeal bodies. And the means of arriving at such beliefs is observation. Studying the natural world empirically yields not knowledge but, in Locke's term, judgement.

'The faculty which God has given man to supply the want of clear and certain knowledge, in cases where that cannot be had, is judgment: whereby the mind takes its ideas to agree or disagree ... without perceiving a demonstrative evidence in the proofs.' Essay, Book IV, Chapter XIV, Section 3

Judgment is still a matter of relationships between ideas - of matter still of ideas 'agreement or disagreement'; only, in contrast to knowledge, the mind involved in 'judgment' has no clear perception of agreement or disagreement to go on, only an impression of these relationships as though looking at them 'at distance' as it were - this is the metaphor Locke uses. (Book IV, Chapter XIV, Section 3).

Elsewhere, Locke explains that sometimes if not always the reason is at work in judgment, and what it does is to assess 'not a certain agreement' between two ideas but 'an usual or likely one'. In a chain of reasoning which falls short of a demonstrative proof several of these assessments of 'usual or likely' agreements will be made, and then in a further step the reason will sum these assessments and deliver a calculation of the likely agreement between premises and conclusion overall. It is this that enables the right judgment to be made:

' The great excellency and use of the judgment is to observe right, and take a true estimate of the force and weight of each probability [that there is agreement between two successive ideas in a chain of reasoning] ; and then casting them up all right together, choose that side which has the overbalance. Essay, Book IV, Chapter XVII, Section 16.

Both knowledge and the opinion that results from the exercise of rational judgement ('probable opinion') are therefore for Locke matters of relationships between ideas. They are the outcome of a review of ideas carried out by our reason.

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