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Locke, Essay IV.iv.1-12; ix.2-3; x.1-7; xi

Knowledge of Real Existence

Locke’s project of determining which of the four types of agreement and disagreement of ideas identified in Essay IV.i are known by which of the means identified in Essay IV.ii is only partially completed in Essay IV.iii. That chapter only considers the means of our knowledge of the identity and diversity, other relations, and the coexistence of ideas. The remaining topic, of the means of our knowledge of real existence corresponding to our ideas, is taken up in Essay IV.iv. Locke approached this topic by dividing our ideas into three groups, simple ideas, ideas of complex modes and relations, and ideas of substances. He then asked what each of these three main types of ideas might allow us to intuit, demonstrate, or experience to be the case of real things existing outside of us. His investigation of the second of these types of ideas motivated an investigation of our knowledge of general principles that was undertaken over Essay IV.v-viii. In investigating the third topic, he drew a distinction between knowledge of the self, knowledge of God, and knowledge of external objects. Our knowledge of the real existence of objects corresponding to our ideas of these main types of substance is discussed over Essay IV.ix-xi.

QUESTIONS ON THE READING

1. What assures us that our perceptions of simple ideas are not made up by us but correspond to powers in bodies?

2. Why can mathematical principles be regarded as “true and certain” even though t hey only describe ideas we have ourselves created in imagination?

3. What is the basis for our knowledge of general truths?

4. Are there any constraints on the power of the imagination in constructing ideas of complex modes?

5. What conditions must be satisfied in order for our ideas of substances to be considered real rather than imaginary? What conditions must be satisfied for them to be considered at least possibly real rather than fantastic creations that could never even possibly exist?

6. Is it possible to prove our own existence, i.e., give a demonstration of the fact?

7. Did Locke accept the causal principle (that every effect must have some cause)? If not, why not, and if so, how did he think we come to know it?

8. What significance does the power to produce and remove ideas have for Locke’s arguments to demonstrate the existence of an external world?

9. What significance do feelings of pleasure and pain have for Locke’s arguments to demonstrate the existence of an external world?

10. Can I know that objects continue to exist when I am not perceiving them?

11. Can I know that other human bodies think and perform acts of will?

NOTES ON THE READING

Though Locke supposed that all of our knowledge ultimately arises from, as he put it, a “perception of the connexion and agreement, or disagreement and repugnancy of any of our Ideas” (Essay IV.i.2), he also supposed that these connections and disagreements of ideas have some reference to the existence of real objects in the external world, and that we can come to know something about these objects through our ideas. This is already the case with our simple ideas.

The real existence of objects corresponding to our simple ideas. For reasons Locke gave at the outset of Essay II and that he canvassed in Essay IV.iv for a second time, we are intuitively aware that we did not create our simple ideas. Furthermore, from the circumstances in which those ideas first arose in us, we can demonstrate that a particular stimulus environment, and the possession of particular sense organs, is requisite to obtaining each simple idea of sensation. Consequently, Locke declared, these simple ideas must have some reality, in the sense that they must refer to some cause outside us, at least insofar as they are presented to us in sensation. This is not to say that an idea must resemble its cause. But it is to suggest that where there are changes in our ideas (at least those of sensation) there ought to be changes in the surrounding causes. Same causes should not continue the same and yet produce different ideas. Thus we can take differences in our ideas as a guide to the presence of differences in the real things about us, even though we might not be able to say exactly in what those differences consist.

The real existence of objects corresponding to complex modes and relations. In mathematics, geometry, and, as far as Locke was concerned, ethics and politics, we are able to establish principles by means of calculations performed on complex modes and relations. These demonstrations have an indirect reference to thing that actually exist in the sense that, if there are any things that correspond to the complex modes or relations that figure in our calculations, then those things would have to conform to what our calculations tell us. There may be no things that are perfectly triangular. But if there are, they must conform to whatever geometry tells us about triangles.

A significant part of our knowledge takes the form of knowledge of general principles like these. This is not true of all laws. Many of the laws of natural science, such as “all bodies gravitate,” are known only by induction from experience. It is because all bodies within the reach of our experience are observed to gravitate that we declare that all bodies gravitate, and this makes this particular law one that is not known to be true at all, but only believed as highly likely correct on the basis of experience. However there are other laws, such as “all bodies transmit motion on impact,” that are based on demonstration concerning complex modes or just those ideas that we take to be characteristic of substances of different sorts. If we take “body” to be a name that could not be applied to a substance unless it were solid, then transmission of motion on impact is a necessary consequence of impact. This law is one that can accordingly be not only believed on the basis of induction, but known as a consequence of what can be demonstrated from what is involved in our ideas. The draw-back is that we need to presume that something exists that actually corresponds to what is thought in the complex mode. Sensory experience often suffices to tell us that, but then the knowledge of the law, based on demonstration, is one thing, and the knowledge of the existence of things that conform to the law, based on sensory experience, is another.

Locke undertook a more extensive inquiry into the types of general principles and the nature of our knowledge of them over Essay IV.v-viii.

The real existence of the self. While the existence of real objects corresponding to our ideas of substances can in general only be known by sensation, that is, by experiencing a collection of ideas answering to the nominal essence of a given substance, Locke supposed that our knowledge of the existence of our own selves and of God are exceptions. The former is supposed to be known by intuition, the latter by demonstration.

Locke’s discussion of our knowledge of our own existence is very brief, and after what he said on this topic in the chapters on substance and identity and in the remark on thinking matter in IV.iii.6 it is something of a disappointment. It simply consists in asserting that I cannot have any sensation or perform any act of mind without intuiting that I exist and am having that sensation or performing that operation.

As thus stated, Locke’s argument appears to be no different from Descartes’s in Principles I.7 and Meditations II. But Descartes was not just concerned to establish that the self exists, but to establish that the self is a substance of a special kind, one capable of thought, and one that can be conceived to exist as a thinking being without being conceived to exist as a solid or even as an extended being. Locke, in contrast, had nothing to say about the nature of the “self” he took us to intuit. It must be capable of sensation and doubt and other forms of thought, but what more we can say about its nature is, apparently, not a matter for intuitive knowledge. If we consider the conclusions of the chapter on personal identity, then even the little that is said here is less than it seems because the existence of a thinking substance is no guarantee of the continued existence of the person who thinks or of the continued presence of the same person in that same thinking substance. Persons can, in principle, “move” from occupying one substance to occupying another, substances can be occupied by successively different persons, and the person, being ultimately no more than a collection of thoughts and memories, is simply a bundle of information, that can easily be destroyed.

The real existence of God. The demonstration that Locke used to prove the existence of God is a variant on the cosmological argument. A standard cosmological argument tries to prove the existence of God by claiming that there has to be some reason why there is something rather than nothing, and in particular why the universe as a whole (a very large “something”) exists. Locke did not, however, want to presuppose the existence of the universe in his proof for the existence of God. That would make our certainty of the existence of God derivative from our certainty of the existence of an external world, and Locke wanted that relation to be the other way around — our knowledge of the existence of God should be prior. But neither did Locke want to follow Descartes’s route and try to prove the existence of God by appeal to the existence of an idea of an all perfect being — an attempt that he disparaged at Essay IV.x.7 and IV.x.1. Accordingly, rather than start from the universe, he started from the one existence he knew with the greatest evidence and certainty — his own existence — and argued that it already puts us in a position to infer that God must exist.

Locke proceeded to claim that it is evident “by intuition” that something cannot come from nothing. From this it follows that anything that begins to be must have been caused by something else, since if there were nothing prior to it, at the time prior to when it began to be, that worked to bring it into existence, then it would have come into being from nothing after all, and that has been rejected. It follows that there must be something that never became to be, but has existed from all eternity, for if everything needs to be caused by something else there would be nothing to start the series off.

Now we know that we ourselves exist, and we think that we began to be. So there must be some being that has existed from eternity. Moreover, this being must have all the power in it that we find in ourselves (such as the power of thought) or have any reason to believe exists anywhere outside of us (and our sensations do give us reason to suppose that there are things with various secondary and tertiary powers existing outside of us). For if it did not contain all these powers, the excess would have come from nothing. And if the various powers were instead distributed amongst a number of eternal beings, it is inconceivable that the world we see around us, with all its coherence and integration of parts, would have come to be. There would instead have been a chaos of warring and disconnected things.

According to Locke we are therefore compelled by reason to accept that an infinitely powerful being must have existed from eternity, that is, that God exists.

The premise of this argument is of course highly questionable, as has been noted in a number of prior lectures. It rests on the notion that causes work by building their effects up out of some pre-existing material that they contain within themselves. But, whatever Locke may have thought, the principle that a thing can only come to be by being brought about by something that already contains everything that is present in that thing, is not intuitively obvious. It cannot be based just on obtaining ideas of something and of nothing, comparing them with one another, and noting that they are entirely distinct and different. Locke’s claim that something cannot come from nothing does not just depend on what we find in our ideas of something and nothing. It depends on a tacit appeal to what we find in our idea of causality: to the notion that what comes to be must come to be from something else, so that what comes to be without any other cause would have to come from the thing we call “nothing.” But anyone who takes the notion of coming to be out of nothing seriously will deny that this is the case. To come to be out of nothing is not to have the thing called “nothing” be the material out of which you are built. It is to have no cause whatsoever, not even the thing we call “nothing.” Anyone who wants to seriously challenge this position had better not simply insist that something cannot come from nothing, but had better explain why we should accept that whatever comes to be must have been put together by some pre-existing thing using materials that it has drawn from somewhere — out of itself if nowhere else.

That is not something Locke managed to do. On the contrary, Locke’s very short chapter on the causal relation (Essay II.xxvi — over half of which is concerned with other matters) itself seems to undermine his claim that something cannot come from nothing. Were this claim intuitively obvious it would arise from inspecting our ideas of something, of nothing, and of causality. But all that Locke said in his chapter on causality is that, having observed that alterations in one thing are regularly preceded by another thing (e.g., that the drying of grapes is regularly preceded by a period of bright sunshine), we come to refer to the one as the cause and the other as the effect. But on this account, the causes are merely conceived as things that constantly or regularly precede effects in past time. They are, moreover, things that we only come to know about through identifying something that regularly precedes alterations of a certain type. If we fail to succeed in the effort to find such a regular antecedent — and nothing seems easier than to suppose that we might — then we will have experience of events for which we can find no cause, and our experience itself will lead us to accept that not all events have causes.

Setting this particular objection aside, Locke’s argument turns on the further claim that the powers we see within and around us could not evolve or emerge from some more primitive kind of pre-existent material. In particular, thought and intelligence could not arise from something that does not think, such as merely solid and cohesive matter. As noted in the last lecture, Locke had maintained that matter might think, that is that the substance that is responsible for giving us our ideas of a cohesion of solid parts might also be responsible for giving us our ideas of sensation and of our acts of volition. But, he argued at some length that the powers of thought and volition could not emerge from the powers of cohesion and solidity. Thinking matter could not evolve out of merely solid and cohesive matter. Thinking matter would have to have its powers of thought “superadded” to it by some intelligent creator, or it would have to have been something more than merely solid and cohesive (that is, something more god-like) to start with. Either way, the pre-existence of a divine being, in some form or other, would have to be accepted.

To back this up, Locke charged that it would be impossible for any arrangement of cohering, solid particles to do anything other than aggregate in particular shapes, and communicate motion through impulse, and that thought could not be reduced to any such operations. We might be more inclined to doubt this today. We live in an age when computer programs have been written that enable machines to converse with us. One program has been designed to imitate the series of questions that would be asked by a Freudian psychologist during a psychoanalysis session. The program starts off asking a standard question and, depending on how the patient responds (on the occurrence of key phrases), it is designed to ask follow up questions. It is so well written that patients interacting with it over the phone cannot tell that they are not speaking to a live human being. Other computing devices have been designed to mimic the way human brain cells work. Human brain cells develop stronger and weaker tendencies to “fire” (to send out an electrical impulse) in same stimulus environments (when receiving same electrical impulses) depending on whether firing in those circumstances in the past has been successful or not. Computers designed to electronically mimic this biochemical function will reprogram themselves in light of experience, and so appear to learn from experience. Word recognition and face recognition software works this way. But as successful as we have been at constructing electronic devices that mimic human thought, the principal problem that Locke brought up as an objection to the possibility that merely solid and cohesive (or, we might add, electric) matter might be made to thought still confronts us. We cannot see how we could do anything to a computing device that would make it share our experience of pain. We can make it do self-diagnostics to report on its own malfunctions, and so program it to produce pain noises. But we don’t think that any of that amounts to feeling what we feel when we feel pain. Similarly, we can program it to illuminate those pixels on a screen that cause someone looking at the screen to see red. But then the sensation of red is only in the person looking at the screen, not on the surface of the screen, which only emits light of a certain wavelength (and a wavelength is not a colour but a shape), or anywhere in the machine itself. Making machines sense and possess consciousness of their functions still seems as impossible to us today as it did to Locke. It is with some justice, therefore, that he concluded that the powers of will and thought could not, therefore, grow out of merely solid and cohesive stuff.

Other minds and the continued existence of unperceived objects. Locke’s reasons for supposing that we know the real existence of objects corresponding to those ideas of substances that we receive from sensory experience have already been canvassed in the previous chapter and so are passed over here. However, it is important to notice that there are two limitations that Locke placed on our knowledge of particular substances. One concerns the continuity in existence of unperceived objects. Suppose Dick is looking at Jane. Then Dick turns away and looks somewhere else. According to Locke, Dick can only know (that is, be certain) that Jane exists while he is actually perceiving her. He cannot know that she continues to exist when he is not perceiving her. Any of a thousand causes may have terminated her existence. Admittedly, this is not very likely. People don’t just die off the way bubbles burst and disappear. But the question here is whether Dick can claim to know, that is, be absolutely certain, that Jane exists, not whether Dick can claim to have strong reasons to believe that she still exists. He may have the best reasons. But they only make him believe, not know. When you know it is not possible to be wrong. This only goes to show that knowledge is perhaps not that important. Some of the most important things are not known but merely believed for excellent reasons. Probability is all we require for the purposes of life, and that anyone who demands certainty in these matters is being unreasonable.

There is another limitation on what can be known by sensation about other human beings. By sensation I can know that other human bodies exist. By sensation I can hear these other bodies speaking. From what I hear these other bodies saying, I can infer that these other speakers have thoughts and feelings, since they tell me so. But this is not knowledge. It is belief, in this case belief based on testimony. I do not directly sense, that is, have ideas of reflection, of the minds of others. I only intuit my own mind and have ideas of reflection of my own mental operations. We would all like it if others were to think of us as thinking beings rather than zombies. But while I can know that I am a thinking being because I perceive all my thoughts through reflection, I do not have a sense that informs me of anybody else’s thoughts. I see other bodies move and hear sounds come out of their mouths that have meaning to me, but I have no experience that there is thinking going on in those other bodies. Locke maintained that the existence of other thinking beings is not something I accept even as a probability. It is rather based on faith in the testimony of others.

These reflections raise the general issue of what probable belief and faith are based on, and how they compare to one another. This is the topic of the next chapter.

ESSAY QUESTIONS AND RESEARCH TOPICS

1. Locke’s claim that it is intuitively evident that every event must have a cause was attacked by Hume in Book I, Part iii, Chapter 3 of his Treatise concerning human understanding. Recount and assess Hume’s argument.

2. It is surprisingly difficult to prove that there are other minds. Survey some of the recent literature on this topic and explain why the standard arguments for this conclusion have proven to be less than convincing.

3. Locke maintained that while we cannot know that objects continue to exist while not perceived, we can have grounds to believe that this is the case. Hume followed Locke in this respect, but unlike Locke he did not think that we have good or reasonable grounds to believe that objects continue to exist unperceived; instead, our belief is a fiction of the imagination, based on certain propensities that, in other circumstances, are condemned by philosophers and logicians as producing fallacious opinions. Hume’s argument for this startling conclusion is offered over Treatise I.iv.2. Recount this argument, giving particular attention both to why Hume said that the belief in the unperceived existence of bodies is not based on any good reason, and what he identified as the illegitimate operations of the imagination that cause us to have this belief anyway.