Chapter IV: Part 4

But there may be other philosophers who will say that, in the case of a perception also, to say that it exists or is real is to say that it is perceived--either that alone or something more as well. And to these philosophers I would first point out that they are admitting that the proposition "This perception is real" is significant. There is some sense or other in which we may say: "Alexander's perception of an elephant was real or did exist, but Sindbad's perception of a Roc was _not_ real--never did exist": the latter proposition is, in some sense or other, not self-contradictory. And then I would ask of them: When they say, that to call a perception "real" is to assert that it is perceived, do they mean by this that to call it real is to assert that it is _really_ perceived, or not? If they say "No," then they are asserting that to call a perception "real" is merely to say that it was perceived in the sense in which Sindbad _did_ perceive a Roc: they are asserting that to call it "real" is not to say, in any sense, that it was _really_ perceived: they are asserting that to call a perception "real" is to say that it was perceived, in some sense quite other than that in which we ordinarily use the word: for we certainly commonly mean, when we say "A was perceived," that a perception of A was "real": we should commonly say that Sindbad did _not_ perceive a Roc--meaning that no such perception ever did exist. I do not think they do mean this; and, in any case, if they do, I think it is plain that they are wrong. When we say that a perception is "real," we certainly do not mean merely that it is the object of another perception, which may itself be quite unreal--purely Imaginary. I assume, therefore, that when they say: To call a perception "real" is to say that it is perceived; they mean, what we should naturally understand, namely, that: To call it "real" is to say that it is _really_ perceived--to say that it is the object of another perception, which is also _real_ in the same sense. And, if they mean this, then what they say is certainly untrue. Their definition of reality is circular. It cannot be the case that the _only_ sense in which a perception may be said to be real, is one in which to call it so is to assert that not it alone, but another perception is real also. It cannot be the case that the assertion "A is real" is _identical_ with the assertion "A and B are both real," where A and B are different, and "real" is used in the same sense as applied to both. If it is to be true that the assertion "A is real" _ever_, in any sense, includes the assertion "A is _really_ perceived," there must be another sense of the word "real," in which to assert "A is real" is to assert _less_ than "A is _really_ perceived"--the sense, namely, in which we here assert that the _perception_ of A is real.

We find, therefore, that the other class of philosophers were at least right in this: they were right in allowing that the sense in which we commonly say that our perceptions exist is one in which "exist" does not include, even as a part of its meaning, "is perceived." We find that there is a common sense of the word "existence," in which to say "A exists" must mean _less_ than "A is _really_ perceived": since, otherwise, the only possible definition of the word "existence" would be a circular definition. And I may point out that two other definitions, which have been sometimes suggested by philosophers as giving what we commonly mean by "reality" or "existence" are vitiated by the same fault--they also are circular. Some philosophers have sometimes suggested that when we call a thing "real," we mean that it is "systematically connected" in some way with other things. But, when we look into their meaning, we find that what they mean is (what, indeed, is alone plausible)--systematically connected with other _real_ things. And it may possibly be the case that we sometimes use the word "real" in this sense: but, at least, it must be certainly the case, that, if we do, we _also_ use it in another and simpler sense--the sense in which it is employed in the proposed definition. And other philosophers have suggested that what we mean by "real" is--"connected in some way with a purpose--helping or hindering, or the object of a purpose." But if we look into their meaning, we find they mean--connected with a _real_ purpose. And hence, even if we do sometimes mean by "real," "connected with a _real_ purpose," it is plain we also sometimes mean by "real" something simpler than this--that namely, which is meant by "real" in the proposed definition.

It is certain, therefore, that we do commonly use the word "existence" in a sense, in which to say "A exists" is _not_ to say "A is perceived," or "A is systematically connected with other real things," or "A is purposive." There is a simpler sense than any of these--the sense in which we say that our own perceptions do exist, and that Sindbad's perceptions did not exist. But when I say this, I am by no means denying that what exists, in this simple sense, may not always _also_ exist in all the others; and that what exists in any of them may not _also_ always exist in this. It is quite possible that what exists is always _also_ perceived, and that what is perceived always _also_ exists. All that I am saying is that, even if this is so, this proposition is significant--is not merely a proposition about the meaning of a word. It is not self-contradictory to suppose that some things which exist are not perceived, and that some things which are perceived do not exist.

But, it may be asked: What is this common simple sense of the word "exists"? For my own part, it seems to me to be so simple that it cannot be expressed in other words, except those which are recognised as its synonyms. I think we are all perfectly familiar with its meaning: it is the meaning which you understood me to have throughout this paper, until I began this discussion. I think we can perceive at once what is meant by asserting that my perception of black marks on a white ground is "real," and that no such perception as Sindbad's of a Roc was ever "real": we are perfectly familiar with the property which the one perception is affirmed to possess, and the other to be without. And I think, as I have said, that this property is a simple one. But, whatever it is, this, which we ordinarily mean, is what I mean by "existence" or "reality." And this property, we have seen, is certainly neither identical with nor inclusive of that complex one which we mean by the words "is perceived."

I may now, then, at last approach the main question of my paper. Which among the "contents" which I observe will give me reason to suppose that my observation of some of them is generally preceded or accompanied or followed by the existence of certain particular perceptions, thoughts or feelings in another person? I have explained that the "contents" which I actually observe may be divided into two classes: on the one hand, those which, as we commonly say, we perceive "through the senses"; and, on the other hand, my perceptions of these last, my thoughts, and my feelings. I have explained that if any of these observed contents are to give reason for a generalisation about what exists, _they_ must exist. And I have explained that with regard to both classes of "contents" I am using the word "exist" in precisely the same sense--a sense, in which it is certainly not self-contradictory to suppose that what _is_ perceived, does not exist, and that what is _not_ perceived, does exist; and, in which, therefore, the assumption that a red patch with gold letters on it exists, is a _different_ assumption from the assumption that my _perception_ of a red patch with gold letters on it exists; and the assumption that my _perception_ of a red patch with gold letters on it exists, is a _different_ assumption from the assumption that a red patch with gold letters on it exists.

What, then, that we observe, can give us any reason for believing that anyone else has certain particular perceptions, thoughts or feelings? It has, I think, been very commonly assumed that the observation of my own perceptions, thoughts, and feelings, can, by itself, give me such a reason. And I propose, therefore, to examine this assumption. If, as I hope to show, it is false; it will then follow, that if our own observation gives us any reason whatever, for believing in the existence of other persons, we must assume the existence, not only of our own perceptions, thoughts and feelings, but also of some, at least, among that other class of data, which I may now, for the sake of brevity, call "sense-contents"; we must assume that some of them exist, in precisely the same sense in which we assume that our perceptions, thoughts, and feelings exist.

The theory which I propose to examine is, then, the following. My observation of my own thoughts, feelings, and perceptions may, it asserts, give me some reason to suppose that another person has thoughts, feelings, and perceptions similar to some of mine. Let us assume, accordingly, that my own thoughts, feelings, and perceptions do exist; but that none of the "sense-contents," which I also observe, do so. Where among my perceptions am I to look for any which might conceivably give me a reason for supposing the existence of other perceptions similar to my own? It is obvious where I must look. I have perceptions which I call perceptions of other people's bodies; and these are certainly similar in many respects to other perceptions of my own body. But I also observe that certain kinds of perceptions of my own body are preceded by certain other perceptions, thoughts, or feelings of mine. I may, for instance, observe that when I perceive my hand suddenly catch hold of my foot in a particular way, this perception was preceded by a particular kind of feeling of pain. I may, perhaps, observe this often enough to justify the generalisation that the perception of that particular motion of my body is generally preceded by that particular feeling of pain. And in this way I may perhaps have reason for quite a number of generalisations which assert that particular kinds of perceptions of my own body are generally preceded by other particular kinds of perceptions, thoughts, or feelings of my own.

But I may also, no doubt, have the perception, which I call the perception of another person's hand catching hold of his foot, in a manner similar to that in which I have perceived my own hand catch hold of my own foot. And my perception of another person's hand catching hold of his foot may undoubtedly be similar in many respects to my perception of my own hand catching hold of my own foot. But I shall not observe the same kind of feeling of pain preceding my perception of _his_ hand catching hold of his foot, which I have observed preceding my perception of _my_ hand catching hold of my foot. Will my generalisation, then, give me any reason to suppose that nevertheless my perception of his hand catching hold of his foot _is_ preceded by a similar feeling of pain, not in me but in him? We undoubtedly do assume that when I perceive another person's body making movements similar to those which I have observed my own body making, this perception has generally been preceded by some feeling or perception of his similar to that which I have observed to precede my perception of similar movements in my own body. We do assume this; and it is precisely the kind of generalisation, which, I have insisted, must be admitted to be true. But my present question is: Will such observations as I have described give any reason for thinking any such generalisation true? I think it is plain that they will not give the slightest reason for thinking so. In the first place, all the perceptions which I call perceptions of another person's body differ very considerably from any of those which I call perceptions of my own. But I am willing to waive this objection. I am not offering any theory as to what degree of likeness is _sufficient_ to justify a generalisation: and therefore I will allow that the degree of likeness _may_ be sufficient. But there remains an objection which is, I think, quite fatal to the proposed inference. This objection is that the inference in question plainly does not satisfy the third condition which I suggested above as _necessary_, wherever any generalisation is to be justified by observation. I am willing to allow that my observations of the fact that my perception of a certain movement in my own body is preceded by a certain feeling of pain, _will_ justify the generalisation that my perception of any such movement, whether in my own body _or_ in that of another person, is generally preceded by a similar feeling of pain. And I allow, therefore, that when I perceive a certain movement in another's body, it _is_ probable that the feeling of pain exists, though I do not perceive it. But, if it _is_ probable that such a feeling of pain exists, such a feeling must stand _in the same relation_ to my perception of the movement in another person's body, in which a similar feeling of pain has been observed by me to stand to my perception of such a movement in my own body. That is to say the only kind of feeling of pain, which my observations do justify me in inferring, if (as I admit they may) they justify me in inferring any at all, is a feeling of pain of _my own._ They cannot possibly justify the belief in the existence of any such feeling _except_ one which stands to my perception in the same relation in which my feelings do stand to _my_ perceptions--one, that is to say, which is my own. I have no more reason to believe that the feeling of pain which probably precedes my perception of a movement in another person's body can be the feeling _of another person_, than, in my former example, I had reason to suppose that the hen, whose existence probably preceded that of a given egg, could be a hen, which had never been near the egg in question. The two cases are exactly analogous. I observe a feeling of pain _of my own_ preceding a perception _of my own._ I observe the two, that is to say, as standing to one another, in those relations (whatever they may be) in which any perception of mine stands to any other thought, perception or feeling of mine, and which are, at all events, different from any relation in which a perception or feeling of another person can stand to one of mine. I never perceive the feeling and the perception as standing in any other relation. In any case, therefore, where I do observe something like the perception, but do not observe the feeling, I can only be justified (_if_ justified in inferring any feeling at all), in inferring an unperceived feeling _of my own._

For this reason I think that no observations of my own perceptions, feelings or thoughts can give me the slightest reason for supposing a connection between any of them and any feeling, perception, or thought in another person. The argument is perfectly general, since _all_ my perceptions, feelings and thoughts do have to one another those relations in virtue of which I call them mine; and which, when I talk of a perception, feeling or thought as being _another persons_, I mean to say that it has _not_ got to any of mine. I can, therefore, merely from observation of _this_ class of data never obtain the slightest reason for belief in the existence of a feeling, perception, or thought which does _not_ stand in these relations to one of mine--which _is,_ that is to say, the feeling, perception or thought, of another person. But how different is the case, if we adopt the hypothesis, which I wish to recommend--if we assume the existence of that other class of data which I have called "sense-contents!" On this hypothesis, that which I perceive, when I perceive a movement of my own body, is _real_; that which I perceive when I perceive a movement of another's body is _real_ also. I can now observe not merely the relation between my _perception_ of a movement of my body and my own feelings, but also a relation between a _real_ movement of my body and my own feelings. And there is no reason why I should not be justified in inferring that another person's feelings stand _in the same relation_ to the real movements of his body, in which I observe my own feelings to stand to similar real movements of mine.

But there is another argument which may still be urged by those who hold that my own perceptions, thoughts, and feelings, by themselves, may be sufficient to justify a belief in the existence of other persons. It may be said: "Our observation of our own perceptions may be sufficient to _verify_ or _confirm_ the hypothesis that other persons exist. This hypothesis is one which "works." The assumption that other persons have particular thoughts, feelings and perceptions enables us to predict that they will have others and that our own perceptions will be modified accordingly: it enables us to predict future perceptions of our own; and we find that these predictions are constantly verified. We observe that we do have the perceptions, which the hypothesis leads us to expect we should have. In short, our perceptions occur just as they would do, _if_ the hypothesis were true; our perceptions behave _as if_ other persons had the perceptions, thoughts and feelings which we suppose them to have. Surely, then, they confirm the truth of the hypothesis--they give some reason to think it probably true?"

All this, which I have supposed an opponent to urge, I admit to be true. I admit that the fact that an hypothesis works may give some reason to suppose it true. I admit that my perceptions occur just as they would do, if other people had the perceptions which I suppose them to have. I admit that that assumption enables me to make predictions as to future perceptions of my own, and that I observe these predictions to come true. I admit all this. But I admit it only in a sense in which it in no way conflicts with the position which I am maintaining. The words, which I have put into the mouth of a supposed opponent, may, in fact, mean three different things, which it is worth while to distinguish. In two of those meanings, which I shall admit to be true and which are what make them seem plausible, they do not deny what I assert. Only in the third sense are they an objection to my position: and in that sense they are false.

One of the meanings which I admit to be true is as follows:--I have not only admitted but insisted that some of my perceptions are just such as would occur if another person had certain particular feelings: I have insisted that I should not have just those perceptions which I do have, unless some other person had certain feelings and perceptions which I suppose him to have. And I admit further that the fact that I have one of the perceptions in question--for instance, that of another person's hand catching hold of his foot--this fact, _together with_ the true assumption that I should not have this perception, unless some other person felt pain, will justify the assertion that another person has felt pain. In this sense, I admit, the fact that I perceive what I do perceive will give me reason to suppose that another person has felt pain. And, on the other hand, I also admit that the fact that I have this perception, _together with_ the true assumption that when I have it another person has felt pain, may help to justify the assumption that the perception in question is one which I should not have had unless another person had felt pain--it helps to justify the generalisation that certain of my perceptions are just what would occur, _if_ another person had felt pain. In general terms, that is to say, I admit that the occurrence of B, _together with_ the assumption that B is just the sort of thing which would occur if A existed, will justify the assertion that A exists in that particular instance. And I also admit that the occurrence of B, _together with_ the assumption that A exists in that particular instance, may help to justify the assumption that B is just the sort of thing which would exist, if A existed. In other words: When it is said that the observation of B's existence confirms or verifies the assumption that A exists, either of two things may be meant. It may be meant that, assuming B to be the sort of thing which would exist if A existed, the observation of B confirms the assumption that A exists _in this particular instance._ Or, on the other hand, it may be meant that, assuming A to exist in this particular instance, the observation of B may confirm the generalisation, that B is just the sort of thing which would exist, if A existed. _Either_ the one _or_ the other of these two things is, I think, what is generally assumed, when it is assumed that what we do observe confirms or verifies the assumption that there exists some particular thing which we don't observe. And I am admitting that both these assumptions are true.

But neither of them conflicts in any way with the position I am maintaining. What I am maintaining is that no observation of my own perceptions, _by itself,_ can confirm the generalisation that any one of them _is_ just what would occur if another person had a particular feeling. I admit this generalisation to be true; and I admit that my observation of my own perceptions and feelings may give me _reason_ to suppose that _if_ another person has certain perceptions or feelings _he_ will also have certain others. What I deny is that they give me the slightest reason to suppose that the existence of any such feeling or perception in another has any connection with the existence of any perception _of my own_--to suppose that any perception of my own is the sort of thing which would occur _if_ another person had a particular feeling. What therefore, my opponent must affirm is that the observation of a perception of my own _without_ the assumption (which Reid makes) that in that particular instance any feeling or perception of another person, of any kind whatever, has preceded it, may give me reason to suppose that that perception of my own is of a kind which is generally preceded by a particular kind of feeling in another person. And this, I think, is plainly false.

But there is yet a third thing which may be meant, and which I am willing to admit may be true. It may be said: "I believe many generalisations of the following kind. I believe that when I have a perception A, some other person has generally had a feeling X; I believe that the existence of the feeling X is generally followed, in the same person, by that of the feeling Y; and I believe also that when another person has the feeling Y, I generally have the perception B. I believe all this." And it must, I think, be admitted that we do believe generalisations of this kind, and generalisations in which there are not merely two steps between A and B, but a great number of steps. "But then," it may be said, "my belief in this generalisation causes me, when I observe my perception A, to expect that I shall have the perception B; and such expectations, I observe, are constantly realised." And this also, I think, must be admitted to be true. "But, finally," it may be said, "beliefs which produce expectations which are constantly realised are generally true. And hence the fact that these beliefs of mine about the connection of feelings in other persons with perceptions of my own do lead to expectations which are realised, gives me reason to suppose that these generalisations are true and hence that other persons do have particular kinds of feelings." And I am willing to admit that this also is true. I am willing to admit that true predictions can, as a rule, only be produced by true beliefs. The generalisation that this is so, is, indeed, one which can only be justified by the observations of beliefs, which are, in some way, independently proved to be true; and hence, if it is to be justified, without assuming the existence of anything other than my own perceptions, thoughts, and feelings, it can only be justified by my observation that beliefs with regard to the manner in which _these_ succeed one another generally lead to true predictions. Whether the observation of such beliefs _alone_ could give sufficient reason for it, is, I think, doubtful; but I am willing to admit that it may be so. One thing, however, is, I think, quite plain: namely, that this generalisation "Beliefs which lead to true predictions are generally true" cannot be true, _unless_ some other of the "contents" which I observe, beside my own perceptions, thoughts, and feelings, do exist. That is to say, in giving a reason for supposing the existence of other people, this generalisation also gives a reason for the very theory which I am advocating, namely, that some of those data which I have called "sense-contents" do exist. It does this, because it is quite certain that beliefs in generalisations about the existence of sense-contents _can_ (and do) constantly lead to true predictions. The belief that when I have observed a fire of a certain size in my grate, something similar to what I have observed will continue to exist for a certain time, can, and constantly does, lead to the true prediction that, when I come back to my room in half an hour's time, I shall observe a fire of a certain size still burning. We make predictions on such grounds, I think, every day and all day long. And hence unless such beliefs as that what I observe when I see a fire burning _does_ exist, _are_ true, we certainly have no reason to suppose that beliefs which lead to true predictions are generally true. And hence on this hypothesis also it remains true: that, unless some of the contents which I observe _other_ than my own perceptions, thoughts, and feelings, do exist, I cannot have the slightest reason for supposing that the existence of certain perceptions of my own is generally connected with that of certain perceptions, thoughts, or feelings in any other person.

I conclude therefore that, unless some of the observed data which I have called sense-contents _do_ exist, my own observations cannot give me the slightest reason for believing that anybody else has ever had any particular perception, thought, or feeling. And, having arrived so far towards an answer to my first question: How do we know that any other persons exist? I may now point out that precisely the same answer must be given to my second question: How do we know that _any_ particular kind of thing exists, other than ourselves, our perceptions, thoughts, and feelings, and what we directly perceive? There is a view concerning what exists, which deserves, I think, much more respect than it generally receives from philosophers nowadays. The view I mean is the view that material objects, such as they are conceived by physical science, do really exist. It is held by some persons (and Reid is among them) that we _do_ know of the existence, not only of other persons, but also of the movements of matter in space. It is held that we do know, with considerable precision, what kinds of movements of matter generally precede my perception, when I have a particular perception. It is held, for instance, that when I perceive a red and blue book side by side on a shelf, at a certain distance from me, there have existed, between two material objects, which may be called books, and another kind of material object, which may be called my eyes, certain wave-like motions of a material medium; that there have existed two different sets of waves, of which the one is connected with my perception of red and the other with my perception of blue; and that the relative heights and breadths of the two different sets of waves, and the relative velocity of their movements are very exactly known. It is held that some men have a vast amount of very precise information about the existence of objects of this kind; and I think the view that this is so deserves a great deal of respect. But what I wish now to point out is that no one's observation of his own perceptions, thoughts and feelings, can, by itself, give him the slightest reason for believing in the existence of any such material objects. All the arguments by which I have tried to show that this kind of observation alone can give me no reason to believe in the existence of any kind of perception or feeling in another person, apply, with at least equal force, to show that it can give me no reason to believe in the existence of any kind of material object. On the other hand, if we are to admit the principle that "Beliefs which lead to true predictions, are generally true," this principle will give us at least as much reason to believe in the existence of certain kinds of material objects as to believe in the existence of other persons; since one of the most remarkable facts about beliefs in the existence of such objects is that they do so often lead to true predictions. But it must be remembered that we can have no reason for believing this principle itself, _unless_ our own perceptions, thoughts and feelings are _not_ the only kind of observed "content" which really does exist: we can have no reason for it, unless some such things as what I perceive, when I see a red and blue book side by side, do really exist.

It would seem, therefore, that if my own observations do give me any reason whatever for believing in the existence either of any perception in any other person or of any material object, it must be true that not only my own perceptions, thoughts and feelings, but also _some_ of the other kinds of things which I directly perceive--colours, sounds, smells, etc.--do really exist: it must be true that some objects of this kind _exist_ or are _real_ in precisely the same simple sense in which my perceptions of them exist or are real. Is there then any reason to think that this is not true? Is there any reason to think, for instance, that _none_ of the colours which I perceive as occupying areas of certain shapes and sizes really exist in the areas which they appear to occupy? This is a question which I wished to discuss at length, because I think that it is one in which there are real difficulties. But I have given so much space to other questions, that I can only deal with it very briefly here.

Some philosophers are very fond of asserting that a colour cannot exist except when it is perceived; and it might possibly be thought that when I suggest that colours do really exist, I am suggesting that they do exist when they are not perceived. I wish, therefore, briefly to point out that the question whether anything does exist, when it is not perceived, is one which I have not argued and shall not attempt to argue in this paper. I have, indeed, tried to show that since "exists" does not _mean_ "is perceived," it is, at least, conceivable that things should exist, when they are not perceived. But I have admitted that it is quite possible none _do_ so: it _may_ be the case that whenever a thing exists, it is _also_ at the same time perceived, for anything that I have said or shall say to the contrary. I think, indeed, that, if such things as colours _do_ exist, my observation of their behaviour will justify me in concluding that they also exist when I myself am, at least, not aware of perceiving them: but since I have not attempted to determine what kinds of observation are sufficient to justify a generalisation, I do not pretend to say whether this is so or not: and still less do I pretend to say whether, _if_ they exist when _I_ do not perceive them, we are justified in supposing that someone else must be perceiving them. The question whether anything exists, when it is not perceived, and, if so, what things, seems to me to be one which can only be settled by observation; and thus, I conceive, observation might justify us in concluding that certain kinds of things--pains, for example, do _not_ exist, when they are not perceived and that other kinds of things--colours, for example, _do_ exist, when they are not perceived. The only way, in which, so far as I am aware, the theory I am advocating does conflict with ordinary Idealistic conclusions, is that it does suggest that things, which are _not_ "spiritual," do _sometimes_ exist, as really and as truly, as things which are.

The theory, therefore, that nothing exists, except when it is perceived, is no objection (even if it be true) to the supposition that colours do exist. What objections are there to this supposition? All serious objections to it are, I think, of one type. They all rest upon the assumption that, if a certain kind of thing exists at a certain time in a certain place, certain other kinds of things cannot exist at the same time in the same place. They are all, that is to say, of the same type as Berkeley's argument: that, though the same body of water may _appear_ to be simultaneously both hot and cold (if one of the hands we plunge into it is warm and the other cold), yet the heat and the cold cannot both _really_ be in the same body at the same time. And it is worth noticing that anyone who uses this argument must admit that he understands what is meant by "really existing in a given place," and that he means by it something _other_ than "being perceived as in a given place." For the argument itself admits that _both_ the heat _and_ the cold _are_ really _perceived_ as being in the same place, and that there is no difficulty in supposing that they are so; whereas It urges that there _is_ a difficulty in supposing that they both _really exist_ in it.

Now there is one obvious defect in this type of argument, if designed to prove that _no_ sensible quality exists at any place where it is perceived as being--a defect, which Berkeley himself admits in his "Principles," though he omits to notice it where he repeats the argument in his "Hylas." Even if we assume that the heat and the cold cannot _both_ exist in the same place (and I admit that, in this case, the contrary assumption does seem repugnant to Common Sense), it does not follow that _neither_ exists there. That is to say this type of argument, even if we grant its initial assumption, will only entitle us to conclude that _some_ sensible qualities which we perceive as being in a certain place at a certain time, do not exist in that place at that time. And this conclusion, I am inclined to think, is true. In the case, for instance, of the so-called "images" which we perceive in a looking-glass, we may very readily admit that the colours and shapes which we perceive do _not_ exist at the places where they appear to be--namely at various distances behind the glass. But yet, so far as I can see, we have no reason whatever for supposing that they do not, _except_ the assumption that our observations give us reason to believe that _other_ sensible qualities _do_ exist in those positions behind the glass; and the assumption that _where_ these _other_ sensible qualities do exist, those which we see in the glass do _not_ exist. I should, therefore, admit that _some_ sensible qualities which we perceive as being in certain places, do _not_ exist in those places, while still retaining my belief that others do. And _perhaps_ this explanation is the one which should also be adopted in the case of sensible qualities which appear to be at a great distance from us. When, for instance, (as we say), "we see the moon," _what_ we perceive (if the moon be full) is a round bright silver disc, of a small size, at a place very distant from us. Does that silver disc exist at that place? With what suppositions does the assumption that it _does_ conflict? Only, so far as I can see, with the supposition that the place in question is _really_ occupied by a body such as science has taught us to suppose that the moon _really_ is--a spherical body immensely larger than objects, in comparison with which the silver disc which we perceive is small; _or else_ with the supposition that the place in question is really occupied by some part of our atmosphere, or some part of the medium which science supposes to exist between our atmosphere and the moon; _or else_ with the supposition that the place in question is really occupied by what we might see, if the moon were nearer to us by many thousands of miles. Unless we suppose that some other object _is_ in the place, in which the silver disc appears to be, and that this object is of a kind which cannot occupy the _same_ place which is occupied by a silver disc, we have no reason to suppose that the silver disc does _not_ really exist in the place where it appears to be. And, in this case, we _perhaps_ have reason for both suppositions and should therefore conclude that the silver disc, which we perceive, does not exist in any real place.

Part, therefore, of these objections to our theory may, I think, be met by admitting that _some_ of the ... sensible qualities which we perceive do not exist at the places where they appear to exist, though ethers do. But there is, I think, another class of cases, in which we may be justified in denying that two things which (it is asserted) cannot occupy the same space, really cannot. I will take an instance which is, I think, typical. When we look at a drop of blood with the naked eye, we perceive a small red spot, uniformly red all over. But when (as we say) we look at the _same_ object under a microscope of a certain power, I am informed that we see a much larger spot, of similar shape, indeed, but _not_ uniformly red--having, in fact, small red spots at different positions in a yellowish field. And if we were again to look at the _same_ object through a microscope of much higher power still, we might perceive yet a third different arrangement of colours. Is there any fatal objection to supposing that all _three_ appearances--the uniform red spot, the yellowish field with reddish spots in it, and the third, whatever that may be--do all really occupy the same real spatial area? I cannot see that there is. We are familiar with the idea that a given spatial area may contain parts which are invisible to us. And hence, I think it is quite conceivable that parts of a given area may be _really_ occupied by one colour, while the whole is _really_ occupied by another. And this, I think, is what we actually _do_ believe in many cases. At all events, we certainly believe that the area which appears to be occupied by one colour really is _the same area_ as that which appears to be occupied by another. And, unless we assume that the area, in both cases, really is the same, we can certainly have no reason to deny that each colour does really occupy the area which it appears to occupy.

For these reasons I think that the difficulties in the way of supposing that _some_ of the sensible qualities which we perceive as being in certain places, really exist in the places in which we perceive them to be, are not insuperable. I have indeed not done justice to these difficulties; but then, neither have I done justice to what is to be said on the other side. At all events, I think it is plain that we have no reason to assert, in any case whatever, that a perceived colour does _not_ really exist in the place where it is perceived as being, _unless_ we assume that that very same place really is occupied by something else_--either_ by some different sensible qualities _or_ by material objects such as physical science supposes to exist. But what reason can we give for such an assumption? I have tried to show that our own observations can give us none, _unless_ we assume that some of the sensible qualities, which we observe as occupying certain places, do really exist in those places. And, if this is so, then we must admit that neither he who believes (with Reid) in the existence of other minds and of matter also, nor he who believes in the existence of other minds and denies that of matter, can have, in his own observations, the slightest reason either for his assertion or for his denial: we must admit that he can have no reason for either assertion or denial, except one which consists in the assumption of the existence or nonexistence of something which he does _not_ observe--something, therefore, of the very same kind as that for which he gives it as a reason. I am very unwilling to suppose that this is the case: I am very unwilling to suppose that he who believes that Sindbad the Sailor really saw what the "Arabian Nights" represent him as seeing, has just as good reason (so far as his own observation goes) for believing this as he who denies it has for denying it. Still this may be the case. We _must_, perhaps, be content to assume as certain that for which our observation gives no reason: to assume such propositions as that Sindbad did _not_ see a Roc, and that you _do_ hear my voice. But if it is said that these things are certain; then it also appears to me to be certain that the colours which I perceive do exist (_some_ of them) where I perceive them. The more I look at objects round me, the more I am unable to resist the conviction that what I see does exist, as truly and as really, as my perception of it The conviction is overwhelming.

This being, then, the state of the case, I think I may at least plead that we have grounds for suspense of judgment as to whether what I see does _not_ really exist; grounds, too, for renewed enquiry, more careful than such enquiry has sometimes been in the past.

[1] Not now in 1921.

WILLIAM JAMES

My object in this paper is to discuss some of the things which Prof. William James says about truth in the recent book, to which he has given the above name.[1] In Lecture VI he professes to give an account of a theory, which he calls "the pragmatist theory of truth;" and he professes to give a briefer preliminary account of the same theory in Lecture II. Moreover, in Lecture VII, he goes on to make some further remarks about truth. In all these Lectures he seems to me to make statements to which there are very obvious objections; and my main object is to point out, as clearly and simply as I can, what seem to me to be the principal objections to some of these statements.

We may, I think, distinguish three different things which he seems particularly anxious to assert about truth.

(I) In the first place, he is plainly anxious to assert some connection between truth and "verification" or "utility." Our true ideas, he seems to say, are those that "work," in the sense that they are or can be "verified," or are "useful."

(II) In the second place, he seems to object to the view that truth is something "static" or "immutable." He is anxious to assert that truths are in some sense "mutable."

(III) In the third place, he asserts that "to an unascertainable extent our truths are man-made products" (p. 242).

To what he asserts under each of these three heads there are, I think, serious objections; and I now propose to point out what seem to me to be the principal ones, under each head separately.

(I)

Professor James is plainly anxious to assert _some_ connection between truth and "verification" or "utility." And that there is _some_ connection between them everybody will admit. That _many_ of our true ideas are verified; that _many_ of them can be verified; and that _many_ of them are useful, is, I take it, quite indisputable. But Professor James seems plainly to wish to assert something more than this. And one more thing which he wishes to assert is, I think, pretty plain. He suggests, at the beginning of Lecture VI, that he is going to tell us in what sense it is that our true ideas "agree with reality." Truth, he says, certainly _means_ their agreement with reality; the only question is as to what we are to understand by the words "agreement" and "reality" in this proposition. And he first briefly considers the theory, that the sense in which our true ideas agree with reality, is that they "copy" some reality. And he affirms that some of our true ideas really do do this. But he rejects the theory, as a theory of what truth means, on the ground that they do not _all_ do so. Plainly, therefore, he implies that no theory of what truth _means_ will be correct, unless it tells us of some property which belongs to _all_ our true ideas without exception. But his own theory is a theory of what truth means. Apparently, therefore, he wishes to assert that not only many but _all_ our true ideas are or can be verified; that _all_ of them are useful. And it is, I think, pretty plain that this is _one_ of the things which he wishes to assert.

Apparently, therefore, Professor James wishes to assert that _all_ our true ideas are or can be verified--that _all_ are useful. And certainly this is not a truism like the proposition that _many_ of them are so. Even if this were all that he meant, it would be worth discussing. But even this, I think, is not all. The very first proposition in which he expresses his theory is the following. "True ideas," he says (p. 201) "are those that we can assimilate, validate, corroborate and verify. False ideas are those that we cannot." And what does this mean? Let us, for brevity's sake, substitute the word "verify" alone for the four words which Professor James uses, as he himself subsequently seems to do. He asserts, then, that true ideas are _those which_ we can verify. And plainly he does not mean by this merely that _some_ of the ideas which we can verify are true, while plenty of others, which we can verify, are not true. The plain meaning of his words is that _all_ the ideas which we can verify are true. No one would use them who did not mean this. Apparently, therefore, Professor James means to assert not merely that we can verify all our true ideas; but also that all the ideas, which we can verify, are true. And so, too, with utility or usefulness. He seems to mean not merely that all our true ideas are useful; but that all those which are useful are true. This would follow, for one thing, from the fact that he seems to use the words "verification" or "verifiability" and "usefulness" as if they came to the same thing. But, in this case too, he asserts it in words that have but one plain meaning. "The true" he says (p. 222) "is only the expedient in the way of our thinking." "The true" is _the_ expedient: that is, _all_ expedient thinking is true. Or again: "An idea is 'true' so long as to believe it is profitable to our lives" (p. 75). That is to say, _every_ idea, which is profitable to our lives, is, while it is so, true. These words certainly have a plain enough meaning. Apparently, therefore, Professor James means to assert not merely that all true ideas are useful, but also that all useful ideas are true.

Professor James' words, then, do at least suggest that he wishes to assert all four of the following propositions. He wishes to assert, it would seem--

(1) That we can verify all those of our ideas, which are true.

(2) That all those among our ideas, which we can verify, are true.

(3) That all our true ideas are useful.

(4) That all those of our ideas, which are useful, are true.

These four propositions are what I propose first to consider. He does mean to assert them, at least. Very likely he wishes to assert something more even than these. He does, in fact, suggest that he means to assert, in addition, that these properties of "verifiability" and "utility" are the _only_ properties (beside that of being properly _called_ "true") which belong to all our true ideas and to none but true ideas. But this obviously cannot be true, unless all these four propositions are true. And therefore we may as well consider them first.

First, then, can we verify all our true ideas?

I wish only to point out the plainest and most obvious reasons why I think it is doubtful whether we can.