Jacques Maritain Center : The First Principles of Knowledge

Chapter II.
The Trustworthiness of the Senses.


    (A) Preliminaries.

  1. How, as a fact, ordinary people come to believe in their own and other bodies, and in the sensible properties of both.
  2. The universal tendency so to believe in the reports of the senses is a strong presumption for the validity of the belief; but the matter must be argued out in form.
  3. Some distinctions and divisions useful in the course of the argument. (a) The number of the senses, and recent discoveries as to the action of the senses. (b) Division of the objects of sense. (c) Distinction between sensation and perception.

  4. (B) Proof.

  5. We start the proof from the admitted community of experiences between our adversaries and ourselves as to the sensible world.
  6. Then the trustworthiness of a man's senses is proved; for (a) that they testify to the existence of his own body and of other bodies is shown (i.) by the admitted existence of other men," (ii.) by an analysis of the facts of sense perception, (iii.) by confirmatory considerations drawn from science: and (b) that they testify something as to the nature of these bodies is also a demonstrable fact.
  7. Summary of the long argument.


(A) It is admitted with tolerable unanimity that the acquisition of knowledge is a procesf, beginning with the senses; and, therefore, with an examination of their testimony we must start our critical nvestigation of certitude in detail. During the performance of this task it will be made apparent, how much we need the ideas of substance and efficient causality, and how little we could do, if we were to accept Professor Clifford's dictum, that "the word cause has no legitimate place in the science of philosophy; "or the saying of Reid, that "for anything we can prove to the contrary, the connexion between impression and sensation may be arbitrary," and that "causes have no proper efficiency as far as we know; "or lastly, the words of Professor Green,"{1} The greatest writer must fall into confusion when he brings under the conceptions of cause and substance the self-conscious thought which is their source; when, in Kantian language, he brings the source of the categories under the categories": for "the mind is not substance, but subject," in which "tersely put formula Hegel emphasizes his position towards the ordinary metaphysics." Such doctrines are absolutely fatal to the claim that man can gain real knowledge through the media of his senses.

1. The philosophical discussion of the validity of the senses may be aptly prefaced by a statement as to what is the way, and the highly reasonable way, in which ordinary people, through their senses, come to the recognition of an external world of matter, distinct from their own bodies. Apart from all philosophy, it is a commonly admitted truth -- which the idealist also allows when he is not idealizing, and still allows when he is idealizing, but in his own perverse way -- that each man has a body with a set of separate bodily senses attached; and that thus constituted the individual is placed in a world made up of things, which also are bodies. From earliest infancy, all through the long ceaseless course of education, which the senses have to undergo before they become fitting instruments of perception, and thenceforth continuously up to the end of healthy existence, man is ever receiving experiences which go to enforce the conclusion, that there is a thing which is his own body, and that, distinct from this, there are other bodies. Constant action and reaction between organism and environment, as also between different parts of the organism itself, serve to impress this conviction. Daily more and more is the reason satisfied that it is rightly interpreting the situation. It may be that no deliberate, explicitly designed line of argument is gone through: or that if such argument be explicitly attempted, it seems a failure, only obscuring what before was clear. This fact leads a number of writers to say, not accurately, that belief in an external world is not a rational process, that reason destroys natural conviction, and that only instinct is to be trusted. It is more satisfactory as a theory, and more in accordance with the truth of facts, to hold that while no mere verbal argument can contain the full cogency of proof, which is found in a life spent literally in knocking about the world and in being knocked about by it -- a life of thumps and bumps against hard matter; yet the argument is capable of verbal expression, in a form which meets the requirement of demonstration. The verbal form is not as forcible as the accumulated experience, but it is argumentatively valid, especially as it is addressed to those who have the experience. From the first tumbles of a child learning to walk, up to the last stumbles of an old man tottering at the verge of his grave, there is, first of all, strong non-philosophical proof that there is solid matter in and out of the human frame. Afterwards the nonphilosophical proof can take philosophic shape: in which transformation philosophy has nothing to rely upon except its power to give systematic shape to nature's spontaneous interpretation of experience.

2. That the common, spontaneous belief of mankind is what it is, affords strong presumption that it is right. Clifford, indeed, tries to cast doubt on the fact that the popular belief in an outer world is such as we assume it to be, but herein he is certainly wrong. So is Mill when he declares that apart from philosophic and theologic bias, his view contains all that mankind really believe. In point of fact the common persuasion is, that we have each a material organism, brought into varied contact with distinctly other matter: and in making this interpretation of the case the common voice, as we now wish to argue, is likely to be correct. For the belief concerns not abstruse, remote speculations, but one of the most fundamental, indispensable notions about the constitution of self-conscious human nature and of its surroundings. Assuredly the presumption is, that the easy, ready, and universal account rendered by our intelligent nature of itself, is better than the strained effort after theory, which, perhaps, its very advocates do not practically believe. Even Fichte himself confessed, that while idealism was, as he fancied, demonstrable, yet it would never be believed.

3. However, we must go beyond presumptions in favour of our thesis, and set about the solid business of proof; for which the way must first be prepared by a few divisions and distinctions, that throw light on the whole matter in hand.

We may leave alone the division of the senses into inner and outer, which raises the controversy whether the seat of all sensation alike is the brain, or whether the outer organs are likewise seats of sensation. Nevertheless, as we are going to treat principally of what are called "the outer senses," we shall do well to frame some answer to the question, How many these are, and how far has the old account of them been upset by modern physiology?

(a) To the traditional five senses modern writers make additions by splitting up what used to be comprised under the one faculty of Touch into several senses. The resulting new terms have now grown pretty familiar to a reading public that must have been sufficiently often brought across such phrases as "the muscular, sense," and "the sensations of organic life." It has heard also of special nerves, or special conditions of nerve, for perceiving heat: it knows of such curious facts as are implied in analgesia, or insensibility to pain, while there is no accompanying anaesthesia or insensibility to touch. A patient has seen the lancet approach the flesh, has felt the incision, and has wondered at the absence of suffering. Rarely there seems to be anaesthesia without analgesia. These facts are worth knowing; and any one who, treating of the validity of the senses, utterly ignored such discoveries might be suspected of incompetency. But really, on careful consideration it will appear, that with the exception of the stress laid on what is called the muscular sense for coming to the knowledge of resistance, of externality, of magnitude, and the like, few of the new ideas enter much into the present dispute. How for instance does it affect our problem, to be told that the rate of propagation in the nerve stimulus is rather slow, and that, on a rough estimate, while stimulus increases in geometric progression, sensibility increases only in arithmetic? For our business, then, it is enough to have examined what is the style of modern discoveries with regard to the outer senses, in order to assure ourselves that these discoveries offer no obstacle to the arguments we are about to use, and then to decide that the old division into five senses will satisfy our requirements well enough, if we only remember that the division is not very precise. But the general fact itself, that there are different senses is a consideration of some weight in our problem; because it raises, for example, such questions as, how can these diverse senses be all true reporters, which report so differently of the same object?

(b) Next to the division of the senses comes a call for a division of the objects of sense; to meet which demand, obviously one way would be to let the first division settle the second. But there is another division which suggests itself to nearly every investigator, and is often introduced into the controversy upon which we are preparing to enter. For the distinction readily occurs, according to which some sensations are specially referred to the object felt, others specially to the subject feeling, and others not specially to either. The size of an apple, its taste, and the combined feeling of pressure and resistance to which it gives rise when the hand is placed upon it, are instances respectively of the three modes of sensitive experience.

Let us go back to Aristotle,{2} who distinguished with pretty much the same result as the above, those sensibles which can be reached by more than one sense -- ta koina aisthêta -- and those which can be reached by only one sense -- ta idia aisthêta. St. Thomas{3} calls the former sensibilia communia and the latter sensibilia propria. Thus, at least, in the educated condition of the senses, superficial extension is perceptible both to sight and touch, and is regarded as specially objective; colour, sound, odour, are each perceptible only by one sense, and are regarded as specially subjective. St. Thomas adds a third class, the "Things which fall accidentally under the senses, as when this Coloured object happens moreover to be a man."{4} Aristotle's parallel instance is seeing the son of Cleon. We see an object of definite colour, light and shade, outline; we know this to be a man, and even to be the son of a certain father: but these latter facts are not at the moment immediate objects of our sight; they are known aliunde. The corresponding classification in favour among English philosophers is that according to primary and secondary qualities; or as Hamilton puts it, into primary, secondary, and secundo-primary. He enters into great minutiae, hit we need not follow him. It is enough to have called attention to the fact, that whereas sensation includes an objective and a subjective side, sometimes our attention is called predominantly to the one, sometimes to the other, and sometimes neither side seems to predominate.

(c) Hamilton again distinguishes between sensation and perception. Those who push this distinction to the uttermost, describe sensation itself as mere subjective feeling, with no object to which it points, or as not a cognitive act.{5}

They make all perception a separate act, supervening on sensation; and they make it the business of the mind to trace this subjective state to some outer cause, almost as we might interpret the meaning of a foot-print in the sand, saying that it is the mark of an extinct animal. Reid only too manifestly tends to this extreme view and is therefore reprehended by Hamilton. He even goes further and almost leaves the work of assigning the objective origin of sensation in the hands of the Creator. Regarding the perception as an act only of the mind, Reid connects it with the sensation as with a mere antecedent, which may have no closer tie with the perception than the will of God, who has settled that, in fact, after a bodily impression, a mental expression shall follow.

It pertains to psychology to treat this matter, but we may state a few leading heads of doctrine. First of all, sensation itself is something neither purely mental, nor purely material. It belongs, as Hamilton says, to the animated organism, or to united soul and body; the proof of its compound nature being apparent in the felt phenomena, which are partly of a spiritual partly of a bodily character. This composite character of our sensations is of great importance in accounting for our notion of Space, which pure empiricists vainly seek to derive from non-spatial feelings, while the a priori school make it a subjective form of our faculty, which they call objective because all men alike have this form. As to whether, besides sensation, there is such a thing as sensitive perception, the condition of the lower animals, is an argument that there is. The Duke of Argyll appeals to our own experience in the matter as very convincing: but, while it is true that we have sense-perceptions, it is also true that we cannot begin reflectively to analyze them except in terms of intellectual perception. What is called the sense-perception of an object is often really the intellectual perception consequent on the sense perception.

(B) Now what, in the coming argument, we must chiefly have regard to, is precisely the intellectual perception and judgment about objects of which we are made cognisant through the medium of the senses. When intellectually we judge that there is an outer material world, having really such and such properties, then we have the act which this chapter is concerned to prove generically valid. We do not suppose outer objects immediately setting a seal upon the spiritual mind: and Ferrier is quite misconceiving our problem, when under the wrong notion just repudiated, he declares, "Descartes saw that things and the senses could no more transmit cognitions to the mind than a man can transmit to a beggar a guinea which he has not got."{6} We, too, see and confess as much: but what we deem still worthy to be examined into is, whether the intellect can arrive at judgments about the external world, because this world first acts on an animated organism adapted to feel and sensitively to perceive it; and because, on the occurrence of the sensitive perception, the intellect, which is only another activity of the same soul that takes part in the sensation, is adapted to form to itself ideas corresponding to the obects which excite its sensibility. Undoubtedly it is a very obscure point how the transition is made from sense to intellect; but, as we have to repeat so often, a fact may become apparent while its mode remains undiscoverable. The mode even of the mere sense-reaction has its obscurities, under cover of which some speak as though the re-agency were merely mechanical, and not the re-agency of a faculty, which, in its own lower order, is cognitive. Yet surely a sense-impression is not received simply like a stamp upon wax or a stroke on a bell. The proper attitude under obscurities is neither to deny ascertainable facts, nor to assert as facts what are fictions.

The above divisions and distinctions, even though seldom explicitly appealed to, are most valuable in shedding light on the matter about which we have now to argue; and the absence of them leaves a great haziness of mind, anything but conducive to the work of framing or appreciating arguments.

4. Briefly stated, the whole proof of the present thesis will consist in showing that the experienced facts of sensation are confessedly alike with our adversaries and ourselves, and that only our way of accounting for them is adequate. In other words, starting from the common ground of an admittedly double series in our sensations, we have next to show that the true account of the fact is what has been broadly expressed by the terms realism or dualism, which mean that there are two real divisions of things, "my body," and " bodies outside mine." Let us start with the declaration of what is common ground.

It would be very. awkward, indeed, for us, if we found adversaries asserting that they have no experiences answering to our own; that outer and inner objects, the different personal pronouns, I, you, and they, are terms which correspond to no distinctions in their consciousness. But it is the very complaint of the idealist that his admissions on these points are not recognized, and that he is supposed to be logically committed to an utter disregard of mad dogs, infuriated bulls, express trains, yawning abysses, on the one side; and on the other side, of good dinners, elegant dress, commodious lodgings, and entertaining company. His protest is that all ordinary forms of speech have a meaning for him. He allows that the sun, on present calculation, is about ninety millions of miles off; he expects in about a week to complete a voyage to America and find "the big continent" at the end. He would correct a child who mixed up the doings of Napoleon and of Wellington, and he claims to himself the exploits of neither: he does not at all allow that they are the fictions of his own fancy. Perhaps he will go so far as to talk of a time a long way back in the process of evolution, when consciousness as yet was not. Mr. Spencer thinks the idealist has no right so to speak, ever. Sully thinks he has, our view of the matter may be given later: at present let us turn to some examples in proof of the unanimity between idealists and realists as to the facts of experience for which an account has to be given. Of course only the idealists need be quoted.

Berkeley,{7} remarking that he can call up fantastic images as he likes, adds, "but when in broad daylight I open my eyes, it is not in my power to choose whether I shall see or not, or to determine what particular objects shall present themselves to my view." "The ideas of sense are more strong, lively, and distinct than those of the imagination. They have a liveliness, a steadiness, order, and coherence, and are not excited at random, as those which are the effects of human wills often are, but in regular train and series." Berkeley, it is true, was only a half-hearted idealist, though, as his notebook shows, he had thoughts of abolishing spiritual substance among created things, just as he abolished material substance,- and then he would have become wholly an idealist. If, however, we want a man who, according to his principles, ought to be the most out-and-out idealist, we have Berkeley's continuator, Hume: and he fully admits the contrast between the actual and the imaginary in our objects of thought. "Nature, by an absolute and uncontrollable necessity, has determined us to judge as well as to breathe and feel; nor can we any more forbear viewing certain objects in a stronger and fuller light upon account of their customary connexion with a present impression, than we can hinder ourselves from thinking as long as we are awake, or seeing the surrounding bodies when we turn our eyes towards them in broad sunshine. Whoever has undertaken to refute the cavils of this total scepticism has really disputed without an antagonist, and endeavoured, by argument, to establish a faculty which nature has antecedently implanted in the mind and rendered unavoidable."{8} Passing on to a great modern representative of Hume, we find Mill{9} owning to an experience like ours, as we gather from what he says about his belief in the permanent existence of icebergs, of a piece of white paper, and of the city of Calcutta. Elsewhere he distinctly recognizes his own bodily senses as the organs whereby he communicates with the external world. "Physical objects are, of course, known to us through the senses. By these channels, and not otherwise, we learn whatever we do learn concerning them. Without the senses we know no more of what they are than the senses tell us. Thus much, in the obvious meaning of the words, is denied by no one, though there are thinkers who prefer to express their meaning in other language." The twin philosopher with Mill, namely, Mr. Bain,{10} though he declares the question whether there is an outer world not to be even intelligible, yet clearly recognizes the experiences which we call those of the outer world: "The perception of matter points to a fundamental distinction in our experience. We are in one condition or attitude of mind when surveying a tree or a mountain. and in a totally different condition or attitude when luxuriating in warmth or suffering from a toothache. The difference here indicates the greatest contrast." And again: "Object means (a) what calls our muscular energies into play as opposed to passive feelings; (b) the uniform connexion of definite feelings with definite energies, as opposed to feelings unconnected with energies: (c) what affects all minds alike, as opposed to what varies in different minds. . . . The greatest antithesis among the phenomena of our mental constitution is the antithesis between the active and passive." A more appropriate quotation still may be given from the same chapter: To say that the perception of matter is an ultimate, indivisible, simple fact " is as doubtful in itself as it is at variance with the common belief. When we turn to the fact called perception, we cannot help being struck with the appearance at least of complexity. There is seemingly a combination of a perceiving mind, a mode of activity of that mind, a something to be perceived -- nothing less than the whole extended universe. To make out this seemingly threefold concurrence to be an indivisible fact, would at least demand a justifying explanation." Lastly, to quote the testimony of a prominent scientific man, who more than the common run of his brethren claims to be likewise a philosopher, Mr. Huxley admits that the realistic hypothesis so well satisfies the facts of the case that it may be true:{11} "there may be a real something which is the cause of our experience." This admission he unfortunately follows up by another admission, which shows the abyss of the agnosticism into which he has fallen, and to which we shall have repeatedly to recur afterwards, because it is such a clear declaration of his philosophical bankruptcy. "For any demonstration that can be given to the contrary effect, the collection of perceptions which makes up our consciousness may be an orderly phantasmagoria, generated by the Ego unfolding its successive scenes on the background of the abyss of nothingness; as a firework, which is but cunningly arranged combustibles, grows from a spark into a coruscation, and from a coruscation into figures and words and cascades of devouring flames, and then vanishes into the darkness of night."

This last avowal is not satisfactory: but at any rate we have the satisfactory result of finding a common account of the phenomena to be explained; and we may now go on to find proof of the manifest breakdown of the idealistic theory and of the manifest stability of the moderate realistic doctrine, when each respectively is called upon to explain the universally admitted facts of experience.

5. It is not with the whole of idealism that we have got to do, but only with the part which concerns the sensible world of matter. However, the fundamental difficulty, on which throughout idealism is based, is contained in the question, how can the individual get outside of itself? how can thought transcend itself? how can the subject know anything except its own affections ?{12} In reply we have to repeat the old truths, that we may be certain of a fact without being acquainted with the how of the fact; and that "from a fact to its possibility the inference is valid."{13} At least it is a piece of more gratuitous dogmatism than they seem to be aware of, when idealists lay it down a priori, that it is a plain self- contradiction to suppose the perception of an object, which object is other than the percipient. and known by him to be such. Not that there is no mystery in the process : indeed there is mystery even in the simplest instance of what we call a transient action, as when a moving body sets in motion a body before at rest. Still more is there mystery in the process of thought, an act at once physically immanent in the subject, and transient, as the scholastics say, intentionaliter, that is, having its term, so far as meaning and intelligence are concerned, something outside the subject. The mystery then we allow: but at the same time we contend, that however mysterious, still a fact which can be established ought to be recognized. In order to the establishment of the fact we have two points to prove: (a) that each one's senses testify to the existence of his own body and of bodies not his own; and (b) that they testify something about the nature of these bodies.

(a) In behalf of the former point three arguments may be adduced.

(i.) Our adversaries each assert the existence of other men, and it is on this ground that we will do battle with them in the first instance. Relegating all account of individual writers to a note in the Addenda, lest it should here perplex the course of an argument already sufficiently difficult in itself, we must be content to speak in quite general terms. We say, then, that on the strength of sensible manifestations, opponents are quite unwarranted in their inference that "other men" besides themselves exist. By the very principles of their position they are shut out from the conclusion that anything is truly other than their own sensations; and their pretence that "other men" are demonstrable while "external matter" is indemonstrable, can be kept up only by a delusion resting on great confusion of thought. For in the end it will be seen that the assumption of a known "external matter" is needful, and is employed in the argument whereby the conclusion is drawn that there are "other men." A reference to Mill's view, as explained in the Addenda, will make this point clear. The strength of our attack on the adversaries always lies in this: they assert distinctly "other men" with bodies like their own, and thereby they give up their own doctrine as to the power of the senses.

After showing the inability of idealists to defend their belief in "other men," we may now venture upon doing what they have failed to do, framing upon their suggestion an argument of our own, which, while it is not one ordinarily used in books, is an effective demonstration of the validity of the senses. The line of proof runs thus. We certainly do, through our senses and the material manifestations furnished to them by "other men," come to a sure knowledge that these men exist. But this could not be, unless our senses were valid means for reaching the knowledge of external bodies. Therefore our senses are such valid means. The major of the syllogism can be established in a special way, which will leave untouched the commoner arguments that are to be adduced presently. For, that we do come across other minds, is most clearly evidenced to us by the intellectual assistance we receive from them. It would require a very foolish or a verv shameless scholar, seriously to maintain that all the information he receives from teachers and books is really as much the exclusive product of his own mind, as that which he ordinarily calls his original thought or discovery; allowing this sole difference, that the former knowledge is accompanied by a special feeling of derivation from outside, which is, after all, only a part of his own inner consciousness. Let us think of our very, very wide indebtedness to other minds; how very much less than we are, we should have been, intellectually, had others not taught us orally or in writing; how very little we really know at first hand; and then let us try to swallow down, we might almost have called it the idealist joke on the subject, were it not that some idealists are manifestly in earnest. We feel that we have not powers of deglutition for so formidable a morsel. If then we really do come in contact with other minds, and draw knowledge from them, the intercommunion is certainly not one purely spiritual: it is through the senses and by means evidently material. With our bodily senses we approach those bodily objects, the books of the British Museum, the Natural History Specimens in its Kensington offshoot, the libraries, the custodians, and the professors, who, as experts, help us inexperts out of many a difficulty. Surely the least recognition we can pay to our kindly helpers is to acknowledge unreservedly their real, independent existence. Mr. Huxley, in spite of his theory that idealism cannot be disproved, expresses himself gratified with the tokens of esteem that he receives from former pupils. Now if he would goodnaturedly consider the impossibility of his barbouring any genuine doubt, as to whether he has been exercising and receiving the offices of real "altruism," or has simply been teaching himself under another form, and receiving from the pseudo-outsider compliments, which his modesty would have forbidden him undisguisedly to pay to himself; he might be brought to recognize that the existence and the actions of really "other men can be fully brought home as a conviction of the reason, and that idealism, in consequence, is exploded, not only practically, but theoretically. He would retract the already quoted passage, that for aught we can demonstrate to the contrary, all our thinking may be so many idle fireworks let off by the mind against "a background of nothingness."

Beyond a doubt, under the single category of the intellectual aids which we derive by our communication, through the senses, with our fellow-men, there lies proof positive that idealism is an insulting attempt to fool a man out of those faculties which are his birth-right. Because we are treating philosophically of the senses, we are not therefore to allow ourselves to be staggered "out of our five wits," by any phantom which a bit of sophistry may conjure up before us. Because we have on the philosophic mantle, we are not, therefore, to yield up that sound judgment which we possess, when we are, so to speak, in our shirt sleeves. In the latter condition we are reach, to fight a pretty vigorous battle for the reasonableness of trusting our senses; and there is nothing to prevent us, as philosophers, from doing the same stout battle. As philosophers we may affirm, what as ordinary men we affirm, that there is evidence from the senses, such as to warrant our belief in the existence of our fellow-mortals; and that in this conclusion is involved the wider proposition, that about the world of matter in general our senses can testify to its outer reality.

(ii.) To pass now from the consideration of "other men," a consideration which our adversaries have usefully forced upon us, we may turn to the arguments more commonly adduced on behalf of the senses by standard authors.{14} Each one who is unburdened by Kantian views as to space and time, may formulate to himself this argument in some such shape as the following: I can verify for myself, as an explorer, the existence of my own extended body, of definite shape and size. At least by repetition and comparison of experiences from different senses, I can become aware of my several sentient organs; of one sensation as being peculiar to one inlet, and another to another; of sights entering in at places different from the places where sounds enter. I can feel the double sense of contact, that of touching and being touched, when I place my right hand upon my left, and I can contrast this duplex sensation with the single sensation given by putting either hand upon the table. Gradually, if not at once, I can explore the limits of my sentient body. I find this body of mine at the same time brought into relation with other bodies, in such sort that the only rational interpretation of the situation is to say, these bodies are really not mine. I touch them and feel their resistance to my energies, but invariably without the double sense of touch or resistance which I usually have when it is one part against another part of my own body that I oppose. Conviction is, in a million instances, brought home to me that I am passively sentient, not of course with a pure passivity, under many outside influences -- influences which I cannot have at will, or carry about with me, or vary with the same degree of control which I have over a mere train of subjectively originated imaginations. The control in the latter case is indeed far from absolute, but at least it is perceptibly something. Nor can I persuade myself, on Hume's suggestion, to get over the difference between real and imaginary objects by attributing it only to a greater and less degree of subjective liveliness; for I have the means, while reason lasts, of detecting even very lively fantasies to be only fantasies.

So might a common man argue, and validly. It is because he so reasons that he is apt to receive the often inculcated lesson of scientific men, like Mr. Huxley, that about physical facts we must consult outer nature, and not try to evolve them from our inner consciousness. If we want personally to explore the home habits of the Polar bear, we must join a Polar expedition, which will mean a great deal more than the idea of a tedious and perilous voyage preceding the idea of finding what we seek. Yet according to strict idealists this is all thatis meant. For instance, Professor Huxley{15} that the analysis of the proposition, "Brain produces thought," "amounts to the following whenever those states of consciousness which are called sensation, motion, or thought, come into existence, complete investigation will show good reason for the belief that they are preceded by those other phenomena of consciousness to which we gave the names of matter and motion." As the Professor cannot mean that we always think of matter and motion before we think of consciousness, he has no right to call the cerebral motion which, on thetheory of brain producing thought, would be the antecedent of consciousness, by the name of a "phenomenon of consciousness." How can that antecedent be the phenomenal antecedent in consciousness which in consciousness does not antecede the result?

The main difficulty brought against this, which we have styled "the ordinary argument" for realism, is made to rest on impossible theories about the origin of the notion extension or outness. It is asserted that local outness is not given simply by the consciousness of one thought being other than a preceding thought, and then great labour is expended to develop externality in space out of succession in sentient states. These bugbears set up by a bad psychology must be encountered in the psychological treatise; but we in our own treatise at least are justified in claiming, on the strength of natural evidence, a clear idea of outness in space as derived through our sensitive experience. We need no more for the purposes of the line of proofjust brought to an end.

(iii.) It is not necessary to develop further the argument against idealism and for realism as furnishing the genuine account of those experienced differences between inner and outer bodies, which all parties admit, but some confirmation of what has been urged may be borrowed from Professor Tait's idea, that the great proof of external reality is the scientific truth that matter can neither be created nor annihilated. On idealist principles this proposition might still be held, but it would have very little value. As soon as the scientific man was persuaded that matter was only the objective side of his ideas, without ascertainable independent existence, he would care very little about its increase or decrease: and might even claim to increase and decrease it at will, at least under certain conditions.

Another confirmation, suggested by Mr. Spencer, and allowed by Mr. Balfour, but disallowed by Mr. Sully, lies in the assertion, that "if idealism is true, then evolution is a dream." For evolution supposes an indefinitely long period, during which there was no consciousness in the universe. Such a universe, as an existence, cannot have been ideal, and cannot be affirmed now by the idealist: for it would once have been a universe out of all human thought, which Mr. Bain, on his principles, rightly concludes to be a "manifest contradiction."

(b) Some, conceding to us all which so far we have been pressing to prove, but not all we have actually proved, would bid us stop short here; they admit that we have evidence for predicating the bare existence of bodies outside our own, but nothing more; we can say nothing of their attributes or nature. Kant, in some passages, but not in all, takes up exactly this position, and Schopenhauer declares "he must be abandoned by all the gods who imagines that there exists outside of us a real world of objects corresponding to our representations."

At this juncture the distinction is of some use between what are called primary and secondary qualities, though it is not to be pushed to excess, as though any sensible quality could be perceived as quite out of all relation to sense. We may contrast the relations we affirm between the object and the organism of the subject, with the relations we affirm between one object and another. Whether sugar is sweet, ginger hot, and aloes bitter, depends upon the subject, and would change with a possible change of subject; but no change of the subject's faculties could validly report that St. Paul's would go inside the smallest shop in Paternoster Row, and that a strip of carpet, which we have in a corner of the room, would cover the whole floor. It is true enough that all objects, whether primary or secondary qualities, affect our senses relatively to the structure of our organs; but not only can there be no knowledge of relations without some knowledge of the absolute terms which are related, but in asserting one class of relations between external bodies, we assert that which would not change with a change of our organism, though this latter change might increase or decrease our perception of the outer facts. That a whale is larger than a whiting does not depend on any percipient organism, but is true for any organism that can perceive it.

Again, when we think of some well-established chemical analysis, for example, the resolution of water into two gases, we ask ourselves, is there no real insight into the nature of things here? Is physical science so devoid of objective reality as to tell us nothing of "things themselves," in the rational meaning of that phrase? Is the resistance we directly encounter from external objects nothing proper to the objects themselves? Is it a fact that we can regard it only under the false analogy of a will-power, never as a material power? It is suicidal in the idealist to quote, as he does, the instances of light and heat, and to argue his case with an air of triumph, from the fact that vibrations of a fluid medium are quite unlike the sensations of sight and hearing. He forgets that it has been by the senses that the vibrations have been discovered, and that if the scientific result is worth anything, it proves the ability of the senses to give us information about facts as they are in external nature. To urge in replv that these facts are, for us, only as known bv us, not as existing out of relation to all knowledge, is futile; for this does not prove that we cannot know objects as they really are. We do not know all about them, but that we never claimed to know; at least we know something, and that contradicts idealism.

In saying that our knowledge is a compound of subjective and objective elements inextricably combined, adversaries make the mistake of going simply on the analogy of a chemical composition.{16} Water is neither oxygen nor hydrogen, being a chemical compound of the two. But thought is not a chemical compound, having for its constituents object and subject. Materially the known object has not to be shot into the mind and fused with it. The reaction of mind after the stimulation of the senses, is not any kind of a reaction, but a definite, most peculiar, and most exalted one. And the argument which urges that no knowledge attains to reality as it is, because all is relative, is so radically false, that it includes not only finite minds, but all minds, even the Divine, and denies to God Himself an absolute knowledge. Its perspicacious and consistent advocates boldly affirm, that from its very nature no knowledge can be absolute, attaining to the thing as it is; knowledge must be relative, must transfigure its object, must mix up elements or forms of self with elements or forms of non-self. No such a priori reasonings are valid. There is no demonstration that even a finite faculty must so transfer its own conditions to objects as known by it, that it can know nothing rightly. The only point demonstrated is, that a finite faculty will have many limitations, because of its imperfection; but that knowledge, as such, cannot in any intellect be absolute and complete, is the merest piece of perverse dogmatism, without the shadow of a proof. Lay bare the falseness of an analogy between knowledge and chemical combination, and all argument for the dogma collapses.

Let us end with an illustration from one of the primary qualities of body, impenetrability, A poor prisoner in Newgate does not beat idly against the walls of his cell, like a bird just caged. For intellectually he perceives that huge blocks of masonry are hopeless obstacles; that they bar the progress of a man who would walk through them. Immoveably they occupy the space where they now are, and in the fact that two different material bodies cannot naturally{17} occupy together identically the same space, consists the familiar property of impenetrability. So thinks the prisoner. But Mr. Huxley, who is at large in the world, solemnly tells it, that, "if I say that impenetrability is a property of matter, all that I can really mean is, that the consciousness I call extension and the consciousness I call resistance, inevitably accompany one other." We cannot think of impenetrability without consciousness; but all the same we can know impenetrability to be a real property found in unconscious matter, and belonging to it, not because of our consciousness.

While maintaining that our senses enable us to form some correct judgments about matter and its properties, we fully admit how far from exhaustive is our knowledge. Take for example the properties of extension in space and succession in time. A Catholic least of all would arrogate to himself, on these points, a comprehensive acquaintance; for some of the mysteries of his faith warn him to the contrary. He easily admits these to involve no clear impossibilities; for he easily admits his own ignorance, and the possibility of that being brought about preternaturally, which naturally would not be. But he does not, on that account, easily forego his own knowledge of simpler truths about the material universe, so long as matter is left in those normal conditions with which he ran familiarize himself.

6. Our argument, which has been long rather than abstruse, calling for patience rather than for extraordinary penetration, may now be summarized. In the phenomena of sense-perception rival schools are substantially agreed about the conscious experiences of which an account has to be rendered. Pure idealists, on their own principles, cannot use sensible manifestations to make certain of the existence of other men like themselves; they assert these "other men," but inconsistently, and at the price of renouncing their theory, and coming over to our side. Contrariwise we realists find a strong argument for our doctrine in finding how enormous is the help we receive from our fellows through the aid of the senses. Again, idealists allow, but do not account for the general contrast between sensations of self and sensations stimulated by bodies outside self: whereas we render a rational interpretation of the antithesis -- an interpretation so rational that Mr. Bain himself, writing in Mind, can condescend to say: "Every one of us readily admits that our impressions are transient things; yet they come up again with astonishing regularity in the appropriate situations; and the easiest way of figuring to ourselves this regularity is to suppose a permanent something, with all its parts well knit together, so as to repeat our ocnscious state with a fixity that we actually find. This is ordinary realism The scientific doctrine of the constancy of the sum total of matter, and the evolutionary hypothesis, accordinto which, for a long time, there was no conscious existence in the material universe, are conceptions which are badly in accord with idealism, but intelligible to realism, even when the realist does not believe that all life has been developed by the mere self-organization of dead matter. Moreover, not only have we proof of the existence of our own and other bodies, but likewise it is clear that we know something about their nature and their attributes. It would be to know something, if we could predicate of them only the secondary qualities, as that sugar is an object exciting a sweet taste in the palate, and that vinegar rouses an acid feeling; but we can go further and know the primary and more intellectual qualities; for instance, we know about extended space such truths as geometry teaches, and we know about motion such laws as help to form the science of mechanics. The judgment may at times err in its interpretation of the object which is exciting a sensation, but the senses themselves always report what, under the circumstances, they ought to report; and no sensation, as such, can be false. Under the normal condition of the faculties, there is no sensation which is not, of its own nature, calculated to give some information about the material world. A diseased state of organism may baffle the understanding; but it is beyond cavil that there is a state of organism which is normal, and which we have a right to assume as our standard for testing the validity of the senses. Thus, an examination of the whole case leads to the conclusion, that the common belief in the testimony of the senses is well within the bounds of reasonable procedure; and that, in doing what he cannot help as regards trust in his senses, man is not being driven by a blind instinct, but is acting according to his intelligent nature. The instincts of a blind nature are blind; but the instincts of an intelligent nature may often be shown to be intelligent. It is so with our use of the senses.


(1) We omitted (with a view to avoiding distraction from the main argument) any details as to the way in which our opponents come to the assertion of "other men" beside themselves; these may now be supplied. The substance of Mill's view is contained in the following passage:{a} "I am aware of a group of Permanent Possibilities of Sensation which I call my body, and which my experience shows to be a universal condition of every part of my thread of consciousness. And I am also aware of a great number of other groups, resembling the one I call my body, but which have no connexion, such as that has, with the remainder of my thread of consciousness. This disposes me to draw an inductive inference, that other groups are connected with other threads of consciousness, as mine is with my own. If the evidence stopped here the inference would be but an hypothesis, reaching only to the inferior degree of inductive evidence called analogy. The evidence, however, does not stop here: for having made the supposition that real feelings, though not experienced by myself, lie behind these phenomena of my own consciousness, which from the resemblance to my own body I call other human bodies, I find that my subsequent consciousness presents these very sensations of speech heard, of movements and other outward demeanour seen, and so forth, which being the effects or consequences of actual feeling in my own case, I should expect to follow upon those other hypothetical feelings, if they really existed: and thus the hypothesis is verified. It is thus Proved inductively that there is a sphere beyond my consciousness, that there are other consciousnesses beyond it. There exists no parallel evidence in regard to matter."

Now the fact is, that Mill proves his "other consciousnesses" only on the tacit assumption of "other matter:" and to real otherness in either department he can never logically attain. For logically he has no right to pass beyond the limits of subjective idealism. Mr. Balfour{b} is positive in the assertion that "there can be no doubt that Mill considered himself an idealist" and certainly he succeeded in establishing nothing above an idealistic existence for his "possibilities of sensation," however boldly, after denying the reality of substance and of efficient causality, he might arrogate to his "possibilities" both substance and efficient powers. It is part of the want of clear consistency in the man{c} to account for physical changes by "one group of possibilities of sensation modifying another such group)" whilst he also taught ,that all we are conscious of may be accounted for without supposing that we perceive matter by our senses: and that the notion and belief may have come to us by the laws of our constitution, without their being a revelation of any objective reality:" and that "the non ego altogether may be a mode in which the mind represents to itself the possible modifications of the ego." Again he asks: 'How do I know that magnitude is not exclusively a property of our sensations?" And he holds that we do not know whether, as affirmed of Matter itself, the word divisible has any meaning. Lastly, in controversy with Mr. Spencer,{d} he says: "Neither of us, if I understand Mr. Spencer's opinion arigbt, believe an attribute to be a real thing possessed of objective existence; we believe it to be a particular mode of naming our sensations, or our expectations of sensation, wben looked at in the relation of an external object which excites them: "yet so that these so-called "exciting objects" must not be considered either as substances, or as efficient causes, or as something really external and independent.

Mill being thus in many ways committed to idealism, cannot argue the existence of "other consciousnesses" or "other men," from the data of their external manifestations: he is wholly shut out from every notion of real "otherness." And yet that his argument does ultimately fall back on the inference of human agents from human activities, other than his own but like his own, will again appear, if we add a concluding specimen of his doctrine.{e} "By what evidence do I know that the walking and speaking figures which I see and hear, have sensations and thoughts -- in other words, possess minds? I conclude that other beings have feelings like me, because first, they have bodies like me; and secondly, because they exhibit acts and other outward signs, which in my own case I know to be caused by feelings." If Mill had once shown us how he arrived at the otherness of the manifestations, we could allow him the otherness of the human agents; but otherness is wholly denied to his principles.

Perhaps what Professor Clifford says will help to explain why Mill insisted so much on "other consciousnesses," namely, that while "material objects" may be spoken of as "the other side of my consciousness," it is absurd to speak of "other consciousnesses" as only "the other side of my consciousness." To signalize this special character, Clifford calls "other consciousnesses," not objects, but ejects, for they must be projected outside of self -- "they cannot be a group of my feelings persisting as a group." As to the difficulty of asserting any "otherness" beyond his own thinking self, Clifford thinks he need not waste time over considering a step which his ancestors took for him long ago.

M. Taine avowedly tries to lend a helping hand to Mill for the purpose of securing a little more reality to external objects than his friend's theory can afford. He allows that to us a stone is "a more or less elaborate extract from our sensations;" but further, "we may upon authentic evidence refer to things some of those more or less transformed and reduced materials, and attribute to such things a distinct existence without us, analogous to that which they have within. In this respect a stone is a being as real and as complete, as distinct from us, as any particular man. By this addition to the theory of Mill and Bain, we restore to bodies an actual existence, independent of our existence."

It is instructive to see idealists trying in vain to get of the position called solipsism," or belief in self alone. Especially they feel that "it is not good for man to be alone," and so they labour strenuously to justify their assertion of "other men" besides themselves; but always with the result of violating their own idealistic principles.

(2) On the subject of primary and secondary qualities of body, Hamilton teaches that we regard objects sometimes "as they are in themselves," sometimes "as they affect us," and sometimes in a half- and-half way: these last qualities he calls secundo-primary. For Hamilton's three terms others substitute mathematical, mechanical, and physiological properties; while Mr. Spencer prefers to use, as almost equivalent terms, statical, dynamical, and stato-dynamical.

(3) Though some regard materialism as the contrary extreme of idealism, Mr. Huxley is constant in his theory that an idealist may be a materialist, though he himself refuses to be either. Let us extend one of the quotations given in the text "If we analyze the proposition that all mental phenomena are the effects or products of material phenomena, all that materialism means amounts to this, that whenever these states of consciousness which we call sensations, or emotions, or thought, come into existence, complete investigation will show good reason for the belief, that they are preceded by other phenomena, to which we give the names of matter and motion. All material change appears in the long run to be modes of motion; but our knowledge of motion is nothing but that of a change in the places and order of our sensations: just as our knowledge of matter is restricted to those feelings of which we assume it to be the cause."{f} This comes to little more than the jejune announcement, that if matter be reduced to idealistic dimensions then materialism and idealism are reconciled. But how does this square with the evolutionary hypothesis that ideas, for a long time, did not uppear, but supervened, in comparatively recent times, on a world of unconscious matter, which cannot be reduced to feelings?

(4) The special form of idealism introduced by Berkeley has so few patrons that it is not necessary to labour much in its refutation. He supposed that all the sensible impressions, which we call material, were due, not to the action of any independent matter, but to the immediate agency of God. With regard to external bodies the difficulty of the theory is somewhat less; but with regard to our own bodies, it would be a task even to Omnipotence to make us feel ourselves as sentient, extended beings, if all the while we were pure spirits, of an essentially unextended nature. Moreover, given such a God as Berkeley rightly admitted, his theory as regards bodies other than our own, is dishonourable to the Creator rather than, as it alms at being, honourable. For an adequate reason, and after a sufficient warning, God may permit such deceptions as may take place through the senses, because of the mystery of the Blessed Eucharist, on the explanation given of it by Catholic theology; but He could not consistently with wisdom and truthfulness, arrange a wholesale system of delusion, such as only a Berkeley here and there would detect, while the mass of mankind were inevitably being duped. Few as have been Berkeley's followers, some of our modern writers in this country have an affinity to him, as, for example, Professors Green and Caird. One of these talks much about finite minds "becoming the vehicle of an eternal complete consciousness," which is "a consciousness operative throughout our successive acquirements, and realizing itself through them," "an eternal consciousness operative in us to produce the gradual development of our knowledge." These are some of Green's phrases, while Professor Caird's expressions are such as these: "The data of sense are taken out of their mere singularity of feelings and made elements in a universal consciousness: that is, they are related to a consciousness which the individual has not, as a mere individual, but as a universal subject of knowledge. Only in relation to such a consciousness can an individual know himself or any other individual as such." But, perhaps, it is Ferrier who most of all approaches to Berkeley. Ferrier, denying that matter per se has any meaning, makes the perception of matter the ultimate, indivisible unit of knowledge. He wholly rejects the analysis into perception as subjective, and matter as objective; he declares the subjective element to be our apprehension, that we perceive matter, and the objective element to be our perception of matter. Still, he will not allow that the perception of matter is a mere modification of our own minds: he will not lapse into subjective idealism. And it is thus he guards himself against this doctrine: "Our primitive conviction is, that the perception of matter is not, either wholly or in part, a condition of the human soul; is not bounded in any direction by the narrow limits of our intellectual span; but that it 'dwells apart,' a mighty and independent system, a city filled up and upheld by the everlasting God. Who told us that we were placed in a world composed of matter, and not that we were let down at once into a universe composed of external perceptions of matter, that were beforehand and from all eternity, and into which we, the creatures of a day, are merely allowed to participate by the gracious Power to whom they really appertain? When a man consults his own nature in an impartial spirit, he inevitably finds that his generous belief in the existence of matter, is not a belief in the independent existence of matter per se, but is a belief in the independent existence, of the perception of matter, which he is for a time participating in. The very last thing which he naturally believes in is, that the perception is a state of his own mind, and that the matter is something different from it, and exists apart in natura rerum. It is the perception of matter, and not matter per se, which is the kind of matter in the independent and permanent existence of which man reposes his belief. This theory of perception is a doctrine of pure intuitionism: it steers clear of all the perplexities of representationism."{g} Ferrier's great point of contention is that matter detached from thought is a delusion; for in pretending to detach it we are all the while thinking about it. It is like pretending to think ourselves annihilated; we find ourselves contemplating the condition; that is, we reintroduce the self we make show of abolishing. It is a simple answer to say, that though we can know matter only so far as it is an object of our ideas, yet we can know that this matter with certain properties has an existence outside our mind. There is no contradiction in the geologist affirming, Had I never discovered it, the fact would still have been, that this rock was scoured and striated by glacial action thousands of years ago.

(5) The very fact of having tried to argue out the validity of the senses is a confession that the result may be reached mediately; but this leaves untouched a further question, whether we have any primarily immediate perception of a material world as external, that is, whether we have any primary intuition of the outness of an object which we perceive, or whether externality at first can be reached only as a matter of inference. In point of fact, the process of ratiocination is so thoroughly a case of repeated and combined judgments, that the distinction put between the two acts, judgment and ratiocination, by logicians is not so radical as some suppose. We judge and judge again, and put our judgments together, but it is the same intellect which is at work throughout. Now every one will admit that in our present condition of experience we can in some cases immediately judge of externality; and every one will admit that the full reflex distinction between outer and inner world, was not made by the child without several repetitions of acts. So much being settled, we may leave it to psychologists to push further the investigation whether it is necessary to assume an immediate intuition of the externality of the sense-world, or whether the knowledge of this rests on a spontaneous inference as to the origin of some of our bodily affections -- an inference so spontaneous that it is taken for immediate perception. All sensations are bodily affections, and the inferential school say that it is only by argument that we can, in some of these affections, detect an outer cause; while the intuitive school declare that this process cannot have begun in argument, without an immediate perception. Outside the sense- world and in relation to metaphysical truths, it is certain that we have immediate intuitions of principles which we at once see to be objective and independent of ourselves; but how the case stands as regards the perception of the outer world of sense, gives rise to dispute among philosophers.

(6) Another psychological difficulty is also involved in our present inquiry. The passage from the image in the sensitive imagination to the idea in the mind is an obscure problem. The mind does not gaze upon the sensitive representation and consciously copy it. We are safe, however, in affirming, though the affirmation hardly amounts to an explanation, that because of the harmonious working of the faculties in a being whose author is all-skilful, when the sense image is duly present, the intellect has the power to produce its own corresponding image. The harmony is as natural, as certain, and as little ultimately explicable as the correlation of growth in the body, as the adaptation of bodily functions inter se, and as any symmetrical arrangement of organic parts; whilst, however, what we call nature has credit for so much, education must step in and take a large share in the formation of our power to perceive by the senses. Our education began so early, and has been so continuous and gradual, that we are apt to overlook the fact. It requires almost a case of congenital cataract cured in later life, to bring home,to us the need which the eye has of being trained to do its work. Most of our educated sense-perceptions are such, that what is actually, here and now, presented, is a small fraction of the whole, which is filled up by association or inference. Whatever revelations have been made by Wheatstone's ingenious contrivances for producing ocular illusions, by means of familiar effects under unfamiliar circumstances, all these we must readily acknowledge, without any fear for the truth of our main proposition that the senses are, in their own order, veracious.

(7) There is a deceptiveness about some authors who seem, in places, to agree with our realism, and yet do not. Thus Mr. Spencer argues for realism, and we may adopt some of his arguments. But a further knowledge of his system tells us that he reduces the really distinct phenomena of self and not-self to a basis in "one Unknowable Reality;" and others who do not explicitly make this final reduction, at least allow its probability. This is called "Monism," the doctrine that all manifestations, however different, are manifestations of but one underlying Entity; and the opposite doctrine is called, with less propriety, Dualism, which means that self and not-self are really distinct existences, the non-self being, of course, a congeries of many existences. The doctrine maintained in this volume is clearly dualistic -- an explicit statement which may seem needless. But any one who has had experience of the difficulty of trying to put together all the various declarations of an author, for example, like Lewes, will feel thankful to a writer who will declare undisguisedly where he stands.

(8) Where Monism makes itself most awkwardly felt, is in the distinction between man and man. Probably Mr. Spurgeon does not more strongly feel that he is really not Mr. Huxley, than Mr. Huxley feels that he is not Mr. Spurgeon; and yet, if they are both manifestations of one "ultimate unknowable reality," the identification between them is closer than they might like. As we saw above, those who are idealists, or who admit idealism as possibly true, do not satisfy us that they have sufficiently applied their theory to the distinction between themselves and other men. They are far too apt to assume this distinction, and to argue only for the common nature of the distinct individuals. Thus Professor Clifford says: "I have absolutely no means of perceiving your mind. I judge by analogy that it exists, and the instinct which leads me to come to that conclusion is the social instinct, as it has been formed in me by generations during which men have lived together; and they could not have lived together, unless they had gone upon that supposition." Similarly Mr. Huxley is intent mainly on the analogy between individuals, not on vindicating, according to his own principles, the real difference between individual and individual: "It is impossible absolutely to prove the presence or absence of consciousness in anything but one's own brain, though by analogy we are justified in assuming its existence in other men." He admits that he cannot be absolutely certain of any "otherness" beyond his own thougbts.

(9) We have taken as our standard the healthy condition of the senses; and without denying to Dr. Maudsley the use of pathological cases, yet we may dissent from the prominence which he gives to them. His professional dealing with so many abnormal specimens of humanity, seems to have given him an unfair opinion of the race in general, or of the average man; and in reading his books it is useful to bear this fact constantly in mind.

{1} Introduction to Hume, § 129, § 132. Compare Kuno Fischer's account of this same doctrine, which forms so important a part in Kantian philosophy: "Causality is not the product, but the condition of experience: it is not experienced, but makes experience. regard to the categories, this is the difference between Kant and Hume -- between criticism and scepticism." (Fischer on Kant's Critick,, c. iii. § vi. p. 89, Mahaffy's Translation.)

{2} De Anima, II. vi.

{3} Summa, Ia, q. xvii. a. ii. c.

{4} "Sensibilia per accidens, sicut quando huic colorato accidit esse hominem." (1.c.)

{5} For example, Lotze: "That which takes place in us immediately under the influence of an external stimulus, the sensation ot feeling, is in itself nothing but a state of our consciousness, a mood of ourselves;" it belongs to the activity of thought to convert this "impression" into an "idea." (Logic, pp. 10, 11.)

{6} Descartes is not uniform in his doctrine about the senses; but he has made distinct admissions that our theory need not imply anything like the literal transference of an image from sense to intellect. See a quotation in Mr. Huxley's Hume, p. 84.

{7} The Principles of Human Knowledge, nn. 28-31.

{8} Human Nature, Bk. 1. Part IV. § 1. As Hume wished to be judged by his later work, we may say that similar confessions are found in the Inquiry.

{9} Examination, c. ix. p. 127; c. xi. pp. 192, 199.

{10} Mental Science, Bk. II. c. vii. pp. 198-202.

{11} Huxley's Hume, p. iii. p. 81.

{12} See Mr. Bain's Mental Science, Bk. II. c. vii. p. 198. "The prevailing doctrine is, that a tree is something in itself, apart from all perception; that by its luminous emanations it impresses our mind and is then perceived; the perception being an effect, and the impressing tree a [partial] cause. But the tree is known only through perception, we can think of it as perceived, but not as unperceived. There is a manifest contradiction in the supposition; at the same moment we are required to perceive and not perceive."

{13} "Ab esse ad posse valet illatio."

{14} Tongiorgi, Logica, Part II. Lib. II. cap. iii.; Logik und Erkenntnisstheorie, von Dr. C. Gutberlet, Zweites Kapitel, pp. 174, seq.

{15} Huxley's Hume, c. iii. pp. 80, 81.

{16} Kantians sometimes speak in this sense, and sometimes they make the whole perception subjective. "The external object, or what we call the thing without us, is not by any means the thing per se. The thing without us, resolved into its elements, consists of sensation and intuition, partly our datum and partly our product: it is nothing but our phenomenon, our representation. The thing per se is a term by which we designate the very opposite of this, namely what ca never be phenomenon or representation." (Fischer on Kant's Critick, pp. 53, 54.)

{17} We say naturally, because we do not deny that preternaturally two bodies may together be in the same place. Hence it is not wholly true to say that the "otherness" of bodies loses its objective reality, if with Kant we make space not something, in our sense of the word, objective, but a mental form of the subject; for "otherness" radically rests not on difference in space, but on the fact that this body individually is not the other body.

{a} Examination, Appendix, p. 253.

{b} A Defence of Philosophical Doubt, c. ix. p. 186.

{c} Logic, Bk. I. c. iii. § 5, 7, 8, 9, et alibi passim.

{d} Logic, Bk. II. c. ii. § 3, in a note at the end of the paragraph.

{e} Examination, c. xii. p. 208.

{f} Huxley's Hume, c. iii. pp. 80, 81.

{g} Ferrier's Remains, Vol. II. pp. 454-456.

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