bundles of our own feelings. This special modification of idealism is peculiarly attractive to many men, because it supplies them with sceptical arguments ready to hand against any view they may wish to oppose, without their feeling forced to apply the same sceptical arguments. against any system of physical science which they may be inclined to favour. The peculiarly illogical character of this form of idealism it will be our endeavour clearly to point out in the eleventh chapter.

The opposite system to idealism-the truth of which Realism. we will do our best to prove in the present section of this work may be stated as follows: "All the different bodies and substances of the universe about us really exist independently of the mind, and with equal reality, whether they be perceived or not. Our senses make us aware not merely of our sensations, but also, and more directly, of the real, independent existence of such bodies, and acquaint us with their objective qualities. Our sensations themselves, though, of course, only subjective, yet serve to make known to us. the truth about objective existences-'things in themselves.' Our perception of objects does not in any way essentially alter them. External material objects exist independently of us, and are unlike the sensations they excite in us, while such sensations none the less produce in us perceptions which are like the objective properties of such material, external objects. Reason assures us that, in our pursuit of truth, we may repose securely on that spontaneous trust in the truthfulness of our natural faculties (when matured and employed with due care and attention) which is natural to us. We may also be absolutely certain that an external world really exists independently of us, and that its various parts really possess these very powers and properties which our senses and our reason combine to assure us such objects do, in fact, possess." This system is now commonly spoken of as "realism." *

Such are the two systems, standing in direct opposition Method of to each other, the truth of which we have now to examine,

* The word "realism" had originally, and still often has, a very different signification, as will be pointed out in the section on Science. See below, Sect. V., chap. xxv.

procedure.

and, if possible, arrive at a certain conclusion about. In considering this great problem, we shall first examine the relation it bears to physical science-which has made such wonderful progress since the time when idealism was propounded by Berkeley. The result of that examination. will, we believe, be to show that idealism cannot be held by followers of physical science, except at the cost of their mental consistency. Those physicists who believe they see truth in idealism must, in fact, hold two sets of truthsone set having to do with that system, and the other set having to do with physical science. They must thus, if we are right, maintain the truth of propositions which contradict each other, and this without being able in any way to reconcile them or remove the contradiction.

We shall next endeavour to show that all which idealists positively affirm is true, but that they fail to perceive another complementary truth, the neglect of which vitiates their system, and causes it not only to conflict with physical science, but with common sense also. In this contention we shall have to deal with what we believe to be the fundamental error of idealism and the fundamental truth of realism. All that will afterwards remain for us to do will be to consider, with as much care and thoroughness as possible, the various objections which have been brought against the validity of our natural and spontaneous persuasion that the external world has a real, independent existence. While passing these various objections in review, we shall find occasion to illustrate idealism more fully than we have been able to do in the brief statement given in this chapter, and, finally, we shall do our best to point out some of the special faults and inconsistencies of those modifications of idealism which have of late obtained a greater or less degree of popularity amongst us. This will conclude the second section of our book. Succeeding sections will be devoted to a consideration of the leading features of that world, the real and independent existence of which we are now endeavouring to make evident.

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CHAPTER VIII.

IDEALISM AND SCIENCE.

A belief in idealism conflicts with the physical sciences in so far as they are concerned with the causes of phenomena.

Idealism consistent with many simple perceptions-Physical science concerns the causes of our perceptions-Examples of scientific prediction-Astronomy-Biology-Evolution-Common sense and

66 idealism."

consistent

simple

STRANGE as it may at first sight appear to be, it is none Idealism the less true that very many of our ordinary, everyday with many perceptions and experiences fully admit of being expressed perceptions. in idealist phraseology, according to the explanations given of it by its supposed advocate in the foregoing chapter. Stranger still, the idealist representation of these simple experiences of ours is not only easily expressed, but the actual truths of that representation cannot be successfully contested if our perceptions really are, what idealists say they are, perceptions of our own ideas and sensations only. Advocates of idealism mostly confine themselves, as did Bishop Berkeley, to combating objections drawn from a consideration of our ordinary simple perceptions. They speak of perceptions such as our perceptions of an orange with its various sensible properties, or they discuss our imagination of such things as "a park with trees," or "a library with books," and so on. This mode of procedure was natural, because those who endeavoured to refute idealism made use of objections drawn from a consideration of such simple matters. If physical science was See above, p. 75.

See above, p. 73.

Physical

science con.

causes of our

merely made up of catalogues of phenomena, simultaneous and successive, of different kinds, the mere number and complexity of those phenomena, however prodigious, would not suffice to make idealist phraseology inapplicable to such science. If an orange may be but a bundle of feelings of different kinds, then the whole contents of a museum, of a geographical region, or of the whole solar system, may also be of similar nature and composition. Physical science, cerns the however, is something very different from a collection of perceptions catalogues of phenomena. It is a systematic investigation as to what are the causes of different phenomena, and it is also its task to try and explain how such causes act. It appeals, in justification of its declarations about causes, to its own successful predictions, and it is accepted just because its various predictions have again and again been justified by the event. Physical science, therefore, not only has to do with our perceptions, but with the causes of our perceptions. It says not only that we shall have experiences which we call "perceiving new bodies," or "new conditions of bodies," but how and why we shall come to have them.

Examples

of scientific

A prediction like the famed one of Leverrier, affords prediction: a striking example of scientific foresight, based on a belief astronomy. in material bodies acting as causes and acting in a certain

manner. Leverrier, by his observations of the planet Uranus-then thought to be the planet most distant from the centre of the solar system-felt sure that its movements must be influenced by the presence of another considerable, but yet unobserved, planet, still more distant from the sun. He also predicted, from a study of those movements, that this as yet unseen planet would be found in a particular place in the heavens at a particular time; and upon the telescope being made use of accordingly, that predicted body was actually for the first time seen, which is now known as the planet Neptune.

Astronomical science in this instance declared not only that we should perceive, under certain conditions, a new body, or, in idealist phraseology, "a new group of feelings," but also how and why we should perceive it. Evidently it really asserted what were the antecedent causes and the

actions of such causes, independently altogether of their being perceived or not perceived. Leverrier's anticipation about Neptune reposed on a conviction of the existence of really existing, independent, extended, material bodies with certain powers, including a really existing force of gravity exerted between Neptune and Uranus, modifying their motions. Let us try to express this in idealist phraseology: The presence of a certain group of feelings I call "Uranus" is accompanied by certain other feelings I call "its movements," and these are succeeded in me by a set of faint feelings I name "an idea of the influence of an external unknown body," together with "a feeling of anticipation" and ideas I call "a particular direction," and "at a particular time." These are again succeeded by other groups of feelings which I call "looking through a telescope at the time and in the direction thought of," after which occurs a final group of feelings which I describe as "seeing the new and predicted planet Neptune."

Over and above the grotesqueness of such modes of expression, which no man of science will feel really and truly portrays his own past mental experience, it is to be remarked that they do not at all represent the facts of the case. The idealist phraseology puts before us only groups. of feelings which co-exist or succeed arbitrarily and without any rational order or any evident reason why they should so co-exist or succeed. The idealist cannot say why the group of feelings he calls "the movements of Uranus should be related to another set of feelings, distinguished as "the influence of an external body," or why the feelings known as "looking through the telescope" should be succeeded by those called "seeing the planet Neptune." If nothing exists but feelings, and some unperceived first cause or agent--whether God or some other existencewhich alone produces them, then everything must depend on the action of that agent, and all secondary causes and interactions, such as those by which one body is supposed to act on another, can be nothing but deceitful, illusory appearances. But since physical science largely consists in a search after secondary causes and the laws of the interaction of bodies one on the other, a system which can take

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