d. System 153

e. Analogy as Step towards System 155 f. Negative Instance 158 g. Classification and Generalisation 159 h. Hypothesis 161

2. Deduction 162 a. Subsumption 163 b. Construction 163

3. Causation 164

4. The Postulate of Knowledge 165

5. Conclusion 166

{1}

LECTURE I THE PROBLEM OF LOGIC

_Difficulty of the science_

1. There is no science more difficult than that on which we are entering in these lectures. It is worth while to discuss the nature of this difficulty. It is a question of interest rather than of intricacy. All sciences have, perhaps, much the same possibilities of broad theory and subtle analysis. But Logic stands alone in the difficulty with which the student sustains his persuasion that its point of view is worth applying.

In most other sciences, even in the philosophical sciences, there is a continual stimulus to sense-perception, to curiosity, to human interest. The learner is called upon to dissect animals or plants, to undertake delicate manipulations with beautifully contrived instruments, to acquaint himself with the history of nations, with the genesis of worlds, with strange and novel speculations upon the nature of space, or with the industry and well-being of various classes among mankind at the present day. And these elements of novelty, these stimulations of sense-perception or of practical interest, carry us forward imperceptibly, and sustain our {2} eagerness to analyse and combine in theoretic completeness the novel matter thus constantly impinging upon us.

In Philosophy, and more especially in Logic, we can promise little or nothing of this kind. The teacher of Philosophy, from Socrates downwards, has talked about common things, things already familiar to his hearers. And although he calls upon them to think of these things in a peculiar way, and from an unaccustomed point of view, yet it is likely to be felt that he is demanding a new effort, without supplying a new interest. And it is a common experience, that after a time the mind rebels against this artificial attitude, which fatigues without instructing, if we have accustomed ourselves to understand by instruction the accumulation of new sense-perceptions and the extension of historical or scientific vision over a wider superficial area.

Now this I cannot help, and I will not disguise. In Philosophy, and in Logic above all, it must be so. The whole point and meaning of the study is that in it we re-traverse familiar ground, and survey it by unfamiliar processes. We do not, except accidentally, so much as widen our mental horizon. For those who care to understand, to trace the connecting principles and functions that permeate our intellectual world, there is indeed an interest of a peculiar kind. But even experienced students will occasionally feel the strain of attending to difficult distinctions, entirely without the excitement of novelty in sense-perception or of a practical bearing upon human life. It is this that makes Logic probably the hardest of all the sciences.

{3} _The problem stated_

2. We cannot hope to vanquish this difficulty unless we face it boldly from the first. There are in the old-fashioned Logic-books tricks and puzzles, fallacies and repartees, which can in some degree be made amusing; but of these I do not intend to speak. The course by which alone I can hope honestly to awaken a true logical interest among any who may be quite unfamiliar with the subject, is to approach the matter descriptively, and try to set before you fully and fairly what the problem is which the process of knowledge has to meet. And then it may be possible to claim a genuine theoretical curiosity--none the less genuine that it may be tinged with a sympathy for man’s common birthright of intelligence--for the detailed explanation of the means by which this problem is solved from day to day. Such an explanation is the science of Logic.

The problem may be thus introduced. Several of those present have, I believe, attended a previous course of lectures on Psychology. They have learned, I presume, to think of the mind as the course of consciousness, a continuous connected presentation, more or less emphasising within it various images, and groups of images and ideas, which may be roughly said to act and re-act upon each other, to cohere in systems, and to give rise to the perception of self. This course of consciousness, including certain latent elements, the existence of which it is necessary to assume, is an individual mind, attached to a particular body, and so far as we know, not separable from the actions and affections of that body. What is the connection between such a course of consciousness in any individual, and the world as that individual knows and wills it? This is the point at {4} which Psychology passes into Logic. Psychology treats of the course of ideas and feelings; Logic of the mental construction of reality. How does the course of my private ideas and feelings contain in it, for me, a world of things and persons which are _not merely in my mind_?

_World as Idea_

3. Schopenhauer called his great work, _The World as Will and Idea_. [1] Leaving out Will for the moment, let us consider the world “as Idea.”

“‘The world is my idea;’ [2] this is a truth which holds good for everything that lives and knows, though man alone can bring it into reflective and abstract consciousness. If he really does this, he has attained to philosophical wisdom. It then becomes clear and certain to him that what he knows is not a sun and an earth, but only an eye that sees a sun, a hand that feels an earth; that the world which surrounds him is there only as an idea, _i.e._ only in relation to something else, the consciousness which is himself. If any truth can be asserted _a priori_, it is this; for it is the expression of the most general form of all possible and thinkable experience: a form which is more general than time, space, or causality, for they all pre-suppose it.

.....

“No truth, therefore, is more certain, more independent of all others, and less in need of proof than this, that all that exists for knowledge, and, therefore, this whole world, is only object in relation to subject, perception of a perceiver, in a word, idea. This is obviously true of the past and the future, as well as of the present, of what is farthest off, as of {5} what is near; for it is true of time and space themselves, in which alone these distinctions arise. All that in any way belongs or can belong to the world is inevitably thus conditioned through the subject and exists only for the subject. The world is idea.”

[1] E. Tr. (Trubner, 1883).

[2] Schopenhauer, _op. cit._ beginning.

The world, then, for each of us, exists in the medium of our mind. It is a sort of building, of which the materials are our ideas and perceptions.

_The “world”_

4. So much for “idea.” What do we mean by “world”? A succession of images passing before us, or rather making up our consciousness, like a dream, is not a world. The term is very expressive; it is a favourite word in Shakespeare. When the courtier says —

“Hereafter, in a better world than this, I shall desire more love and knowledge of you,”

he does not mean, as I used to think, “in heaven”; he means in a better condition of social affairs. In “mad world, mad kings, mad composition,” the term means more especially the set of political and family connections within which extraordinary reversals of behaviour have just taken place. Often we use the expression, with a qualifying epithet, to indicate some particular sphere of connected action, “the ecclesiastical world,” “the political world,” and so forth. Always there seems to be implied the notion of a set of things or persons bound together by some common quality which enables them to act upon each other, and to constitute what is technically termed a “whole.” _The_ “world” _par excellence_, then, ought to mean the one connected set of things and persons which we all recognise {6} and refer to as the same, and as including ourselves along with all who use the word in the same sense.

Then the “world as idea” means no less than this, that the system of things and persons which surrounds all of us, and which each of us speaks of and refers to as the same for every one, exists for each of us as something built up in his own mind--the mind attached to his own body--and out of the material of his own mind.

_The animal’s world_

5. Let us illustrate this building up by thinking of the world, our surroundings, as an animal must be aware of it. The lowest beginnings of sight, for example, give no colour and no shape. An animal in this stage can, probably, only just take warning if a dark object comes between him and the light. Therefore he cannot have the ordered visual image of space definitely stretching away all round him, which is the primary basis of our idea of a world. He can move, no doubt, but there is nothing to make us suppose that he records and co-ordinates the results of his movements into anything like that permanent order of objects which must be constructed in some way by a human being even though born blind. Succession, we might say, is much more powerful with animals than co-existence; but we should have to guard ourselves against supposing that this was what we mean by succession, that is, a process definitely recognised as in time, with a connection of some reasonable kind between its phases. For the most part with animals out of sight is out of mind; if so, the present is not interpreted, enlarged, and arranged with reference to what is not present in time or space by them as it is by us. And therefore the consciousness of a single system of things, {7} permanent, and distinct from the momentary presentations of the senses, cannot, in all probability, grow up for them. If so, they have no real world, but only a dream world, [1] _i.e._ a world not contrasted with the stream of presentation, nor taken as the common theatre of all actions and events. This difference between the world of an animal and that of a human being, is a rough measure of what man does by mental or intellectual construction in making his world.

[1] The character of the sensory powers, which are strongest in many animals, contributes to this conclusion. Mr. F.H. Bradley is sure that his dog’s system of logic, if he had one, would run, “What exists smells; what does not smell is nothing.” The sense of smell can scarcely give rise to the idea of a world of objects. It has hardly any capacity of structural discernment.

_The world as objective_

6. We have now got the idea of a “world,” as a system of things and persons connected together, taken to be the same for oneself at different times and for different minds at the same time, yet existing, for oneself, in the medium of one’s individual consciousness.

We see at once that we cannot stop here. We have really got a contradiction. If the parts of our world are connected with each other, they are not merely dependent upon us, that is, upon the changes of our consciousness. And we all take them to be independent of us, in the sense that we do not suppose the presence or absence of our perception to make any difference to the world except by the continuance or cessation of our perception of it or of its parts. This is the state of mind in which we practically live, philosophers and all. I do not really take notice of any difference in mode of existence between the wall in front of me, which I see, and the wall behind me, which I {8} do not see. While you are in this lecture-hall, if you think of your rooms at home, you think of them as they look, that is, as they would look if you were there to see them. How else, indeed, could you think of them? This is practically necessary, and therefore, for practical purposes, true.

But if you take it as a theory, omitting the hypothetical factor, “if I was there to see,” you go wrong. You then treat your world as being, outside your consciousness, the same that it is inside your consciousness, without allowing for the withdrawal of your consciousness. You are then on the way to think that the world, _as you see, hear, and feel it_, is outside your mind, and that the sight, hearing, feeling, and the ideas born of them, are inside your mind as a sort of faint and imperfect _copy_ of the world which you then call “external,” _in the sense of outside the mind_.

_Common sense_

i. The first position was that of common sense. The second is that of common-sense theory. Common sense is quite justified. It says, “Things affect each other, but the mere presence and absence of our perception does not affect them.” For practical purposes we must treat them as being, when unapprehended by our minds, just the same as when apprehended by our minds. This is the first idea or rather postulate--for it is not a theoretical idea--of objectivity. Objective = “independent of our consciousness for practical purposes.”

_Common-sense theory_