To explain this we must call in our first fallacious principle, the Impatience of Doubt or Delay, the imperative inward need for a belief of some sort.
And this leads to another remark, that though for convenience of exposition, we separate these various influences, they are not separated in practice. They may and often do act all together, the Inner Sophist concentrating his forces.
Finally, it may be asked whether, seeing that illusions are the offspring of such highly respectable qualities as excess of energy, excess of feeling, excess of docility, it is a good thing for man to be disillusioned. The rose-colour that lies over the world for youth is projected from the abundant energy and feeling within: disillusion comes with failing energies, when hope is "unwilling to be fed". Is it good then to be disillusioned? The foregoing exposition would be egregiously wrong if the majority of mankind did not resent the intrusion of Reason and its organising lieutenant Logic. But really there is no danger that this intrusion succeeds to the extent of paralysing action and destroying feeling, and uprooting custom. The utmost that Logic can do is to modify the excess of these good qualities by setting forth the conditions of rational belief. The student who masters those conditions will soon see the practical wisdom of applying his knowledge only in cases where the grounds of rational belief are within his reach. To apply it to the consequences of every action would be to yield to that bias of incontinent activity which is, perhaps, our most fruitful source of error.
[Footnote 1:] Bain's Logic, bk. vi. chap. iii. Bacon intended his Idola to bear the same relation to his Novum Organum that Aristotle's Fallacies or Sophistical Tricks bore to the old Organum. But in truth, as I have already indicated, what Bacon classifies is our inbred tendencies to form idola or false images, and it is these same tendencies that make us liable to the fallacies named by Aristotle. Some of Aristotle's, as we shall see, are fallacies of Induction.
[Footnote 2:] Bagehot's Literary Studies, ii. 427.
III.—THE AXIOMS OF DIALECTIC AND OF SYLLOGISM.
There are certain principles known as the Laws of Thought or the Maxims of Consistency. They are variously expressed, variously demonstrated, and variously interpreted, but in one form or another they are often said to be the foundation of all Logic. It is even said that all the doctrines of Deductive or Syllogistic Logic may be educed from them. Let us take the most abstract expression of them, and see how they originated. Three laws are commonly given, named respectively the Law of Identity, the Law of Contradiction and the Law of Excluded Middle.
1. The Law of Identity. A is A. Socrates is Socrates. Guilt is guilt.
2. The Law of Contradiction. A is not not-A. Socrates is not other than Socrates. Guilt is not other than guilt. Or A is not at once b and not-b. Socrates is not at once good and not-good. Guilt is not at once punishable and not-punishable.
3. The Law of Excluded Middle. Everything is either A or not-A; or, A is either b or not-b. A given thing is either Socrates or not-Socrates, either guilty or not-guilty. It must be one or the other: no middle is possible.