28
those opinions. We are much nearer to finding truth when we search for it in broad daylight. Error, pursued rigorously to all that is implied in it, seldom fails to get detected by coming into collision with some known and admitted fact.
You will find abundance of people to tell you that logic is no help to thought, and that people cannot be taught to think by rules. Undoubtedly rules by themselves, without practice, go but a little way in teaching anything. But if the practice of thinking is not improved by rules, I venture to say it is the only difficult thing done by human beings that is not so. A man learns to saw wood principally by practice, but there are rules for doing it, grounded on the nature of the operation, and if he is not taught the rules, he will not saw well until he has discovered them for himself. Wherever there is a right way and a wrong, there must be a difference between them, and it must be possible to find out what the difference is; and when found out and expressed in words, it is a rule for the operation. If any one is inclined to disparage rules, I say to him, try to learn anything which there are rules for, without knowing the rules, and see how you succeed. To those who think lightly of the school logic, I say, take the trouble to learn it. You will easily do so in a few weeks, and you will see whether it is of no use to you in making your mind clear, and keeping you from stumbling in the dark over the most outrageous fallacies. Nobody, I believe, who has really learnt it, and who goes on using his mind, is insensible to its benefits, unless he started with a prejudice, or, like some eminent English and Scottish thinkers of the last century, is under the influence of a reaction against the exaggerated pretensions made by the schoolmen, not so much in behalf of logic as of the reasoning process itself. Still more highly must the use of logic be estimated, if we include in it, as we ought to do, the principles and rules of Induction as well as of Ratiocination. As the one logic guards us against bad deduction, so does the other against bad generalization, which is a still more universal error. If men easily err in arguing from one general proposition to another, still more easily do they go wrong in interpreting the observations made by themselves and others. There is nothing in which an untrained mind shows itself more hopelessly incapable, than in drawing the proper general conclusions from its own experience. And even trained minds, when all their training is on a special subject, and does not extend to the general principles of induction, are only kept right when there are ready opportunities of verifying their inferences by facts. Able scientific men, when they venture upon subjects in which they have no facts to check them, are often found drawing conclusions or making generalizations from their experi-
