I have stated that method is essential to good thinking. I have given rules and examples of methodic thinking. But I do not want to create a false impression. If a man has not within him the materials of a thinker, no amount of method can make him one. Half the thinking process, as pointed out, depends on the occurrence of suggestions. The occurrence of suggestions depends on how ideas are associated in a man’s mind. While this depends to some extent on the education and the whole past life and environment of the individual, it depends far more on inborn mental qualities. All method can do is to awaken the most fruitful associations of ideas already in mind. Hence the more methods we adopt—the greater the number of views we take of any problem—the more solutions will suggest themselves. There is one further reason why we should take as many different viewpoints as possible. In our example of the inheritance of acquired characteristics in animals, if we had been sure that the results of our deductive reasoning were correct, it would have been a sinful waste of time to experiment. But when we attack a problem by several methods we can compare the results from each. If these results agree we have good evidence that our solution is correct. But if we have adopted quite a number of viewpoints, and have not let the results of one influence those of the next, they are almost certain to be at variance. This means that we have erred in applying one or several methods. How are we to find which of the methods it was, and how are we to prevent such errors? This is the subject of our next chapter. III A FEW CAUTIONS Thus far we have considered only positive and constructive thinking, and means for obtaining relevant suggestions. We have had almost nothing to do with cautions, means for avoiding fallacy and error, and means for testing the truth and value of suggestions. Most writers who have discussed thinking have dwelt so much on the negative aspect—so much on what we should not do—and have so slighted the question of what we should do, that I have perhaps been led to adopt this order, more from a feeling of revolt than because it is logically better. But I believe I have logic on my side. Constructive methods make thinking “go”; cautions steer it in the right path. An automobile without a steering gear is almost as useless as one without a motor. But an automobile can go without being steered, whereas it cannot be steered unless it is going. But while with automobiles we can clearly divide moving from steering, we cannot do this with thinking. The two processes are so inextricably bound up, that we cannot engage in one without engaging in the other; we cannot even speak of one without implying the other. I have divided them for convenience of exposition. But in the last chapter we were forced to deal slightly with cautions, and here we shall have to consider constructive methods to some extent.