But it could be applied quite easily to most questions. Suppose you wanted to determine beyond question which of two methods of teaching a given subject was the better. We shall assume for the moment that you have unlimited time and money to experiment. It may be thought that we could settle this simply by teaching one person according to one method and another person according to the other, and that we could determine the relative merits of each method from the progress made by each pupil. This, however, would be practically of no use whatever. One pupil might be naturally brighter than the other, and so would naturally learn quicker, even were he taught by an inferior method.
To make the experiment of any use we should first take two groups of pupils—the larger the better. For it is obvious that if we take a great number of pupils and place them in two groups the differences between the individuals will tend to offset one another. Let us say the subject is one in which the progress can be quantitatively measured, say typewriting, and let us suppose there are fifty pupils in each group. If after a given time all the pupils in one group had attained a greater speed with accuracy than all the pupils in the other, the test would be almost unquestionable. This would be even more conclusive if the groups were reasonably well balanced. For if all of one group were men and all of the other were boys, the men might make more rapid progress than the boys even with a less efficient system. But it should be easy to divide classes and groups so as to have a reasonable balance of intelligence between them. The probable result of any experiment would be that in neither class would all the pupils make more progress than all the pupils of the other, though you might find that the preponderating majority in one class improved faster than those in the other, and this would probably be sufficient to indicate the superiority of one method, even though one or two pupils in the second group progressed faster than one or two in the first.
I say “probably” because there are still many irrelevant factors which might influence the result. For instance, if you had a different teacher for each group, one group might make greater progress not because of the method but because of the teacher. This means either that one teacher should teach both groups, or that we should multiply the number of groups and the number of teachers, and have half the teachers teaching half the groups by one method, and the other half teaching by the other method. Of course here too the more we could multiply the number the better it would be. Even then there might be some reasonable question as to the validity of the experiment, for it might be that one method would tend to encourage faster progress at the beginning, but that the other would lead to greater progress in the long run. This could be determined only by carrying our experiment over a long period. And we might still have irrelevant factors, for the machines on which one group learnt to typewrite might be superior to those on which the other group learnt, and this factor would have to be eliminated in a similar way to the others.
The experimental method has been well summed up by Thomson and Tait in their Natural Philosophy:
“In all cases when a particular agent or cause is to be studied, experiments should be arranged in such a way as to lead if possible to results depending on it alone; or, if this cannot be done, they should be arranged so as to increase the effects due to the cause to be studied till these so far exceed the unavoidable concomitants, that the latter may be considered as only disturbing, not essentially modifying the effects of the principal agent.”
In all experiments one must exercise ingenuity in finding other causes besides the one to be studied which may possibly influence a result, and in eliminating these. It might benefit the reader considerably if he were to think out for himself how he would apply experiment in its most thoroughgoing form to solve a given question, say the inheritance of acquired characteristics.
I have now cited enough methods to at least indicate what “thinking with method” means. To satisfy a certain human craving all of these have been named, though sometimes arbitrarily. Of course each may have to be modified to some extent to adjust it to different problems. I must repeat: there are methods numberless, and some problems will require methods all their own.
But what is important is that every problem should be dealt with by as many methods as possible. Doubtless you have used, at some time or other in the course of your thinking, nearly every one of the methods I have so far suggested. But the point is not that you have never used these methods at all, but that you have not used them often enough. You were unaware what method you were using. Consequently you used it only occasionally. You used it only when you stumbled on it accidentally. To formulate methods is to bring them to your attention, so that you may use them always, thoroughly, correctly, consistently.
We have treated political science from most angles. We have applied more than one method to several other problems. To still further clarify, exemplify and impress this point, I shall show the application of method to one more subject.