[Sidenote: Science as knowledge of things in their causes and relations.]
The foregoing distinction may be valuable in the training of university students whose career is to be that of original research and discovery, but it has very little value for teachers in schools of lower grade. For ordinary purposes, science is the knowledge of things in their causes and relations. If the teacher begets the habit of asking why, and makes the pupils dissatisfied with simply knowing the how and the what, he has gone far towards making them thinkers in the scientific sense of the word.
How shall the knowledge of things in their causes and relations be attained? The mind first thinks things as isolated units apart from and without reference to other things. Under the impulse to know it resolves the thing into its elements or constituent parts, and then puts them together in a more complete idea of each thing as a whole. The boy whose curiosity impels him to take apart a watch or clock is following the bent of the mind to proceed analytically. If he does not try to put the pieces together, so that the reconstructed whole will keep time as before, he needs stimulus in the direction of synthetic thinking. Soon his interest in time-pieces leads him to detect similarities between American watches and those made in Switzerland, and he learns to classify time-pieces, to see a multitude of details and peculiarities at a glance, one characteristic or peculiarity bringing to his mind the distinctive parts and construction of every watch in a given class. From the way in which a given watch keeps time, he draws inferences in regard to the entire class. This is inductive thinking. From the conclusions he has framed, he makes up his mind as to the new watch which the jeweller offers him for sale. He is now thinking deductively.
[Sidenote: Distinction between laws and causes.]
From thinking things as units, the mind passes to thinking the relations of things. The adaptation of means to ends in play, in ministering to bodily wants, occupies the mind in very early stages of thinking. The gifts of the kindergarten appeal to this tendency in the mind, and help to develop it into habit and faculty. Design and its execution, means and end, the tool and its use, the raw material and the purpose for which it is to be used, thought-material and the essay in which it is to be formulated,—these are so many ways of thinking things or ideas in their relations. Not only may a relation become a distinct object of thought, but relations between relations, classes of relations,—for instance, in simple and compound proportion,—can thus be made to stand apart before the mind as distinct objects of thought. The most important of all these relations is that of cause and effect. How things come to be, their origin and development, the forces that make them what they are, are the questions of profound and abiding interest to the scientific mind. Laws are often spoken of as if they were causes. A law is a generalized statement of an invariable sequence of things or motions of things. We sometimes personify these sequences, and speak of them as if they were forces in nature. The laws are personified, as if they were conscious beings demanding obedience, and inflicting punishment for disobedience. The consciousness of the personification is lost, and then along with spelling nature with a capital letter, we fall into the mistake of making laws stand for the Maker and Creator of all things. Furthermore, it is very important to distinguish the ground of knowledge from causes that are operative in the world outside of mind. The rain of last night caused the streets to be muddy; but the condition of the streets, an effect of rainfall, may be the ground of our knowledge that it must have rained last night. The fact that the earth is flattened at the poles, or, in other words, that its curvature is less at the poles than at the equator, explains the fact that degrees of latitude get longer as we approach the poles. The former is the cause, the latter is an effect. But the mind drew the former as an inference from the determination of degrees of latitude by actual measurement. The effect became the ground of knowledge. Frequently the cause is known or inferred from its effect. That which is causal in the world of mind is effect in the world outside of mind; and that which is effect in nature becomes the ground of knowledge in the processes of thought. From this point as vantage-ground, we spy the land in which thinking becomes knowing.