A brief course in the teaching process

CHAPTER VI
THE DEDUCTIVE LESSON

The complete process of thought involves both induction and deduction. Every general principle, unless it is self-evident, must either be arrived at through the process of induction, or be accepted without any attempt at verification. Having formed our generalizations, we use them as a basis for further thinking. If we find that the principle always holds, we are satisfied with its validity. In this testing of the generalization tentatively made, the process of thought is deductive. The fact is that in the process which we designate as induction, deduction enters to verify our inference. In the face of the problem which can be settled only by reference to some established principle, we find ourselves questioning the generalizations formerly accepted, and the process of thought in solving our problem will involve induction as well as deduction. For convenience we treat the problems of teaching under the two heads, the inductive and the deductive lesson, according as one or the other type of thought seems to predominate in reasoning required to solve the problem involved.

Every one thinks deductively who has had sufficient experience to form any generalizations. In the early life of the child we find the psychological basis for deduction in the tendency to act in accordance with ideas. Children define things in terms of their function. Thus a hat is something to wear on the head; a drawer something to pull out and push in; a shovel something to move the sand with; and so for the other objects in the child world. A child makes a dog in clay, draws a picture of a flower, makes a house of his blocks—and in this way tests his ideas. Not all deductive thinking ends in motor activity; but we can never be satisfied with our deductions until we have established them experimentally. The question concerning our ideas always is, will they work?

Whenever we offer an explanation of our ideas or of our actions, the process of thought is deductive. Not that either adults or children often state the general principle upon which they base their statement or action. We are all only too prone to assume the general principle. The foolish answers which children give may be logical enough. From his very limited experience a boy may have generalized that grass is something to look at and not to be walked on, and that people always live in houses from four to ten stories high, with many families in a house. Now, if such erroneous generalizations have been developed, the way to handle the boy is not to laugh at his deductions from these premises, but rather to require him to state the generalizations upon which he has based his thinking, and to lead him to discover their inadequacy. It matters not what group of children one works with, this same need for a declaration of the principle upon which the argument is based, the generalization which covers the situation under consideration, will be found essential. That teacher does much for the children who frequently pushes them back to a statement of what they assume to be true. This statement is not always easy to make. Even with adults it is very common to explain action by reference to some feeling or attitude which it is assumed has some basis in reason. Some instinctive tendency, or a mode of feeling, thinking, or acting which has become habitual, frequently explains, but fails to justify our actions. The ability to state clearly what one assumes, and to claim as valid only such conclusions as are based on premises which are admitted to be true, is the mark of the man of unusual rationality.

There is no set of rules which a teacher may follow in order to make the children she teaches logically minded. On the other hand, all of her activity tends in some degree to encourage or to eliminate the logical habit of mind. The teacher who dogmatizes continually in her teaching can do little to overcome a like tendency in the children by conducting exercises logically correct. The wrong emphasis on correctness of the result, instead of correctness of the method employed in getting the result, encourages much illogical work and develops careless habits of thought. And it is just as true that an open-minded attitude on the part of the teacher will be reflected in the children. The teacher who insists upon the verification of generalizations, who asks children frequently to give the ground for the statements which they make, and who encourages reflection, will engender logical habits of thought.

To recognize the wide application of the deductive method in our thinking, one has only to consider what is meant by reflection. It is well also in this connection to remember that the habit of reflection distinguishes the educated from the uneducated man. It is not the number of experiences which makes the difference between men, but rather the use that has been made of those experiences. When we reflect, we think over, organize, and relate our past experiences. Suppose, for example, that some one makes the statement that corporal punishment should be banished from all schools. If you reflect upon such a thesis, you bring to bear your experiences, whether of action, observation, or thought stimulated by reading what some one else has said; and, as a result of your thinking, you consciously or unconsciously assume a general principle under which you feel satisfied that this question of discipline falls; and then you will refer all of your experiences to this principle, testing its validity by seeing whether or not it does uniformly hold. The process of thinking which you have employed is essentially deductive. If stated in the form of a syllogism, it might be expressed somewhat as follows:—

1. Any action which tends to brutalize either pupil or teacher should not be permitted in any school.

2. Corporal punishment tends to brutalize both teacher and pupil.

3. Hence corporal punishment should be banished from all schools.

The process of thought employed has led you to search for a general principle which you accept as true and which offers an explanation of the position which you take in agreeing that corporal punishment should be banished. If you are really reflecting, you will not stop with this reference to a generalization apparently true. Rather you will inquire whether in your experience the infliction of corporal punishment has tended to brutalize you. You will also ask yourself whether this is true of others, and to what degree. You will recall specific cases of punishment of this sort, and will try to decide whether the disadvantages or evil outweighed the good. Only after such careful thought is the process of reflection complete, and it is only then that you can feel satisfied of the soundness of the position which you have taken. It will be noted that the process of thought has been both inductive and deductive.

If children are to learn to reflect, they must have leisure to think over their past experiences. There is danger that in our desire for more knowledge and more activity on the part of our pupils, we may give them little time for reflection. To ask a child to state the significance of what he has done, to encourage him to examine every assumed truth in the light of his experience, and to state somewhat formally the result of his reflection is worth much more than the new experiences which might have been gained in the same length of time. The habit of reflection will be developed only when sufficient time is given for children to stop and take account of the experience which they have had, when respect is accorded the experiences of the individual, and when the teacher requires such work and guides children in the process.

An attempt has been made in the preceding pages to indicate in a general way the significance of the deductive method in our school work. It remains to indicate briefly the method of procedure in the conduct of class exercises which are essentially deductive in their nature. Such exercises will be found in any subject in which there is developed a body of general principles. For example, the real test of a pupil’s knowledge of a principle of arithmetic is found, not in familiarity with the process of induction by which the principle is derived, nor in his ability to apply this principle to the problems given in the book, immediately following the rule, all of which fit the generalization, but rather in his ability, when a miscellaneous list of problems is given, to pick out the principle which applies to this one case. The test of one’s knowledge of geography is found not simply in the facts which he knows, but also in his ability to explain phenomena or to anticipate situations by reference to a body of general principles.

The problem: From what has already been said it is clear that in deductive thinking, as well as when the process is inductive, the occasion for thought is found in a problem to be solved. We wish to know why a certain region is arid or what the possibilities of agriculture are in another, and we, therefore, recall our knowledge of the principles of geography in order to solve our problem. A moral situation confronts us; we need to act; and in response to this necessity we endeavor to refer the situation to some norm or standard of conduct which we accept as fundamental. The success of our work in securing clear thinking by children will always be conditioned by our success in enabling them to realize the significance of the problem presented for solution.

Finding the generalization or principles which fit the situation to be accounted for or explained is the next step. In order to accomplish this part of the process successfully one must be able to discover that which is essential and to neglect the non-essential in the problem to be solved. Suppose, for example, that the problem is: Why has the greater part of Africa not been settled by civilized men? The factor which is significant is the climate of this region, and it will be of no use for the pupil to recall the size of the continent, the color of its inhabitants, the fact that Livingstone made a journey across it, except that by eliminating these facts he may be brought to realize that none of them determine the situation, and hence he need no longer pay any attention to them. It is the function of the teacher to suggest to the pupil a number of alternatives and then to guide him in his search for the determining factor. For example, the teacher might ask: Is it because of the savage inhabitants, because of a lack of means of transportation, because the country is overrun by dangerous wild animals, or because of climate? Each of these classes of facts may be known to the pupils, and each in turn may be eliminated as non-determining factors until he comes finally to the last. He must then, provided he decides that climate may determine the availability of a region as a habitation for civilized man, discover under what condition of climate civilized man fails to make advance. He has thus fitted his situation, his problem, to the generalization under which it falls, and has, in fact, taken the next step in the process.

Inference: The inference that the greater part of Africa is not inhabited by civilized men because of adverse climatic conditions is arrived at just as soon as the pupil settles upon climate as the essential factor. Just as in the inductive process we pass immediately from the step of comparison and abstraction to the statement of the generalization, so in the deductive lesson, when once we have related the particular case under consideration to the principle which explains the situation, we are ready to state our inference. There is real value in making such a statement. The further process of verification depends upon a clear and definite statement of the inference; and the best test we have of the completion of the preceding step is the ability which the pupil shows to state his inference.

Verification: When the inference has been made, we have yet to satisfy ourselves concerning the validity of our reasoning by an appeal to known facts. Following the illustration already used, we should ask ourselves what has happened in the past to civilized men who have gone to Central Africa. We will be satisfied that our reasoning has been correct, only if all of the facts we are able to discover point unmistakably to the conclusion that the climate of the larger part of Africa is unendurable by civilized men.

The element which needs most emphasis in deductive teaching is the realization on the part of the teacher that the success of the process is directly proportional to the independence with which the pupil discovers for himself that which is essential in the situation under consideration, his attempt to fit or relate the particular case to the principle or generalization by which it will be explained, and his willingness, when he discovers his error by an attempted verification, to repeat the process. We do not think logically by having some one else do our thinking for us, nor is our growth measured by the uniformity with which we hit upon the correct solution of the problem at the first attempt. Rather we may measure success by the power of our pupils to criticize the reasoning which appears plausible until carefully scrutinized, and by their readiness to retrace their steps and to search for firmer ground when they have of their own accord given up a scheme of reasoning which has proved invalid.