Intelligence does not consist merely in a good memory, making possible the exact reproduction of experiences of long ago. A good memory in this sense contributes much toward a high degree of intelligence, but is not identical with it. Even the feeble-minded are often found to possess an astonishing capacity for retaining dates, poetry, music. But memory adapts the thought processes only to very simple and frequently recurring events. When the circumstances become complicated, it soon proves inadequate.
Imagine a servant sent on an errand. He finds it impossible to execute the instructions received from his master. That ends it, if he is deficient in intelligence. No instructions have been given for this case; thus there is nothing to do but to return home. But the thought of an intelligent servant is more comprehensive. He recalls his master’s situation and analogous cases; the probable purpose of the master’s order; other possibilities of realizing the same end. Thus he succeeds perhaps in reconstructing the totality of the conditions which led his master to send him, and in meeting these conditions.
Take another example. Of several physicians, all but one are mistaken in the diagnosis of a case. Why do they differ? Every disease is characterized by a multitude of symptoms. Some of them are obvious, so that no one can fail to notice them: the complaints of the patient. Others are more hidden, but no less important. The physician must search for them. Each symptom, for example, fever, lack of appetite, dizziness, megalomania, may appear in very different diseases. A definite group of symptoms in definite degrees of intensity is characteristic of a particular disease. Two conditions, therefore, must be fulfilled to make a correct diagnosis. The symptoms which are hidden must be called up by those which are obvious, so that the physician can search for them and determine whether they are present or absent; for without first thinking of them he cannot search for them. Secondly, the thought of the present and absent symptoms must reproduce the idea of the disease which is characterized by the presence or absence of just these symptoms. This reproduction is possible only in a mind in which all these ideas are very closely connected, forming a well-organized system. Where this is not the case, the less obvious symptoms cannot influence the decision, and the correctness of the diagnosis becomes a matter of chance.
Lack of intelligence, then, means a deficiency in the organization of ideas, a lack of those manifold interconnections by which a large number of ideas may enter into a unitary group—no matter how effectively each idea is associated with a small number of others, that is, how excellent the person’s memory. Intelligence means organization of ideas, manifold interconnection of all those ideas which ought to enter into a unitary group, because of the natural relations of the objective facts represented by them. The discovery of a physical law in a multitude of phenomena apparently unrelated, the interpretation of an historical event of which only a few details are directly known, are examples of intelligent thought which takes into consideration innumerable experiences neglected by the less intelligent mind. Neither memory alone nor attention alone is the foundation of intelligence, but a union of memory and attention. Energy of concentration must be combined with breadth of interest. It is clear that thought determined by both these conditions is more likely to agree with the enormously complicated events in the external world than thought which is governed mainly by one of them.
How does human intelligence differ from that of animals? That man is immeasurably superior to animals cannot be doubted. But human superiority does not consist in the possession of a higher faculty—let us call it reason—in no way dependent on the lower, animal faculties, to which it is added as a jeweler’s tools might be added to a blacksmith’s tools. The difference between the animal mind and the human mind is simply this: that the imaginative anticipation of possible experiences of the future is brought about in the human mind by means of more abstract and therefore more comprehensive ideas than in the animal mind. Man’s mind is by natural inheritance far more capable of forming abstract ideas than is the mind of the highest animals. Man is further immensely aided in abstract thought by language—his own invention—which furnishes him with symbols taking the place of the most complicated ideas, and because of their simplicity, effecting economy in mental work as tools and machines do in manual labor. Animals, too, possess symbols, cries; but their number is insignificant. The difference between man and animals is therefore only one of degree in properties which are common to both. But these degrees are indeed very far apart in the scale.
QUESTIONS
160. How does coherent thought differ from dreaming?
161. How does coherent thought differ from mere recurrent thought?
162. What are the conditions on which coherent thought depends?
163. What is the significance of language for coherent thought?