How We Think · John Dewey
THE NEED FOR TRAINING THOUGHT
II. By thought man also develops and arranges artificial signs to remind him in advance of consequences, and of ways of securing and avoiding them. As the trait just mentioned makes the difference between savage man and brute, so this trait makes the difference between civilized man and savage. A savage who has been shipwrecked in a river may note certain things which serve him as signs of danger in the future. But civilized man deliberately _makes_ such signs; he sets up in advance of wreckage warning buoys, and builds lighthouses where he sees signs that such events may occur. A savage reads weather signs with great expertness; civilized man institutes a weather service by which signs are artificially secured and information is distributed in advance of the appearance of any signs that could be detected without special methods. A savage finds his way skillfully through a wilderness by reading certain obscure indications; civilized man builds a highway which shows the road to all. The savage learns to detect the signs of fire and thereby to invent methods of producing flame; civilized man invents permanent conditions for producing light and heat whenever they are needed. The very essence of civilized culture is that we deliberately erect monuments and memorials, lest we forget; and deliberately institute, in advance of the happening of various contingencies and emergencies of life, devices for detecting their approach and registering their nature, for warding off what is unfavorable, or at least for protecting ourselves from its full impact and for making more secure and extensive what is favorable. All forms of artificial apparatus are intentionally designed modifications of natural things in order that they may serve better than in their natural estate to indicate the hidden, the absent, and the remote.
An English logician (Mr. Venn) has remarked that it may be questioned whether a dog _sees_ a rainbow any more than he apprehends the political constitution of the country in which he lives. The same principle applies to the kennel in which he sleeps and the meat that he eats. When he is sleepy, he goes to the kennel; when he is hungry, he is excited by the smell and color of meat; beyond this, in what sense does he see an _object_? Certainly he does not see a house--_i.e._ a thing with all the properties and relations of a permanent residence, _unless_ he is capable of making what is present a uniform sign of what is absent--unless he is capable of thought. Nor does he see what he eats _as_ meat unless it suggests the absent properties by virtue of which it is a certain joint of some animal, and is known to afford nourishment. Just what is left of an _object_ stripped of all such qualities of meaning, we cannot well say; but we can be sure that the object is then a very different sort of thing from the objects that we perceive. There is moreover no particular limit to the possibilities of growth in the fusion of a thing as it is to sense and as it is to thought, or as a sign of other things. The child today soon regards as constituent parts of objects qualities that once it required the intelligence of a Copernicus or a Newton to apprehend.
But this disciplinary training, efficacious as it is within certain limits, does not carry us beyond a restricted boundary. Logical attainment in one direction is no bar to extravagant conclusions in another. A savage expert in judging signs of the movements and location of animals that he hunts, will accept and gravely narrate the most preposterous yarns concerning the origin of their habits and structures. When there is no directly appreciable reaction of the inference upon the security and prosperity of life, there are no natural checks to the acceptance of wrong beliefs. Conclusions may be generated by a modicum of fact merely because the suggestions are vivid and interesting; a large accumulation of data may fail to suggest a proper conclusion because existing customs are averse to entertaining it. Independent of training, there is a "primitive credulity" which tends to make no distinction between what a trained mind calls fancy and that which it calls a reasonable conclusion. The face in the clouds is believed in as some sort of fact, merely because it is forcibly suggested. Natural intelligence is no barrier to the propagation of error, nor large but untrained experience to the accumulation of fixed false beliefs. Errors may support one another mutually and weave an ever larger and firmer fabric of misconception. Dreams, the positions of stars, the lines of the hand, may be regarded as valuable signs, and the fall of cards as an inevitable omen, while natural events of the most crucial significance go disregarded. Beliefs in portents of various kinds, now mere nook and cranny superstitions, were once universal. A long discipline in exact science was required for their conquest.
It is instructive to note some of the attempts that have been made to classify the main sources of error in reaching beliefs. Francis Bacon, for example, at the beginnings of modern scientific inquiry, enumerated four such classes, under the somewhat fantastic title of "idols" (Gr. [Greek: eidola], images), spectral forms that allure the mind into false paths. These he called the idols, or phantoms, of the (_a_) tribe, (_b_) the marketplace, (_c_) the cave or den, and (_d_) the theater; or, less metaphorically, (_a_) standing erroneous methods (or at least temptations to error) that have their roots in human nature generally; (_b_) those that come from intercourse and language; (_c_) those that are due to causes peculiar to a specific individual; and finally, (_d_) those that have their sources in the fashion or general current of a period. Classifying these causes of fallacious belief somewhat differently, we may say that two are intrinsic and two are extrinsic. Of the intrinsic, one is common to all men alike (such as the universal tendency to notice instances that corroborate a favorite belief more readily than those that contradict it), while the other resides in the specific temperament and habits of the given individual. Of the extrinsic, one proceeds from generic social conditions--like the tendency to suppose that there is a fact wherever there is a word, and no fact where there is no linguistic term--while the other proceeds from local and temporary social currents.
1. "That which is inconsistent with our _principles_ is so far from passing for probable with us that it will not be allowed possible. The reverence borne to these principles is so great, and their authority so paramount to all other, that the testimony, not only of other men, but the evidence of our own senses are often rejected, when they offer to vouch anything contrary to these _established rules_.... There is nothing more ordinary than children's receiving into their minds propositions ... from their parents, nurses, or those about them; which being insinuated in their unwary as well as unbiased understandings, and fastened by degrees, are at last (and this whether true or false) riveted there by long custom and education, beyond all possibility of being pulled out again. For men, when they are grown up, reflecting upon their opinions and finding those of this sort to be as ancient in their minds as their very memories, not having observed their early insinuation, nor by what means they got them, they are apt to reverence them as sacred things, and not to suffer them to be profaned, touched, or questioned." They take them as standards "to be the great and unerring deciders of truth and falsehood, and the judges to which they are to appeal in all manner of controversies."
Such attention consists in regulation (1) of the conditions under which the function of suggestion takes place, and (2) of the conditions under which credence is yielded to the suggestions that occur. Inference controlled in these two ways (the study of which in detail constitutes one of the chief objects of this book) forms _proof_. To prove a thing means primarily to try, to test it. The guest bidden to the wedding feast excused himself because he had to _prove_ his oxen. Exceptions are said to prove a rule; _i.e._ they furnish instances so extreme that they try in the severest fashion its applicability; if the rule will stand such a test, there is no good reason for further doubting it. Not until a thing has been tried--"tried out," in colloquial language--do we know its true worth. Till then it may be pretense, a bluff. But the thing that has come out victorious in a test or trial of strength carries its credentials with it; it is approved, because it has been proved. Its value is clearly evinced, shown, _i.e._ demonstrated. So it is with inferences. The mere fact that inference in general is an invaluable function does not guarantee, nor does it even help out the correctness of any particular inference. Any inference may go astray; and as we have seen, there are standing influences ever ready to assist its going wrong. _What is important, is that every inference shall be a tested inference_; _or_ (since often this is not possible) _that we shall discriminate between beliefs that rest upon tested evidence and those that do not, and shall be accordingly on our guard as to the kind and degree of assent yielded_.
Text from Project Gutenberg, public domain in the United States.