the case; with itself? As a rule this test, like the preceding, gives only presumption. Nearly every original idea seems more or less unreasonable, inconsistent, at first sight. Nevertheless, the test is of great practical usefulness, in warning us to be cautious as to further investigation. Sometimes it is decisive, revealing fatal dishonesty or error. The lawyers use it constantly in this way. On one occasion Lincoln was defending a man charged with murder-the Grayson case. He obtained from the chief witness for the prosecution the sworn statement that he had himself seen the shooting by the light of the moon. Then Lincoln proved from an almanac that there was no moon on the night in question. 2. Its Importance. This test of the importance of an idea is used constantly by every man in practical life. Supposing that a given statement is true or that a suggested plan will work, what difference will it make on the whole? Is the amount at stake in one or another way sufficient to justify possible interference with other matters? Does it justify even further investigation? Many a project, irreproachable but trivial, is shown the door at this point. On the other hand, the executive with insight sometimes perceives a profoundly important issue at stake in something which appears to be trivial-as Henry Ford did in the case of the radiator cap. (See Chapter X.) Correctness of the Process of Reasoning Finally, we may test the reasoning, the accuracy that is to say, of the process by which one thought leads to another. This is the most certain, but the most difficult way of testing. Reasoning consists of a series or chain of judgments. You know-or believe-that a certain thing is true. You discover that that thing depends upon another so closely that if the first is true the second must be equally true. This in its turn you discover depends with equal closeness upon a third. You accept the third accordingly as equally true, and so on. Psychologists and lawyers, who must do their work thoroughly, have carefully worked out and classified the more frequent defects of reasoning, the ways in which we may be deceived in passing from one judgment to another, and have indicated convenient methods of detecting these errors. The difficulty is that these classifications made by psychologists and logicians for their own use are far too detailed and complicated for the busy executive. They are to be used by specialists. We may simplify these "rules," "tests," "canons," etc., applied to the process of reasoning somewhat as follows: When we seek to test the soundness of any argument, any process of reasoning whatever, we should apply to it the following three questions in as much detail as seems necessary. Correctness of Premises 1. Are the "premises," that is, the successive statements as to fact, accurate, correct? This is really applying to the single statements the test applied above to the whole idea. Often errors are discovered at this point. Take for example the argument: Interference with another man's business is illegal. Here, as a little reflection shows, the term "interference with another man's business" is used in two different senses in the first and second statements. Incorrect Sequence-Analogy 2. Do the premises really lead to the conclusion offered? Under this come at least two possible cases: (a) Is the apparent connection of premises with conclusion merely accidental; for instance, is the relation of premises and conclusion merely one of analogy? The following instance seems so extravagant as to be quite improbable, yet we have all known apparently sensible persons to reason just as hastily: "I positively refuse to employ any cashier in this bank who wears rubber heels," declared the president of a fairly prominent bank. "Such a man is dishonest." It was found that a former cashier, who wore rubber heels, had absconded with funds sufficient to entail a heavy loss upon the institution. In advocating business plans the temptation to use analogy is constant. It is not always so easily detected as in the following from a prospectus: "The history of the Standard Oil Company is known by everybody from Maine to California," announces a promoter, with much truth. "It is the greatest money-making industry in the world. The X Y Z Company does not expect to achieve such great financial success as the Standard Oil Company, but it is in the same line of business-refining-and therefore its stock should be purchased for the very great profits that seem to be assured for those who invest now in its treasury stock." Of course the fact that one oil company has succeeded is by no means proof positive that another will do so. Incorrect Sequence-Evidence Not Sufficient The second case under this head is even more troublesome : (b) Is the inference of conclusion from premises based upon too few instances, or upon those which are not representative? This is one of the chief causes of faulty reasoning in life and in business. It is important but often difficult to recollect that one swallow does not make a summer. The apparent success of a plan in a few cases, of which we have heard, cannot safely be taken as conclusive. In important matters a decision should be based on instances which are sufficient. The following is from an advertisement of a school of advertising: Walter McMillan will serve as a good illustration of a Interesting but not conclusive. The formula "clerk+ Carlton College of Advertising course newspaper position +4 times former salary" is far from universal. An engineering company constructing a large power-plant dam was investigating the local rainfall and flood conditions. All the records for 18 years back showed moderate, even rainfall and no floods. But the investigators were not satisfied; they went back further yet; and they found that for the preceding 18-year period the records showed heavy rains and repeated floods. In all matters upon which statistics are supposed to be the final authority it is well to note whether or not these statistics cover sufficient cases to justify the conclusions drawn from them. The police reports in a certain Massachusetts town showed that its Turkish population was criminal to the astonishing degree of 300 per cent! Inquiry elicited the fact, however, that said Turkish population consisted of one man, who had been jailed for drunkenness three times! Errors of this nature have been responsible for the famous remark that there were three grades of liars; plain liars, d-d liars, and statisticians! Factors Overlooked 3. Have other and presumably important factors in the case been left out of consideration? This is the most frequent and most troublesome error for the business executive. The question he has to decide concerns the future-is it probable that such and such an action will be on the whole beneficial, profitable? Where human action is involved the factors are many and variable. "The winter before our ventilation system was installed," so runs the advertisement of a well-known manufacturer, "in this insurance company 271⁄2 per cent of the employees were absent owing to illness; the installation of our system the next winter cut this down to 71⁄2 per cent." Not proved. Perhaps a mild winter, or the absence of epidemics, or the engagement of a company physician, or the installation of a different heating system, etc., may have been even more responsible than the ventilation system for this decrease from 271⁄2 to 72 per cent. This example could be paralleled no doubt in the daily experience of almost every executive. The prudent man learns to look on all sides of a proposal before he lets his mind come to a final conclusion. Validity of These Tests This system described, we must repeat, consists merely in applying more deliberately and systematically the same sort of tests which we all apply in matters of daily life; whether or not to carry an overcoat this morning, whether to take this road or that, on a drive. In most of these little personal |