Scientific thinking is thus primarily inquiring and skeptical. It queries the usual; it tries, as we say, to penetrate beneath the surface. Common sense, for example, gives suction as the explanation of water rising in a pump. But where, as at a great height above sea level, this mysterious power of suction does not operate, or when it is found that it does not raise water above thirty-two feet, common sense is at a loss. Scientific thinking tries to analyze the gross fact, and by accurately and completely observing all the facts bearing on the phenomenon endeavors to find out "what special conditions are present when the effect occurs" and absent when it does not occur. Instead of trying to fit all unusual, contradictory, or exceptional facts into a priori ideas based on miscellaneous and unsifted facts, it starts without any fixed conclusions beforehand, but carefully observes all the facts which it can secure with reference to a particular problem, deliberately seeking the exceptional and unusual as crucial instances. Thus in a sociological inquiry, the scientist, instead of accepting "common-sense" judgments (based on a variety of miscellaneous, incomplete, and unsifted facts) that certain races are inferior or superior, tries, by specific inquiries, to establish the facts of racial capacities or defects. Instead of accepting proverbial wisdom and popular estimates of the relative capacities of men and women, he tries by careful observation and experiment accurately to discover all the facts bearing on the question, and to generalize from those facts.
Scientific method thus discounts prejudice or dogmatism. A prejudice is literally a pre-judgment. Common sense sizes up the situation beforehand. Instead of examining a situation in its own terms, and arriving at a conclusion, it starts with one. The so-called hard-headed man of common sense knows beforehand. He has a definite and stereotyped reaction for every situation with which he comes in contact. These rubber-stamp responses, these unconsidered generalizations, originate in instinctive desires, or in preferences acquired through habit. Common sense finds fixed pigeon holes into which to fit all the variety of specific circumstances and conditions which characterize experience. "When its judgments happen to be correct, it is almost as much a matter of good luck as of method.... That potatoes should be planted only during the crescent moon, that near the sea people are born at high tide and die at low tide, that a comet is an omen of danger, that bad luck follows the cracking of a mirror," all these are the results of common-sense observation. Matters of common knowledge are thus not infrequently matters of common misinformation.
Common-sense knowledge is largely a matter of uncritical belief. When there is absent scientific examination of the sources and grounds of belief, those judgments and conclusions are likely to be accepted which happen to have wide social currency and authority. In an earlier chapter, it was shown how the mere fact of an opinion prevailing among a large number of one's group or class gives it great emotional weight. Where opinions are not determined by intelligent examination and decision, they are determined by force of habit, early education, and the social influences to which one is constantly exposed.
The scientific spirit is a spirit of emancipated inquiry as contrasted with blind acceptance of belief upon authority. The phenomenal developments of modern science began when men ceased to accept authoritatively their beliefs about man and nature, and undertook to examine phenomena in their own terms. The phenomenal rise of modern science is coincident with the collapse of unquestioning faith as the leading ingredient of intellectual life.
Common sense renders men peculiarly insensitive to the possibilities of the novel, peculiarly susceptible to the influence of tradition. It was common sense that credited the influence of the position of the stars upon men's welfare, the power of old women as witches, and the unhealthiness of night air. It was common sense also that ridiculed Fulton's steamboat, laughed at the early attempts of telegraphy and telephony, and dismissed the aeroplane as an interesting toy. The characteristic feature of common sense or empirical thinking is its excess traditionalism, its wholesale acceptance of authority,[1] its reliance upon precedent. Where beliefs are not subjected to critical revision and examination, to the constant surveillance of the inquiring intelligence, there will be no criterion by which to estimate the true and the false, the important and the trivial. All beliefs that have wide social sanction, or that chime in with immediate sense impressions, established individual habits, or social customs will be accepted with the same indiscriminate hospitality. To common sense the sun does appear to go round the earth; the stick does appear broken in water. Thus "totally false opinions may appear to the holder of them to possess all the character of rationally verifiable truth."
[Footnote 1: "Authority" in this sense of social prestige must be distinguished from "authority" in the sense of scientific authority. The acceptance of the authority of the expert is the acceptance of opinions that we have good reason to believe are the result of scientific inquiry.]
The dangers and falsities of common-sense judgments are conditioned not only by expectations and standards fixed by the social environment, but by one's own personal predilections and aversions. Recent developments in psychology have made much of the fact that many of our so-called reasoned judgments are rationalizations, secondary reasons found after our initial, primary, and deep-seated emotional responses have been made. They are the result of emotional "complexes," fears, expectations, and desires of which we are not ourselves conscious.[1] It is from these limiting conditions of personal preference and social environment that scientific method frees us.
[Footnote 1: "When a party politician is called upon to consider a new measure, his verdict is largely determined by certain constant systems of ideas and trends of thought, constituting what is generally known as 'party bias.' We should describe these systems in our newly acquired terminology as his 'political complex.' The complex causes him to take up an attitude toward the proposed measure which is quite independent of any absolute merits that the latter may possess. If we argue with our politician, we shall find that the complex will reinforce in his mind those arguments which support the view of his party, while it will infallibly prevent him from realizing the force of the arguments propounded by the opposite side. Now, it should be observed that the individual himself is probably quite unaware of this mechanism in his mind. He fondly imagines that his opinion is formed solely by the logical pros and cons of the measure before him. We see, in fact, that not only is his thinking determined by a complex of whose action he is unconscious, but that he believes his thoughts to be the result of other causes which are in reality insufficient and illusory. This latter process of self-deception, in which the individual conceals the real foundation of his thought by a series of adventitious props, is termed 'rationalization.'
"The two mechanisms which manifest themselves in our example of the politician, the unconscious origin of beliefs and actions, and the subsequent process of rationalization to which they are subjected, are of fundamental importance in psychology." (Bernard Hart: The Psychology of Insanity, pp. 64-66.)]
Again, even where common-sense judgments are not particularly qualified by such conditions, they are frequently based upon the observation of purely accidental conjunctions of circumstances. A sequence once or twice observed is taken as the basis of a causal relation. This gives rise to what is known in technical logic as the post hoc ergo propter hoc fallacy; that is, the assumption that because one thing happens after another, therefore it happens because of it. Many superstitions probably had their origin in such chance observations, and belief in them is strengthened by some accidental confirmation. Thus if a man walks under a ladder one day and dies the next, the believer in the superstition that walking under a ladder brings fatal results will find in this instance a clear ratification of his belief. There seems to be an inveterate human tendency to seek for causes, and by those who are not scientific inquirers causes are lightly assigned. It is easiest and most plausible to assign as a cause an immediately preceding circumstance. Exceptional or contradictory circumstances are then either unnoticed or pared down to fit the belief.