The first thing to happen is the arousal of a feeling of perplexity, the appearance of a problem. The man has been shambling along, doubtless “thinking” in that loose sense referred to. He has perhaps kicked several stones loose that would have set a geologist worrying, and has picked branches from bushes which would have puzzled a botanist. But this man has not had his curiosity aroused until he has come to these footprints. His thinking starts with his perplexity. After this doubt has been aroused the most obvious solution suggests itself—“my own footprints.” But if true, this suggestion involves the co-existence of other facts, some of which are known and some of which may be determined. Thus, if they were his own footprints, it must, among other things, necessarily follow (1) that he had been at that spot before, (2) that nothing had happened since that time to remove the prints, (3) that the footprints corresponded to his own. The first consequence involved—that he had been there before—was a fact, but the others were not, and so the suggestion was dropped. Then a second hypothesis occurred—“the man came in a ship”—and this was tried out in a similar way. Notice that in each case the consequences dependent on the truth of the suggestion are tried out (1) by memory, (2) by observation or experiment. Memory came when he thought of the last time he had walked near the beach and of yesterday’s storm. Observation came when he compared his footprint with the one seen, when he followed the footprints along the sand and noticed where they led, when he climbed a tree and looked for a ship. There were a number of other things which he could have observed. He might have noticed the texture of the sand, what kind of a tree he was climbing, what sort of clouds were in the sky. But he did not observe these interesting things simply because they would throw no light on the truth or falsity of his supposition. In another problem one of these facts might have been of value.
It is almost possible to sum up the whole process of thinking as the occurrence of suggestions for the solution of difficulties and the testing out of those suggestions. The suggestions or suppositions are tested by observation, memory, experiment. Supposition and observation alternate. The first facts observed—in the case foregoing, the footprints—make the problem, they suggest the supposition. A supposition is that the man came in a boat. If the man came in a boat such and such would be the case—the boat would still be visible, etc. If the boat is not visible the supposition is given up and another one made; if the boat is visible the supposition is confirmed. This is a case of simple and rudimentary thinking, but it illustrates roughly the process of thought on even the most complicated problems of science. The methods we have been discussing may all be considered simply as means for helping good suggestions occur to us.
Let us illustrate by considering a few methods of rather restricted application. We are often aided in the solution of a problem by asking its opposite. If we ask ourselves “What constitutes gracefulness?” we may find ourselves at a loss for suggestions, because gracefulness always seems “so natural.” But if we ask its opposite, “What constitutes awkwardness?,” suggestions are more apt to occur. If we find, for instance, that awkwardness consists in undue bodily effort in making a movement, we may assume that gracefulness consists in ease of movement. In the same way the question of what makes us forget may be helped by asking ourselves what makes us remember, and light may be thrown on the causes of success in business and in life by a study of the causes of failure.
The method of analogy likewise encourages suggestions. Analogy consists in noting certain likenesses between things, and assuming that they also possess other common qualities. Striking use of analogy is made in dealing with the planet Mars. At each pole there are great white patches. The size of these varies markedly with the seasons, which suggests that like the earth, Mars has great areas of ice and snow at its two poles which melt and re-form. The general surface is reddish, but three-eighths of it is covered by blue-green tracts, and these are usually inferred to be seas. These again are connected by an intricate system of blue-green lines, which some scientists believe to be canals, but on this there is much controversy. In Mars we have at once an illustration of the possibilities and dangers of analogy.
In the whole discussion of constructive method thus far, I have left out the two most common and useful methods of all. The first of these we may designate by a somewhat formidable title: empirical observation. Empirical, at least for our present purposes, means merely that which comes within experience. But the term is generally opposed to scientific. Thus Dewey gives an example: “A says, ‘It will probably rain to-morrow.’ B asks, ‘Why do you think so?’ And A replies, ‘Because the sky was lowering at sunset.’ When B asks, ‘What has that to do with it?’ A responds, ‘I do not know, but it generally does rain after such a sunset.’ He does not perceive any connection between the appearance of the sky and the coming rain; he is not aware of any continuity in the facts themselves—any law or principle, as we usually say. He simply, from frequently recurring conjunction of the events, has associated them so that when he sees one he thinks of the other.”[5]
This, however, is not what I mean to imply by the term empirical observation. I mean rather thinking on the basis merely of facts which occur in the natural course of events, which have not been systematically produced by ourselves or others for the purpose of solving a problem. Logicians usually call this method simply observation, and oppose it to experiment. But I object to calling this simply observation because experiment itself is really observation, only in one case we observe merely events which happen to occur, and in the other we observe the results of events which we have made occur. The true way of distinguishing these two methods would be to call one empirical observation, and the other experimental observation.
This empirical method—if indeed I am justified in calling it a method—is the most common in all thinking. To give examples of it would be to show how men generally think. But the method has real value, and may even be the most important of all, for if we thought without it our ideas would doubtless be original, but very dangerous. Let us apply it to some of the problems considered under other methods.
Empirical observation is used where experiment is impossible—often, unfortunately, where experiment is merely inconvenient. In political science the empirical method would consist in noting the effect of certain laws,—e.g., tariffs of different countries and of the same country at different periods—and noting economic conditions at the time the different tariffs were in effect. Allowance would be made for other factors which could influence the country’s economic condition and the effect of the tariff could then be determined.
The empirical method of dealing with meteorology, the science of weather, would consist in making a study of cloud formations, wind velocity, moisture in the air, temperature, etc., and noting what conditions usually or perhaps invariably followed certain of these conditions. From this, conclusions could be drawn as to what weather to expect following certain conditions.
But valuable as empirical observation is, and often as we must use it, it should never be employed when we can experiment. When the empirical method is rightly used allowance always has to be made for certain irrelevant factors. But “making allowances” is always sheer guess work. The experimental method consists not in making allowances for certain factors, but in eliminating those factors. In our example from political science experiment is practically impossible, because the factors which may influence economic conditions are innumerable, and even were they few, no country could survive the dangers of being experimented upon—to say nothing of its permitting it. Experiment is similarly impossible in dealing with weather conditions directly. It is impossible in astronomy.