Varieties of Reasoning
Reasoning as a whole is a process of mental exploration culminating in inference. Now, without regard to possible [{469}] variations of the perceptive response of inference, there are at least different varieties of the exploratory process leading up to inference. The situation that arouses reasoning differs from one case to another, the motive for engaging in this rather laborious mental process differs, and the order of events in the process differs. There are several main types of reasoning, considered as a process of mental exploration.
1. Reasoning out the solution of a practical problem.
A "problem" is a situation for which we have no ready and successful response. We cannot successfully respond by instinct or by previously acquired habit. We must find out what to do. We explore the situation, partly by the senses and actual movement, partly by the use of our wits. We observe facts in the situation that recall previous experiences or previously learned rules and principles, and apply these to the present case. Many of these clues we reject at once as of no use; others we may try out and find useless; some we may think through and thus find useless; but finally, if our exploration is successful, we observe a real clue, recall a pertinent guiding principle, and see the way out of our problem.
Two boys went into the woods for a day's outing. They climbed about all the morning, and ate their lunch in a little clearing by the side of a brook. Then they started for home, striking straight through the woods, as they thought, in the direction of home. After quite a long tramp, when they thought they should be about out of the woods, they saw clear space ahead, and, pushing forward eagerly, found themselves in the same little clearing where they had eaten their lunch! Reasoning process No. 1 now occurred: one of the boys recalled that when traversing the woods without any compass or landmark, the traveller is very likely to go in a circle; inference, "That is what we have done and [{470}] we probably shall do the same thing again if we go ahead. We may as well sit down and think it over."
Mental exploration ensued. "How about following the brook?" "That won't do, for it flows down into a big swamp that we couldn't get through". "How about telling directions by the sun?" "But it has so clouded over that you can't tell east from west, or north from south." "Yes, those old clouds! How fast they are going! They seem to go straight enough." "Well, say! How about following the clouds? If we keep on going straight, in any direction, for a couple of hours, we shall surely get out of the woods somewhere." This seems worth trying and actually brings the boys out to a road where they can inquire the way home.
What we find in this case is typical of problem solution. First, a desire is aroused, and it facilitates the observation and recall of facts relevant to itself. One pertinent fact is observed, another pertinent fact, or rule, is recalled; and in these two taken together the key to the problem is found.
2. Rationalization or self-justification.
While in the preceding case reasoning showed what to do, here it is called upon to justify what has been done, or what is going to be done anyway. The question is, what reason to assign for the act; we feel the need of meeting criticism, either from other people or from ourselves. The real motive for the act may be unknown to ourselves, as it often is unless we have made a careful study of motives; or, if known, it may not be such as we care to confess. We require a reasonable motive, some acceptable general principle that explains our action.
A child is unaccountably polite and helpful to his mother some day, and when asked about it replies that he simply wants to help--while his real motive may have been to score against his brother or sister, who is to some extent his rival.