I object also to the term “applied science,” because to me this term implies that the science it refers to is based on one positive science only. I can think of no so-called applied science which is so based. Hygiene, not alone dependent on physiology, must derive some of its rules from the chemistry of foods, as well as from the sciences of sanitation and ventilation, themselves normative. Agriculture is based not only on biology and botany, but on chemistry and meteorology.
The science of thinking, then, if such a science there be, is normative. Its purpose is to find those methods which will help us to think constructively and correctly.
One more distinction and our preliminaries are over. There are two other sciences with which the science of thinking is liable to become confused; one positive, the other normative.
The positive science is that branch of psychology which deals with the reasoning process and examines the basis of belief. We shall make frequent use of this science in trying to find rules for thinking, but it will not be the only science we shall use, nor will that science be the subject of this book.
The normative science with which the science of thinking may become confused is logic. Indeed, logic has sometimes been called the science of thinking. Now for our purposes logic is a part of the science of thinking, but it is not the part which we are primarily to consider. Its function is merely negative; it consists in leading us from error. The part of the science of thinking in which we are interested deals with those positive rules which will help to make us creative thinkers. . . .
Our ship is headed for the port Truth. Our mind is the engine, the science of thinking the propeller, and logic the rudder. Without our engine, the mind, the propeller of the science of thinking, which transforms our mental energy most effectively into motion, would be useless. Without the propeller, which gives motion, the rudder of logic would be useless. But all three are needed to reach our goal.
And now I must bespeak a little patience. The next chapter, and the one following it, are going to deal very largely with method and methods. They will touch on classification, and a lot of other things to which the plain man has an aversion; to which, at least, he usually evinces no very active interest. But it is necessary to consider these things in order to make our study complete.
II THINKING WITH METHOD
Most of us, at those rare intervals when we think at all, do so in a slipshod sort of way. If we come across a mental difficulty we try to get rid of it in almost any kind of hit or miss manner. Even those few of us who think occasionally for the mere sake of thinking, generally do so without regard for method—indeed, are often unconscious that method could be applied to our thought. But what is meant by method? I may best explain by an example.