SCIENTIFIC METHOD is a collective term denoting the various processes by the aid of which the sciences are built up. In a wide sense, any mode of investigation by which scientific or other impartial and systematic knowledge is acquired is called a scientific method. Such methods are of two principal types— technical and logical. A technical or technological method is a method of manipulating the phenomena under investigation, meas uring them with precision, and determining the conditions under which they occur, so as to be able to observe them in a favourable and fruitful manner. A logical method is a method of reasoning about the phenomena investigated, a method of drawing inferences from the conditions under which they occur, so as to interpret them as accurately as possible. The term "scientific method" in the first instance probably suggests to most minds the technical methods of manipulation and measurement. These technical methods are very numerous and they are different in the different sciences. Few men ever master the technical methods of more than one science, or one group of closely connected sciences. An account of the most important technical methods is usually given in connection with the several sciences. It would be impossible, even if it were desirable, to give a useful survey of all, or even of the most important, technical methods of science. It is differ ent with the logical methods of science. These methods of reason ing from the available evidence are not really numerous, and are essentially the same in all the sciences. It is both possible and desirable to survey them in outline. Moreover, these logical methods of science are in a very real sense the soul of the techni cal methods.
In pure science the technical methods are not regarded as an end in themselves, but merely as a means to the discovery of the nature of the phenomena under investigation. This is done by drawing conclusions from the observations and experiments which the technical methods render possible. Sometimes the technical methods make it possible for the expert investigator to observe and measure certain phenomena, which otherwise could either not he observed and measured at all, or not so accurately. Sometimes they enable him so to determine the conditions of their occurrence that he can draw reliable conclusions about them, instead of hav ing to be content with unverified conjectures. The highly specu
lative, mainly conjectural character of early science was no doubt due entirely to the lack of suitable technical methods and scientific instruments. In a sense, therefore, it may be said that the techni cal methods of science are auxiliary to the logical methods, or methods of reasoning. And it is these methods that are to be con sidered in the present article. The technical methods of science, as ought to be clear from the preceding remarks, are of first rate importance, and we have not the remotest desire to underrate them; but it would be futile to attempt to survey them here.
Some Mental Activities Common to All Methods.—There are certain mental activities which are so absolutely indispensable to science that they are practically always employed in scientific investigations, however much these may vary in other respects. In a wide sense these mental activities might consequently be called methods of science, and they are frequently so called. But this practice is objectionable, because it leads to cross division and confusion. What is common to all methods should not itself be called a method, for it only encourages the effacing of important differences ; and when there are many such factors common to all the methods, or most of them, confusion is inevitable. When the mental activities involved are more or less common to the methods, these must be differentiated by reference to other, variable factors—such as the different types of data from which the inferences are drawn, and the different types of order sought or discovered in the different kinds of phenomena investigated— the two sets of differences being, of course, intimately connected. The mental activities referred to are the following : Observation (including experiment), analysis and synthesis, imagination, sup position and idealization, inference (inductive and deductive), and comparison (including analogy). A few words must be said about each of these ; but no significance should be attached to the order in which they are dealt with.