the task of analysis is to resolve it into a number of definite propositions. The latter, when the ultimate premises have been reached, are arranged in logical sequence. The premises should be stated with the minimum of redundance. They must then be scrutinized in turn with a view to ascertaining the particular degree of doubt or certainty attaching to each. This provides us with a criterion of the doubtfulness or certainty pertaining to each proposition of the sequence, and to the initial data in particular.
In general the scientific method makes use of three types of data:[1] sense-data, the testimony of others, and certain primitive logical truths. In making use of testimony, the existence of other people must be tacitly assumed. It is impossible entirely to justify this assumption. On the other hand, its falsity cannot be established, and it is indispensable in opening up a relatively immense field of knowledge, whereas solipsism is practically barren.
One of the most important applications of the scientific method is to the analysis of the meaning of the concepts of physical science,[2] and the investigation of their validity as representative of the world of fact. Evidently, the material from which the start must in this case be made, is the data of sense. Since all scientific observation consists in perceiving sequences of sense-data, and since the verification of a physical prediction lies in an appeal to the occurrence of some sense-datum, it follows that if the entities of the physicist are to be valid conceptions, they must be capable of representation as logical functions of sense-data. Even if they be so represented, it does not follow necessarily that they exist concretely, nor does it matter. The importance of such a critique of physical science is great, for the physicist is often apt to consider his entities as the true realities of the universe, regarding them as inferences whereas they are merely constructions. The data of sense are the indubitable concrete facts.
The exponents of the scientific method claim that it is capable of ascertaining all that is soluble in the problems of philosophy,
