1909. This is designed as a textbook and aims to present an outline of scientific study as briefly and as concretely as possible. Contents: First Stages in Knowledge; Classification; The Use and Misuse of Words; Propositions; Induction; Verification and Deduction; The Syllogism; Traditional Treatment of the Syllogism; Abbreviated and Complex Forms of Reasoning-Hypothetical and Disjunctive Syllogisms; Proof and Disproof, Failure to Prove; Statistics; Averages; Probability; The Construction of Systems; Explanation; Hypothesis; and Typical Systems of Knowledge.