[61] Newton's "Rules for Philosophizing" (_Principia_, Book III) are as follows: Rule I. "No more causes of natural things are to be admitted than such as are both true, and sufficient to explain the phenomena of those things." Rule II. "Natural effects of the same kind are to be referred as far as possible to the same causes." Rule III. "Those qualities of bodies that can neither be increased nor diminished in intensity, and which are found to belong to all bodies within reach of our experiments are to be regarded as qualities of all bodies whatever." Rule IV. "In experimental philosophy propositions collected by induction from phenomena are to be regarded either as accurately true or very nearly true notwithstanding any contrary hypothesis, till other phenomena occur, by which they are made more accurate or are rendered subject to exceptions." [62] Book III, chap. 2, sec. 5; italics mine. The latter part of the passage, beginning with the words "If we did not often commence," etc., is quoted by Mill from Comte. The words "neither induction nor deduction would enable us to understand even the simplest phenomena" are his own. [63] Book III, chap. 7, sec. 1. [64] Book III, chap. 14, secs. 4 and 5. [65] WILLIAM WHEWELL, _The Philosophy of the Inductive Sciences_, London, 1840. [66] The essential similarity between Whewell's view and that of Lotze, already discussed (see chap. 3) is of course explainable on the basis of their common relationship to Kant. [67] _Logic_, Book IV, chap. 2, sec. 2; italics mine. [68] _Ibid._ [69] _Ibid._, sec. 4; in sec. 6 he states even more expressly that any conception is appropriate in the degree in which it "helps us toward what we wish to understand." [70] _Ibid._, sec. 6; italics mine. [71] VENN, _Empirical Logic_, p. 383. [72] VENN, _Empirical Logic_, p. 25; italics mine. [73] WELTON, _Manual of Logic_, Vol. II, chap. 3. [74] W. S. JEVONS, _Principles of Science_, pp. 231, 232. [75] B. ERDMANN, "Zur Theorie des Syllogismus und der Induktion," _Philosophische Abhandlungen_, Vol. VI, p. 230. [76] WUNDT, _Logik_, 2d ed., Vol. II, p. 131. [77] WELTON, _Manual of Logic_, Vol. II, p. 72. [78] _Op. cit._, Vol. I, p. 452 ff. [79] _Op. cit._, Vol. I, pp. 454-461. [80] BOSANQUET, _Logic_, Vol. I, p. 46. [81] BRADLEY, _Principles of Logic_, p. 10. [82] _Op. cit._, Vol. I, p. 74. [83] BRADLEY, _Principles of Logic_, p. 11. [84] _Op. cit._, Vol. I, pp. 75, 76. [85] BRADLEY, _op. cit._, pp. 4-6. [86] _Op. cit._, pp. 7, 8. [87] This study may be regarded as in some sense a development of pp. 7-10 of _The Necessary and the Contingent in the Aristotelian System_, published in 1896 by The University of Chicago Press. While quite independent in treatment, the two papers supplement each other.