[184:6] The reader will find a good illustration of eristic in Plato's _Euthydemus_, 275. [187:7] The reader can find these rules, and the detail of the traditional formal logic, in any elementary text-book, such as, e. g., Jevons: _Elements of Logic_. [189:8] What is called "the algebra of logic" seeks to obtain an unequivocal symbolic expression for these truths. [192:9] Plato: _Protagoras_, 351. Translation by Jowett. [194:10] Plato: _Apology_, 41. Translation by Jowett. [195:11] Quoted by Paulsen in his _System of Ethics_. Translation by Thilly, p. 69. [198:12] Cf. § 160. [198:13] Cf. § 177. [199:14] Concerning the duty of philosophy to religion in these matters, cf. Descartes: _Meditations_, _Dedication_. Translation by Veitch, p. 81. [201:15] The school-philosophy that flourished from the eleventh to the fifteenth century, under the authority of the church. [209:16] Especially in the _Phædo_. [211:17] Schopenhauer is a notable exception. Cf. §§ 135, 138. [213:18] It is interesting, however, to observe that current spiritualistic theories maintain a naturalistic theory of immortality, verifiable, it is alleged, in certain extraordinary empirical observations. [215:19] Translation by Pillsbury and Titchener, p. 59. PART III SYSTEMS OF PHILOSOPHY CHAPTER VIII NATURALISM[223:1] [Sidenote: The General Meaning of Materialism.] § 102. The meaning conveyed by any philosophical term consists largely of the distinctions which it suggests. Its peculiar quality, like the physiognomy of the battle-scarred veteran, is a composite of the controversies which it has survived. There is, therefore, an almost unavoidable confusion attendant upon the denomination of any early phase of philosophy as _materialism_. But in the historical beginnings of thought, as also in the common-sense of all ages, there is at any rate present a very essential strand of this theory. The naive habit of mind which, in the sixth century before Christ, prompted successive Greek thinkers to define reality in terms of water, air, and fire, is in this respect one with that exhibited in Dr. Samuel Johnson's smiting the ground with his stick in curt refutation of Bishop Berkeley's idea-philosophy. There is a theoretical instinct, not accidental or perverse, but springing from the very life-preserving equipment of the organism, which attributes reality to _tangible space-filling things encountered by the body_. For obvious reasons of self-interest the organism is first of all endowed with a sense of contact, and the more delicate senses enter into its practical economy as means of anticipating or avoiding contact. From such practical expectations concerning the proximity of that which may press upon, injure, or displace the body, arise the first crude judgments of reality. And these are at the same time the nucleus of naive philosophy and the germinal phase of materialism. [Sidenote: Corporeal Being.]