The Principles of Logic: For High Schools and Colleges |
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absurd antecedent Arguments in Figure Assumptions attributes Cæsar categorical categorical proposition Classification clusion coextensive comprehensive consequent contained contrary Definition denotes Denying the antecedent Disjunctive Syllogisms distribute the middle distribute the predicate division earth Enthymeme Euathlus excluded expression extensive quantity fallacy false fErIO finite form is determined Formal Fallacies genus Hamilton's harmony of thought Hence Hypothetical Syllogisms illicit process implies the falsity implies the truth infer intersects intuitions invalid involves judgment Law of Contradictories laws of thought logical major premise major term Mathematical induction middle term mind minor term Moods in Figure moon moral motion nega non-P objects order to distribute petitio principii phenomena polygon polytomy Prem premise is universal principle prove Real induction reason reductio ad absurdum relation right angles space is infinite species subordinate thing tion tive triangles true universal negative Valid Moods warrant whole
Popular passages
Page 145 - it will argue nothing against the trustworthiness of consciousness that all, or any of its deliverances, are inexplicable, are incomprehensible; that is, that we are unable to conceive through a higher notion how that is possible, which the deliverance avouches actually to be. To make the comprehensibility of a datum of consciousness the criterion of its truth would be, indeed, the climax of absurdity.
Page 46 - The com nf fff\ and free agent; that is, the class of responsible agents is a species of which the class of free agents is the genus. The concept, man, is contained under the concept, responsible agent ; that is, the class, man, is a species of which the class of responsible agents is the genus. Hence, on the principle, that a part of a part is a part of the whole, the concept, man, is contained under the concept free agent.
Page 148 - It must be granted that in every syllogism, considered as an argument to prove the conclusion, there is a petitio principii. When we say, All men are mortal, Socrates is a man, therefore Socrates is mortal; it is unanswerably urged by the adversaries of the syllogistic theory, that the proposition, Socrates is mortal...
Page 121 - MIRACLE defined. •& miracle is an effect or event, contrary to the established constitution or course of things, or a sensible suspension or controlment of, or deviation from, the known laws of nature, wrought either by the immediate act, or by the assistance, or by the permission of God...
Page 99 - And is this form — that too inconsistently — to be excluded from logic ? — But again (to prove both the obnoxious propositions summarily and at once) — what objection, apart from the arbitrary laws of our present logical system, can be taken to the following syllogism ? — ' All man is some animal, Any man is not (no man is) some animal ; Therefore some animal is not some animal.' Vary this syllogism of the third figure to any other ; it will always be legitimate by nature, if illegitimate...
Page 119 - Polygons are classified according to the number of sides. A triangle is a polygon of three sides. A quadrilateral is a polygon of four sides. A pentagon is a polygon of five sides. A hexagon is a polygon of six sides.
Page 114 - Whether the belief in the constancy of Nature's laws — a belief of which no one can divest himself — be intuitive and a part of the constitution of the human mind, as some eminent metaphysicians hold, or acquired, and in what way acquired, is a question foreign to our purpose.
Page 89 - The mind is a thinking substance; A thinking substance is a spirit; A spirit has no composition of parts; That, which has no composition of parts, is indissoluble; That, which is indissoluble, is immortal; Therefore the mind is immortal.
Page 148 - ; that the general principle, instead of being given as evidence of the particular case, cannot itself be taken for true without exception, until every shadow of doubt which could affect any case comprised with it is dispelled by evidence...
Page 155 - Thus, that the square of the hypothenuse of a right-angled triangle is equal to the sum of the squares of the other two sides, was an experimental discovery, or why did the discoverer sacrifice a hecatomb when he made out its proof ?