Picture Logic

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Longmans, Green, 1887 - Logic - 188 pages
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Page 174 - If two or more instances in which the phenomenon occurs have only one circumstance in common, while two or more instances in which it does not occur have nothing in common save the absence of that circumstance, the circumstance in which alone the two sets of instances differ is the effect, or the cause, or an indispensable part of the cause of the phenomenon.
Page 174 - If an instance in which the phenomenon under investigation occurs, and an instance in which it does not occur, have every circumstance in common save one, that one occurring only in the former; the circumstance in which alone the two instances differ is the effect, or the cause, or an indispensable part of the cause, of the phenomenon.
Page 175 - Subduct from any phenomenon such part as is known by previous inductions to be the effect of certain antecedents...
Page 175 - Whatever phenomenon varies in any manner whenever another phenomenon varies in some particular manner, is either a cause or an effect of that phenomenon, or is connected with it through some fact of causation.
Page 117 - Here, then, is another point in which these triplets of propositions, called syllogisms, may differ. And as syllogisms differ in mood according to the arrangement of their propositions, so they differ in figure according to the position of the middle term in those propositions. There can only be four figures. Where the middle term is subject in the major and predicate in the minor premiss, where it is predicate in both, where it is subject in both, and where it is predicate and subject ; eg, take...
Page 135 - ... negative minor in the first figure (contrary to canon). ' [If asked (as possibly you might be) what is the regressive or Goclenian Sorites, remember it is the reverse of the above. Begin with the last premiss and write the train from last to first, and keep the old conclusion, eg, All D is E, All 0 is D, All B is C, All A is B, .-.All A is E. ' The rules are reversed, too ; only one premiss particular, the last ; only one negative, the first (the same propositions being negative and particular...
Page 38 - the science of the necessary forms of thought," and so it has been called a " formal science ; " for, as we have seen, Logic is only concerned with the forms or modes in which people think as opposed to the matter. It has also been called " the art of thinking," ie the application of universal laws to particular thoughts; and the universal laws imply the existence of science. Lastly, it has been well defined as "the science of the conditions on which correct thoughts depend, and the art of attaining...
Page 24 - A thing cannot both be and not be. 3. The Law of Duality. A thing must either be or not be.
Page 134 - All A is B All B is C All C is D All D is E .'. 'All A is E 20.
Page 128 - All men are mortal, . • . Socrates is mortal," or " All men are mortal and Socrates is a man." The order of the first two in conversation would be " Socrates is mortal, because he is a man," and " Socrates is mortal, because all men are so.

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