# Symbolic Logic

Macmillan, 1881 - Logic - 446 pages

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### Contents

 I ix II 1 IV 32 V 67 VI 88 VII 100 VIII 126 IX 154
 XIII 240 XIV 261 XV 285 XVI 296 XVII 309 XVIII 326 XIX 350 XX 363

 X 180 XI 190 XII 222
 XXI 380 XXII 405

### Popular passages

Page 70 - Tr"1 is defined. Thus it is the office of the inverse symbol to propose a question, not to describe an operation. It is, in its primary meaning, interrogative, not directive. Suppose the given equation to be Then on the above principle of notation we should have...
Page 107 - ... w but are no part of z). It must be admitted that such a diagram is not quite so simple to draw as one might wish it to be; but then consider what the alternative is if one undertakes to deal with five terms and all their combinations; — nothing short of th'e disagreeable task of writing out, or in some way putting before us, all the 32 combinations involved.
Page 120 - In this respect logical calculations stand in marked contrast with those of mathematics, where economical devices of any kind may subserve a really valuable purpose by enabling us to avoid otherwise inevitable labour. Moreover, in the second place, it does not seem to me that any contrivances at present known or likely to be discovered really deserve the name of logical machines. It is but a very small part of the entire process, which goes to form a piece of reasoning, which they are capable of...
Page 121 - It then becomes a question of judgment which of these is the simplest and best. For instance, in the last example but one, there are a quantity of alternative ways of reading off our conclusion ; and until this is done the problem cannot be said to be solved. I cannot see that any machine can hope to help us except in the third of these steps ; so that it seems very doubtful whether any thing of this sort really deserves the name of a logical engine.
Page 429 - Ji & ff so as to coincide with DE. This seems to me to constitute the essential characteristic of his scheme, which is worked out in a variety of figures of a more or less complicated kind. It is decidedly cumbrous, and not entirely effective as regards this its main aim, but it deserves recognition as an attempt to remedy a real defect in the ordinary scheme. Hamilton who, as we know, never could succeed in grasping the nature of a triangle, entirely misconceived all this; and seeing that Maass...
Page 427 - I have seen no attempt to extend diagrammatic notation to the results of four terms, and it is only quite recently that really adequate figures have been proposed for those of three terms : — for instance both Drobisch and Schroder have used what we may call the three-circle diagram1.