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nydus/The Game of LogicPublic

This instructional book presents a logic game played with a diagram and nine counters. It explains how to express propositions through the relationship between things and their attributes.

Page 57 of 126
Table of Contents

CROSS QUESTIONS.

                         -----------
                        |     |     |
                        |     x     |
                        |--y--|--y'-|
                        |     x'    |
                        |     |     |
                         -----------
  1. All y are x.
  1. Some y are not-x.
  1. No not-x are not-y.
  1. Some x are not-y.
  1. Some not-y are x.
  1. No not-x are y.
  1. Some not-x are not-y.
  1. All not-x are not-y.
  1. Some not-y exist.
  1. No not-x exist.
  1. Some y are x, and some are not-x.
  1. All x are y, and all not-y are not-x.

[See pp. 62, 3]

Taking "nations" as Universe; x="civilised"; y="warlike";

  1. No uncivilised nation is warlike.
  1. All unwarlike nations are uncivilised.
  1. Some nations are unwarlike.
  1. All warlike nations are civilised, and all civilised nations are warlike.
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