Combining Texts

All the ideas for 'Dialektik', 'An Introduction to Modal Logic' and 'On the Syllogism IV'

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7 ideas

4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / b. Terminology of PL

9540	A 'value-assignment' (V) is when to each variable in the set V assigns either the value 1 or the value 0 [Hughes/Cresswell]

4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / d. Basic theorems of PL

9541	The Law of Transposition says (P→Q) → (¬Q→¬P) [Hughes/Cresswell]

4. Formal Logic / B. Propositional Logic PL / 4. Soundness of PL

9543	The rules preserve validity from the axioms, so no thesis negates any other thesis [Hughes/Cresswell]

5. Theory of Logic / E. Structures of Logic / 6. Relations in Logic

17744

De Morgan started the study of relations and their properties [De Morgan, by Walicki]

13501

De Morgan found inferences involving relations, which eluded Aristotle's syllogistic [De Morgan, by Hart,WD]

5. Theory of Logic / K. Features of Logics / 4. Completeness

9544	A system is 'weakly' complete if all wffs are derivable, and 'strongly' if theses are maximised [Hughes/Cresswell]

19. Language / E. Analyticity / 4. Analytic/Synthetic Critique

20959

Concepts are only analytic once the predicate is absorbed into the subject [Schleiermacher]