Combining Philosophers

All the ideas for Augustin-Louis Cauchy, Hecato and Augustus De Morgan

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6 ideas

5. Theory of Logic / E. Structures of Logic / 6. Relations in Logic
De Morgan started the study of relations and their properties [De Morgan, by Walicki]
De Morgan found inferences involving relations, which eluded Aristotle's syllogistic [De Morgan, by Hart,WD]
5. Theory of Logic / G. Quantification / 2. Domain of Quantification
De Morgan introduced a 'universe of discourse', to replace Boole's universe of 'all things' [De Morgan, by Walicki]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / k. Infinitesimals
Values that approach zero, becoming less than any quantity, are 'infinitesimals' [Cauchy]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / l. Limits
When successive variable values approach a fixed value, that is its 'limit' [Cauchy]
23. Ethics / C. Virtue Theory / 3. Virtues / a. Virtues
The cardinal virtues are theoretical (based on knowledge), and others are 'non-theoretical' [Hecato, by Dorandi]