Combining Philosophers

All the ideas for Speussipus, Jonathan Barnes and Augustus De Morgan

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8 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]
9. Objects / B. Unity of Objects / 2. Substance / c. Types of substance
Speusippus suggested underlying principles for every substance, and ended with a huge list [Speussipus, by Aristotle]
18. Thought / E. Abstraction / 8. Abstractionism Critique
Abstraction from an ambiguous concept like 'mole' will define them as the same [Barnes,J]
Abstraction cannot produce the concept of a 'game', as there is no one common feature [Barnes,J]
Defining concepts by abstractions will collect together far too many attributes from entities [Barnes,J]
28. God / C. Attitudes to God / 5. Atheism
Speusippus said things were governed by some animal force rather than the gods [Speussipus, by Cicero]