Combining Texts

All the ideas for 'Locke on Essences and Kinds', 'Set Theory and related topics (2nd ed)' and 'Elements of Mathematical Logic'

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6 ideas

4. Formal Logic / E. Nonclassical Logics / 3. Many-Valued Logic

8942	Lukasiewicz's L3 logic has three truth-values, T, F and I (for 'indeterminate') [Lukasiewicz, by Fisher]

4. Formal Logic / F. Set Theory ST / 3. Types of Set / e. Equivalence classes

8920	Equivalence relations are reflexive, symmetric and transitive, and classify similar objects [Lipschutz]

9. Objects / D. Essence of Objects / 13. Nominal Essence

15642

If kinds depend only on what can be observed, many underlying essences might produce the same kind [Eagle]

15645

Nominal essence are the observable properties of things [Eagle]

15643

Nominal essence mistakenly gives equal weight to all underlying properties that produce appearances [Eagle]

26. Natural Theory / B. Natural Kinds / 4. Source of Kinds

15641

Kinds are fixed by the essential properties of things - the properties that make it that kind of thing [Eagle]