Combining Texts

All the ideas for 'Foundations of Geometry', 'The Epistemology of Essence (draft)' and 'Counterparts and Identity'

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13 ideas

4. Formal Logic / D. Modal Logic ML / 7. Barcan Formula
To say there could have been people who don't exist, but deny those possible things, rejects Barcan [Stalnaker, by Rumfitt]
6. Mathematics / A. Nature of Mathematics / 2. Geometry
Hilbert aimed to eliminate number from geometry [Hilbert, by Hart,WD]
6. Mathematics / B. Foundations for Mathematics / 3. Axioms for Geometry
Euclid axioms concerns possibilities of construction, but Hilbert's assert the existence of objects [Hilbert, by Chihara]
Hilbert's formalisation revealed implicit congruence axioms in Euclid [Hilbert, by Horsten/Pettigrew]
Hilbert's geometry is interesting because it captures Euclid without using real numbers [Hilbert, by Field,H]
10. Modality / D. Knowledge of Modality / 4. Conceivable as Possible / a. Conceivable as possible
If conceivability is a priori coherence, that implies possibility [Tahko]
10. Modality / E. Possible worlds / 3. Transworld Objects / c. Counterparts
Unlike Lewis, I defend an actualist version of counterpart theory [Stalnaker]
If possible worlds really differ, I can't be in more than one at a time [Stalnaker]
If counterparts exist strictly in one world only, this seems to be extreme invariant essentialism [Stalnaker]
14. Science / D. Explanation / 2. Types of Explanation / k. Explanations by essence
Essences are used to explain natural kinds, modality, and causal powers [Tahko]
19. Language / C. Assigning Meanings / 8. Possible Worlds Semantics
Extensional semantics has individuals and sets; modal semantics has intensions, functions of world to extension [Stalnaker]
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / a. Scientific essentialism
Scientific essentialists tend to characterise essence in terms of modality (not vice versa) [Tahko]
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / b. Scientific necessity
If essence is modal and laws are necessary, essentialist knowledge is found by scientists [Tahko]