Combining Texts

All the ideas for 'Euthyphro', 'World and Essence' and 'On Second-Order Logic'

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21 ideas

5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
14249 Boolos reinterprets second-order logic as plural logic [Boolos, by Oliver/Smiley]
10830 Second-order logic metatheory is set-theoretic, and second-order validity has set-theoretic problems [Boolos]
5. Theory of Logic / C. Ontology of Logic / 1. Ontology of Logic
10829 A sentence can't be a truth of logic if it asserts the existence of certain sets [Boolos]
5. Theory of Logic / G. Quantification / 2. Domain of Quantification
10832 '∀x x=x' only means 'everything is identical to itself' if the range of 'everything' is fixed [Boolos]
5. Theory of Logic / K. Features of Logics / 4. Completeness
10834 Weak completeness: if it is valid, it is provable. Strong: it is provable from a set of sentences [Boolos]
5. Theory of Logic / K. Features of Logics / 6. Compactness
13841 Why should compactness be definitive of logic? [Boolos, by Hacking]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / e. Peano arithmetic 2nd-order
10833 Many concepts can only be expressed by second-order logic [Boolos]
9. Objects / A. Existence of Objects / 4. Impossible objects
16435 Plantinga proposes necessary existent essences as surrogates for the nonexistent things [Plantinga, by Stalnaker]
9. Objects / A. Existence of Objects / 5. Individuation / a. Individuation
14655 The 'identity criteria' of a name are a group of essential and established facts [Plantinga]
9. Objects / A. Existence of Objects / 5. Individuation / d. Individuation by haecceity
14658 'Being Socrates' and 'being identical with Socrates' characterise Socrates, so they are among his properties [Plantinga]
9. Objects / D. Essence of Objects / 2. Types of Essence
14656 Does Socrates have essential properties, plus a unique essence (or 'haecceity') which entails them? [Plantinga]
9. Objects / D. Essence of Objects / 9. Essence and Properties
14654 Properties are 'trivially essential' if they are instantiated by every object in every possible world [Plantinga]
14653 X is essentially P if it is P in every world, or in every X-world, or in the actual world (and not ¬P elsewhere) [Plantinga]
14660 If a property is ever essential, can it only ever be an essential property? [Plantinga]
14661 Essences are instantiated, and are what entails a thing's properties and lack of properties [Plantinga]
9. Objects / F. Identity among Objects / 5. Self-Identity
14657 Does 'being identical with Socrates' name a property? I can think of no objections to it [Plantinga]
10. Modality / A. Necessity / 4. De re / De dicto modality
14652 'De re' modality is as clear as 'de dicto' modality, because they are logically equivalent [Plantinga]
10. Modality / D. Knowledge of Modality / 4. Conceivable as Possible / a. Conceivable as possible
14659 We can imagine being beetles or alligators, so it is possible we might have such bodies [Plantinga]
13. Knowledge Criteria / E. Relativism / 6. Relativism Critique
335 Do the gods also hold different opinions about what is right and honourable? [Plato]
28. God / A. Divine Nature / 6. Divine Morality / b. Euthyphro question
336 Is what is pious loved by the gods because it is pious, or is it pious because they love it? (the 'Euthyphro Question') [Plato]
337 It seems that the gods love things because they are pious, rather than making them pious by loving them [Plato]