Combining Texts

All the ideas for 'Transworld Identity or worldbound Individuals?', 'Reply to Professor Marcus' and 'Gentzen's Analysis of First-Order Proofs'

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11 ideas

5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
13831 Logic is based on transitions between sentences [Prawitz]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
13825 Natural deduction introduction rules may represent 'definitions' of logical connectives [Prawitz]
5. Theory of Logic / G. Quantification / 4. Substitutional Quantification
10801 Either reference really matters, or we don't need to replace it with substitutions [Quine]
5. Theory of Logic / H. Proof Systems / 4. Natural Deduction
13823 In natural deduction, inferences are atomic steps involving just one logical constant [Prawitz]
10. Modality / E. Possible worlds / 1. Possible Worlds / a. Possible worlds
11984 Asserting a possible property is to say it would have had the property if that world had been actual [Plantinga]
10. Modality / E. Possible worlds / 2. Nature of Possible Worlds / a. Nature of possible worlds
11980 A possible world is a maximal possible state of affairs [Plantinga]
10. Modality / E. Possible worlds / 3. Transworld Objects / a. Transworld identity
11982 If possible Socrates differs from actual Socrates, the Indiscernibility of Identicals says they are different [Plantinga]
11983 It doesn't matter that we can't identify the possible Socrates; we can't identify adults from baby photos [Plantinga]
11985 If individuals can only exist in one world, then they can never lack any of their properties [Plantinga]
10. Modality / E. Possible worlds / 3. Transworld Objects / c. Counterparts
11986 The counterparts of Socrates have self-identity, but only the actual Socrates has identity-with-Socrates [Plantinga]
11987 Counterpart Theory absurdly says I would be someone else if things went differently [Plantinga]