Combining Texts

All the ideas for 'Gentzen's Analysis of First-Order Proofs', 'fragments/reports' and 'Natural Science (lost)'

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5 ideas

5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
Logic is based on transitions between sentences [Prawitz]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
Natural deduction introduction rules may represent 'definitions' of logical connectives [Prawitz]
5. Theory of Logic / H. Proof Systems / 4. Natural Deduction
In natural deduction, inferences are atomic steps involving just one logical constant [Prawitz]
7. Existence / A. Nature of Existence / 6. Criterion for Existence
Everything exists which anyone perceives [Metrodorus of Chios]
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / c. Ultimate substances
For Anaximenes nature is air, which takes different forms by rarefaction and condensation [Anaximenes, by Simplicius]