Combining Texts

All the ideas for 'Philosophical Fragments', 'First-Order Logic' and 'Truth and the Past'

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21 ideas

5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
10282 Logic is the study of sound argument, or of certain artificial languages (or applying the latter to the former) [Hodges,W]
5. Theory of Logic / D. Assumptions for Logic / 1. Bivalence
8195 Undecidable statements result from quantifying over infinites, subjunctive conditionals, and the past tense [Dummett]
5. Theory of Logic / I. Semantics of Logic / 1. Semantics of Logic
10283 A formula needs an 'interpretation' of its constants, and a 'valuation' of its variables [Hodges,W]
10284 There are three different standard presentations of semantics [Hodges,W]
10285 I |= φ means that the formula φ is true in the interpretation I [Hodges,W]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
10288 Down Löwenheim-Skolem: if a countable language has a consistent theory, that has a countable model [Hodges,W]
10289 Up Löwenheim-Skolem: if infinite models, then arbitrarily large models [Hodges,W]
5. Theory of Logic / K. Features of Logics / 6. Compactness
10287 If a first-order theory entails a sentence, there is a finite subset of the theory which entails it [Hodges,W]
5. Theory of Logic / L. Paradox / 6. Paradoxes in Language / b. The Heap paradox ('Sorites')
8194 Surely there is no exact single grain that brings a heap into existence [Dummett]
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
10286 A 'set' is a mathematically well-behaved class [Hodges,W]
6. Mathematics / C. Sources of Mathematics / 10. Constructivism / b. Intuitionism
8190 Intuitionists rely on the proof of mathematical statements, not their truth [Dummett]
7. Existence / A. Nature of Existence / 5. Reason for Existence
16007 I assume existence, rather than reasoning towards it [Kierkegaard]
7. Existence / B. Change in Existence / 1. Nature of Change
8198 A 'Cambridge Change' is like saying 'the landscape changes as you travel east' [Dummett]
7. Existence / D. Theories of Reality / 4. Anti-realism
8192 I no longer think what a statement about the past says is just what can justify it [Dummett]
10. Modality / A. Necessity / 2. Nature of Necessity
16013 Nothing necessary can come into existence, since it already 'is' [Kierkegaard]
11. Knowledge Aims / C. Knowing Reality / 2. Phenomenalism
8199 The existence of a universe without sentience or intelligence is an unintelligible fantasy [Dummett]
19. Language / A. Nature of Meaning / 5. Meaning as Verification
8193 Verification is not an individual but a collective activity [Dummett]
19. Language / C. Assigning Meanings / 6. Truth-Conditions Semantics
8189 Truth-condition theorists must argue use can only be described by appeal to conditions of truth [Dummett]
8191 The truth-conditions theory must get agreement on a conception of truth [Dummett]
27. Natural Reality / D. Time / 1. Nature of Time / f. Eternalism
8197 Maybe past (which affects us) and future (which we can affect) are both real [Dummett]
27. Natural Reality / D. Time / 2. Passage of Time / k. Temporal truths
8196 The present cannot exist alone as a mere boundary; past and future truths are rendered meaningless [Dummett]