Ideas of John P. Burgess, by Theme
[American, b.1948, Studied at Berkeley. Teacher at Princeton University.]
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4. Formal Logic / D. Modal Logic ML / 6. Temporal Logic
15413
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With four tense operators, all complex tenses reduce to fourteen basic cases
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4. Formal Logic / D. Modal Logic ML / 7. Barcan Formula
15415
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The temporal Barcan formulas fix what exists, which seems absurd
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4. Formal Logic / E. Nonclassical Logics / 2. Intuitionist Logic
15430
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Is classical logic a part of intuitionist logic, or vice versa?
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15431
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It is still unsettled whether standard intuitionist logic is complete
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4. Formal Logic / E. Nonclassical Logics / 5. Relevant Logic
15429
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Relevance logic's → is perhaps expressible by 'if A, then B, for that reason'
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5. Theory of Logic / A. Overview of Logic / 4. Pure Logic
15404
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Technical people see logic as any formal system that can be studied, not a study of argument validity
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5. Theory of Logic / A. Overview of Logic / 6. Classical Logic
15405
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Classical logic neglects the non-mathematical, such as temporality or modality
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15421
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Classical logic neglects counterfactuals, temporality and modality, because maths doesn't use them
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15427
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The Cut Rule expresses the classical idea that entailment is transitive
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5. Theory of Logic / A. Overview of Logic / 9. Philosophical Logic
15403
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Philosophical logic is a branch of logic, and is now centred in computer science
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5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
15407
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Formalising arguments favours lots of connectives; proving things favours having very few
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5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / e. or
15424
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Asserting a disjunction from one disjunct seems odd, but can be sensible, and needed in maths
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5. Theory of Logic / E. Structures of Logic / 4. Variables in Logic
15409
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All occurrences of variables in atomic formulas are free
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5. Theory of Logic / F. Referring in Logic / 2. Descriptions / b. Definite descriptions
15414
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The denotation of a definite description is flexible, rather than rigid
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5. Theory of Logic / H. Proof Systems / 1. Proof Systems
15406
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'Induction' and 'recursion' on complexity prove by connecting a formula to its atomic components
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5. Theory of Logic / H. Proof Systems / 6. Sequent Calculi
15425
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The sequent calculus makes it possible to have proof without transitivity of entailment
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15426
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We can build one expanding sequence, instead of a chain of deductions
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5. Theory of Logic / I. Semantics of Logic / 3. Logical Truth
15408
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'Tautologies' are valid formulas of classical sentential logic - or substitution instances in other logics
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5. Theory of Logic / I. Semantics of Logic / 4. Satisfaction
15418
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Validity (for truth) and demonstrability (for proof) have correlates in satisfiability and consistency
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5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
15416
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We aim to get the technical notion of truth in all models matching intuitive truth in all instances
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15412
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Models leave out meaning, and just focus on truth values
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15411
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We only need to study mathematical models, since all other models are isomorphic to these
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5. Theory of Logic / L. Paradox / 6. Paradoxes in Language / a. The Liar paradox
15428
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The Liar seems like a truth-value 'gap', but dialethists see it as a 'glut'
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6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
10185
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Set theory is the standard background for modern mathematics
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6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / a. Structuralism
10184
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Structuralists take the name 'R' of the reals to be a variable ranging over structures, not a structure
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10189
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There is no one relation for the real number 2, as relations differ in different models
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6. Mathematics / B. Foundations for Mathematics / 7. Mathematical Structuralism / e. Structuralism critique
10186
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If set theory is used to define 'structure', we can't define set theory structurally
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10187
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Abstract algebra concerns relations between models, not common features of all the models
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10188
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How can mathematical relations be either internal, or external, or intrinsic?
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10. Modality / A. Necessity / 4. De re / De dicto modality
15420
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De re modality seems to apply to objects a concept intended for sentences
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10. Modality / A. Necessity / 6. Logical Necessity
15417
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Logical necessity has two sides - validity and demonstrability - which coincide in classical logic
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15419
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General consensus is S5 for logical modality of validity, and S4 for proof
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10. Modality / B. Possibility / 8. Conditionals / a. Conditionals
15423
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It is doubtful whether the negation of a conditional has any clear meaning
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15422
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Three conditionals theories: Materialism (material conditional), Idealism (true=assertable), Nihilism (no truth)
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