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All the ideas for 'Logical Consequence', 'Vagueness: a global approach' and 'Philosophical Logic'

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46 ideas

4. Formal Logic / A. Syllogistic Logic / 2. Syllogistic Logic
10688 'Equivocation' is when terms do not mean the same thing in premises and conclusion [Beall/Restall]
4. Formal Logic / D. Modal Logic ML / 6. Temporal Logic
15413 With four tense operators, all complex tenses reduce to fourteen basic cases [Burgess]
4. Formal Logic / D. Modal Logic ML / 7. Barcan Formula
15415 The temporal Barcan formulas fix what exists, which seems absurd [Burgess]
4. Formal Logic / E. Nonclassical Logics / 2. Intuitionist Logic
15430 Is classical logic a part of intuitionist logic, or vice versa? [Burgess]
15431 It is still unsettled whether standard intuitionist logic is complete [Burgess]
4. Formal Logic / E. Nonclassical Logics / 5. Relevant Logic
15429 Relevance logic's → is perhaps expressible by 'if A, then B, for that reason' [Burgess]
5. Theory of Logic / A. Overview of Logic / 4. Pure Logic
15404 Technical people see logic as any formal system that can be studied, not a study of argument validity [Burgess]
10690 Formal logic is invariant under permutations, or devoid of content, or gives the norms for thought [Beall/Restall]
5. Theory of Logic / A. Overview of Logic / 6. Classical Logic
15405 Classical logic neglects the non-mathematical, such as temporality or modality [Burgess]
15427 The Cut Rule expresses the classical idea that entailment is transitive [Burgess]
23548 Indeterminacy is in conflict with classical logic [Fine,K]
15421 Classical logic neglects counterfactuals, temporality and modality, because maths doesn't use them [Burgess]
5. Theory of Logic / A. Overview of Logic / 9. Philosophical Logic
15403 Philosophical logic is a branch of logic, and is now centred in computer science [Burgess]
5. Theory of Logic / B. Logical Consequence / 2. Types of Consequence
10691 Logical consequence needs either proofs, or absence of counterexamples [Beall/Restall]
5. Theory of Logic / B. Logical Consequence / 4. Semantic Consequence |=
10695 Logical consequence is either necessary truth preservation, or preservation based on interpretation [Beall/Restall]
5. Theory of Logic / B. Logical Consequence / 8. Material Implication
10689 A step is a 'material consequence' if we need contents as well as form [Beall/Restall]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
15407 Formalising arguments favours lots of connectives; proving things favours having very few [Burgess]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / e. or
15424 Asserting a disjunction from one disjunct seems odd, but can be sensible, and needed in maths [Burgess]
5. Theory of Logic / E. Structures of Logic / 4. Variables in Logic
15409 All occurrences of variables in atomic formulas are free [Burgess]
5. Theory of Logic / F. Referring in Logic / 2. Descriptions / b. Definite descriptions
15414 The denotation of a definite description is flexible, rather than rigid [Burgess]
5. Theory of Logic / H. Proof Systems / 1. Proof Systems
15406 'Induction' and 'recursion' on complexity prove by connecting a formula to its atomic components [Burgess]
5. Theory of Logic / H. Proof Systems / 6. Sequent Calculi
15425 The sequent calculus makes it possible to have proof without transitivity of entailment [Burgess]
15426 We can build one expanding sequence, instead of a chain of deductions [Burgess]
5. Theory of Logic / I. Semantics of Logic / 1. Semantics of Logic
23539 Classical semantics has referents for names, extensions for predicates, and T or F for sentences [Fine,K]
5. Theory of Logic / I. Semantics of Logic / 3. Logical Truth
10696 A 'logical truth' (or 'tautology', or 'theorem') follows from empty premises [Beall/Restall]
15408 'Tautologies' are valid formulas of classical sentential logic - or substitution instances in other logics [Burgess]
5. Theory of Logic / I. Semantics of Logic / 4. Satisfaction
15418 Validity (for truth) and demonstrability (for proof) have correlates in satisfiability and consistency [Burgess]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
15416 We aim to get the technical notion of truth in all models matching intuitive truth in all instances [Burgess]
15412 Models leave out meaning, and just focus on truth values [Burgess]
15411 We only need to study mathematical models, since all other models are isomorphic to these [Burgess]
10693 Models are mathematical structures which interpret the non-logical primitives [Beall/Restall]
5. Theory of Logic / L. Paradox / 6. Paradoxes in Language / a. The Liar paradox
15428 The Liar seems like a truth-value 'gap', but dialethists see it as a 'glut' [Burgess]
6. Mathematics / B. Foundations for Mathematics / 2. Proof in Mathematics
10692 Hilbert proofs have simple rules and complex axioms, and natural deduction is the opposite [Beall/Restall]
7. Existence / D. Theories of Reality / 10. Vagueness / a. Problem of vagueness
23544 Local indeterminacy concerns a single object, and global indeterminacy covers a range [Fine,K]
23540 Conjoining two indefinites by related sentences seems to produce a contradiction [Fine,K]
23546 Standardly vagueness involves borderline cases, and a higher standpoint from which they can be seen [Fine,K]
7. Existence / D. Theories of Reality / 10. Vagueness / c. Vagueness as ignorance
23542 Identifying vagueness with ignorance is the common mistake of confusing symptoms with cause [Fine,K]
7. Existence / D. Theories of Reality / 10. Vagueness / f. Supervaluation for vagueness
23541 Supervaluation can give no answer to 'who is the last bald man' [Fine,K]
9. Objects / B. Unity of Objects / 3. Unity Problems / e. Vague objects
23545 We do not have an intelligible concept of a borderline case [Fine,K]
10. Modality / A. Necessity / 4. De re / De dicto modality
15420 De re modality seems to apply to objects a concept intended for sentences [Burgess]
10. Modality / A. Necessity / 6. Logical Necessity
15419 General consensus is S5 for logical modality of validity, and S4 for proof [Burgess]
15417 Logical necessity has two sides - validity and demonstrability - which coincide in classical logic [Burgess]
10. Modality / B. Possibility / 8. Conditionals / a. Conditionals
15422 Three conditionals theories: Materialism (material conditional), Idealism (true=assertable), Nihilism (no truth) [Burgess]
15423 It is doubtful whether the negation of a conditional has any clear meaning [Burgess]
16. Persons / D. Continuity of the Self / 2. Mental Continuity / b. Self as mental continuity
23547 It seems absurd that there is no identity of any kind between two objects which involve survival [Fine,K]
26. Natural Theory / D. Laws of Nature / 4. Regularities / a. Regularity theory
23543 We identify laws with regularities because we mistakenly identify causes with their symptoms [Fine,K]