Combining Texts

All the ideas for 'Logical Consequence', 'Realism, Mathematics and Modality' and '23: Book of Isaiah'

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12 ideas

1. Philosophy / D. Nature of Philosophy / 2. Invocation to Philosophy
Let us reason together, saith the Lord [Isaiah]
4. Formal Logic / A. Syllogistic Logic / 2. Syllogistic Logic
'Equivocation' is when terms do not mean the same thing in premises and conclusion [Beall/Restall]
5. Theory of Logic / A. Overview of Logic / 4. Pure Logic
Formal logic is invariant under permutations, or devoid of content, or gives the norms for thought [Beall/Restall]
5. Theory of Logic / B. Logical Consequence / 2. Types of Consequence
Logical consequence needs either proofs, or absence of counterexamples [Beall/Restall]
5. Theory of Logic / B. Logical Consequence / 4. Semantic Consequence |=
Logical consequence is either necessary truth preservation, or preservation based on interpretation [Beall/Restall]
5. Theory of Logic / B. Logical Consequence / 8. Material Implication
A step is a 'material consequence' if we need contents as well as form [Beall/Restall]
5. Theory of Logic / I. Semantics of Logic / 3. Logical Truth
A 'logical truth' (or 'tautology', or 'theorem') follows from empty premises [Beall/Restall]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
Models are mathematical structures which interpret the non-logical primitives [Beall/Restall]
6. Mathematics / B. Foundations for Mathematics / 2. Proof in Mathematics
Hilbert proofs have simple rules and complex axioms, and natural deduction is the opposite [Beall/Restall]
6. Mathematics / C. Sources of Mathematics / 9. Fictional Mathematics
Fictionalists say 2+2=4 is true in the way that 'Oliver Twist lived in London' is true [Field,H]
27. Natural Reality / E. Cosmology / 1. Cosmology
The world is established, and cannot be moved [Isaiah]
28. God / A. Divine Nature / 1. God
Beside me there is no God [Isaiah]