Combining Texts

All the ideas for 'A Pragmatic Conception of the A Priori', 'On Second-Order Logic' and 'Quaestiones de Potentia Dei'

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15 ideas

5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
There are several logics, none of which will ever derive falsehoods from truth [Lewis,CI]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
Boolos reinterprets second-order logic as plural logic [Boolos, by Oliver/Smiley]
Second-order logic metatheory is set-theoretic, and second-order validity has set-theoretic problems [Boolos]
5. Theory of Logic / C. Ontology of Logic / 1. Ontology of Logic
A sentence can't be a truth of logic if it asserts the existence of certain sets [Boolos]
5. Theory of Logic / D. Assumptions for Logic / 2. Excluded Middle
Excluded middle is just our preference for a simplified dichotomy in experience [Lewis,CI]
5. Theory of Logic / F. Referring in Logic / 1. Naming / a. Names
Names represent a uniformity in experience, or they name nothing [Lewis,CI]
5. Theory of Logic / G. Quantification / 2. Domain of Quantification
'∀x x=x' only means 'everything is identical to itself' if the range of 'everything' is fixed [Boolos]
5. Theory of Logic / K. Features of Logics / 4. Completeness
Weak completeness: if it is valid, it is provable. Strong: it is provable from a set of sentences [Boolos]
5. Theory of Logic / K. Features of Logics / 6. Compactness
Why should compactness be definitive of logic? [Boolos, by Hacking]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / e. Peano arithmetic 2nd-order
Many concepts can only be expressed by second-order logic [Boolos]
9. Objects / B. Unity of Objects / 1. Unifying an Object / b. Unifying aggregates
'One' can mean undivided and not a multitude, or it can add measurement, giving number [Aquinas]
10. Modality / A. Necessity / 11. Denial of Necessity
Necessary truths are those we will maintain no matter what [Lewis,CI]
12. Knowledge Sources / A. A Priori Knowledge / 7. A Priori from Convention
We can maintain a priori principles come what may, but we can also change them [Lewis,CI]
18. Thought / E. Abstraction / 2. Abstracta by Selection
We have to separate the mathematical from physical phenomena by abstraction [Lewis,CI]
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / a. Scientific essentialism
Science seeks classification which will discover laws, essences, and predictions [Lewis,CI]