Ideas of C.I. Lewis, by Theme

[American, 1883 - 1964, Born at Stoneham. Professor at Harvard University.]

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4. Formal Logic / D. Modal Logic ML / 3. Modal Logic Systems / h. System S5

7791	The simplest of the logics based on possible worlds is Lewis's S5 [Girle]

5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic

9358	There are several logics, none of which will ever derive falsehoods from truth

5. Theory of Logic / D. Assumptions for Logic / 2. Excluded Middle

9357	Excluded middle is just our preference for a simplified dichotomy in experience

5. Theory of Logic / F. Referring in Logic / 1. Naming / a. Names

9364	Names represent a uniformity in experience, or they name nothing

10. Modality / A. Necessity / 2. Nature of Necessity

11002

Equating necessity with informal provability is the S4 conception of necessity [Read]

10. Modality / A. Necessity / 11. Denial of Necessity

9362	Necessary truths are those we will maintain no matter what

10. Modality / B. Possibility / 8. Conditionals / a. Conditionals

7803	Modal logic began with translation difficulties for 'If...then' [Girle]

12. Knowledge Sources / A. A Priori Knowledge / 7. A Priori from Convention

9365	We can maintain a priori principles come what may, but we can also change them

12. Knowledge Sources / E. Direct Knowledge / 4. Memory

21500

We rely on memory for empirical beliefs because they mutually support one another

21501

If we doubt memories we cannot assess our doubt, or what is being doubted

13. Knowledge Criteria / B. Internal Justification / 4. Foundationalism / a. Foundationalism

6556	If anything is to be probable, then something must be certain

13. Knowledge Criteria / B. Internal Justification / 5. Coherentism / b. Pro-coherentism

21498

Congruents assertions increase the probability of each individual assertion in the set

18. Thought / C. Content / 8. Intension

5828	Extension is the class of things, intension is the correct definition of the thing, and intension determines extension

18. Thought / E. Abstraction / 2. Abstracta by Selection

9361	We have to separate the mathematical from physical phenomena by abstraction

26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / a. Scientific essentialism

9363	Science seeks classification which will discover laws, essences, and predictions