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
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
There are several logics, none of which will ever derive falsehoods from truth
5. Theory of Logic / D. Assumptions for Logic / 2. Excluded Middle
Excluded middle is just our preference for a simplified dichotomy in experience
5. Theory of Logic / F. Referring in Logic / 1. Naming / a. Names
Names represent a uniformity in experience, or they name nothing
10. Modality / A. Necessity / 2. Nature of Necessity
Equating necessity with informal provability is the S4 conception of necessity [Read]
10. Modality / A. Necessity / 11. Denial of Necessity
Necessary truths are those we will maintain no matter what
10. Modality / B. Possibility / 8. Conditionals / a. Conditionals
Modal logic began with translation difficulties for 'If...then' [Girle]
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
12. Knowledge Sources / E. Direct Knowledge / 3. Memory
We rely on memory for empirical beliefs because they mutually support one another
If we doubt memories we cannot assess our doubt, or what is being doubted
13. Knowledge Criteria / B. Internal Justification / 4. Foundationalism / a. Foundationalism
If anything is to be probable, then something must be certain
13. Knowledge Criteria / B. Internal Justification / 5. Coherentism / b. Pro-coherentism
Congruents assertions increase the probability of each individual assertion in the set
18. Thought / C. Content / 8. Intension
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
We have to separate the mathematical from physical phenomena by abstraction
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / a. Scientific essentialism
Science seeks classification which will discover laws, essences, and predictions