Combining Texts

All the ideas for 'fragments/reports', 'On the Ultimate Origination of Things' and 'Higher-Order Logic'

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22 ideas

1. Philosophy / A. Wisdom / 1. Nature of Wisdom
19336 Wisdom involves the desire to achieve perfection [Leibniz]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX
10301 The axiom of choice is controversial, but it could be replaced [Shapiro]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
10588 First-order logic is Complete, and Compact, with the Löwenheim-Skolem Theorems [Shapiro]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
10298 Some say that second-order logic is mathematics, not logic [Shapiro]
10299 If the aim of logic is to codify inferences, second-order logic is useless [Shapiro]
5. Theory of Logic / B. Logical Consequence / 1. Logical Consequence
10300 Logical consequence can be defined in terms of the logical terminology [Shapiro]
5. Theory of Logic / G. Quantification / 5. Second-Order Quantification
10290 Second-order variables also range over properties, sets, relations or functions [Shapiro]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
10297 The Löwenheim-Skolem theorem seems to be a defect of first-order logic [Shapiro]
10590 Up Löwenheim-Skolem: if natural numbers satisfy wffs, then an infinite domain satisfies them [Shapiro]
10292 Downward Löwenheim-Skolem: if there's an infinite model, there is a countable model [Shapiro]
10296 The Löwenheim-Skolem Theorems fail for second-order languages with standard semantics [Shapiro]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / e. Peano arithmetic 2nd-order
10294 Second-order logic has the expressive power for mathematics, but an unworkable model theory [Shapiro]
7. Existence / A. Nature of Existence / 3. Being / d. Non-being
18933 Not-Being obviously doesn't exist, and the five modes of Being are all impossible [Gorgias, by Diog. Laertius]
7. Existence / A. Nature of Existence / 5. Reason for Existence
7696 Leibniz first asked 'why is there something rather than nothing?' [Leibniz, by Jacquette]
19341 There must be a straining towards existence in the essence of all possible things [Leibniz]
19428 Because something does exist, there must be a drive in possible things towards existence [Leibniz]
8. Modes of Existence / B. Properties / 11. Properties as Sets
10591 Logicians use 'property' and 'set' interchangeably, with little hanging on it [Shapiro]
10. Modality / A. Necessity / 7. Natural Necessity
5047 The world is physically necessary, as its contrary would imply imperfection or moral absurdity [Leibniz]
19. Language / F. Communication / 1. Rhetoric
9866 Gorgias says rhetoric is the best of arts, because it enslaves without using force [Gorgias, by Plato]
5864 Destroy seriousness with laughter, and laughter with seriousness [Gorgias]
20. Action / C. Motives for Action / 3. Acting on Reason / a. Practical reason
19343 We follow the practical rule which always seeks maximum effect for minimum cost [Leibniz]
26. Natural Theory / A. Speculations on Nature / 1. Nature
19429 The principle of determination in things obtains the greatest effect with the least effort [Leibniz]