Combining Texts

All the ideas for 'Putnam's Paradox', 'Against the Professors (six books)' and 'Elements of Set Theory'

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18 ideas

3. Truth / A. Truth Problems / 5. Truth Bearers
6021 It is only when we say a proposition that we speak truly or falsely [Sext.Empiricus]
4. Formal Logic / F. Set Theory ST / 2. Mechanics of Set Theory / b. Terminology of ST
13201 ∈ says the whole set is in the other; ⊆ says the members of the subset are in the other [Enderton]
13206 A 'linear or total ordering' must be transitive and satisfy trichotomy [Enderton]
13204 The 'ordered pair' <x,y> is defined to be {{x}, {x,y}} [Enderton]
4. Formal Logic / F. Set Theory ST / 3. Types of Set / b. Empty (Null) Set
13200 Note that {Φ} =/= Φ, because Φ ∈ {Φ} but Φ ∉ Φ [Enderton]
13199 The empty set may look pointless, but many sets can be constructed from it [Enderton]
4. Formal Logic / F. Set Theory ST / 3. Types of Set / c. Unit (Singleton) Sets
13203 The singleton is defined using the pairing axiom (as {x,x}) [Enderton]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / h. Axiom of Replacement VII
13202 Fraenkel added Replacement, to give a theory of ordinal numbers [Enderton]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX
13205 We can only define functions if Choice tells us which items are involved [Enderton]
5. Theory of Logic / E. Structures of Logic / 1. Logical Form
6020 'Man is a rational mortal animal' is equivalent to 'if something is a man, that thing is a rational mortal animal' [Sext.Empiricus]
5. Theory of Logic / J. Model Theory in Logic / 2. Isomorphisms
14212 A consistent theory just needs one model; isomorphic versions will do too, and large domains provide those [Lewis]
7. Existence / D. Theories of Reality / 4. Anti-realism
14213 Anti-realists see the world as imaginary, or lacking joints, or beyond reference, or beyond truth [Lewis]
9. Objects / C. Structure of Objects / 8. Parts of Objects / b. Sums of parts
14210 A gerrymandered mereological sum can be a mess, but still have natural joints [Lewis]
14. Science / A. Basis of Science / 1. Observation
6026 How can you investigate without some preconception of your object? [Sext.Empiricus]
19. Language / B. Reference / 3. Direct Reference / b. Causal reference
14215 Causal theories of reference make errors in reference easy [Lewis]
19. Language / B. Reference / 4. Descriptive Reference / b. Reference by description
14209 Descriptive theories remain part of the theory of reference (with seven mild modifications) [Lewis]
23. Ethics / B. Contract Ethics / 9. Contractualism
6032 Right actions, once done, are those with a reasonable justification [Sext.Empiricus]
26. Natural Theory / A. Speculations on Nature / 4. Mathematical Nature
1517 The tektraktys (1+2+3+4=10) is the 'fount of ever-flowing nature' [Sext.Empiricus]