Combining Texts

All the ideas for 'On What Grounds What', 'First-order Logic, 2nd-order, Completeness' and 'Must We Believe in Set Theory?'

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32 ideas

1. Philosophy / E. Nature of Metaphysics / 1. Nature of Metaphysics
13734 Modern Quinean metaphysics is about what exists, but Aristotelian metaphysics asks about grounding [Schaffer,J]
1. Philosophy / E. Nature of Metaphysics / 3. Metaphysical Systems
13751 If you tore the metaphysics out of philosophy, the whole enterprise would collapse [Schaffer,J]
2. Reason / B. Laws of Thought / 6. Ockham's Razor
13743 We should not multiply basic entities, but we can have as many derivative entities as we like [Schaffer,J]
4. Formal Logic / F. Set Theory ST / 1. Set Theory
10482 The logic of ZF is classical first-order predicate logic with identity [Boolos]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets
10492 A few axioms of set theory 'force themselves on us', but most of them don't [Boolos]
4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / d. Naïve logical sets
10485 Naïve sets are inconsistent: there is no set for things that do not belong to themselves [Boolos]
4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / e. Iterative sets
10484 The iterative conception says sets are formed at stages; some are 'earlier', and must be formed first [Boolos]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
10751 Second-order logic needs the sets, and its consequence has epistemological problems [Rossberg]
10757 Henkin semantics has a second domain of predicates and relations (in upper case) [Rossberg]
10759 There are at least seven possible systems of semantics for second-order logic [Rossberg]
5. Theory of Logic / B. Logical Consequence / 2. Types of Consequence
10753 Logical consequence is intuitively semantic, and captured by model theory [Rossberg]
5. Theory of Logic / B. Logical Consequence / 3. Deductive Consequence |-
10752 Γ |- S says S can be deduced from Γ; Γ |= S says a good model for Γ makes S true [Rossberg]
5. Theory of Logic / E. Structures of Logic / 1. Logical Form
10754 In proof-theory, logical form is shown by the logical constants [Rossberg]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
10756 A model is a domain, and an interpretation assigning objects, predicates, relations etc. [Rossberg]
5. Theory of Logic / J. Model Theory in Logic / 2. Isomorphisms
10758 If models of a mathematical theory are all isomorphic, it is 'categorical', with essentially one model [Rossberg]
5. Theory of Logic / K. Features of Logics / 4. Completeness
10761 Completeness can always be achieved by cunning model-design [Rossberg]
5. Theory of Logic / K. Features of Logics / 5. Incompleteness
10755 A deductive system is only incomplete with respect to a formal semantics [Rossberg]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / a. The Infinite
10491 Infinite natural numbers is as obvious as infinite sentences in English [Boolos]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / f. Uncountable infinities
10483 Mathematics and science do not require very high orders of infinity [Boolos]
6. Mathematics / C. Sources of Mathematics / 1. Mathematical Platonism / a. For mathematical platonism
10490 Mathematics isn't surprising, given that we experience many objects as abstract [Boolos]
13741 If 'there are red roses' implies 'there are roses', then 'there are prime numbers' implies 'there are numbers' [Schaffer,J]
7. Existence / C. Structure of Existence / 1. Grounding / a. Nature of grounding
13748 Grounding is unanalysable and primitive, and is the basic structuring concept in metaphysics [Schaffer,J]
7. Existence / C. Structure of Existence / 5. Supervenience / a. Nature of supervenience
13747 Supervenience is just modal correlation [Schaffer,J]
7. Existence / C. Structure of Existence / 7. Abstract/Concrete / a. Abstract/concrete
13744 The cosmos is the only fundamental entity, from which all else exists by abstraction [Schaffer,J]
7. Existence / E. Categories / 4. Category Realism
13739 Maybe categories are just the different ways that things depend on basic substances [Schaffer,J]
8. Modes of Existence / D. Universals / 1. Universals
10488 It is lunacy to think we only see ink-marks, and not word-types [Boolos]
9. Objects / A. Existence of Objects / 2. Abstract Objects / a. Nature of abstracta
10487 I am a fan of abstract objects, and confident of their existence [Boolos]
9. Objects / A. Existence of Objects / 2. Abstract Objects / c. Modern abstracta
10489 We deal with abstract objects all the time: software, poems, mistakes, triangles.. [Boolos]
9. Objects / C. Structure of Objects / 8. Parts of Objects / c. Wholes from parts
13742 There exist heaps with no integral unity, so we should accept arbitrary composites in the same way [Schaffer,J]
13752 The notion of 'grounding' can explain integrated wholes in a way that mere aggregates can't [Schaffer,J]
10. Modality / E. Possible worlds / 1. Possible Worlds / b. Impossible worlds
13749 Belief in impossible worlds may require dialetheism [Schaffer,J]
11. Knowledge Aims / B. Certain Knowledge / 2. Common Sense Certainty
13740 'Moorean certainties' are more credible than any sceptical argument [Schaffer,J]