Combining Texts

All the ideas for 'First-order Logic, 2nd-order, Completeness', '26: Oracles in Decline' and 'Letters to Coste'

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13 ideas

2. Reason / A. Nature of Reason / 9. Limits of Reason
The universe is infinitely varied, so the Buridan's Ass dilemma could never happen [Leibniz]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
Second-order logic needs the sets, and its consequence has epistemological problems [Rossberg]
Henkin semantics has a second domain of predicates and relations (in upper case) [Rossberg]
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
Logical consequence is intuitively semantic, and captured by model theory [Rossberg]
5. Theory of Logic / B. Logical Consequence / 3. Deductive Consequence |-
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
In proof-theory, logical form is shown by the logical constants [Rossberg]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
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
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
Completeness can always be achieved by cunning model-design [Rossberg]
5. Theory of Logic / K. Features of Logics / 5. Incompleteness
A deductive system is only incomplete with respect to a formal semantics [Rossberg]
10. Modality / E. Possible worlds / 1. Possible Worlds / a. Possible worlds
There may be a world where dogs smell their game at a thousand leagues [Leibniz]
11. Knowledge Aims / C. Knowing Reality / 3. Idealism / a. Idealism
The sun is always bright; it doesn't become bright when it emerges [Plutarch]