Combining Texts

All the ideas for 'works', 'First-order Logic, 2nd-order, Completeness' and 'Letter to Pythocles'

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14 ideas

5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
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]
Second-order logic needs the sets, and its consequence has epistemological problems [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]
14. Science / D. Explanation / 3. Best Explanation / c. Against best explanation
We should accept as explanations all the plausible ways in which something could come about [Epicurus]
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / e. Human nature
There are two sides to men - the pleasantly social, and the violent and creative [Diderot, by Berlin]
27. Natural Reality / E. Cosmology / 1. Cosmology
A cosmos is a collection of stars and an earth, with some sort of boundary, movement and shape [Epicurus]
28. God / C. Attitudes to God / 3. Deism
God does not intervene in heavenly movements, but is beyond all action and perfectly happy [Epicurus]