Combining Texts

All the ideas for 'First-order Logic, 2nd-order, Completeness', 'Two-Dimensional Semantics' and 'Abstract of 'The Fourfold Root''

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35 ideas

2. Reason / B. Laws of Thought / 2. Sufficient Reason
'There is nothing without a reason why it should be rather than not be' (a generalisation of 'Why?') [Schopenhauer]
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 / A. Necessity / 3. Types of Necessity
Superficial necessity is true in all worlds; deep necessity is thus true, no matter which world is actual [Schroeter]
10. Modality / C. Sources of Modality / 1. Sources of Necessity
All necessity arises from causation, which is conditioned; there is no absolute or unconditioned necessity [Schopenhauer]
10. Modality / D. Knowledge of Modality / 4. Conceivable as Possible / b. Conceivable but impossible
Contradictory claims about a necessary god both seem apriori coherent [Schroeter]
11. Knowledge Aims / A. Knowledge / 2. Understanding
All understanding is an immediate apprehension of the causal relation [Schopenhauer]
12. Knowledge Sources / A. A Priori Knowledge / 8. A Priori as Analytic
2D semantics gives us apriori knowledge of our own meanings [Schroeter]
16. Persons / C. Self-Awareness / 2. Knowing the Self
What we know in ourselves is not a knower but a will [Schopenhauer]
16. Persons / D. Continuity of the Self / 3. Reference of 'I'
The knot of the world is the use of 'I' to refer to both willing and knowing [Schopenhauer]
18. Thought / C. Content / 5. Twin Earth
Your view of water depends on whether you start from the actual Earth or its counterfactual Twin [Schroeter]
18. Thought / C. Content / 7. Narrow Content
Rationalists say knowing an expression is identifying its extension using an internal cognitive state [Schroeter]
19. Language / A. Nature of Meaning / 1. Meaning
Internalist meaning is about understanding; externalist meaning is about embedding in a situation [Schroeter]
19. Language / C. Assigning Meanings / 2. Semantics
Semantic theory assigns meanings to expressions, and metasemantics explains how this works [Schroeter]
19. Language / C. Assigning Meanings / 4. Compositionality
Semantic theories show how truth of sentences depends on rules for interpreting and joining their parts [Schroeter]
19. Language / C. Assigning Meanings / 7. Extensional Semantics
Simple semantics assigns extensions to names and to predicates [Schroeter]
'Federer' and 'best tennis player' can't mean the same, despite having the same extension [Schroeter]
19. Language / C. Assigning Meanings / 8. Possible Worlds Semantics
Possible worlds semantics uses 'intensions' - functions which assign extensions at each world [Schroeter]
Possible worlds make 'I' and that person's name synonymous, but they have different meanings [Schroeter]
Possible worlds semantics implies a constitutive connection between meanings and modal claims [Schroeter]
In the possible worlds account all necessary truths are same (because they all map to the True) [Schroeter]
19. Language / C. Assigning Meanings / 10. Two-Dimensional Semantics
Array worlds along the horizontal, and contexts (world,person,time) along the vertical [Schroeter]
If we introduce 'actually' into modal talk, we need possible worlds twice to express this [Schroeter]
Do we know apriori how we refer to names and natural kinds, but their modal profiles only a posteriori? [Schroeter]
2D fans defend it for conceptual analysis, for meaning, and for internalist reference [Schroeter]
2D semantics can't respond to contingent apriori claims, since there is no single proposition involved [Schroeter]
27. Natural Reality / D. Time / 1. Nature of Time / b. Relative time
Time may be defined as the possibility of mutually exclusive conditions of the same thing [Schopenhauer]