Combining Texts

All the ideas for 'Questions on Aristotle's Physics', 'Elusive Knowledge' and 'First-order Logic, 2nd-order, Completeness'

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19 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]
Second-order logic needs the sets, and its consequence has epistemological problems [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]
9. Objects / C. Structure of Objects / 4. Quantity of an Object
Without magnitude a thing would retain its parts, but they would have no location [Buridan]
9. Objects / E. Objects over Time / 8. Continuity of Rivers
A thing is (less properly) the same over time if each part is succeeded by another [Buridan]
11. Knowledge Aims / A. Knowledge / 4. Belief / a. Beliefs
The timid student has knowledge without belief, lacking confidence in their correct answer [Lewis]
11. Knowledge Aims / B. Certain Knowledge / 3. Fallibilism
To say S knows P, but cannot eliminate not-P, sounds like a contradiction [Lewis]
13. Knowledge Criteria / A. Justification Problems / 1. Justification / b. Need for justification
Justification is neither sufficient nor necessary for knowledge [Lewis]
13. Knowledge Criteria / C. External Justification / 6. Contextual Justification / a. Contextualism
Knowing is context-sensitive because the domain of quantification varies [Lewis, by Cohen,S]
We have knowledge if alternatives are eliminated, but appropriate alternatives depend on context [Lewis, by Cohen,S]
14. Science / A. Basis of Science / 2. Demonstration
Induction is not demonstration, because not all of the instances can be observed [Buridan]
14. Science / C. Induction / 2. Aims of Induction
Science is based on induction, for general truths about fire, rhubarb and magnets [Buridan]