Combining Philosophers

All the ideas for Xenophanes, Robert B. Brandom and Michal Walicki

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27 ideas

3. Truth / C. Correspondence Truth / 2. Correspondence to Facts
Facts can't make claims true, because they are true claims [Brandom, by Kusch]
4. Formal Logic / B. Propositional Logic PL / 1. Propositional Logic
Post proved the consistency of propositional logic in 1921 [Walicki]
Propositional language can only relate statements as the same or as different [Walicki]
4. Formal Logic / B. Propositional Logic PL / 3. Truth Tables
Boolean connectives are interpreted as functions on the set {1,0} [Walicki]
4. Formal Logic / F. Set Theory ST / 3. Types of Set / b. Empty (Null) Set
The empty set is useful for defining sets by properties, when the members are not yet known [Walicki]
The empty set avoids having to take special precautions in case members vanish [Walicki]
4. Formal Logic / F. Set Theory ST / 6. Ordering in Sets
Ordinals play the central role in set theory, providing the model of well-ordering [Walicki]
5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
To determine the patterns in logic, one must identify its 'building blocks' [Walicki]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
A 'model' of a theory specifies interpreting a language in a domain to make all theorems true [Walicki]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
The L-S Theorem says no theory (even of reals) says more than a natural number theory [Walicki]
5. Theory of Logic / K. Features of Logics / 1. Axiomatisation
Axiomatic systems are purely syntactic, and do not presuppose any interpretation [Walicki]
A compact axiomatisation makes it possible to understand a field as a whole [Walicki]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / e. Ordinal numbers
Members of ordinals are ordinals, and also subsets of ordinals [Walicki]
Ordinals are transitive sets of transitive sets; or transitive sets totally ordered by inclusion [Walicki]
Ordinals are the empty set, union with the singleton, and any arbitrary union of ordinals [Walicki]
The union of finite ordinals is the first 'limit ordinal'; 2ω is the second... [Walicki]
Two infinite ordinals can represent a single infinite cardinal [Walicki]
6. Mathematics / B. Foundations for Mathematics / 3. Axioms for Geometry
In non-Euclidean geometry, all Euclidean theorems are valid that avoid the fifth postulate [Walicki]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / f. Mathematical induction
Inductive proof depends on the choice of the ordering [Walicki]
10. Modality / A. Necessity / 2. Nature of Necessity
Scotus based modality on semantic consistency, instead of on what the future could allow [Walicki]
13. Knowledge Criteria / D. Scepticism / 1. Scepticism
If we succeed in speaking the truth, we cannot know we have done it [Xenophanes]
13. Knowledge Criteria / E. Relativism / 1. Relativism
If God had not created honey, men would say figs are sweeter [Xenophanes]
19. Language / A. Nature of Meaning / 6. Meaning as Use
The use of a sentence is its commitments and entitlements [Brandom, by Lycan]
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / e. The One
The basic Eleatic belief was that all things are one [Xenophanes, by Plato]
28. God / A. Divine Nature / 2. Divine Nature
Xenophanes said the essence of God was spherical and utterly inhuman [Xenophanes, by Diog. Laertius]
28. God / C. Attitudes to God / 5. Atheism
Mortals believe gods are born, and have voices and clothes just like mortals [Xenophanes]
Ethiopian gods have black hair, and Thracian gods have red hair [Xenophanes]