Combining Philosophers

All the ideas for John Buridan, Wilfrid Hodges and George Engelbretsen

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36 ideas

2. Reason / A. Nature of Reason / 9. Limits of Reason
1403 A rational donkey would starve to death between two totally identical piles of hay [Buridan, by PG]
2. Reason / D. Definition / 7. Contextual Definition
10476 The idea that groups of concepts could be 'implicitly defined' was abandoned [Hodges,W]
3. Truth / B. Truthmakers / 5. What Makes Truths / a. What makes truths
18915 If facts are the truthmakers, they are not in the world [Engelbretsen]
18919 There are no 'falsifying' facts, only an absence of truthmakers [Engelbretsen]
4. Formal Logic / A. Syllogistic Logic / 1. Aristotelian Logic
18913 Traditional term logic struggled to express relations [Engelbretsen]
4. Formal Logic / A. Syllogistic Logic / 3. Term Logic
18907 Term logic rests on negated terms or denial, and that propositions are tied pairs [Engelbretsen]
5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
10282 Logic is the study of sound argument, or of certain artificial languages (or applying the latter to the former) [Hodges,W]
5. Theory of Logic / A. Overview of Logic / 2. History of Logic
18912 Was logic a branch of mathematics, or mathematics a branch of logic? [Engelbretsen]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
10478 Since first-order languages are complete, |= and |- have the same meaning [Hodges,W]
5. Theory of Logic / B. Logical Consequence / 4. Semantic Consequence |=
10477 |= in model-theory means 'logical consequence' - it holds in all models [Hodges,W]
5. Theory of Logic / E. Structures of Logic / 1. Logical Form
18922 Logical syntax is actually close to surface linguistic form [Engelbretsen]
18905 Propositions can be analysed as pairs of terms glued together by predication [Engelbretsen]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / c. not
18908 Standard logic only negates sentences, even via negated general terms or predicates [Engelbretsen]
5. Theory of Logic / I. Semantics of Logic / 1. Semantics of Logic
10283 A formula needs an 'interpretation' of its constants, and a 'valuation' of its variables [Hodges,W]
10284 There are three different standard presentations of semantics [Hodges,W]
10285 I |= φ means that the formula φ is true in the interpretation I [Hodges,W]
5. Theory of Logic / I. Semantics of Logic / 4. Satisfaction
10474 |= should be read as 'is a model for' or 'satisfies' [Hodges,W]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
10475 A 'structure' is an interpretation specifying objects and classes of quantification [Hodges,W]
10473 Model theory studies formal or natural language-interpretation using set-theory [Hodges,W]
10481 Models in model theory are structures, not sets of descriptions [Hodges,W]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
10289 Up Löwenheim-Skolem: if infinite models, then arbitrarily large models [Hodges,W]
10288 Down Löwenheim-Skolem: if a countable language has a consistent theory, that has a countable model [Hodges,W]
5. Theory of Logic / K. Features of Logics / 6. Compactness
10287 If a first-order theory entails a sentence, there is a finite subset of the theory which entails it [Hodges,W]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / i. Cardinal infinity
10480 First-order logic can't discriminate between one infinite cardinal and another [Hodges,W]
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
10286 A 'set' is a mathematically well-behaved class [Hodges,W]
7. Existence / A. Nature of Existence / 6. Criterion for Existence
18917 Existence and nonexistence are characteristics of the world, not of objects [Engelbretsen]
7. Existence / D. Theories of Reality / 8. Facts / a. Facts
18916 Facts are not in the world - they are properties of the world [Engelbretsen]
7. Existence / E. Categories / 4. Category Realism
18921 Individuals are arranged in inclusion categories that match our semantics [Engelbretsen]
9. Objects / C. Structure of Objects / 4. Quantity of an Object
16678 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
16793 A thing is (less properly) the same over time if each part is succeeded by another [Buridan]
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / b. Primary/secondary
16726 Why can't we deduce secondary qualities from primary ones, if they cause them? [Buridan]
14. Science / A. Basis of Science / 2. Demonstration
16577 Induction is not demonstration, because not all of the instances can be observed [Buridan]
14. Science / C. Induction / 2. Aims of Induction
16576 Science is based on induction, for general truths about fire, rhubarb and magnets [Buridan]
19. Language / B. Reference / 2. Denoting
18918 Terms denote objects with properties, and statements denote the world with that property [Engelbretsen]
19. Language / D. Propositions / 1. Propositions
18920 'Socrates is wise' denotes a sentence; 'that Socrates is wise' denotes a proposition [Engelbretsen]
19. Language / F. Communication / 3. Denial
18906 Negating a predicate term and denying its unnegated version are quite different [Engelbretsen]