Combining Philosophers

All the ideas for Menedemus, Wilfrid Hodges and David Liggins

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29 ideas

2. Reason / D. Definition / 7. Contextual Definition
The idea that groups of concepts could be 'implicitly defined' was abandoned [Hodges,W]
2. Reason / F. Fallacies / 7. Ad Hominem
We should always apply someone's theory of meaning to their own utterances [Liggins]
3. Truth / B. Truthmakers / 2. Truthmaker Relation
Truth-maker theory can't cope with non-causal dependence [Liggins]
3. Truth / B. Truthmakers / 12. Rejecting Truthmakers
Truthmakers for existence is fine; otherwise maybe restrict it to synthetic truths? [Liggins]
5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
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 / 5. First-Order Logic
Since first-order languages are complete, |= and |- have the same meaning [Hodges,W]
5. Theory of Logic / B. Logical Consequence / 4. Semantic Consequence |=
|= in model-theory means 'logical consequence' - it holds in all models [Hodges,W]
5. Theory of Logic / G. Quantification / 6. Plural Quantification
We normally formalise 'There are Fs' with singular quantification and predication, but this may be wrong [Liggins]
5. Theory of Logic / I. Semantics of Logic / 1. Semantics of Logic
There are three different standard presentations of semantics [Hodges,W]
I |= φ means that the formula φ is true in the interpretation I [Hodges,W]
A formula needs an 'interpretation' of its constants, and a 'valuation' of its variables [Hodges,W]
5. Theory of Logic / I. Semantics of Logic / 4. Satisfaction
|= should be read as 'is a model for' or 'satisfies' [Hodges,W]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
A 'structure' is an interpretation specifying objects and classes of quantification [Hodges,W]
Model theory studies formal or natural language-interpretation using set-theory [Hodges,W]
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
Up Löwenheim-Skolem: if infinite models, then arbitrarily large models [Hodges,W]
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
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
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
A 'set' is a mathematically well-behaved class [Hodges,W]
7. Existence / A. Nature of Existence / 5. Reason for Existence
Either p is true or not-p is true, so something is true, so something exists [Liggins]
7. Existence / C. Structure of Existence / 1. Grounding / b. Relata of grounding
The dependence of {Socrates} on Socrates involves a set and a philosopher, not facts [Liggins]
7. Existence / C. Structure of Existence / 4. Ontological Dependence
Non-causal dependence is at present only dimly understood [Liggins]
7. Existence / C. Structure of Existence / 5. Supervenience / c. Significance of supervenience
Necessities supervene on everything, but don't depend on everything [Liggins]
9. Objects / C. Structure of Objects / 8. Parts of Objects / a. Parts of objects
Nihilists needn't deny parts - they can just say that some of the xs are among the ys [Liggins]
14. Science / D. Explanation / 1. Explanation / a. Explanation
'Because' can signal an inference rather than an explanation [Liggins]
14. Science / D. Explanation / 2. Types of Explanation / a. Types of explanation
Value, constitution and realisation are non-causal dependences that explain [Liggins]
If explanations track dependence, then 'determinative' explanations seem to exist [Liggins]
23. Ethics / A. Egoism / 1. Ethical Egoism
The greatest good is not the achievement of desire, but to desire what is proper [Menedemus, by Diog. Laertius]