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All the ideas for 'What is Logic?st1=Ian Hacking', 'The Philosophy of Logical Atomism' and 'Empty Names'

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48 ideas

1. Philosophy / E. Nature of Metaphysics / 4. Metaphysics as Science
The business of metaphysics is to describe the world [Russell]
2. Reason / B. Laws of Thought / 6. Ockham's Razor
Reducing entities and premisses makes error less likely [Russell]
2. Reason / D. Definition / 3. Types of Definition
A decent modern definition should always imply a semantics [Hacking]
3. Truth / B. Truthmakers / 5. What Makes Truths / a. What makes truths
Facts make propositions true or false, and are expressed by whole sentences [Russell]
3. Truth / B. Truthmakers / 8. Making General Truths
Not only atomic truths, but also general and negative truths, have truth-makers [Russell, by Rami]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / d. Basic theorems of PL
Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking]
Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking]
'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking]
4. Formal Logic / F. Set Theory ST / 3. Types of Set / c. Unit (Singleton) Sets
Normally a class with only one member is a problem, because the class and the member are identical [Russell]
5. Theory of Logic / A. Overview of Logic / 4. Pure Logic
The various logics are abstractions made from terms like 'if...then' in English [Hacking]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking]
A limitation of first-order logic is that it cannot handle branching quantifiers [Hacking]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
Second-order completeness seems to need intensional entities and possible worlds [Hacking]
5. Theory of Logic / E. Structures of Logic / 1. Logical Form
In a logically perfect language, there will be just one word for every simple object [Russell]
Romulus does not occur in the proposition 'Romulus did not exist' [Russell]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking]
5. Theory of Logic / E. Structures of Logic / 4. Variables in Logic
Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking]
5. Theory of Logic / F. Referring in Logic / 1. Naming / a. Names
You can understand 'author of Waverley', but to understand 'Scott' you must know who it applies to [Russell]
There are a set of criteria for pinning down a logically proper name [Russell, by Sainsbury]
Semantic theory should specify when an act of naming is successful [Sawyer]
5. Theory of Logic / F. Referring in Logic / 1. Naming / b. Names as descriptive
Treat description using quantifiers, and treat proper names as descriptions [Russell, by McCullogh]
5. Theory of Logic / F. Referring in Logic / 1. Naming / c. Names as referential
Millians say a name just means its object [Sawyer]
5. Theory of Logic / F. Referring in Logic / 1. Naming / e. Empty names
A name has got to name something or it is not a name [Russell]
Sentences with empty names can be understood, be co-referential, and even be true [Sawyer]
Frege's compositional account of truth-vaues makes 'Pegasus doesn't exist' neither true nor false [Sawyer]
5. Theory of Logic / F. Referring in Logic / 2. Descriptions / c. Theory of definite descriptions
Definites descriptions don't solve the empty names problem, because the properties may not exist [Sawyer]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking]
6. Mathematics / C. Sources of Mathematics / 9. Fictional Mathematics
Numbers are classes of classes, and hence fictions of fictions [Russell]
7. Existence / C. Structure of Existence / 6. Fundamentals / d. Logical atoms
Russell's new logical atomist was of particulars, universals and facts (not platonic propositions) [Russell, by Linsky,B]
Russell's atomic facts are actually compounds, and his true logical atoms are sense data [Russell, by Quine]
Logical atomism aims at logical atoms as the last residue of analysis [Russell]
Once you have enumerated all the atomic facts, there is a further fact that those are all the facts [Russell]
Logical atoms aims to get down to ultimate simples, with their own unique reality [Russell]
7. Existence / D. Theories of Reality / 8. Facts / a. Facts
You can't name all the facts, so they are not real, but are what propositions assert [Russell]
7. Existence / D. Theories of Reality / 8. Facts / b. Types of fact
Russell asserts atomic, existential, negative and general facts [Russell, by Armstrong]
7. Existence / D. Theories of Reality / 9. States of Affairs
Modern trope theory tries, like logical atomism, to reduce things to elementary states [Russell, by Ellis]
7. Existence / D. Theories of Reality / 11. Ontological Commitment / a. Ontological commitment
'Existence' means that a propositional function is sometimes true [Russell]
10. Modality / A. Necessity / 2. Nature of Necessity
Modal terms are properties of propositional functions, not of propositions [Russell]
12. Knowledge Sources / B. Perception / 5. Interpretation
Perception goes straight to the fact, and not through the proposition [Russell]
18. Thought / A. Modes of Thought / 6. Judgement / b. Error
The theory of error seems to need the existence of the non-existent [Russell]
19. Language / C. Assigning Meanings / 3. Predicates
Russell uses 'propositional function' to refer to both predicates and to attributes [Quine on Russell]
19. Language / D. Propositions / 1. Propositions
Propositions don't name facts, because each fact corresponds to a proposition and its negation [Russell]
19. Language / D. Propositions / 3. Concrete Propositions
In 1918 still believes in nonlinguistic analogues of sentences, but he now calls them 'facts' [Russell, by Quine]
19. Language / D. Propositions / 6. Propositions Critique
An inventory of the world does not need to include propositions [Russell]
I no longer believe in propositions, especially concerning falsehoods [Russell]
I know longer believe in shadowy things like 'that today is Wednesday' when it is actually Tuesday [Russell]
19. Language / F. Communication / 4. Private Language
The names in a logically perfect language would be private, and could not be shared [Russell]
28. God / B. Proving God / 2. Proofs of Reason / b. Ontological Proof critique
You can discuss 'God exists', so 'God' is a description, not a name [Russell]