Combining Texts

All the ideas for 'What is Logic?st1=Ian Hacking', 'A Pragmatic Conception of the A Priori' and 'Metaphysics: an introduction'

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26 ideas

1. Philosophy / E. Nature of Metaphysics / 1. Nature of Metaphysics
Metaphysics is a quest for truthmakers [Tallant]
2. Reason / D. Definition / 3. Types of Definition
A decent modern definition should always imply a semantics [Hacking]
2. Reason / D. Definition / 12. Paraphrase
Maybe number statements can be paraphrased into quantifications plus identities [Tallant]
3. Truth / B. Truthmakers / 3. Truthmaker Maximalism
Maybe only 'positive' truths need truth-makers [Tallant]
3. Truth / B. Truthmakers / 5. What Makes Truths / a. What makes truths
A truthmaker is the minimal portion of reality that will do the job [Tallant]
3. Truth / B. Truthmakers / 12. Rejecting Truthmakers
What is the truthmaker for a possible new power? [Tallant]
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]
5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
There are several logics, none of which will ever derive falsehoods from truth [Lewis,CI]
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 / D. Assumptions for Logic / 2. Excluded Middle
Excluded middle is just our preference for a simplified dichotomy in experience [Lewis,CI]
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
Names represent a uniformity in experience, or they name nothing [Lewis,CI]
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]
8. Modes of Existence / B. Properties / 13. Tropes / a. Nature of tropes
The wisdom of Plato and of Socrates are not the same property [Tallant]
9. Objects / B. Unity of Objects / 2. Substance / d. Substance defined
Substance must have two properties: individuation, and property-bearing [Tallant]
10. Modality / A. Necessity / 11. Denial of Necessity
Necessary truths are those we will maintain no matter what [Lewis,CI]
12. Knowledge Sources / A. A Priori Knowledge / 7. A Priori from Convention
We can maintain a priori principles come what may, but we can also change them [Lewis,CI]
18. Thought / E. Abstraction / 2. Abstracta by Selection
We have to separate the mathematical from physical phenomena by abstraction [Lewis,CI]
19. Language / D. Propositions / 2. Abstract Propositions / a. Propositions as sense
Are propositions all the thoughts and sentences that are possible? [Tallant]
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / a. Scientific essentialism
Science seeks classification which will discover laws, essences, and predictions [Lewis,CI]