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All the ideas for 'What is Logic?st1=Ian Hacking', 'The Concept of Truth for Formalized Languages' and 'Letters to Antoine Arnauld'

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89 ideas

1. Philosophy / A. Wisdom / 1. Nature of Wisdom
Wisdom is the science of happiness [Leibniz]
1. Philosophy / A. Wisdom / 2. Wise People
Wise people have fewer acts of will, because such acts are linked together [Leibniz]
1. Philosophy / E. Nature of Metaphysics / 5. Metaphysics beyond Science
Metaphysics is geometrical, resting on non-contradiction and sufficient reason [Leibniz]
2. Reason / D. Definition / 3. Types of Definition
A decent modern definition should always imply a semantics [Hacking]
2. Reason / D. Definition / 4. Real Definition
Definitions can only be real if the item is possible [Leibniz]
3. Truth / A. Truth Problems / 1. Truth
The predicate is in the subject of a true proposition [Leibniz]
A truth is just a proposition in which the predicate is contained within the subject [Leibniz]
3. Truth / A. Truth Problems / 2. Defining Truth
Tarski proved that truth cannot be defined from within a given theory [Tarski, by Halbach]
Tarski proved that any reasonably expressive language suffers from the liar paradox [Tarski, by Horsten]
'True sentence' has no use consistent with logic and ordinary language, so definition seems hopeless [Tarski]
3. Truth / C. Correspondence Truth / 3. Correspondence Truth critique
Tarski's Theorem renders any precise version of correspondence impossible [Tarski, by Halbach]
3. Truth / F. Semantic Truth / 1. Tarski's Truth / a. Tarski's truth definition
Tarskian semantics says that a sentence is true iff it is satisfied by every sequence [Tarski, by Hossack]
Tarski gave up on the essence of truth, and asked how truth is used, or how it functions [Tarski, by Horsten]
Tarski did not just aim at a definition; he also offered an adequacy criterion for any truth definition [Tarski, by Halbach]
Tarski enumerates cases of truth, so it can't be applied to new words or languages [Davidson on Tarski]
Tarski define truths by giving the extension of the predicate, rather than the meaning [Davidson on Tarski]
Tarski made truth relative, by only defining truth within some given artificial language [Tarski, by O'Grady]
Tarski has to avoid stating how truths relate to states of affairs [Kirkham on Tarski]
3. Truth / F. Semantic Truth / 1. Tarski's Truth / b. Satisfaction and truth
Truth only applies to closed formulas, but we need satisfaction of open formulas to define it [Burgess on Tarski]
Tarski uses sentential functions; truly assigning the objects to variables is what satisfies them [Tarski, by Rumfitt]
We can define the truth predicate using 'true of' (satisfaction) for variables and some objects [Tarski, by Horsten]
For physicalism, reduce truth to satisfaction, then define satisfaction as physical-plus-logic [Tarski, by Kirkham]
Insight: don't use truth, use a property which can be compositional in complex quantified sentence [Tarski, by Kirkham]
Tarski gave axioms for satisfaction, then derived its explicit definition, which led to defining truth [Tarski, by Davidson]
3. Truth / F. Semantic Truth / 2. Semantic Truth
Tarski made truth respectable, by proving that it could be defined [Tarski, by Halbach]
Tarski defined truth for particular languages, but didn't define it across languages [Davidson on Tarski]
Tarski didn't capture the notion of an adequate truth definition, as Convention T won't prove non-contradiction [Halbach on Tarski]
Tarski says that his semantic theory of truth is completely neutral about all metaphysics [Tarski, by Haack]
Physicalists should explain reference nonsemantically, rather than getting rid of it [Tarski, by Field,H]
A physicalist account must add primitive reference to Tarski's theory [Field,H on Tarski]
Tarski had a theory of truth, and a theory of theories of truth [Tarski, by Read]
Tarski's 'truth' is a precise relation between the language and its semantics [Tarski, by Walicki]
Tarskian truth neglects the atomic sentences [Mulligan/Simons/Smith on Tarski]
3. Truth / G. Axiomatic Truth / 1. Axiomatic Truth
Tarski's had the first axiomatic theory of truth that was minimally adequate [Tarski, by Horsten]
Tarski defined truth, but an axiomatisation can be extracted from his inductive clauses [Tarski, by Halbach]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / d. Basic theorems of PL
'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking]
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]
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 / 4. Identity in Logic
Identity is invariant under arbitrary permutations, so it seems to be a logical term [Tarski, by McGee]
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 / c. Names as referential
A name denotes an object if the object satisfies a particular sentential function [Tarski]
5. Theory of Logic / I. Semantics of Logic / 1. Semantics of Logic
Tarski built a compositional semantics for predicate logic, from dependent satisfactions [Tarski, by McGee]
Tarksi invented the first semantics for predicate logic, using this conception of truth [Tarski, by Kirkham]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
The object language/ metalanguage distinction is the basis of model theory [Tarski, by Halbach]
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]
5. Theory of Logic / L. Paradox / 6. Paradoxes in Language / a. The Liar paradox
Tarski avoids the Liar Paradox, because truth cannot be asserted within the object language [Tarski, by Fisher]
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / a. Units
There is no multiplicity without true units [Leibniz]
6. Mathematics / C. Sources of Mathematics / 7. Formalism
Tarski's theory of truth shifted the approach away from syntax, to set theory and semantics [Feferman/Feferman on Tarski]
7. Existence / A. Nature of Existence / 3. Being / g. Particular being
What is not truly one being is not truly a being either [Leibniz]
7. Existence / C. Structure of Existence / 5. Supervenience / a. Nature of supervenience
A thing 'expresses' another if they have a constant and fixed relationship [Leibniz]
8. Modes of Existence / C. Powers and Dispositions / 2. Powers as Basic
A substance contains the laws of its operations, and its actions come from its own depth [Leibniz]
9. Objects / B. Unity of Objects / 1. Unifying an Object / a. Intrinsic unification
Philosophy needs the precision of the unity given by substances [Leibniz]
9. Objects / B. Unity of Objects / 1. Unifying an Object / b. Unifying aggregates
Accidental unity has degrees, from a mob to a society to a machine or organism [Leibniz]
9. Objects / B. Unity of Objects / 1. Unifying an Object / c. Unity as conceptual
We find unity in reason, and unity in perception, but these are not true unity [Leibniz]
9. Objects / B. Unity of Objects / 2. Substance / a. Substance
A body is a unified aggregate, unless it has an indivisible substance [Leibniz]
Unity needs an indestructible substance, to contain everything which will happen to it [Leibniz]
Every bodily substance must have a soul, or something analogous to a soul [Leibniz]
9. Objects / B. Unity of Objects / 2. Substance / b. Need for substance
Aggregates don’t reduce to points, or atoms, or illusion, so must reduce to substance [Leibniz]
9. Objects / D. Essence of Objects / 1. Essences of Objects
Basic predicates give the complete concept, which then predicts all of the actions [Leibniz]
Essences exist in the divine understanding [Leibniz]
9. Objects / D. Essence of Objects / 6. Essence as Unifier
Bodies need a soul (or something like it) to avoid being mere phenomena [Leibniz]
9. Objects / D. Essence of Objects / 10. Essence as Species
Truths about species are eternal or necessary, but individual truths concern what exists [Leibniz]
10. Modality / E. Possible worlds / 3. Transworld Objects / a. Transworld identity
If varieties of myself can be conceived of as distinct from me, then they are not me [Leibniz]
If someone's life went differently, then that would be another individual [Leibniz]
11. Knowledge Aims / B. Certain Knowledge / 4. The Cogito
I cannot think my non-existence, nor exist without being myself [Leibniz]
11. Knowledge Aims / B. Certain Knowledge / 5. Cogito Critique
I can't just know myself to be a substance; I must distinguish myself from others, which is hard [Leibniz]
13. Knowledge Criteria / B. Internal Justification / 4. Foundationalism / a. Foundationalism
Nothing should be taken as certain without foundations [Leibniz]
14. Science / D. Explanation / 2. Types of Explanation / a. Types of explanation
Nature is explained by mathematics and mechanism, but the laws rest on metaphysics [Leibniz]
14. Science / D. Explanation / 2. Types of Explanation / k. Explanations by essence
To fully conceive the subject is to explain the resulting predicates and events [Leibniz]
15. Nature of Minds / A. Nature of Mind / 1. Mind / b. Purpose of mind
Mind is a thinking substance which can know God and eternal truths [Leibniz]
15. Nature of Minds / A. Nature of Mind / 7. Animal Minds
It seems probable that animals have souls, but not consciousness [Leibniz]
16. Persons / F. Free Will / 7. Compatibilism
Everything which happens is not necessary, but is certain after God chooses this universe [Leibniz]
18. Thought / D. Concepts / 1. Concepts / a. Nature of concepts
Concepts are what unite a proposition [Leibniz]
21. Aesthetics / A. Aesthetic Experience / 3. Taste
Taste is the capacity to judge an object or representation which is thought to be beautiful [Tarski, by Schellekens]
21. Aesthetics / A. Aesthetic Experience / 4. Beauty
Beauty increases with familiarity [Leibniz]
22. Metaethics / C. The Good / 2. Happiness / a. Nature of happiness
Happiness is advancement towards perfection [Leibniz]
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / g. Atomism
I think the corpuscular theory, rather than forms or qualities, best explains particular phenomena [Leibniz]
26. Natural Theory / D. Laws of Nature / 1. Laws of Nature
Each possible world contains its own laws, reflected in the possible individuals of that world [Leibniz]
27. Natural Reality / A. Classical Physics / 1. Mechanics / c. Forces
Motion alone is relative, but force is real, and establishes its subject [Leibniz]
28. God / B. Proving God / 3. Proofs of Evidence / e. Miracles
Everything, even miracles, belongs to order [Leibniz]
Miracles are extraordinary operations by God, but are nevertheless part of his design [Leibniz]
29. Religion / D. Religious Issues / 2. Immortality / a. Immortality
Immortality without memory is useless [Leibniz]
29. Religion / D. Religious Issues / 2. Immortality / b. Soul
The soul is indestructible and always self-aware [Leibniz]
29. Religion / D. Religious Issues / 2. Immortality / c. Animal Souls
Animals have souls, but lack consciousness [Leibniz]