Combining Texts

All the ideas for 'Monadology', 'Defending the Axioms' and 'What is Logic?'

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37 ideas

2. Reason / B. Laws of Thought / 2. Sufficient Reason
No fact can be real and no proposition true unless there is a Sufficient Reason (even if we can't know it) [Leibniz]
2. Reason / D. Definition / 3. Types of Definition
A decent modern definition should always imply a semantics [Hacking]
3. Truth / D. Coherence Truth / 1. Coherence Truth
Everything in the universe is interconnected, so potentially a mind could know everything [Leibniz]
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]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX
The Axiom of Choice paradoxically allows decomposing a sphere into two identical spheres [Maddy]
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 / C. Ontology of Logic / 3. If-Thenism
Critics of if-thenism say that not all starting points, even consistent ones, are worth studying [Maddy]
5. Theory of Logic / D. Assumptions for Logic / 3. Contradiction
Falsehood involves a contradiction, and truth is contradictory of falsehood [Leibniz]
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 / 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 / K. Features of Logics / 1. Axiomatisation
Hilbert's geometry and Dedekind's real numbers were role models for axiomatization [Maddy]
If two mathematical themes coincide, that suggest a single deep truth [Maddy]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / g. Continuum Hypothesis
Every infinite set of reals is either countable or of the same size as the full set of reals [Maddy]
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
Set-theory tracks the contours of mathematical depth and fruitfulness [Maddy]
6. Mathematics / C. Sources of Mathematics / 4. Mathematical Empiricism / c. Against mathematical empiricism
The connection of arithmetic to perception has been idealised away in modern infinitary mathematics [Maddy]
7. Existence / C. Structure of Existence / 6. Fundamentals / c. Monads
The monad idea incomprehensibly spiritualises matter, instead of materialising soul [La Mettrie on Leibniz]
He replaced Aristotelian continuants with monads [Leibniz, by Wiggins]
Is a drop of urine really an infinity of thinking monads? [Voltaire on Leibniz]
It is unclear in 'Monadology' how extended bodies relate to mind-like monads. [Garber on Leibniz]
Changes in a monad come from an internal principle, and the diversity within its substance [Leibniz]
A 'monad' has basic perception and appetite; a 'soul' has distinct perception and memory [Leibniz]
9. Objects / B. Unity of Objects / 2. Substance / e. Substance critique
If a substance is just a thing that has properties, it seems to be a characterless non-entity [Leibniz, by Macdonald,C]
9. Objects / F. Identity among Objects / 7. Indiscernible Objects
There must be some internal difference between any two beings in nature [Leibniz]
10. Modality / D. Knowledge of Modality / 1. A Priori Necessary
Truths of reason are known by analysis, and are necessary; facts are contingent, and their opposites possible [Leibniz]
12. Knowledge Sources / A. A Priori Knowledge / 4. A Priori as Necessities
Mathematical analysis ends in primitive principles, which cannot be and need not be demonstrated [Leibniz]
12. Knowledge Sources / C. Rationalism / 1. Rationalism
We all expect the sun to rise tomorrow by experience, but astronomers expect it by reason [Leibniz]
15. Nature of Minds / B. Features of Minds / 3. Privacy
Increase a conscious machine to the size of a mill - you still won't see perceptions in it [Leibniz]
16. Persons / C. Self-Awareness / 2. Knowing the Self
We know the 'I' and its contents by abstraction from awareness of necessary truths [Leibniz]
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / f. Ancient elements
The true elements are atomic monads [Leibniz]
28. God / A. Divine Nature / 3. Divine Perfections
This is the most perfect possible universe, in its combination of variety with order [Leibniz]
28. God / B. Proving God / 2. Proofs of Reason / a. Ontological Proof
God alone (the Necessary Being) has the privilege that He must exist if He is possible [Leibniz]