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All the ideas for 'What is Logic?st1=Ian Hacking', 'The Problem of the Essential Indexical' and 'Quaestiones Disputatae de Malo'

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34 ideas

2. Reason / A. Nature of Reason / 1. On Reason
We are coerced into assent to a truth by reason's violence [Aquinas]
2. Reason / A. Nature of Reason / 4. Aims of Reason
The mind is compelled by necessary truths, but not by contingent truths [Aquinas]
2. Reason / D. Definition / 3. Types of Definition
A decent modern definition should always imply a semantics [Hacking]
3. Truth / A. Truth Problems / 3. Value of Truth
For the mind Good is one truth among many, and Truth is one good among many [Aquinas]
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 / 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]
11. Knowledge Aims / A. Knowledge / 4. Belief / b. Elements of beliefs
Indexicals are a problem for beliefs being just subject-proposition relations [Perry]
12. Knowledge Sources / D. Empiricism / 5. Empiricism Critique
Knowledge may be based on senses, but we needn't sense all our knowledge [Aquinas]
16. Persons / F. Free Will / 3. Constraints on the will
If we saw something as totally and utterly good, we would be compelled to will it [Aquinas]
16. Persons / F. Free Will / 4. For Free Will
Nothing can be willed except what is good, but good is very varied, and so choices are unpredictable [Aquinas]
However habituated you are, given time to ponder you can go against a habit [Aquinas]
Since will is a reasoning power, it can entertain opposites, so it is not compelled to embrace one of them [Aquinas]
The will is not compelled to move, even if pleasant things are set before it [Aquinas]
Because the will moves by examining alternatives, it doesn't compel itself to will [Aquinas]
16. Persons / F. Free Will / 5. Against Free Will
We must admit that when the will is not willing something, the first movement to will must come from outside the will [Aquinas]
19. Language / C. Assigning Meanings / 9. Indexical Semantics
If we replace 'I' in sentences about me, they are different beliefs and explanations of behaviour [Perry]
Indexicals individuate certain belief states, helping in explanation and prediction [Perry]
19. Language / D. Propositions / 6. Propositions Critique
Indexicals reveal big problems with the traditional idea of a proposition [Perry]
20. Action / B. Preliminaries of Action / 2. Willed Action / a. Will to Act
The will must aim at happiness, but can choose the means [Aquinas]
We don't have to will even perfect good, because we can choose not to think of it [Aquinas]
The will can only want what it thinks is good [Aquinas]
22. Metaethics / A. Ethics Foundations / 1. Nature of Ethics / g. Moral responsibility
Without free will not only is ethical action meaningless, but also planning, commanding, praising and blaming [Aquinas]
22. Metaethics / C. The Good / 1. Goodness / g. Consequentialism
Good applies to goals, just as truth applies to ideas in the mind [Aquinas]
26. Natural Theory / C. Causation / 9. General Causation / d. Causal necessity
Even a sufficient cause doesn't compel its effect, because interference could interrupt the process [Aquinas]
27. Natural Reality / D. Time / 2. Passage of Time / c. Tenses and time
Tense is essential for thought and action [Perry, by Le Poidevin]
Actual tensed sentences cannot be tenseless, because they can cite their own context [Perry, by Le Poidevin]