Combining Texts

All the ideas for 'What is Logic?st1=Ian Hacking', 'Course of Positive Philosophy' and 'On the Happy Life'

expand these ideas     |    start again     |     specify just one area for these texts


21 ideas

1. Philosophy / A. Wisdom / 2. Wise People
A wise man is not subservient to anything [Seneca]
1. Philosophy / G. Scientific Philosophy / 2. Positivism
The phases of human thought are theological, then metaphysical, then positivist [Comte, by Watson]
2. Reason / D. Definition / 3. Types of Definition
A decent modern definition should always imply a semantics [Hacking]
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]
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / a. Idealistic ethics
The supreme good is harmony of spirit [Seneca]
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / c. Motivation for virtue
I seek virtue, because it is its own reward [Seneca]
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / j. Unity of virtue
Virtue is always moderate, so excess need not be feared [Seneca]
23. Ethics / C. Virtue Theory / 3. Virtues / a. Virtues
It is shameful to not even recognise your own slaves [Seneca]
23. Ethics / C. Virtue Theory / 4. External Goods / c. Wealth
There is far more scope for virtue if you are wealthy; poverty only allows endurance [Seneca]
Why does your wife wear in her ears the income of a wealthy house? [Seneca]
If wealth was a good, it would make men good [Seneca]
24. Political Theory / D. Ideologies / 5. Democracy / f. Against democracy
Unfortunately the majority do not tend to favour what is best [Seneca]