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All the ideas for 'What is Logic?st1=Ian Hacking', 'Transcendence of the Ego' and 'Intro: Theories of Vagueness'

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49 ideas

1. Philosophy / H. Continental Philosophy / 2. Phenomenology
Phenomenology assumes that all consciousness is of something [Sartre]
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]
4. Formal Logic / D. Modal Logic ML / 3. Modal Logic Systems / h. System S5
S5 collapses iterated modalities (◊□P→□P, and ◊◊P→◊P) [Keefe/Smith]
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]
7. Existence / D. Theories of Reality / 10. Vagueness / b. Vagueness of reality
Objects such as a cloud or Mount Everest seem to have fuzzy boundaries in nature [Keefe/Smith]
7. Existence / D. Theories of Reality / 10. Vagueness / c. Vagueness as ignorance
If someone is borderline tall, no further information is likely to resolve the question [Keefe/Smith]
The simplest approach, that vagueness is just ignorance, retains classical logic and semantics [Keefe/Smith]
The epistemic view of vagueness must explain why we don't know the predicate boundary [Keefe/Smith]
7. Existence / D. Theories of Reality / 10. Vagueness / f. Supervaluation for vagueness
Supervaluationism keeps true-or-false where precision can be produced, but not otherwise [Keefe/Smith]
Vague statements lack truth value if attempts to make them precise fail [Keefe/Smith]
Some of the principles of classical logic still fail with supervaluationism [Keefe/Smith]
The semantics of supervaluation (e.g. disjunction and quantification) is not classical [Keefe/Smith]
Supervaluation misunderstands vagueness, treating it as a failure to make things precise [Keefe/Smith]
7. Existence / D. Theories of Reality / 10. Vagueness / g. Degrees of vagueness
A third truth-value at borderlines might be 'indeterminate', or a value somewhere between 0 and 1 [Keefe/Smith]
People can't be placed in a precise order according to how 'nice' they are [Keefe/Smith]
If truth-values for vagueness range from 0 to 1, there must be someone who is 'completely tall' [Keefe/Smith]
How do we decide if my coat is red to degree 0.322 or 0.321? [Keefe/Smith]
9. Objects / B. Unity of Objects / 3. Unity Problems / e. Vague objects
Vague predicates involve uncertain properties, uncertain objects, and paradoxes of gradual change [Keefe/Smith]
Many vague predicates are multi-dimensional; 'big' involves height and volume; heaps include arrangement [Keefe/Smith]
If there is a precise borderline area, that is not a case of vagueness [Keefe/Smith]
11. Knowledge Aims / B. Certain Knowledge / 5. Cogito Critique
The Cogito depends on a second-order experience, of being conscious of consciousness [Sartre]
The consciousness that says 'I think' is not the consciousness that thinks [Sartre]
Is the Cogito reporting an immediate experience of doubting, or the whole enterprise of doubting? [Sartre]
15. Nature of Minds / A. Nature of Mind / 4. Other Minds / b. Scepticism of other minds
We can never, even in principle, grasp other minds, because the Ego is self-conceiving [Sartre]
A consciousness can conceive of no other consciousness than itself [Sartre]
15. Nature of Minds / A. Nature of Mind / 5. Unity of Mind
The eternal truth of 2+2=4 is what gives unity to the mind which regularly thinks it [Sartre]
15. Nature of Minds / B. Features of Minds / 1. Consciousness / f. Higher-order thought
Consciousness exists as consciousness of itself [Sartre]
15. Nature of Minds / B. Features of Minds / 2. Unconscious Mind
Since we are a consciousness, Sartre entirely rejected the unconscious mind [Sartre, by Daigle]
15. Nature of Minds / B. Features of Minds / 4. Intentionality / a. Nature of intentionality
Intentionality defines, transcends and unites consciousness [Sartre]
16. Persons / B. Nature of the Self / 4. Presupposition of Self
If you think of '2+2=4' as the content of thought, the self must be united transcendentally [Sartre]
16. Persons / B. Nature of the Self / 6. Self as Higher Awareness
The Ego is not formally or materially part of consciousness, but is outside in the world [Sartre]
16. Persons / C. Self-Awareness / 2. Knowing the Self
How could two I's, the reflective and the reflected, communicate with each other? [Sartre]
Knowing yourself requires an exterior viewpoint, which is necessarily false [Sartre]
My ego is more intimate to me, but not more certain than other egos [Sartre]
16. Persons / C. Self-Awareness / 3. Limits of Introspection
The Ego never appears except when we are not looking for it [Sartre]
When we are unreflective (as when chasing a tram) there is no 'I' [Sartre]
16. Persons / D. Continuity of the Self / 2. Mental Continuity / a. Memory is Self
It is theoretically possible that the Ego consists entirely of false memories [Sartre]
16. Persons / D. Continuity of the Self / 4. Split Consciousness
If the 'I' is transcendental, it unnecessarily splits consciousness in two [Sartre]
16. Persons / E. Rejecting the Self / 4. Denial of the Self
Maybe it is the act of reflection that brings 'me' into existence [Sartre]
The Ego only appears to reflection, so it is cut off from the World [Sartre]