Combining Texts

All the ideas for 'Perpetual Peace', 'On Formally Undecidable Propositions' and 'Essays on Intellectual Powers 2: Senses'

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38 ideas

3. Truth / F. Semantic Truth / 1. Tarski's Truth / a. Tarski's truth definition
Prior to Gödel we thought truth in mathematics consisted in provability [Gödel, by Quine]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets
Gödel show that the incompleteness of set theory was a necessity [Gödel, by Hallett,M]
5. Theory of Logic / K. Features of Logics / 1. Axiomatisation
The limitations of axiomatisation were revealed by the incompleteness theorems [Gödel, by Koellner]
5. Theory of Logic / K. Features of Logics / 2. Consistency
Second Incompleteness: nice theories can't prove their own consistency [Gödel, by Smith,P]
5. Theory of Logic / K. Features of Logics / 3. Soundness
If soundness can't be proved internally, 'reflection principles' can be added to assert soundness [Gödel, by Halbach/Leigh]
5. Theory of Logic / K. Features of Logics / 5. Incompleteness
Gödel's First Theorem sabotages logicism, and the Second sabotages Hilbert's Programme [Smith,P on Gödel]
The undecidable sentence can be decided at a 'higher' level in the system [Gödel]
6. Mathematics / A. Nature of Mathematics / 1. Mathematics
There can be no single consistent theory from which all mathematical truths can be derived [Gödel, by George/Velleman]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / g. Incompleteness of Arithmetic
Gödel showed that arithmetic is either incomplete or inconsistent [Gödel, by Rey]
First Incompleteness: arithmetic must always be incomplete [Gödel, by Smith,P]
Arithmetical truth cannot be fully and formally derived from axioms and inference rules [Gödel, by Nagel/Newman]
Gödel's Second says that semantic consequence outruns provability [Gödel, by Hanna]
First Incompleteness: a decent consistent system is syntactically incomplete [Gödel, by George/Velleman]
Second Incompleteness: a decent consistent system can't prove its own consistency [Gödel, by George/Velleman]
There is a sentence which a theory can show is true iff it is unprovable [Gödel, by Smith,P]
'This system can't prove this statement' makes it unprovable either way [Gödel, by Clegg]
6. Mathematics / C. Sources of Mathematics / 10. Constructivism / d. Predicativism
Realists are happy with impredicative definitions, which describe entities in terms of other existing entities [Gödel, by Shapiro]
7. Existence / A. Nature of Existence / 1. Nature of Existence
Accepting the existence of anything presupposes the notion of existence [Reid]
12. Knowledge Sources / A. A Priori Knowledge / 2. Self-Evidence
Truths are self-evident to sensible persons who understand them clearly without prejudice [Reid]
12. Knowledge Sources / B. Perception / 1. Perception
Sensation is not committed to any external object, but perception is [Reid]
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / c. Primary qualities
Primary qualities are the object of mathematics [Reid]
12. Knowledge Sources / B. Perception / 2. Qualities in Perception / d. Secondary qualities
Secondary qualities conjure up, and are confused with, the sensations which produce them [Reid]
12. Knowledge Sources / B. Perception / 5. Interpretation
It is unclear whether a toothache is in the mind or in the tooth, but the word has a single meaning [Reid]
12. Knowledge Sources / E. Direct Knowledge / 1. Common Sense
Reid is seen as the main direct realist of the eighteenth century [Reid, by Robinson,H]
13. Knowledge Criteria / B. Internal Justification / 3. Evidentialism / a. Evidence
People dislike believing without evidence, and try to avoid it [Reid]
13. Knowledge Criteria / B. Internal Justification / 5. Coherentism / b. Pro-coherentism
If non-rational evidence reaches us, it is reason which then makes use of it [Reid]
17. Mind and Body / C. Functionalism / 2. Machine Functionalism
Basic logic can be done by syntax, with no semantics [Gödel, by Rey]
18. Thought / E. Abstraction / 2. Abstracta by Selection
Only mature minds can distinguish the qualities of a body [Reid]
24. Political Theory / A. Basis of a State / 1. A People / b. The natural life
The state of nature always involves the threat of war [Kant]
24. Political Theory / B. Nature of a State / 2. State Legitimacy / c. Social contract
Kant made the social contract international and cosmopolitan [Kant, by Oksala]
24. Political Theory / B. Nature of a State / 2. State Legitimacy / d. General will
The a priori general will of a people shows what is right [Kant]
24. Political Theory / B. Nature of a State / 3. Constitutions
Each nation should, from self-interest, join an international security constitution [Kant]
A constitution must always be improved when necessary [Kant]
25. Social Practice / B. Equalities / 3. Legal equality
Equality is where you cannot impose a legal obligation you yourself wouldn't endure [Kant]
25. Social Practice / C. Rights / 1. Basis of Rights
There is now a growing universal community, and violations of rights are felt everywhere [Kant]
There are political and inter-national rights, but also universal cosmopolitan rights [Kant]
25. Social Practice / E. Policies / 1. War / c. Combatants
Hiring soldiers is to use them as instruments, ignoring their personal rights [Kant]
25. Social Practice / E. Policies / 1. War / e. Peace
Some trust in the enemy is needed during wartime, or peace would be impossible [Kant]