Combining Texts

All the ideas for 'On the Question of Absolute Undecidability', 'Regressive Method for Premises in Mathematics' and 'Contingent Identity'

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32 ideas

1. Philosophy / D. Nature of Philosophy / 5. Aims of Philosophy / e. Philosophy as reason
Discoveries in mathematics can challenge philosophy, and offer it a new foundation [Russell]
2. Reason / A. Nature of Reason / 6. Coherence
If one proposition is deduced from another, they are more certain together than alone [Russell]
2. Reason / B. Laws of Thought / 3. Non-Contradiction
Non-contradiction was learned from instances, and then found to be indubitable [Russell]
4. Formal Logic / F. Set Theory ST / 1. Set Theory
Mathematical set theory has many plausible stopping points, such as finitism, and predicativism [Koellner]
'Reflection principles' say the whole truth about sets can't be captured [Koellner]
5. Theory of Logic / K. Features of Logics / 1. Axiomatisation
Which premises are ultimate varies with context [Russell]
The sources of a proof are the reasons why we believe its conclusion [Russell]
Finding the axioms may be the only route to some new results [Russell]
5. Theory of Logic / K. Features of Logics / 5. Incompleteness
We have no argument to show a statement is absolutely undecidable [Koellner]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / i. Cardinal infinity
There are at least eleven types of large cardinal, of increasing logical strength [Koellner]
6. Mathematics / B. Foundations for Mathematics / 2. Proof in Mathematics
It seems absurd to prove 2+2=4, where the conclusion is more certain than premises [Russell]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / d. Peano arithmetic
PA is consistent as far as we can accept, and we expand axioms to overcome limitations [Koellner]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / g. Incompleteness of Arithmetic
Arithmetical undecidability is always settled at the next stage up [Koellner]
6. Mathematics / C. Sources of Mathematics / 4. Mathematical Empiricism / a. Mathematical empiricism
Arithmetic was probably inferred from relationships between physical objects [Russell]
9. Objects / B. Unity of Objects / 3. Unity Problems / c. Statue and clay
If a statue is identical with the clay of which it is made, that identity is contingent [Gibbard]
A 'piece' of clay begins when its parts stick together, separately from other clay [Gibbard]
Clay and statue are two objects, which can be named and reasoned about [Gibbard]
We can only investigate the identity once we have designated it as 'statue' or as 'clay' [Gibbard]
9. Objects / D. Essence of Objects / 7. Essence and Necessity / a. Essence as necessary properties
Essentialism is the existence of a definite answer as to whether an entity fulfils a condition [Gibbard]
9. Objects / D. Essence of Objects / 15. Against Essentialism
Essentialism for concreta is false, since they can come apart under two concepts [Gibbard]
9. Objects / E. Objects over Time / 12. Origin as Essential
A particular statue has sortal persistence conditions, so its origin defines it [Gibbard]
9. Objects / F. Identity among Objects / 6. Identity between Objects
Claims on contingent identity seem to violate Leibniz's Law [Gibbard]
9. Objects / F. Identity among Objects / 8. Leibniz's Law
Two identical things must share properties - including creation and destruction times [Gibbard]
Leibniz's Law isn't just about substitutivity, because it must involve properties and relations [Gibbard]
10. Modality / E. Possible worlds / 3. Transworld Objects / a. Transworld identity
Possible worlds identity needs a sortal [Gibbard]
Only concepts, not individuals, can be the same across possible worlds [Gibbard]
10. Modality / E. Possible worlds / 3. Transworld Objects / b. Rigid designation
Kripke's semantics needs lots of intuitions about which properties are essential [Gibbard]
11. Knowledge Aims / B. Certain Knowledge / 3. Fallibilism
The most obvious beliefs are not infallible, as other obvious beliefs may conflict [Russell]
13. Knowledge Criteria / B. Internal Justification / 5. Coherentism / a. Coherence as justification
Believing a whole science is more than believing each of its propositions [Russell]
14. Science / C. Induction / 2. Aims of Induction
Induction is inferring premises from consequences [Russell]
19. Language / B. Reference / 3. Direct Reference / b. Causal reference
Naming a thing in the actual world also invokes some persistence criteria [Gibbard]
26. Natural Theory / D. Laws of Nature / 1. Laws of Nature
The law of gravity has many consequences beyond its grounding observations [Russell]