58 ideas
3600 | Slow and accurate thought makes the greatest progress [Descartes] |
3601 | Most things in human life seem vain and useless [Descartes] |
3602 | Almost every daft idea has been expressed by some philosopher [Descartes] |
3603 | Methodical thinking is cautious, analytical, systematic, and panoramic [Descartes, by PG] |
4643 | The Principle of Sufficient Reason does not presuppose that all explanations will be causal explanations [Baggini /Fosl] |
4633 | You cannot rationally deny the principle of non-contradiction, because all reasoning requires it [Baggini /Fosl] |
4635 | Dialectic aims at unified truth, unlike analysis, which divides into parts [Baggini /Fosl] |
3612 | Clear and distinct conceptions are true because a perfect God exists [Descartes] |
3610 | Truth is clear and distinct conception - of which it is hard to be sure [Descartes] |
21752 | Prior to Gödel we thought truth in mathematics consisted in provability [Gödel, by Quine] |
4632 | 'Natural' systems of deduction are based on normal rational practice, rather than on axioms [Baggini /Fosl] |
4631 | In ideal circumstances, an axiom should be such that no rational agent could possibly object to its use [Baggini /Fosl] |
17835 | Gödel show that the incompleteness of set theory was a necessity [Gödel, by Hallett,M] |
4638 | The principle of bivalence distorts reality, as when claiming that a person is or is not 'thin' [Baggini /Fosl] |
17886 | The limitations of axiomatisation were revealed by the incompleteness theorems [Gödel, by Koellner] |
10071 | Second Incompleteness: nice theories can't prove their own consistency [Gödel, by Smith,P] |
19123 | If soundness can't be proved internally, 'reflection principles' can be added to assert soundness [Gödel, by Halbach/Leigh] |
10621 | Gödel's First Theorem sabotages logicism, and the Second sabotages Hilbert's Programme [Smith,P on Gödel] |
17888 | The undecidable sentence can be decided at a 'higher' level in the system [Gödel] |
10132 | There can be no single consistent theory from which all mathematical truths can be derived [Gödel, by George/Velleman] |
3198 | Gödel showed that arithmetic is either incomplete or inconsistent [Gödel, by Rey] |
10072 | First Incompleteness: arithmetic must always be incomplete [Gödel, by Smith,P] |
9590 | Arithmetical truth cannot be fully and formally derived from axioms and inference rules [Gödel, by Nagel/Newman] |
11069 | Gödel's Second says that semantic consequence outruns provability [Gödel, by Hanna] |
10118 | First Incompleteness: a decent consistent system is syntactically incomplete [Gödel, by George/Velleman] |
10122 | Second Incompleteness: a decent consistent system can't prove its own consistency [Gödel, by George/Velleman] |
10611 | There is a sentence which a theory can show is true iff it is unprovable [Gödel, by Smith,P] |
10867 | 'This system can't prove this statement' makes it unprovable either way [Gödel, by Clegg] |
8747 | Realists are happy with impredicative definitions, which describe entities in terms of other existing entities [Gödel, by Shapiro] |
4640 | If identity is based on 'true of X' instead of 'property of X' we get the Masked Man fallacy ('I know X but not Y') [Baggini /Fosl, by PG] |
4647 | 'I have the same car as you' is fine; 'I have the same fiancée as you' is not so good [Baggini /Fosl] |
4639 | Leibniz's Law is about the properties of objects; the Identity of Indiscernibles is about perception of objects [Baggini /Fosl] |
4646 | Is 'events have causes' analytic a priori, synthetic a posteriori, or synthetic a priori? [Baggini /Fosl] |
3605 | We can believe a thing without knowing we believe it [Descartes] |
1583 | In morals Descartes accepts the conventional, but rejects it in epistemology [Roochnik on Descartes] |
3607 | In thinking everything else false, my own existence remains totally certain [Descartes] |
4645 | 'A priori' does not concern how you learn a proposition, but how you show whether it is true or false [Baggini /Fosl] |
3617 | I aim to find the principles and causes of everything, using the seeds within my mind [Descartes] |
3611 | Understanding, rather than imagination or senses, gives knowledge [Descartes] |
3606 | I was searching for reliable rock under the shifting sand [Descartes] |
4582 | Basic beliefs are self-evident, or sensual, or intuitive, or revealed, or guaranteed [Baggini /Fosl] |
3604 | When rebuilding a house, one needs alternative lodgings [Descartes] |
3618 | Only experiments can settle disagreements between rival explanations [Descartes] |
4644 | A proposition such as 'some swans are purple' cannot be falsified, only verified [Baggini /Fosl] |
4584 | The problem of induction is how to justify our belief in the uniformity of nature [Baggini /Fosl] |
4583 | How can an argument be good induction, but poor deduction? [Baggini /Fosl] |
4634 | Abduction aims at simplicity, testability, coherence and comprehensiveness [Baggini /Fosl] |
4637 | To see if an explanation is the best, it is necessary to investigate the alternative explanations [Baggini /Fosl] |
3615 | Little reason is needed to speak, so animals have no reason at all [Descartes] |
3609 | I am a thinking substance, which doesn't need a place or material support [Descartes] |
3608 | I can deny my body and the world, but not my own existence [Descartes] |
3613 | Reason is universal in its responses, but a physical machine is constrained by its organs [Descartes] |
3616 | The soul must unite with the body to have appetites and sensations [Descartes] |
3192 | Basic logic can be done by syntax, with no semantics [Gödel, by Rey] |
4629 | Consistency is the cornerstone of rationality [Baggini /Fosl] |
3614 | A machine could speak in response to physical stimulus, but not hold a conversation [Descartes] |
1581 | Greeks elevate virtues enormously, but never explain them [Descartes] |
16686 | God has established laws throughout nature, and implanted ideas of them within us [Descartes] |