91 ideas
326 | For relaxation one can consider the world of change, instead of eternal things [Plato] |
315 | Philosophy is the supreme gift of the gods to mortals [Plato] |
15357 | Philosophy is the most general intellectual discipline [Horsten] |
306 | Nothing can come to be without a cause [Plato] |
15352 | A definition should allow the defined term to be eliminated [Horsten] |
16539 | A definition of a circle will show what it is, and show its generating principle [Lowe] |
16540 | Defining an ellipse by conic sections reveals necessities, but not the essence of an ellipse [Lowe] |
16548 | An essence is what an entity is, revealed by a real definition; this is not an entity in its own right [Lowe] |
16549 | Simple things like 'red' can be given real ostensive definitions [Lowe] |
15324 | Semantic theories of truth seek models; axiomatic (syntactic) theories seek logical principles [Horsten] |
15323 | Truth is a property, because the truth predicate has an extension [Horsten] |
15374 | Truth has no 'nature', but we should try to describe its behaviour in inferences [Horsten] |
15348 | Propositions have sentence-like structures, so it matters little which bears the truth [Horsten] |
15333 | Modern correspondence is said to be with the facts, not with true propositions [Horsten] |
15337 | The correspondence 'theory' is too vague - about both 'correspondence' and 'facts' [Horsten] |
15334 | The coherence theory allows multiple coherent wholes, which could contradict one another [Horsten] |
15336 | The pragmatic theory of truth is relative; useful for group A can be useless for group B [Horsten] |
15354 | Tarski's hierarchy lacks uniform truth, and depends on contingent factors [Horsten] |
15340 | Tarski Bi-conditional: if you'll assert φ you'll assert φ-is-true - and also vice versa [Horsten] |
15345 | Semantic theories have a regress problem in describing truth in the languages for the models [Horsten] |
15373 | Axiomatic approaches avoid limiting definitions to avoid the truth predicate, and limited sizes of models [Horsten] |
15332 | 'Reflexive' truth theories allow iterations (it is T that it is T that p) [Horsten] |
15346 | Axiomatic approaches to truth avoid the regress problem of semantic theories [Horsten] |
15361 | A good theory of truth must be compositional (as well as deriving biconditionals) [Horsten] |
15371 | An axiomatic theory needs to be of maximal strength, while being natural and sound [Horsten] |
15350 | The Naďve Theory takes the bi-conditionals as axioms, but it is inconsistent, and allows the Liar [Horsten] |
15351 | Axiomatic theories take truth as primitive, and propose some laws of truth as axioms [Horsten] |
15367 | By adding truth to Peano Arithmetic we increase its power, so truth has mathematical content! [Horsten] |
15330 | Friedman-Sheard theory keeps classical logic and aims for maximum strength [Horsten] |
15331 | Kripke-Feferman has truth gaps, instead of classical logic, and aims for maximum strength [Horsten] |
15325 | Inferential deflationism says truth has no essence because no unrestricted logic governs the concept [Horsten] |
15344 | Deflationism skips definitions and models, and offers just accounts of basic laws of truth [Horsten] |
15356 | Deflationism concerns the nature and role of truth, but not its laws [Horsten] |
15368 | This deflationary account says truth has a role in generality, and in inference [Horsten] |
15358 | Deflationism says truth isn't a topic on its own - it just concerns what is true [Horsten] |
15359 | Deflation: instead of asserting a sentence, we can treat it as an object with the truth-property [Horsten] |
15329 | Nonclassical may accept T/F but deny applicability, or it may deny just T or F as well [Horsten] |
15326 | Doubt is thrown on classical logic by the way it so easily produces the liar paradox [Horsten] |
15341 | Deduction Theorem: ψ only derivable from φ iff φ→ψ are axioms [Horsten] |
15328 | A theory is 'non-conservative' if it facilitates new mathematical proofs [Horsten] |
15349 | It is easier to imagine truth-value gaps (for the Liar, say) than for truth-value gluts (both T and F) [Horsten] |
15366 | Satisfaction is a primitive notion, and very liable to semantical paradoxes [Horsten] |
15353 | The first incompleteness theorem means that consistency does not entail soundness [Horsten] |
15355 | Strengthened Liar: 'this sentence is not true in any context' - in no context can this be evaluated [Horsten] |
15364 | English expressions are denumerably infinite, but reals are nondenumerable, so many are unnameable [Horsten] |
15360 | ZFC showed that the concept of set is mathematical, not logical, because of its existence claims [Horsten] |
15369 | Set theory is substantial over first-order arithmetic, because it enables new proofs [Horsten] |
15370 | Predicativism says mathematical definitions must not include the thing being defined [Horsten] |
324 | Before the existence of the world there must have been being, space and becoming [Plato] |
20364 | The apprehensions of reason remain unchanging, but reasonless sensation shows mere becoming [Plato] |
15338 | We may believe in atomic facts, but surely not complex disjunctive ones? [Horsten] |
15362 | If 'Italy is large' lacks truth, so must 'Italy is not large'; but classical logic says it's large or it isn't [Horsten] |
15363 | In the supervaluationist account, disjunctions are not determined by their disjuncts [Horsten] |
12042 | Plato's Forms were seen as part of physics, rather than of metaphysics [Plato, by Annas] |
307 | Something will always be well-made if the maker keeps in mind the eternal underlying pattern [Plato] |
318 | In addition to the underlying unchanging model and a changing copy of it, there must also be a foundation of all change [Plato] |
321 | For knowledge and true opinion to be different there must be Forms; otherwise we are just stuck with sensations [Plato] |
317 | The universe is basically an intelligible and unchanging model, and a visible and changing copy of it [Plato] |
16545 | The essence of lumps and statues shows that two objects coincide but are numerically distinct [Lowe] |
16546 | The essence of a bronze statue shows that it could be made of different bronze [Lowe] |
16551 | Grasping an essence is just grasping a real definition [Lowe] |
16542 | Explanation can't give an account of essence, because it is too multi-faceted [Lowe] |
16552 | If we must know some entity to know an essence, we lack a faculty to do that [Lowe] |
16533 | Logical necessities, based on laws of logic, are a proper sub-class of metaphysical necessities [Lowe] |
16531 | 'Metaphysical' necessity is absolute and objective - the strongest kind of necessity [Lowe] |
16532 | 'Epistemic' necessity is better called 'certainty' [Lowe] |
16543 | If an essence implies p, then p is an essential truth, and hence metaphysically necessary [Lowe] |
16544 | Metaphysical necessity is either an essential truth, or rests on essential truths [Lowe] |
16538 | We could give up possible worlds if we based necessity on essences [Lowe] |
15372 | Some claim that indicative conditionals are believed by people, even though they are not actually held true [Horsten] |
334 | Only bird-brained people think astronomy is entirely a matter of evidence [Plato] |
16534 | 'Intuitions' are just unreliable 'hunches'; over centuries intuitions change enormously [Lowe] |
5962 | Plato says the soul is ordered by number [Plato, by Plutarch] |
330 | No one wants to be bad, but bad men result from physical and educational failures, which they do not want or choose [Plato] |
16535 | A concept is a way of thinking of things or kinds, whether or not they exist [Lowe] |
16550 | Direct reference doesn't seem to require that thinkers know what it is they are thinking about [Lowe] |
15347 | A theory of syntax can be based on Peano arithmetic, thanks to the translation by Gödel coding [Horsten] |
316 | Music has harmony like the soul, and serves to reorder disharmony within us [Plato] |
332 | One should exercise both the mind and the body, to avoid imbalance [Plato] |
328 | Everything that takes place naturally is pleasant [Plato] |
322 | Intelligence is the result of rational teaching; true opinion can result from irrational persuasion [Plato] |
331 | Bad governments prevent discussion, and discourage the study of virtue [Plato] |
310 | The creator of the cosmos had no envy, and so wanted things to be as like himself as possible [Plato] |
311 | The cosmos must be unique, because it resembles the creator, who is unique [Plato] |
325 | We must consider the four basic shapes as too small to see, only becoming visible in large numbers [Plato] |
327 | There are two types of cause, the necessary and the divine [Plato] |
16547 | H2O isn't necessary, because different laws of nature might affect how O and H combine [Lowe] |
314 | Heavenly movements gave us the idea of time, and caused us to inquire about the heavens [Plato] |
312 | Time came into existence with the heavens, so that there will be a time when they can be dissolved [Plato] |
309 | Clearly the world is good, so its maker must have been concerned with the eternal, not with change [Plato] |
308 | If the cosmos is an object of perception then it must be continually changing [Plato] |