104 ideas
13466 | We are all post-Kantians, because he set the current agenda for philosophy [Hart,WD] |
13477 | The problems are the monuments of philosophy [Hart,WD] |
13515 | To study abstract problems, some knowledge of set theory is essential [Hart,WD] |
3811 | Entailment and validity are relations, but inference is a human activity [Searle] |
3822 | Theory involves accepting conclusions, and so is a special case of practical reason [Searle] |
3806 | Rationality is built into the intentionality of the mind, and its means of expression [Searle] |
3812 | Rationality is the way we coordinate our intentionality [Searle] |
13469 | Tarski showed how we could have a correspondence theory of truth, without using 'facts' [Hart,WD] |
13504 | Truth for sentences is satisfaction of formulae; for sentences, either all sequences satisfy it (true) or none do [Hart,WD] |
13503 | A first-order language has an infinity of T-sentences, which cannot add up to a definition of truth [Hart,WD] |
13500 | Conditional Proof: infer a conditional, if the consequent can be deduced from the antecedent [Hart,WD] |
13502 | ∃y... is read as 'There exists an individual, call it y, such that...', and not 'There exists a y such that...' [Hart,WD] |
13456 | Set theory articulates the concept of order (through relations) [Hart,WD] |
13497 | Nowadays ZFC and NBG are the set theories; types are dead, and NF is only useful for the whole universe [Hart,WD] |
13443 | ∈ relates across layers, while ⊆ relates within layers [Hart,WD] |
13442 | Without the empty set we could not form a∩b without checking that a and b meet [Hart,WD] |
13493 | In the modern view, foundation is the heart of the way to do set theory [Hart,WD] |
13495 | Foundation Axiom: an nonempty set has a member disjoint from it [Hart,WD] |
13461 | We can choose from finite and evident sets, but not from infinite opaque ones [Hart,WD] |
13462 | With the Axiom of Choice every set can be well-ordered [Hart,WD] |
13516 | If we accept that V=L, it seems to settle all the open questions of set theory [Hart,WD] |
13441 | Naïve set theory has trouble with comprehension, the claim that every predicate has an extension [Hart,WD] |
13494 | The iterative conception may not be necessary, and may have fixed points or infinitely descending chains [Hart,WD] |
13457 | A 'partial ordering' is irreflexive and transitive; the sets are ordered, but not the subsets [Hart,WD] |
13458 | A partial ordering becomes 'total' if any two members of its field are comparable [Hart,WD] |
13460 | 'Well-ordering' must have a least member, so it does the natural numbers but not the integers [Hart,WD] |
13490 | Von Neumann defines α<β as α∈β [Hart,WD] |
13481 | Maybe sets should be rethought in terms of the even more basic categories [Hart,WD] |
15845 | It seems absurd that seeing a person's limbs, the one is many, and yet the many are one [Plato] |
3809 | If complex logic requires rules, then so does basic logic [Searle] |
13506 | The universal quantifier can't really mean 'all', because there is no universal set [Hart,WD] |
3810 | In real reasoning semantics gives validity, not syntax [Searle] |
13512 | Modern model theory begins with the proof of Los's Conjecture in 1962 [Hart,WD] |
13505 | Model theory studies how set theory can model sets of sentences [Hart,WD] |
13511 | Model theory is mostly confined to first-order theories [Hart,WD] |
13513 | Models are ways the world might be from a first-order point of view [Hart,WD] |
13496 | First-order logic is 'compact': consequences of a set are consequences of a finite subset [Hart,WD] |
13484 | Berry's Paradox: we succeed in referring to a number, with a term which says we can't do that [Hart,WD] |
13482 | The Burali-Forti paradox is a crisis for Cantor's ordinals [Hart,WD] |
13507 | The machinery used to solve the Liar can be rejigged to produce a new Liar [Hart,WD] |
9867 | It is absurd to define a circle, but not be able to recognise a real one [Plato] |
13459 | The less-than relation < well-orders, and partially orders, and totally orders the ordinal numbers [Hart,WD] |
13491 | The axiom of infinity with separation gives a least limit ordinal ω [Hart,WD] |
13463 | There are at least as many infinite cardinals as transfinite ordinals (because they will map) [Hart,WD] |
13492 | Von Neumann's ordinals generalise into the transfinite better, because Zermelo's ω is a singleton [Hart,WD] |
13446 | 19th century arithmetization of analysis isolated the real numbers from geometry [Hart,WD] |
9865 | Daily arithmetic counts unequal things, but pure arithmetic equalises them [Plato] |
13509 | We can establish truths about infinite numbers by means of induction [Hart,WD] |
13474 | Euclid has a unique parallel, spherical geometry has none, and saddle geometry has several [Hart,WD] |
13471 | Mathematics makes existence claims, but philosophers usually say those are never analytic [Hart,WD] |
3841 | Users of 'supervenience' blur its causal and constitutive meanings [Searle] |
13488 | Mass words do not have plurals, or numerical adjectives, or use 'fewer' [Hart,WD] |
15857 | Any mixture which lacks measure and proportion doesn't even count as a mixture at all [Plato] |
14503 | If a mixture does not contain measure and proportion, it is corrupted and destroyed [Plato] |
4447 | If the good is one, is it unchanged when it is in particulars, and is it then separated from itself? [Plato] |
15856 | A thing can become one or many, depending on how we talk about it [Plato] |
374 | If one object is divided into its parts, someone can then say that one are many and many is one [Plato] |
3833 | A belief is a commitment to truth [Searle] |
3837 | We can't understand something as a lie if beliefs aren't commitment to truth [Searle] |
3816 | Our beliefs are about things, not propositions (which are the content of the belief) [Searle] |
389 | How can you be certain about aspects of the world if they aren't constant? [Plato] |
3828 | Thinking must involve a self, not just an "it" [Searle] |
13480 | Fregean self-evidence is an intrinsic property of basic truths, rules and definitions [Hart,WD] |
13476 | The failure of key assumptions in geometry, mereology and set theory throw doubt on the a priori [Hart,WD] |
3831 | Reasons can either be facts in the world, or intentional states [Searle] |
3830 | In the past people had a reason not to smoke, but didn't realise it [Searle] |
3832 | Causes (usually events) are not the same as reasons (which are never events) [Searle] |
3823 | Being held responsible for past actions makes no sense without personal identity [Searle] |
3821 | Giving reasons for action requires reference to a self [Searle] |
3824 | A 'self' must be capable of conscious reasonings about action [Searle] |
3834 | An intentional, acting, rational being must have a self [Searle] |
3825 | Action requires a self, even though perception doesn't [Searle] |
3829 | Selfs are conscious, enduring, reasonable, active, free, and responsible [Searle] |
3826 | A self must at least be capable of consciousness [Searle] |
3827 | The self is neither an experience nor a thing experienced [Searle] |
3820 | The bundle must also have agency in order to act, and a self to act rationally [Searle] |
3817 | Free will is most obvious when we choose between several reasons for an action [Searle] |
3808 | Rational decision making presupposes free will [Searle] |
3818 | We freely decide whether to make a reason for action effective [Searle] |
13475 | The Fregean concept of GREEN is a function assigning true to green things, and false to the rest [Hart,WD] |
3814 | Preferences can result from deliberation, not just precede it [Searle] |
3840 | We don't accept practical reasoning if the conclusion is unpalatable [Searle] |
3815 | The essence of humanity is desire-independent reasons for action [Searle] |
3839 | Only an internal reason can actually motivate the agent to act [Searle] |
390 | If goodness involves moderation and proportion, then it seems to be found in beauty [Plato] |
3835 | If it is true, you ought to believe it [Searle] |
3836 | If this is a man, you ought to accept similar things as men [Searle] |
391 | The good involves beauty, proportion and truth [Plato] |
392 | Neither intellect nor pleasure are the good, because they are not perfect and self-sufficient [Plato] |
393 | Good first, then beauty, then reason, then knowledge, then pleasure [Plato, by PG] |
385 | Some of the pleasures and pains we feel are false [Plato] |
387 | A small pure pleasure is much finer than a large one contaminated with pain [Plato] |
373 | Pleasure is certainly very pleasant, but it doesn't follow that all pleasures are good [Plato] |
379 | The good must be sufficient and perfect, and neither intellect nor pleasure are that [Plato] |
371 | Reason, memory, truth and wisdom are far better than pleasure, for those who can attain them [Plato] |
376 | Would you prefer a life of pleasure without reason, or one of reason without pleasure? [Plato] |
382 | It is unlikely that the gods feel either pleasure or pain [Plato] |
381 | We feel pleasure when we approach our natural state of harmony [Plato] |
386 | Intense pleasure and pain are not felt in a good body, but in a worthless one [Plato] |
377 | If you lived a life of maximum pleasure, would you still be lacking anything? [Plato] |
378 | A life of pure pleasure with no intellect is the life of a jellyfish [Plato] |
388 | Hedonists must say that someone in pain is bad, even if they are virtuous [Plato] |
3838 | Promises hold because I give myself a reason, not because it is an institution [Searle] |
3813 | 'Ought' implies that there is a reason to do something [Searle] |