90 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] |
23917 | Contrary statements can both be reasonable, if they are meant in two different ways [Aristotle] |
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] |
13462 | With the Axiom of Choice every set can be well-ordered [Hart,WD] |
13461 | We can choose from finite and evident sets, but not from infinite opaque ones [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] |
13460 | 'Well-ordering' must have a least member, so it does the natural numbers but not the integers [Hart,WD] |
13458 | A partial ordering becomes 'total' if any two members of its field are comparable [Hart,WD] |
13457 | A 'partial ordering' is irreflexive and transitive; the sets are ordered, but not the subsets [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] |
13506 | The universal quantifier can't really mean 'all', because there is no universal set [Hart,WD] |
13513 | Models are ways the world might be from a first-order point of view [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] |
13512 | Modern model theory begins with the proof of Los's Conjecture in 1962 [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] |
13459 | The less-than relation < well-orders, and partially orders, and totally orders the ordinal numbers [Hart,WD] |
13463 | There are at least as many infinite cardinals as transfinite ordinals (because they will map) [Hart,WD] |
13491 | The axiom of infinity with separation gives a least limit ordinal ω [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] |
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] |
13488 | Mass words do not have plurals, or numerical adjectives, or use 'fewer' [Hart,WD] |
5869 | The thesis of the Form of the Good (or of anything else) is verbal and vacuous [Aristotle] |
22505 | The two right angles of a triangle necessitate that a quadrilateral has four [Aristotle] |
22513 | Knowing is having knowledge; understanding is using knowledge [Aristotle] |
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] |
23906 | Courage from spirit is natural and unconquerable, as seen in the young [Aristotle] |
20204 | Whether the mind has parts is irrelevant, since it obviously has distinct capacities [Aristotle] |
22506 | A man is the cause of what is within his power, and what he causes is in his power [Aristotle] |
22504 | Only a human being can be a starting point for an action [Aristotle] |
22510 | Some emotional states are too strong for human nature [Aristotle] |
23913 | Nearly all the good and bad states of character are concerned with feelings [Aristotle] |
13475 | The Fregean concept of GREEN is a function assigning true to green things, and false to the rest [Hart,WD] |
23918 | Akrasia is the clash of two feelings - goodness and pleasure [Aristotle] |
22515 | Choice results when deliberation brings together an opinion with an inclination [Aristotle] |
22508 | Unlike in inanimate things, in animate things actions have more than one starting point [Aristotle] |
22514 | The deliberative part of the soul discerns explanatory causes [Aristotle] |
22507 | An action is voluntary when it is accompanied by thought of some kind [Aristotle] |
23319 | We are responsible if our actions reflect our motivation [Aristotle, by Frede,M] |
22512 | Acts are voluntary if done knowingly, by the agent, and in his power to avoid it [Aristotle] |
22509 | What is natural for us is either there at birth, or appears by normal processes [Aristotle] |
18230 | No one would choose life just for activities not done for their own sake [Aristotle] |
23909 | Wearing a shoe is its intrinsic use, and selling it (as a shoe) is its coincidental use [Aristotle] |
5870 | Everything seeks, not a single good, but its own separate good [Aristotle] |
5877 | We judge people from their deeds because we cannot see their choices (which matter more) [Aristotle] |
5868 | Horses, birds and fish are not happy, lacking a divine aspect to their natures [Aristotle] |
5865 | Happiness involves three things, of which the greatest is either wisdom, virtue, or pleasure [Aristotle] |
5876 | Virtue is different from continence [Aristotle] |
5872 | Excellence is the best state of anything (like a cloak) which has an employment or function [Aristotle] |
5875 | Character (éthos) is developed from habit (ethos) [Aristotle] |
5874 | Character virtues (such as courage) are of the non-rational part, which follows the rational part [Aristotle] |
22516 | Character is shown by what is or is not enjoyed, and virtue chooses the mean among them [Aristotle] |
22517 | We judge character not by their actions, but by their reasons for actions [Aristotle] |
23914 | People sometimes exhibit both extremes together, but the mean is contrary to both of them [Aristotle] |
23911 | Possessors of a virtue tend to despise what reason shows to be its opposite [Aristotle] |
23910 | Greatness of soul produces all the virtues - and vice versa [Aristotle] |
23908 | If someone just looks at or listens to beautiful things, they would not be thought intemperate [Aristotle] |
23905 | Courage follows reason, which tells us to choose what is noble [Aristotle] |
23912 | Honour depends on what it is for, and whether it is bestowed by worthy people [Aristotle] |
5871 | Goods in the soul are more worthy than those outside it, as everybody wants them [Aristotle] |
23919 | Friendship cannot be immediate; it takes time, and needs testing [Aristotle] |
23920 | Decent people can be friends with base people [Aristotle] |
23915 | The main function of politics is to produce friendship [Aristotle] |
23916 | The best cure for mutual injustice is friendship [Aristotle] |
5866 | It is folly not to order one's life around some end [Aristotle] |
5878 | Eyes could be used for a natural purpose, or for unnatural seeing, or for a non-seeing activity [Aristotle] |
5873 | Each thing's function is its end [Aristotle] |
16591 | Prime matter is nothing but its parts [Vanini] |