134 ideas
| 224 | When questions are doubtful we should concentrate not on objects but on ideas of the intellect [Plato] |
| 232 | Opposites are as unlike as possible [Plato] |
| 8937 | Plato's 'Parmenides' is the greatest artistic achievement of the ancient dialectic [Hegel on Plato] |
| 15901 | Trying to represent curves, we study arbitrary functions, leading to the ordinals, which produces set theory [Cantor, by Lavine] |
| 13444 | Cantor's Theorem: for any set x, its power set P(x) has more members than x [Cantor, by Hart,WD] |
| 18098 | Cantor proved that all sets have more subsets than they have members [Cantor, by Bostock] |
| 15505 | If a set is 'a many thought of as one', beginners should protest against singleton sets [Cantor, by Lewis] |
| 10701 | Cantor showed that supposed contradictions in infinity were just a lack of clarity [Cantor, by Potter] |
| 10865 | The continuum is the powerset of the integers, which moves up a level [Cantor, by Clegg] |
| 13016 | The Axiom of Union dates from 1899, and seems fairly obvious [Cantor, by Maddy] |
| 14199 | Cantor's sets were just collections, but Dedekind's were containers [Cantor, by Oliver/Smiley] |
| 10082 | There are infinite sets that are not enumerable [Cantor, by Smith,P] |
| 13986 | Plato found antinomies in ideas, Kant in space and time, and Bradley in relations [Plato, by Ryle] |
| 14150 | Plato's 'Parmenides' is perhaps the best collection of antinomies ever made [Russell on Plato] |
| 13483 | Cantor's Paradox: the power set of the universe must be bigger than the universe, yet a subset of it [Cantor, by Hart,WD] |
| 8710 | The powerset of all the cardinal numbers is required to be greater than itself [Cantor, by Friend] |
| 15910 | Cantor named the third realm between the finite and the Absolute the 'transfinite' [Cantor, by Lavine] |
| 15905 | Cantor proved the points on a plane are in one-to-one correspondence to the points on a line [Cantor, by Lavine] |
| 9983 | Cantor took the ordinal numbers to be primary [Cantor, by Tait] |
| 17798 | Cantor presented the totality of natural numbers as finite, not infinite [Cantor, by Mayberry] |
| 9971 | Cantor introduced the distinction between cardinals and ordinals [Cantor, by Tait] |
| 9892 | Cantor showed that ordinals are more basic than cardinals [Cantor, by Dummett] |
| 14136 | A cardinal is an abstraction, from the nature of a set's elements, and from their order [Cantor] |
| 15906 | Cantor tried to prove points on a line matched naturals or reals - but nothing in between [Cantor, by Lavine] |
| 11015 | Cantor's diagonal argument proved you can't list all decimal numbers between 0 and 1 [Cantor, by Read] |
| 15903 | A real is associated with an infinite set of infinite Cauchy sequences of rationals [Cantor, by Lavine] |
| 18251 | Irrational numbers are the limits of Cauchy sequences of rational numbers [Cantor, by Lavine] |
| 15902 | Irrationals and the Dedekind Cut implied infinite classes, but they seemed to have logical difficulties [Cantor, by Lavine] |
| 15908 | It was Cantor's diagonal argument which revealed infinities greater than that of the real numbers [Cantor, by Lavine] |
| 13464 | Cantor proposes that there won't be a potential infinity if there is no actual infinity [Cantor, by Hart,WD] |
| 10112 | The naturals won't map onto the reals, so there are different sizes of infinity [Cantor, by George/Velleman] |
| 8733 | The Continuum Hypothesis says there are no sets between the natural numbers and reals [Cantor, by Shapiro] |
| 17889 | CH: An infinite set of reals corresponds 1-1 either to the naturals or to the reals [Cantor, by Koellner] |
| 13447 | Cantor: there is no size between naturals and reals, or between a set and its power set [Cantor, by Hart,WD] |
| 10883 | Cantor's Continuum Hypothesis says there is a gap between the natural and the real numbers [Cantor, by Horsten] |
| 13528 | Continuum Hypothesis: there are no sets between N and P(N) [Cantor, by Wolf,RS] |
| 9555 | Continuum Hypothesis: no cardinal greater than aleph-null but less than cardinality of the continuum [Cantor, by Chihara] |
| 18174 | Cantor extended ordinals into the transfinite, and they can thus measure infinite cardinalities [Cantor, by Maddy] |
| 15893 | Cantor's theory concerns collections which can be counted, using the ordinals [Cantor, by Lavine] |
| 18173 | Cardinality strictly concerns one-one correspondence, to test infinite sameness of size [Cantor, by Maddy] |
| 10232 | Property extensions outstrip objects, so shortage of objects caused the Caesar problem [Cantor, by Shapiro] |
| 18176 | Pure mathematics is pure set theory [Cantor] |
| 16150 | One is, so numbers exist, so endless numbers exist, and each one must partake of being [Plato] |
| 8631 | Cantor says that maths originates only by abstraction from objects [Cantor, by Frege] |
| 229 | The one was and is and will be and was becoming and is becoming and will become [Plato] |
| 21821 | Plato's Parmenides has a three-part theory, of Primal One, a One-Many, and a One-and-Many [Plato, by Plotinus] |
| 221 | Absolute ideas, such as the Good and the Beautiful, cannot be known by us [Plato] |
| 227 | You must always mean the same thing when you utter the same name [Plato] |
| 223 | If you deny that each thing always stays the same, you destroy the possibility of discussion [Plato] |
| 210 | It would be absurd to think there were abstract Forms for vile things like hair, mud and dirt [Plato] |
| 220 | The concept of a master includes the concept of a slave [Plato] |
| 211 | If admirable things have Forms, maybe everything else does as well [Plato] |
| 219 | If absolute ideas existed in us, they would cease to be absolute [Plato] |
| 228 | Greatness and smallness must exist, to be opposed to one another, and come into being in things [Plato] |
| 16151 | Plato moves from Forms to a theory of genera and principles in his later work [Plato, by Frede,M] |
| 218 | Participation is not by means of similarity, so we are looking for some other method of participation [Plato] |
| 212 | The whole idea of each Form must be found in each thing which participates in it [Plato] |
| 213 | Each idea is in all its participants at once, just as daytime is a unity but in many separate places at once [Plato] |
| 216 | If things are made alike by participating in something, that thing will be the absolute idea [Plato] |
| 215 | If things partake of ideas, this implies either that everything thinks, or that everything actually is thought [Plato] |
| 217 | Nothing can be like an absolute idea, because a third idea intervenes to make them alike (leading to a regress) [Plato] |
| 214 | If absolute greatness and great things are seen as the same, another thing appears which makes them seem great [Plato] |
| 15851 | Parts must belong to a created thing with a distinct form [Plato] |
| 15846 | In Parmenides, if composition is identity, a whole is nothing more than its parts [Plato, by Harte,V] |
| 15849 | Plato says only a one has parts, and a many does not [Plato, by Harte,V] |
| 15850 | Anything which has parts must be one thing, and parts are of a one, not of a many [Plato] |
| 13259 | It seems that the One must be composed of parts, which contradicts its being one [Plato] |
| 15847 | Two things relate either as same or different, or part of a whole, or the whole of the part [Plato] |
| 8715 | Infinities expand the bounds of the conceivable; we explore concepts to explore conceivability [Cantor, by Friend] |
| 13454 | Cantor says (vaguely) that we abstract numbers from equal sized sets [Hart,WD on Cantor] |
| 19956 | True goodness is political, and consists of love of and submission to the laws [Montesquieu] |
| 19961 | Primitive people would be too vulnerable and timid to attack anyone, so peace would reign [Montesquieu] |
| 19962 | Men do not desire to subjugate one another; domination is a complex and advanced idea [Montesquieu] |
| 19963 | People are drawn into society by needs, shared fears, pleasure, and knowledge [Montesquieu] |
| 20008 | People are guided by a multitude of influences, from which the spirit of a nation emerges [Montesquieu] |
| 19993 | In small republics citizens identify with the public good, and abuses are fewer [Montesquieu] |
| 19992 | In a large republic there is too much wealth for individuals to manage it [Montesquieu] |
| 20005 | The rich would never submit to a lottery deciding which part of their society should be slaves [Montesquieu] |
| 19995 | All states aim at preservation, and then have distinctive individual purposes [Montesquieu] |
| 19964 | The natural power of a father suggests rule by one person, but that authority can be spread [Montesquieu] |
| 19986 | Monarchies can act more quickly, because one person is in charge [Montesquieu] |
| 19972 | The nobility are an indispensable part of a monarchy [Montesquieu] |
| 19974 | Monarchs must not just have links to the people; they need a body which maintains the laws [Montesquieu] |
| 19976 | Ambition is good in a monarchy, because the monarch can always restrain it [Montesquieu] |
| 19978 | In monarchies, men's actions are judged by their grand appearance, not their virtues [Montesquieu] |
| 19985 | In a monarchy, the nobility must be hereditary, to bind them together [Montesquieu] |
| 19988 | A despot's agents must be given power, so they inevitably become corrupt [Montesquieu] |
| 19977 | Despotism and honour are incompatible, because honour scorns his power, and lives by rules [Montesquieu] |
| 20007 | Tyranny is either real violence, or the imposition of unpopular legislation [Montesquieu] |
| 19989 | The will of a despot is an enigma, so magistrates can only follow their own will [Montesquieu] |
| 19975 | Despots are always lazy and ignorant, so they always delegate their power to a vizier [Montesquieu] |
| 19970 | If the nobility is numerous, the senate is the artistocracy, and the nobles are a democracy [Montesquieu] |
| 19971 | Aristocracy is democratic if they resemble the people, but not if they resemble the monarch [Montesquieu] |
| 19984 | Great inequality between aristocrats and the rest is bad - and also among aristocrats themselves [Montesquieu] |
| 19980 | If a government is to be preserved, it must first be loved [Montesquieu] |
| 19996 | A government has a legislature, an international executive, and a domestic executive [Montesquieu] |
| 19997 | The judiciary must be separate from the legislature, to avoid arbitrary power [Montesquieu] |
| 19965 | The fundamental laws of a democracy decide who can vote [Montesquieu] |
| 19968 | It is basic to a democracy that the people themselves must name their ministers [Montesquieu] |
| 19969 | Voting should be public, so the lower classes can be influenced by the example of notable people [Montesquieu] |
| 19999 | All citizens (apart from the very humble poor) should choose their representatives [Montesquieu] |
| 19967 | In a democracy the people should manage themselves, and only delegate what they can't do [Montesquieu] |
| 19966 | A democratic assembly must have a fixed number, to see whether everyone has spoken [Montesquieu] |
| 19998 | If deputies represent people, they are accountable, but less so if they represent places [Montesquieu] |
| 20003 | Slaves are not members of the society, so no law can forbid them to run away [Montesquieu] |
| 20000 | Slavery is entirely bad; the master abandons the virtues, and they are pointless in the slave [Montesquieu] |
| 20006 | The demand for slavery is just the masters' demand for luxury [Montesquieu] |
| 20009 | Freedom of speech and writing, within the law, is essential to preserve liberty [Montesquieu] |
| 19994 | Freedom in society is ability to do what is right, and not having to do what is wrong [Montesquieu] |
| 19981 | No one even thinks of equality in monarchies and despotism; they all want superiority [Montesquieu] |
| 19991 | Equality is not command by everyone or no one, but command and obedience among equals [Montesquieu] |
| 19990 | Democracy is corrupted by lack of equality, or by extreme equality (between rulers and ruled) [Montesquieu] |
| 19983 | Democracies may sometimes need to restrict equality [Montesquieu] |
| 19982 | Some equality can be achieved by social categories, combined with taxes and poor relief [Montesquieu] |
| 19959 | Prior to positive laws there is natural equity, of obedience, gratitude, dependence and merit [Montesquieu] |
| 19960 | Sensation gives animals natural laws, but knowledge can make them break them [Montesquieu] |
| 20002 | The death penalty is permissible, because its victims enjoyed the protection of that law [Montesquieu] |
| 20010 | If religion teaches determinism, penalties must be severe; if free will, then that is different [Montesquieu] |
| 20001 | The only right victors have over captives is the protection of the former [Montesquieu] |
| 19973 | The clergy are essential to a monarchy, but dangerous in a republic [Montesquieu] |
| 19987 | Religion has the most influence in despotic states, and reinforces veneration for the ruler [Montesquieu] |
| 20011 | Religion can support the state when the law fails to do so [Montesquieu] |
| 20004 | French slavery was accepted because it was the best method of religious conversion [Montesquieu] |
| 19979 | In monarchies education ennobles people, and in despotisms it debases them [Montesquieu] |
| 222 | Only a great person can understand the essence of things, and an even greater person can teach it [Plato] |
| 19957 | Teaching is the best practice of the general virtue that leads us to love everyone [Montesquieu] |
| 225 | The unlimited has no shape and is endless [Plato] |
| 233 | Some things do not partake of the One [Plato] |
| 2062 | The only movement possible for the One is in space or in alteration [Plato] |
| 231 | Everything partakes of the One in some way [Plato] |
| 19958 | Laws are the necessary relations that derive from the nature of things [Montesquieu] |
| 10863 | Cantor proved that three dimensions have the same number of points as one dimension [Cantor, by Clegg] |
| 13465 | Only God is absolutely infinite [Cantor, by Hart,WD] |
| 234 | We couldn't discuss the non-existence of the One without knowledge of it [Plato] |