83 ideas
354 | Wisdom makes virtue and true goodness possible [Plato] |
370 | Philosophy is a purification of the soul ready for the afterlife [Plato] |
350 | In investigation the body leads us astray, but the soul gets a clear view of the facts [Plato] |
362 | The greatest misfortune for a person is to develop a dislike for argument [Plato] |
192 | Only one thing can be contrary to something [Plato] |
18137 | Impredicative definitions are wrong, because they change the set that is being defined? [Bostock] |
18122 | Classical interdefinitions of logical constants and quantifiers is impossible in intuitionism [Bostock] |
18114 | There is no single agreed structure for set theory [Bostock] |
18107 | A 'proper class' cannot be a member of anything [Bostock] |
18115 | We could add axioms to make sets either as small or as large as possible [Bostock] |
18139 | The Axiom of Choice relies on reference to sets that we are unable to describe [Bostock] |
18105 | Replacement enforces a 'limitation of size' test for the existence of sets [Bostock] |
18109 | The completeness of first-order logic implies its compactness [Bostock] |
18108 | First-order logic is not decidable: there is no test of whether any formula is valid [Bostock] |
18123 | Substitutional quantification is just standard if all objects in the domain have a name [Bostock] |
18120 | The Deduction Theorem is what licenses a system of natural deduction [Bostock] |
18125 | Berry's Paradox considers the meaning of 'The least number not named by this name' [Bostock] |
18100 | ω + 1 is a new ordinal, but its cardinality is unchanged [Bostock] |
18101 | Each addition changes the ordinality but not the cardinality, prior to aleph-1 [Bostock] |
18102 | A cardinal is the earliest ordinal that has that number of predecessors [Bostock] |
18106 | Aleph-1 is the first ordinal that exceeds aleph-0 [Bostock] |
18095 | Instead of by cuts or series convergence, real numbers could be defined by axioms [Bostock] |
18099 | The number of reals is the number of subsets of the natural numbers [Bostock] |
18093 | For Eudoxus cuts in rationals are unique, but not every cut makes a real number [Bostock] |
13155 | If you add one to one, which one becomes two, or do they both become two? [Plato] |
18110 | Infinitesimals are not actually contradictory, because they can be non-standard real numbers [Bostock] |
18156 | Modern axioms of geometry do not need the real numbers [Bostock] |
18097 | The Peano Axioms describe a unique structure [Bostock] |
18149 | There are many criteria for the identity of numbers [Bostock] |
18148 | Hume's Principle is a definition with existential claims, and won't explain numbers [Bostock] |
18145 | Many things will satisfy Hume's Principle, so there are many interpretations of it [Bostock] |
18143 | Frege makes numbers sets to solve the Caesar problem, but maybe Caesar is a set! [Bostock] |
18116 | Numbers can't be positions, if nothing decides what position a given number has [Bostock] |
18117 | Structuralism falsely assumes relations to other numbers are numbers' only properties [Bostock] |
18141 | Nominalism about mathematics is either reductionist, or fictionalist [Bostock] |
18157 | Nominalism as based on application of numbers is no good, because there are too many applications [Bostock] |
18150 | Actual measurement could never require the precision of the real numbers [Bostock] |
18158 | Ordinals are mainly used adjectively, as in 'the first', 'the second'... [Bostock] |
18127 | Simple type theory has 'levels', but ramified type theory has 'orders' [Bostock] |
18144 | Neo-logicists agree that HP introduces number, but also claim that it suffices for the job [Bostock] |
18147 | Neo-logicists meet the Caesar problem by saying Hume's Principle is unique to number [Bostock] |
18111 | Treating numbers as objects doesn't seem like logic, since arithmetic fixes their totality [Bostock] |
18129 | Many crucial logicist definitions are in fact impredicative [Bostock] |
18146 | If Hume's Principle is the whole story, that implies structuralism [Bostock] |
18159 | Higher cardinalities in sets are just fairy stories [Bostock] |
18155 | A fairy tale may give predictions, but only a true theory can give explanations [Bostock] |
18140 | The best version of conceptualism is predicativism [Bostock] |
18138 | Conceptualism fails to grasp mathematical properties, infinity, and objective truth values [Bostock] |
18133 | The usual definitions of identity and of natural numbers are impredicative [Bostock] |
18131 | If abstracta only exist if they are expressible, there can only be denumerably many of them [Bostock] |
18134 | Predicativism makes theories of huge cardinals impossible [Bostock] |
18135 | If mathematics rests on science, predicativism may be the best approach [Bostock] |
18136 | If we can only think of what we can describe, predicativism may be implied [Bostock] |
18132 | The predicativity restriction makes a difference with the real numbers [Bostock] |
21347 | If Simmias is taller than Socrates, that isn't a feature that is just in Simmias [Plato] |
360 | We must have a prior knowledge of equality, if we see 'equal' things and realise they fall short of it [Plato] |
1 | There is only one source for all beauty [Plato] |
368 | Other things are named after the Forms because they participate in them [Plato] |
190 | If asked whether justice itself is just or unjust, you would have to say that it is just [Plato] |
16516 | The ship which Theseus took to Crete is now sent to Delos crowned with flowers [Plato] |
20184 | The only real evil is loss of knowledge [Plato] |
20185 | The most important things in life are wisdom and knowledge [Plato] |
357 | People are obviously recollecting when they react to a geometrical diagram [Plato] |
359 | If we feel the inadequacy of a resemblance, we must recollect the original [Plato] |
9343 | To achieve pure knowledge, we must get rid of the body and contemplate things with the soul [Plato] |
15859 | To investigate the causes of things, study what is best for them [Plato] |
13154 | Do we think and experience with blood, air or fire, or could it be our brain? [Plato] |
191 | Everything resembles everything else up to a point [Plato] |
364 | One soul can't be more or less of a soul than another [Plato] |
18121 | In logic a proposition means the same when it is and when it is not asserted [Bostock] |
203 | Courage is knowing what should or shouldn't be feared [Plato] |
202 | No one willingly and knowingly embraces evil [Plato] |
193 | Some things are good even though they are not beneficial to men [Plato] |
200 | People tend only to disapprove of pleasure if it leads to pain, or prevents future pleasure [Plato] |
197 | Some pleasures are not good, and some pains are not evil [Plato] |
361 | It is a mistake to think that the most violent pleasure or pain is therefore the truest reality [Plato] |
188 | Socrates did not believe that virtue could be taught [Plato] |
204 | Socrates is contradicting himself in claiming virtue can't be taught, but that it is knowledge [Plato] |
189 | If we punish wrong-doers, it shows that we believe virtue can be taught [Plato] |
351 | War aims at the acquisition of wealth, because we are enslaved to the body [Plato] |
13156 | Fancy being unable to distinguish a cause from its necessary background conditions! [Plato] |
369 | If the Earth is spherical and in the centre, it is kept in place by universal symmetry, not by force [Plato] |
363 | Whether the soul pre-exists our body depends on whether it contains the ultimate standard of reality [Plato] |