93 ideas
| 19917 | Without reason and human help, human life is misery [Spinoza] |
| 13838 | A decent modern definition should always imply a semantics [Hacking] |
| 18137 | Impredicative definitions are wrong, because they change the set that is being defined? [Bostock] |
| 13834 | Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking] |
| 13835 | Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking] |
| 13833 | 'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking] |
| 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] |
| 13845 | The various logics are abstractions made from terms like 'if...then' in English [Hacking] |
| 13840 | First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking] |
| 13844 | A limitation of first-order logic is that it cannot handle branching quantifiers [Hacking] |
| 18108 | First-order logic is not decidable: there is no test of whether any formula is valid [Bostock] |
| 18109 | The completeness of first-order logic implies its compactness [Bostock] |
| 13842 | Second-order completeness seems to need intensional entities and possible worlds [Hacking] |
| 13837 | With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking] |
| 13839 | Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking] |
| 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] |
| 13843 | If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking] |
| 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] |
| 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] |
| 19922 | People are only free if they are guided entirely by reason [Spinoza] |
| 18121 | In logic a proposition means the same when it is and when it is not asserted [Bostock] |
| 19935 | Peoples are created by individuals, not by nature, and only distinguished by language and law [Spinoza] |
| 19914 | In nature everything has an absolute right to do anything it is capable of doing [Spinoza] |
| 19915 | Natural rights are determined by desire and power, not by reason [Spinoza] |
| 7487 | Society exists to extend human awareness [Spinoza, by Watson] |
| 19943 | The state aims to allow personal development, so its main purpose is freedom [Spinoza] |
| 19930 | Sovereignty must include the power to make people submit to it [Spinoza] |
| 19936 | Kings tend to fight wars for glory, rather than for peace and liberty [Spinoza] |
| 19940 | Deposing a monarch is dangerous, because the people are used to royal authority [Spinoza] |
| 19937 | Monarchs are always proud, and can't back down [Spinoza] |
| 19931 | Every state is more frightened of its own citizens than of external enemies [Spinoza] |
| 19920 | Democracy is a legitimate gathering of people who do whatever they can do [Spinoza] |
| 19938 | Allowing religious ministers any control of the state is bad for both parties [Spinoza] |
| 19933 | If religion is law, then piety is justice, impiety is crime, and non-believers must leave [Spinoza] |
| 19923 | Slavery is not just obedience, but acting only in the interests of the master [Spinoza] |
| 19939 | Government is oppressive if opinions can be crimes, because people can't give them up [Spinoza] |
| 19944 | Without liberty of thought there is no trust in the state, and corruption follows [Spinoza] |
| 19942 | Treason may be committed as much by words as by deeds [Spinoza] |
| 19924 | The freest state is a rational one, where people can submit themselves to reason [Spinoza] |
| 7827 | Spinoza wanted democracy based on individual rights, and is thus the first modern political philosopher [Stewart,M on Spinoza] |
| 19926 | The sovereignty has absolute power over citizens [Spinoza] |
| 19918 | Forming a society meant following reason, and giving up dangerous appetites and mutual harm [Spinoza] |
| 19919 | People only give up their rights, and keep promises, if they hope for some greater good [Spinoza] |
| 19921 | Once you have given up your rights, there is no going back [Spinoza] |
| 19925 | In democracy we don't abandon our rights, but transfer them to the majority of us [Spinoza] |
| 19928 | No one, in giving up their power and right, ceases to be a human being [Spinoza] |
| 19929 | Everyone who gives up their rights must fear the recipients of them [Spinoza] |
| 19932 | The early Hebrews, following Moses, gave up their rights to God alone [Spinoza] |
| 19916 | The order of nature does not prohibit anything, and allows whatever appetite produces [Spinoza] |
| 19927 | State and religious law can clash, so the state must make decisions about religion [Spinoza] |
| 19934 | Hebrews were very hostile to other states, who had not given up their rights to God [Spinoza] |
| 4300 | The Bible has nothing in common with reasoning and philosophy [Spinoza] |