78 ideas
19917 | Without reason and human help, human life is misery [Spinoza] |
10073 | There cannot be a set theory which is complete [Smith,P] |
10616 | Second-order arithmetic can prove new sentences of first-order [Smith,P] |
10074 | A 'total function' maps every element to one element in another set [Smith,P] |
10612 | An argument is a 'fixed point' for a function if it is mapped back to itself [Smith,P] |
10605 | Two functions are the same if they have the same extension [Smith,P] |
10075 | A 'partial function' maps only some elements to another set [Smith,P] |
10076 | The 'range' of a function is the set of elements in the output set created by the function [Smith,P] |
10615 | The Comprehension Schema says there is a property only had by things satisfying a condition [Smith,P] |
10595 | A 'theorem' of a theory is a sentence derived from the axioms using the proof system [Smith,P] |
10602 | A 'natural deduction system' has no axioms but many rules [Smith,P] |
10613 | No nice theory can define truth for its own language [Smith,P] |
10079 | A 'bijective' function has one-to-one correspondence in both directions [Smith,P] |
10077 | A 'surjective' ('onto') function creates every element of the output set [Smith,P] |
10078 | An 'injective' ('one-to-one') function creates a distinct output element from each original [Smith,P] |
10070 | If everything that a theory proves is true, then it is 'sound' [Smith,P] |
10086 | Soundness is true axioms and a truth-preserving proof system [Smith,P] |
10596 | A theory is 'sound' iff every theorem is true (usually from true axioms and truth-preservation) [Smith,P] |
10598 | A theory is 'negation complete' if it proves all sentences or their negation [Smith,P] |
10597 | 'Complete' applies both to whole logics, and to theories within them [Smith,P] |
10069 | A theory is 'negation complete' if one of its sentences or its negation can always be proved [Smith,P] |
10609 | Two routes to Incompleteness: semantics of sound/expressible, or syntax of consistency/proof [Smith,P] |
10087 | A theory is 'decidable' if all of its sentences could be mechanically proved [Smith,P] |
10088 | Any consistent, axiomatized, negation-complete formal theory is decidable [Smith,P] |
10080 | 'Effective' means simple, unintuitive, independent, controlled, dumb, and terminating [Smith,P] |
10081 | A set is 'enumerable' is all of its elements can result from a natural number function [Smith,P] |
10083 | A set is 'effectively enumerable' if a computer could eventually list every member [Smith,P] |
10084 | A finite set of finitely specifiable objects is always effectively enumerable (e.g. primes) [Smith,P] |
10085 | The set of ordered pairs of natural numbers <i,j> is effectively enumerable [Smith,P] |
10601 | The thorems of a nice arithmetic can be enumerated, but not the truths (so they're diffferent) [Smith,P] |
10600 | Being 'expressible' depends on language; being 'capture/represented' depends on axioms and proof system [Smith,P] |
10599 | For primes we write (x not= 1 ∧ ∀u∀v(u x v = x → (u = 1 ∨ v = 1))) [Smith,P] |
10610 | The reals contain the naturals, but the theory of reals doesn't contain the theory of naturals [Smith,P] |
10619 | The truths of arithmetic are just true equations and their universally quantified versions [Smith,P] |
10618 | All numbers are related to zero by the ancestral of the successor relation [Smith,P] |
10608 | The number of Fs is the 'successor' of the Gs if there is a single F that isn't G [Smith,P] |
10849 | Baby arithmetic covers addition and multiplication, but no general facts about numbers [Smith,P] |
10850 | Baby Arithmetic is complete, but not very expressive [Smith,P] |
10851 | Robinson Arithmetic 'Q' has basic axioms, quantifiers and first-order logic [Smith,P] |
10852 | Robinson Arithmetic (Q) is not negation complete [Smith,P] |
10068 | Natural numbers have zero, unique successors, unending, no circling back, and no strays [Smith,P] |
10603 | The logic of arithmetic must quantify over properties of numbers to handle induction [Smith,P] |
10604 | Incompleteness results in arithmetic from combining addition and successor with multiplication [Smith,P] |
10848 | Multiplication only generates incompleteness if combined with addition and successor [Smith,P] |
10617 | The 'ancestral' of a relation is a new relation which creates a long chain of the original relation [Smith,P] |
19922 | People are only free if they are guided entirely by reason [Spinoza] |
5495 | Instances of pain are physical tokens, but the nature of pain is more abstract [Putnam, by Lycan] |
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] |