73 ideas
| 23728 | Analysis aims to express the full set of platitudes surrounding a given concept [Smith,M] |
| 23744 | Defining a set of things by paradigms doesn't pin them down enough [Smith,M] |
| 18696 | The vagueness of truthmaker claims makes it easier to run anti-realist arguments [Button] |
| 18701 | The coherence theory says truth is coherence of thoughts, and not about objects [Button] |
| 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] |
| 10075 | A 'partial function' maps only some elements to another set [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] |
| 10076 | The 'range' of a function is the set of elements in the output set created by the function [Smith,P] |
| 10605 | Two functions are the same if they have the same extension [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] |
| 18694 | Permutation Theorem: any theory with a decent model has lots of models [Button] |
| 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] |
| 10080 | 'Effective' means simple, unintuitive, independent, controlled, dumb, and terminating [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] |
| 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] |
| 10608 | The number of Fs is the 'successor' of the Gs if there is a single F that isn't G [Smith,P] |
| 10618 | All numbers are related to zero by the ancestral of the successor relation [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] |
| 10848 | Multiplication only generates incompleteness if combined with addition and successor [Smith,P] |
| 10604 | Incompleteness results in arithmetic from combining addition and successor with multiplication [Smith,P] |
| 18692 | Realists believe in independent objects, correspondence, and fallibility of all theories [Button] |
| 18693 | Indeterminacy arguments say if a theory can be made true, it has multiple versions [Button] |
| 18695 | An ideal theory can't be wholly false, because its consistency implies a true model [Button] |
| 10617 | The 'ancestral' of a relation is a new relation which creates a long chain of the original relation [Smith,P] |
| 18700 | Cartesian scepticism doubts what is true; Kantian scepticism doubts that it is sayable [Button] |
| 18698 | Predictions give the 'content' of theories, which can then be 'equivalent' or 'adequate' [Button] |
| 23743 | Capturing all the common sense facts about rationality is almost impossible [Smith,M] |
| 18697 | A sentence's truth conditions are all the situations where it would be true [Button] |
| 23724 | A pure desire could be criticised if it were based on a false belief [Smith,M] |
| 23736 | A person can have a desire without feeling it [Smith,M] |
| 23723 | In the Humean account, desires are not true/false, or subject to any rational criticism [Smith,M] |
| 23735 | Subjects may be fallible about the desires which explain their actions [Smith,M] |
| 23738 | Humeans (unlike their opponents) say that desires and judgements can separate [Smith,M] |
| 23742 | If first- and second-order desires conflict, harmony does not require the second-order to win [Smith,M] |
| 23746 | Objective reasons to act might be the systematic desires of a fully rational person [Smith,M] |
| 23739 | Goals need desires, and so only desires can motivate us [Smith,M] |
| 23733 | Motivating reasons are psychological, while normative reasons are external [Smith,M] |
| 23740 | Humeans take maximising desire satisfaction as the normative reasons for actions [Smith,M] |
| 23745 | We cannot expect even fully rational people to converge on having the same desires for action [Smith,M] |
| 23731 | 'Externalists' say moral judgements are not reasons, and maybe not even motives [Smith,M] |
| 23732 | A person could make a moral judgement without being in any way motivated by it [Smith,M] |
| 23729 | Moral internalism says a judgement of rightness is thereby motivating [Smith,M] |
| 23730 | 'Rationalism' says the rightness of an action is a reason to perform it [Smith,M] |
| 23727 | Expressivists count attitudes as 'moral' if they concern features of things, rather than their mere existence [Smith,M] |
| 23741 | Is valuing something a matter of believing or a matter of desiring? [Smith,M] |