35 ideas
| 10888 | Sets can be defined by 'enumeration', or by 'abstraction' (based on a property) [Zalabardo] |
| 10889 | The 'Cartesian Product' of two sets relates them by pairing every element with every element [Zalabardo] |
| 10890 | A 'partial ordering' is reflexive, antisymmetric and transitive [Zalabardo] |
| 10886 | Determinacy: an object is either in a set, or it isn't [Zalabardo] |
| 10887 | Specification: Determinate totals of objects always make a set [Zalabardo] |
| 10897 | A first-order 'sentence' is a formula with no free variables [Zalabardo] |
| 10893 | Γ |= φ for sentences if φ is true when all of Γ is true [Zalabardo] |
| 10899 | Γ |= φ if φ is true when all of Γ is true, for all structures and interpretations [Zalabardo] |
| 10896 | Propositional logic just needs ¬, and one of ∧, ∨ and → [Zalabardo] |
| 10898 | The semantics shows how truth values depend on instantiations of properties and relations [Zalabardo] |
| 10902 | We can do semantics by looking at given propositions, or by building new ones [Zalabardo] |
| 10892 | We make a truth assignment to T and F, which may be true and false, but merely differ from one another [Zalabardo] |
| 10895 | 'Logically true' (|= φ) is true for every truth-assignment [Zalabardo] |
| 10900 | Logically true sentences are true in all structures [Zalabardo] |
| 10894 | A sentence-set is 'satisfiable' if at least one truth-assignment makes them all true [Zalabardo] |
| 10901 | Some formulas are 'satisfiable' if there is a structure and interpretation that makes them true [Zalabardo] |
| 10903 | A structure models a sentence if it is true in the model, and a set of sentences if they are all true in the model [Zalabardo] |
| 10891 | If a set is defined by induction, then proof by induction can be applied to it [Zalabardo] |
| 21687 | It seems obvious to prefer the simpler of two theories, on grounds of beauty and convenience [Quine] |
| 21688 | There are four suspicious reasons why we prefer simpler theories [Quine] |
| 22673 | Wherever there is a small community, the association of the people is natural [Tocqueville] |
| 22676 | The people are just individuals, and only present themselves as united to foreigners [Tocqueville] |
| 22679 | Vast empires are bad for well-being and freedom, though they may promote glory [Tocqueville] |
| 22680 | People would be much happier and freer in small nations [Tocqueville] |
| 22675 | In American judges rule according to the Constitution, not the law [Tocqueville] |
| 22677 | A monarchical family is always deeply concerned with the interests of the state [Tocqueville] |
| 22683 | Despots like to see their own regulations ignored, by themselves and their agents [Tocqueville] |
| 22669 | Aristocracy is constituted by inherited landed property [Tocqueville] |
| 22674 | In Europe it is thought that local government is best handled centrally [Tocqueville] |
| 22678 | An election, and its lead up time, are always a national crisis [Tocqueville] |
| 22682 | Universal suffrage is no guarantee of wise choices [Tocqueville] |
| 22670 | Slavery undermines the morals and energy of a society [Tocqueville] |
| 22681 | The liberty of the press is more valuable for what it prevents than what it promotes [Tocqueville] |
| 22672 | It is admirable to elevate the humble to the level of the great, but the opposite is depraved [Tocqueville] |
| 22671 | Equality can only be established by equal rights for all (or no rights for anyone) [Tocqueville] |