44 ideas
| 10476 | The idea that groups of concepts could be 'implicitly defined' was abandoned [Hodges,W] |
| 17749 | Post proved the consistency of propositional logic in 1921 [Walicki] |
| 17765 | Propositional language can only relate statements as the same or as different [Walicki] |
| 17764 | Boolean connectives are interpreted as functions on the set {1,0} [Walicki] |
| 17752 | The empty set is useful for defining sets by properties, when the members are not yet known [Walicki] |
| 17753 | The empty set avoids having to take special precautions in case members vanish [Walicki] |
| 17759 | Ordinals play the central role in set theory, providing the model of well-ordering [Walicki] |
| 17741 | To determine the patterns in logic, one must identify its 'building blocks' [Walicki] |
| 10478 | Since first-order languages are complete, |= and |- have the same meaning [Hodges,W] |
| 21122 | Liberal Nationalism says welfare states and democracy needed a shared sense of nationality [Shorten] |
| 10477 | |= in model-theory means 'logical consequence' - it holds in all models [Hodges,W] |
| 10474 | |= should be read as 'is a model for' or 'satisfies' [Hodges,W] |
| 10475 | A 'structure' is an interpretation specifying objects and classes of quantification [Hodges,W] |
| 10473 | Model theory studies formal or natural language-interpretation using set-theory [Hodges,W] |
| 10481 | Models in model theory are structures, not sets of descriptions [Hodges,W] |
| 17747 | A 'model' of a theory specifies interpreting a language in a domain to make all theorems true [Walicki] |
| 17748 | The L-S Theorem says no theory (even of reals) says more than a natural number theory [Walicki] |
| 17763 | Axiomatic systems are purely syntactic, and do not presuppose any interpretation [Walicki] |
| 17761 | A compact axiomatisation makes it possible to understand a field as a whole [Walicki] |
| 17757 | Members of ordinals are ordinals, and also subsets of ordinals [Walicki] |
| 17758 | Ordinals are transitive sets of transitive sets; or transitive sets totally ordered by inclusion [Walicki] |
| 17755 | Ordinals are the empty set, union with the singleton, and any arbitrary union of ordinals [Walicki] |
| 17756 | The union of finite ordinals is the first 'limit ordinal'; 2ω is the second... [Walicki] |
| 17760 | Two infinite ordinals can represent a single infinite cardinal [Walicki] |
| 10480 | First-order logic can't discriminate between one infinite cardinal and another [Hodges,W] |
| 17762 | In non-Euclidean geometry, all Euclidean theorems are valid that avoid the fifth postulate [Walicki] |
| 17754 | Inductive proof depends on the choice of the ordering [Walicki] |
| 17742 | Scotus based modality on semantic consistency, instead of on what the future could allow [Walicki] |
| 21136 | Utilitarians conflate acts and omissions; causing to drown and failing to save are the same [Shorten] |
| 21135 | There are eight different ways in which groups of people can be oppressed [Shorten, by PG] |
| 21118 | Constitutional Patriotism unites around political values (rather than national identity) [Shorten] |
| 21129 | Democracy is a method of selection, or it involves participation, or it concerns public discussion [Shorten] |
| 21130 | Some say democracy is intrinsically valuable, others that it delivers good outcomes [Shorten] |
| 21126 | Representative should be either obedient, or sensible, or typical [Shorten] |
| 21128 | There is 'mirror representation' when the institution statistically reflects the population [Shorten] |
| 21127 | In a changed situation a Mandated Representative can't keep promises and fight for constituents [Shorten] |
| 21117 | Liberal citizens have a moral requirement to respect freedom and equality [Shorten] |
| 21134 | Maybe the rational autonomous liberal individual is merely the result of domination [Shorten] |
| 21113 | Liberal equality concerns rights, and liberal freedom concerns choice of ends [Shorten] |
| 21121 | Liberal Nationalism encourages the promotion of nationalistic values [Shorten] |
| 21115 | Liberalism should not make assumptions such as the value of choosing your own life plan [Shorten] |
| 21114 | Liberals treat individuals as mutual strangers, rather than as social beings [Shorten] |
| 21123 | Liberal Nationalism is more communitarian, and Constitutional Patriotism more cosmopolitan [Shorten] |
| 21124 | Religious toleration has been institutionalised by the separation of church and state [Shorten] |