35 ideas
| 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] |
| 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] |
| 17761 | A compact axiomatisation makes it possible to understand a field as a whole [Walicki] |
| 17763 | Axiomatic systems are purely syntactic, and do not presuppose any interpretation [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] |
| 17757 | Members of ordinals are ordinals, and also subsets of ordinals [Walicki] |
| 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] |
| 18648 | Freedom to live according to our own conception of the good is the ultimate value [Nozick, by Kymlicka] |
| 20585 | If an experience machine gives you any experience you want, should you hook up for life? [Nozick] |
| 18643 | A minimal state should protect, but a state forcing us to do more is unjustified [Nozick] |
| 18642 | Individual rights are so strong that the state and its officials must be very limited in power [Nozick] |
| 18644 | States can't enforce mutual aid on citizens, or interfere for their own good [Nozick] |
| 22661 | My Anarchy, State and Utopia neglected our formal social ties and concerns [Nozick on Nozick] |
| 18641 | If people hold things legitimately, just distribution is simply the result of free exchanges [Nozick, by Kymlicka] |
| 20539 | Property is legitimate by initial acquisition, voluntary transfer, or rectification of injustice [Nozick, by Swift] |
| 18645 | Nozick assumes initial holdings include property rights, but we can challenge that [Kymlicka on Nozick] |
| 20521 | Can I come to own the sea, by mixing my private tomato juice with it? [Nozick] |
| 18646 | How did the private property get started? If violence was involved, we can redistribute it [Kymlicka on Nozick] |
| 18647 | If property is only initially acquired by denying the rights of others, Nozick can't get started [Kymlicka on Nozick] |
| 21737 | Unowned things may be permanently acquired, if it doesn't worsen the position of other people [Nozick] |
| 21738 | Maybe land was originally collectively owned, rather than unowned? [Cohen,GA on Nozick] |
| 13304 | Learned men gain more in one day than others do in a lifetime [Posidonius] |
| 20820 | Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus] |