21 ideas
10301 | The axiom of choice is controversial, but it could be replaced [Shapiro] |
10588 | First-order logic is Complete, and Compact, with the Löwenheim-Skolem Theorems [Shapiro] |
10298 | Some say that second-order logic is mathematics, not logic [Shapiro] |
10299 | If the aim of logic is to codify inferences, second-order logic is useless [Shapiro] |
10300 | Logical consequence can be defined in terms of the logical terminology [Shapiro] |
10290 | Second-order variables also range over properties, sets, relations or functions [Shapiro] |
10297 | The Löwenheim-Skolem theorem seems to be a defect of first-order logic [Shapiro] |
10590 | Up Löwenheim-Skolem: if natural numbers satisfy wffs, then an infinite domain satisfies them [Shapiro] |
10292 | Downward Löwenheim-Skolem: if there's an infinite model, there is a countable model [Shapiro] |
10296 | The Löwenheim-Skolem Theorems fail for second-order languages with standard semantics [Shapiro] |
10294 | Second-order logic has the expressive power for mathematics, but an unworkable model theory [Shapiro] |
10591 | Logicians use 'property' and 'set' interchangeably, with little hanging on it [Shapiro] |
13230 | Particular essence is often captured by generality [Steiner,M] |
13229 | Maybe an instance of a generalisation is more explanatory than the particular case [Steiner,M] |
13231 | Explanatory proofs rest on 'characterizing properties' of entities or structure [Steiner,M] |
22465 | We see a moral distinction between doing and allowing to happen [Foot] |
22466 | We see a moral distinction between our aims and their foreseen consequences [Foot] |
22467 | Acts and omissions only matter if they concern doing something versus allowing it [Foot] |
22470 | A good moral system benefits its participants, and so demands reciprocity [Foot] |
22468 | Virtues can have aims, but good states of affairs are not among them [Foot] |
22469 | Some virtues imply rules, and others concern attachment [Foot] |