72 ideas
| 12249 | 'Animal' is a genus and 'rational' is a specific difference [Oderberg] |
| 12242 | Definition distinguishes one kind from another, and individuation picks out members of the kind [Oderberg] |
| 10987 | Three traditional names of rules are 'Simplification', 'Addition' and 'Disjunctive Syllogism' [Read] |
| 11004 | Necessity is provability in S4, and true in all worlds in S5 [Read] |
| 11018 | There are fuzzy predicates (and sets), and fuzzy quantifiers and modifiers [Read] |
| 11011 | Same say there are positive, negative and neuter free logics [Read] |
| 11020 | Realisms like the full Comprehension Principle, that all good concepts determine sets [Read] |
| 14187 | If logic is topic-neutral that means it delves into all subjects, rather than having a pure subject matter [Read] |
| 10986 | Not all validity is captured in first-order logic [Read] |
| 10972 | The non-emptiness of the domain is characteristic of classical logic [Read] |
| 11024 | Semantics must precede proof in higher-order logics, since they are incomplete [Read] |
| 10985 | We should exclude second-order logic, precisely because it captures arithmetic [Read] |
| 14188 | Not all arguments are valid because of form; validity is just true premises and false conclusion being impossible [Read] |
| 14182 | If the logic of 'taller of' rests just on meaning, then logic may be the study of merely formal consequence [Read] |
| 14183 | Maybe arguments are only valid when suppressed premises are all stated - but why? [Read] |
| 10970 | A theory of logical consequence is a conceptual analysis, and a set of validity techniques [Read] |
| 10984 | Logical consequence isn't just a matter of form; it depends on connections like round-square [Read] |
| 14184 | In modus ponens the 'if-then' premise contributes nothing if the conclusion follows anyway [Read] |
| 14186 | Logical connectives contain no information, but just record combination relations between facts [Read] |
| 10973 | A theory is logically closed, which means infinite premisses [Read] |
| 11007 | Quantifiers are second-order predicates [Read] |
| 10978 | In second-order logic the higher-order variables range over all the properties of the objects [Read] |
| 10971 | A logical truth is the conclusion of a valid inference with no premisses [Read] |
| 10988 | Any first-order theory of sets is inadequate [Read] |
| 10974 | Compactness is when any consequence of infinite propositions is the consequence of a finite subset [Read] |
| 10975 | Compactness does not deny that an inference can have infinitely many premisses [Read] |
| 10977 | Compactness blocks the proof of 'for every n, A(n)' (as the proof would be infinite) [Read] |
| 10976 | Compactness makes consequence manageable, but restricts expressive power [Read] |
| 11014 | Self-reference paradoxes seem to arise only when falsity is involved [Read] |
| 12238 | The Aristotelian view is that numbers depend on (and are abstracted from) other things [Oderberg] |
| 11025 | Infinite cuts and successors seems to suggest an actual infinity there waiting for us [Read] |
| 10979 | Although second-order arithmetic is incomplete, it can fully model normal arithmetic [Read] |
| 10980 | Second-order arithmetic covers all properties, ensuring categoricity [Read] |
| 10997 | Von Neumann numbers are helpful, but don't correctly describe numbers [Read] |
| 12254 | Being is substantial/accidental, complete/incomplete, necessary/contingent, possible, relative, intrinsic.. [Oderberg] |
| 11016 | Would a language without vagueness be usable at all? [Read] |
| 11019 | Supervaluations say there is a cut-off somewhere, but at no particular place [Read] |
| 11012 | A 'supervaluation' gives a proposition consistent truth-value for classical assignments [Read] |
| 11013 | Identities and the Indiscernibility of Identicals don't work with supervaluations [Read] |
| 12253 | If tropes are in space and time, in what sense are they abstract? [Oderberg] |
| 12256 | We need to distinguish the essential from the non-essential powers [Oderberg] |
| 10995 | A haecceity is a set of individual properties, essential to each thing [Read] |
| 12252 | Empiricists gave up 'substance', as unknowable substratum, or reducible to a bundle [Oderberg] |
| 12241 | Essences are real, about being, knowable, definable and classifiable [Oderberg, by PG] |
| 12244 | Nominalism is consistent with individual but not with universal essences [Oderberg] |
| 12240 | Essentialism is the main account of the unity of objects [Oderberg] |
| 12247 | Essence is not explanatory but constitutive [Oderberg] |
| 12258 | Properties are not part of an essence, but they flow from it [Oderberg] |
| 12257 | Could we replace essence with collections of powers? [Oderberg] |
| 12236 | Leibniz's Law is an essentialist truth [Oderberg] |
| 11001 | Equating necessity with truth in every possible world is the S5 conception of necessity [Read] |
| 12250 | Bodies have act and potency, the latter explaining new kinds of existence [Oderberg] |
| 10989 | The standard view of conditionals is that they are truth-functional [Read] |
| 11017 | Some people even claim that conditionals do not express propositions [Read] |
| 10992 | The point of conditionals is to show that one will accept modus ponens [Read] |
| 14185 | Conditionals are just a shorthand for some proof, leaving out the details [Read] |
| 10983 | Knowledge of possible worlds is not causal, but is an ontology entailed by semantics [Read] |
| 10982 | How can modal Platonists know the truth of a modal proposition? [Read] |
| 10996 | Actualism is reductionist (to parts of actuality), or moderate realist (accepting real abstractions) [Read] |
| 12234 | Realism about possible worlds is circular, since it needs a criterion of 'possible' [Oderberg] |
| 10981 | A possible world is a determination of the truth-values of all propositions of a domain [Read] |
| 12235 | Necessity of identity seems trivial, because it leaves out the real essence [Oderberg] |
| 12237 | Rigid designation has at least three essentialist presuppositions [Oderberg] |
| 11000 | If worlds are concrete, objects can't be present in more than one, and can only have counterparts [Read] |
| 20653 | Six reduction levels: groups, lives, cells, molecules, atoms, particles [Putnam/Oppenheim, by Watson] |
| 10998 | The mind abstracts ways things might be, which are nonetheless real [Read] |
| 11005 | Negative existentials with compositionality make the whole sentence meaningless [Read] |
| 10966 | A proposition objectifies what a sentence says, as indicative, with secure references [Read] |
| 12245 | Essence is the source of a thing's characteristic behaviour [Oderberg] |
| 12246 | What makes Parmenidean reality a One rather than a Many? [Oderberg] |
| 12239 | The real essentialist is not merely a scientist [Oderberg] |
| 12243 | The reductionism found in scientific essentialism is mistaken [Oderberg] |