86 ideas
| 23000 | Vicious regresses force you to another level; non-vicious imply another level [Baron/Miller] |
| 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] |
| 10975 | Compactness does not deny that an inference can have infinitely many premisses [Read] |
| 10974 | Compactness is when any consequence of infinite propositions is the consequence of a finite subset [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] |
| 23024 | A traveller takes a copy of a picture into the past, gives it the artist, who then creates the original! [Baron/Miller] |
| 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] |
| 23008 | Grounding is intended as a relation that fits dependences between things [Baron/Miller] |
| 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] |
| 10995 | A haecceity is a set of individual properties, essential to each thing [Read] |
| 23018 | How does a changing object retain identity or have incompatible properties over time? [Baron/Miller] |
| 11001 | Equating necessity with truth in every possible world is the S5 conception of necessity [Read] |
| 10989 | The standard view of conditionals is that they are truth-functional [Read] |
| 10992 | The point of conditionals is to show that one will accept modus ponens [Read] |
| 11017 | Some people even claim that conditionals do not express propositions [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] |
| 10981 | A possible world is a determination of the truth-values of all propositions of a domain [Read] |
| 11000 | If worlds are concrete, objects can't be present in more than one, and can only have counterparts [Read] |
| 3061 | Anaxarchus said that he was not even sure that he knew nothing [Anaxarchus, by Diog. Laertius] |
| 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] |
| 23011 | Modern accounts of causation involve either processes or counterfactuals [Baron/Miller] |
| 23013 | The main process theory of causation says it is transference of mass, energy, momentum or charge [Baron/Miller] |
| 23014 | If causes are processes, what is causation by omission? (Distinguish legal from scientific causes?) [Baron/Miller] |
| 23015 | The counterfactual theory of causation handles the problem no matter what causes actually are [Baron/Miller] |
| 23016 | Counterfactual theories struggle with pre-emption by a causal back-up system [Baron/Miller] |
| 23009 | There is no second 'law' of thermodynamics; it just reflects probabilities of certain microstates [Baron/Miller] |
| 23002 | In relativity space and time depend on one's motion, but spacetime gives an invariant metric [Baron/Miller] |
| 22988 | The block universe theory says entities of all times exist, and time is the B-series [Baron/Miller] |
| 22991 | How can we know this is the present moment, if other times are real? [Baron/Miller] |
| 22992 | If we are actually in the past then we shouldn't experience time passing [Baron/Miller] |
| 22994 | Erzatz Presentism allows the existence of other times, with only the present 'actualised' [Baron/Miller] |
| 22998 | How do presentists explain relations between things existing at different times? [Baron/Miller] |
| 23017 | Presentism needs endurantism, because other theories imply most of the object doesn't exist [Baron/Miller] |
| 23023 | How can presentists move to the next future moment, if that doesn't exist? [Baron/Miller] |
| 22995 | Most of the sciences depend on the concept of time [Baron/Miller] |
| 22993 | For abstractionists past times might still exist, althought their objects don't [Baron/Miller] |
| 23001 | The error theory of time's passage says it is either a misdescription or a false inference [Baron/Miller] |
| 22999 | It is meaningless to measure the rate of time using time itself, and without a rate there is no flow [Baron/Miller] |
| 22986 | The C-series rejects A and B, and just sees times as order by betweenness, without direction [Baron/Miller] |
| 22996 | The A-series has to treat being past, present or future as properties [Baron/Miller] |
| 23007 | The B-series can have a direction, as long as it does not arise from temporal flow [Baron/Miller] |
| 23003 | Static theories cannot account for time's obvious asymmetry, so time must be dynamic [Baron/Miller] |
| 23004 | The direction of time is either primitive, or reducible to something else [Baron/Miller] |
| 23005 | The kaon does not seem to be time-reversal invariant, unlike the rest of nature [Baron/Miller] |
| 23006 | Maybe the past is just the direction of decreasing entropy [Baron/Miller] |
| 23010 | We could explain time's direction by causation: past is the direction of causes, future of effects [Baron/Miller] |
| 22989 | Static time theory presents change as one property at t1, and a different property at t2 [Baron/Miller] |
| 23020 | If a time traveller kills his youthful grandfather, he both exists and fails to exist [Baron/Miller] |
| 23022 | Presentism means there no existing past for a time traveller to visit [Baron/Miller] |
| 22987 | The past (unlike the future) is fixed, along with truths about it, by the existence of past objects [Baron/Miller] |
| 22990 | The moving spotlight says entities can have properties of being present, past or future [Baron/Miller] |
| 22997 | The present moment is a matter of existence, not of acquiring a property [Baron/Miller] |