98 ideas
| 24047 | An account is either a definition or a demonstration [Aristotle] |
| 24052 | From one thing alone we can infer its contrary [Aristotle] |
| 18487 | We want to know what makes sentences true, rather than defining 'true' [McFetridge] |
| 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] |
| 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] |
| 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] |
| 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] |
| 1729 | We perceive number by the denial of continuity [Aristotle] |
| 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] |
| 24057 | What is prior is always potentially present in what is next in order [Aristotle] |
| 18488 | We normally explain natural events by citing further facts [McFetridge] |
| 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] |
| 16752 | Sight is the essence of the eye, fitting its definition; the eye itself is just the matter [Aristotle] |
| 10995 | A haecceity is a set of individual properties, essential to each thing [Read] |
| 24058 | The substance is the cause of a thing's being [Aristotle] |
| 24055 | Matter is potential, form is actual [Aristotle] |
| 24040 | Scientists explain anger by the matter, dialecticians by the form and the account [Aristotle] |
| 11001 | Equating necessity with truth in every possible world is the S5 conception of necessity [Read] |
| 10992 | The point of conditionals is to show that one will accept modus ponens [Read] |
| 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] |
| 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] |
| 5051 | The intellect has potential to think, like a tablet on which nothing has yet been written [Aristotle] |
| 16723 | Perception of sensible objects is virtually never wrong [Aristotle] |
| 1724 | Perception necessitates pleasure and pain, which necessitates appetite [Aristotle] |
| 1730 | Why do we have many senses, and not just one? [Aristotle] |
| 17711 | Our minds take on the form of what is being perceived [Aristotle, by Mares] |
| 1725 | Why can't we sense the senses? And why do senses need stimuli? [Aristotle] |
| 1732 | Sense organs aren't the end of sensation, or they would know what does the sensing [Aristotle] |
| 1728 | Many objects of sensation are common to all the senses [Aristotle] |
| 1727 | Some objects of sensation are unique to one sense, where deception is impossible [Aristotle] |
| 1734 | In moral thought images are essential, to be pursued or avoided [Aristotle] |
| 1726 | We may think when we wish, but not perceive, because universals are within the mind [Aristotle] |
| 16647 | Demonstration starts from a definition of essence, so we can derive (or conjecture about) the properties [Aristotle] |
| 24048 | Demonstrations move from starting-points to deduced conclusions [Aristotle] |
| 16646 | To understand a triangle summing to two right angles, we need to know the essence of a line [Aristotle] |
| 1714 | Mind involves movement, perception, incorporeality [Aristotle] |
| 5507 | Aristotle led to the view that there are several souls, all somewhat physical [Aristotle, by Martin/Barresi] |
| 24051 | Soul is seen as what moves, or what is least physical, or a combination of elements [Aristotle] |
| 12086 | Psuché is the form and actuality of a body which potentially has life [Aristotle] |
| 16754 | The soul is the cause or source of movement, the essence of body, and its end [Aristotle] |
| 24046 | Understanding is impossible, if it involves the understanding having parts [Aristotle] |
| 1717 | If the soul is composed of many physical parts, it can't be a true unity [Aristotle] |
| 24053 | If a soul have parts, what unites them? [Aristotle] |
| 1721 | What unifies the soul would have to be a super-soul, which seems absurd [Aristotle] |
| 1735 | In a way the soul is everything which exists, through its perceptions and thoughts [Aristotle] |
| 24061 | If we divide the mind up according to its capacities, there are a lot of them [Aristotle] |
| 24062 | Self-moving animals must have desires, and that entails having imagination [Aristotle] |
| 10998 | The mind abstracts ways things might be, which are nonetheless real [Read] |
| 1710 | Emotion involves the body, thinking uses the mind, imagination hovers between them [Aristotle] |
| 24039 | All the emotions seem to involve the body, simultaneously with the feeling [Aristotle] |
| 24056 | The soul (or parts of it) is not separable from the body [Aristotle] |
| 24050 | If soul is separate from body, why does it die when the body dies? [Aristotle] |
| 24049 | Thinkers place the soul within the body, but never explain how they are attached [Aristotle] |
| 1514 | Early thinkers concentrate on the soul but ignore the body, as if it didn't matter what body received the soul [Aristotle] |
| 2683 | Aristotle has a problem fitting his separate reason into the soul, which is said to be the form of the body [Ackrill on Aristotle] |
| 1718 | Does the mind think or pity, or does the whole man do these things? [Aristotle] |
| 13275 | The soul and the body are inseparable, like the imprint in some wax [Aristotle] |
| 1733 | Thinking is not perceiving, but takes the form of imagination and speculation [Aristotle] |
| 23307 | Aristotle makes belief a part of reason, but sees desires as separate [Aristotle, by Sorabji] |
| 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] |
| 24060 | Self-controlled follow understanding, when it is opposed to desires [Aristotle] |
| 4376 | Pleasure and pain are perceptions of things as good or bad [Aristotle] |
| 1740 | Nature does nothing in vain [Aristotle] |
| 1739 | If all movement is either pushing or pulling, there must be a still point in between where it all starts [Aristotle] |
| 24045 | Movement is spatial, alteration, withering or growth [Aristotle] |
| 1738 | Practical reason is based on desire, so desire must be the ultimate producer of movement [Aristotle] |
| 24044 | Movement can be intrinsic (like a ship) or relative (like its sailors) [Aristotle] |
| 24064 | If something is pushed, it pushes back [Aristotle] |
| 24063 | What is born has growth, a prime, and a withering away [Aristotle] |