67 ideas
162 | Can we understand an individual soul without knowing the soul in general? [Plato] |
160 | The highest ability in man is the ability to discuss unity and plurality in the nature of things [Plato] |
166 | A speaker should be able to divide a subject, right down to the limits of divisibility [Plato] |
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] |
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] |
7953 | Reasoning needs to cut nature accurately at the joints [Plato] |
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] |
16121 | I revere anyone who can discern a single thing that encompasses many things [Plato] |
153 | It takes a person to understand, by using universals, and by using reason to create a unity out of sense-impressions [Plato] |
154 | We would have an overpowering love of knowledge if we had a pure idea of it - as with the other Forms [Plato] |
10995 | A haecceity is a set of individual properties, essential to each thing [Read] |
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] |
151 | True knowledge is of the reality behind sense experience [Plato] |
165 | If the apparent facts strongly conflict with probability, it is in everyone's interests to suppress the facts [Plato] |
9296 | The soul is self-motion [Plato] |
10998 | The mind abstracts ways things might be, which are nonetheless real [Read] |
23997 | Plato saw emotions and appetites as wild horses, in need of taming [Plato, by Goldie] |
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] |
159 | Only a good philosopher can be a good speaker [Plato] |
5946 | 'Phaedrus' pioneers the notion of philosophical rhetoric [Lawson-Tancred on Plato] |
158 | An excellent speech seems to imply a knowledge of the truth in the mind of the speaker [Plato] |
155 | Beauty is the clearest and most lovely of the Forms [Plato] |
143 | The two ruling human principles are the natural desire for pleasure, and an acquired love of virtue [Plato] |
157 | Most pleasure is release from pain, and is therefore not worthwhile [Plato] |
144 | Reason impels us towards excellence, which teaches us self-control [Plato] |
7903 | The six perfections are giving, morality, patience, vigour, meditation, and wisdom [Nagarjuna] |
156 | Bad people are never really friends with one another [Plato] |
148 | If the prime origin is destroyed, it will not come into being again out of anything [Plato] |
152 | The mind of God is fully satisfied and happy with a vision of reality and truth [Plato] |
150 | We cannot conceive of God, so we have to think of Him as an immortal version of ourselves [Plato] |
149 | There isn't a single reason for positing the existence of immortal beings [Plato] |
146 | Soul is always in motion, so it must be self-moving and immortal [Plato] |