75 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] |
12124 | Metaphysics is the best knowledge, because it is the simplest [Bacon] |
12123 | Natural history supports physical knowledge, which supports metaphysical knowledge [Bacon] |
12119 | Physics studies transitory matter; metaphysics what is abstracted and necessary [Bacon] |
12120 | Physics is of material and efficient causes, metaphysics of formal and final causes [Bacon] |
166 | A speaker should be able to divide a subject, right down to the limits of divisibility [Plato] |
9955 | Contextual definitions replace a complete sentence containing the expression [George/Velleman] |
10031 | Impredicative definitions quantify over the thing being defined [George/Velleman] |
10098 | The 'power set' of A is all the subsets of A [George/Velleman] |
10099 | The 'ordered pair' <a, b>, for two sets a and b, is the set {{a, b},{a}} [George/Velleman] |
10101 | Cartesian Product A x B: the set of all ordered pairs in which a∈A and b∈B [George/Velleman] |
10103 | Grouping by property is common in mathematics, usually using equivalence [George/Velleman] |
10104 | 'Equivalence' is a reflexive, symmetric and transitive relation; 'same first letter' partitions English words [George/Velleman] |
10096 | Even the elements of sets in ZFC are sets, resting on the pure empty set [George/Velleman] |
10097 | Axiom of Extensionality: for all sets x and y, if x and y have the same elements then x = y [George/Velleman] |
10100 | Axiom of Pairing: for all sets x and y, there is a set z containing just x and y [George/Velleman] |
17900 | The Axiom of Reducibility made impredicative definitions possible [George/Velleman] |
10109 | ZFC can prove that there is no set corresponding to the concept 'set' [George/Velleman] |
10108 | As a reduction of arithmetic, set theory is not fully general, and so not logical [George/Velleman] |
10111 | Asserting Excluded Middle is a hallmark of realism about the natural world [George/Velleman] |
10129 | A 'model' is a meaning-assignment which makes all the axioms true [George/Velleman] |
10105 | Differences between isomorphic structures seem unimportant [George/Velleman] |
10119 | Consistency is a purely syntactic property, unlike the semantic property of soundness [George/Velleman] |
10126 | A 'consistent' theory cannot contain both a sentence and its negation [George/Velleman] |
10120 | Soundness is a semantic property, unlike the purely syntactic property of consistency [George/Velleman] |
10127 | A 'complete' theory contains either any sentence or its negation [George/Velleman] |
10106 | Rational numbers give answers to division problems with integers [George/Velleman] |
10102 | The integers are answers to subtraction problems involving natural numbers [George/Velleman] |
10107 | Real numbers provide answers to square root problems [George/Velleman] |
9946 | Logicists say mathematics is applicable because it is totally general [George/Velleman] |
10125 | The classical mathematician believes the real numbers form an actual set [George/Velleman] |
17899 | Second-order induction is stronger as it covers all concepts, not just first-order definable ones [George/Velleman] |
10128 | The Incompleteness proofs use arithmetic to talk about formal arithmetic [George/Velleman] |
17902 | A successor is the union of a set with its singleton [George/Velleman] |
10133 | Frege's Theorem shows the Peano Postulates can be derived from Hume's Principle [George/Velleman] |
10130 | Set theory can prove the Peano Postulates [George/Velleman] |
10089 | Talk of 'abstract entities' is more a label for the problem than a solution to it [George/Velleman] |
10131 | If mathematics is not about particulars, observing particulars must be irrelevant [George/Velleman] |
10092 | In the unramified theory of types, the types are objects, then sets of objects, sets of sets etc. [George/Velleman] |
10094 | The theory of types seems to rule out harmless sets as well as paradoxical ones. [George/Velleman] |
10095 | Type theory has only finitely many items at each level, which is a problem for mathematics [George/Velleman] |
17901 | Type theory prohibits (oddly) a set containing an individual and a set of individuals [George/Velleman] |
10114 | Bounded quantification is originally finitary, as conjunctions and disjunctions [George/Velleman] |
10134 | Much infinite mathematics can still be justified finitely [George/Velleman] |
10123 | The intuitionists are the idealists of mathematics [George/Velleman] |
10124 | Gödel's First Theorem suggests there are truths which are independent of proof [George/Velleman] |
7953 | Reasoning needs to cut nature accurately at the joints [Plato] |
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] |
151 | True knowledge is of the reality behind sense experience [Plato] |
12121 | We don't assume there is no land, because we can only see sea [Bacon] |
12117 | Science moves up and down between inventions of causes, and experiments [Bacon] |
165 | If the apparent facts strongly conflict with probability, it is in everyone's interests to suppress the facts [Plato] |
12127 | Many different theories will fit the observed facts [Bacon] |
9296 | The soul is self-motion [Plato] |
12126 | People love (unfortunately) extreme generality, rather than particular knowledge [Bacon] |
23997 | Plato saw emotions and appetites as wild horses, in need of taming [Plato, by Goldie] |
10110 | Corresponding to every concept there is a class (some of them sets) [George/Velleman] |
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] |
156 | Bad people are never really friends with one another [Plato] |
12125 | Teleological accounts are fine in metaphysics, but they stop us from searching for the causes [Bacon] |
12118 | Essences are part of first philosophy, but as part of nature, not part of logic [Bacon] |
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] |