93 ideas
421 | Men who love wisdom must be inquirers into very many things indeed [Heraclitus] |
1491 | Everyone has the potential for self-knowledge and sound thinking [Heraclitus] |
5863 | Reason is eternal, but men are foolish [Heraclitus] |
18835 | Logic doesn't have a metaphysical basis, but nor can logic give rise to the metaphysics [Rumfitt] |
414 | Logos is common to all, but most people live as if they have a private understanding [Heraclitus] |
416 | Beautiful harmony comes from things that are in opposition to one another [Heraclitus] |
425 | A thing can have opposing tensions but be in harmony, like a lyre [Heraclitus] |
18819 | The idea that there are unrecognised truths is basic to our concept of truth [Rumfitt] |
18826 | 'True at a possibility' means necessarily true if what is said had obtained [Rumfitt] |
18803 | Semantics for propositions: 1) validity preserves truth 2) non-contradition 3) bivalence 4) truth tables [Rumfitt] |
12204 | The logic of metaphysical necessity is S5 [Rumfitt] |
18814 | 'Absolute necessity' would have to rest on S5 [Rumfitt] |
18798 | It is the second-order part of intuitionistic logic which actually negates some classical theorems [Rumfitt] |
18799 | Intuitionists can accept Double Negation Elimination for decidable propositions [Rumfitt] |
18830 | Most set theorists doubt bivalence for the Continuum Hypothesis, but still use classical logic [Rumfitt] |
18843 | The iterated conception of set requires continual increase in axiom strength [Rumfitt] |
18836 | A set may well not consist of its members; the empty set, for example, is a problem [Rumfitt] |
18837 | A set can be determinate, because of its concept, and still have vague membership [Rumfitt] |
18845 | If the totality of sets is not well-defined, there must be doubt about the Power Set Axiom [Rumfitt] |
11211 | If a sound conclusion comes from two errors that cancel out, the path of the argument must matter [Rumfitt] |
18815 | Logic is higher-order laws which can expand the range of any sort of deduction [Rumfitt] |
9390 | Logic guides thinking, but it isn't a substitute for it [Rumfitt] |
18804 | The case for classical logic rests on its rules, much more than on the Principle of Bivalence [Rumfitt] |
18805 | Classical logic rules cannot be proved, but various lines of attack can be repelled [Rumfitt] |
18827 | If truth-tables specify the connectives, classical logic must rely on Bivalence [Rumfitt] |
12195 | Soundness in argument varies with context, and may be achieved very informally indeed [Rumfitt] |
12199 | There is a modal element in consequence, in assessing reasoning from suppositions [Rumfitt] |
12201 | We reject deductions by bad consequence, so logical consequence can't be deduction [Rumfitt] |
18813 | Logical consequence is a relation that can extended into further statements [Rumfitt] |
18808 | Normal deduction presupposes the Cut Law [Rumfitt] |
18840 | When faced with vague statements, Bivalence is not a compelling principle [Rumfitt] |
1312 | If everything is and isn't then everything is true, and a midway between true and false makes everything false [Aristotle on Heraclitus] |
12194 | Contradictions include 'This is red and not coloured', as well as the formal 'B and not-B' [Rumfitt] |
11210 | Standardly 'and' and 'but' are held to have the same sense by having the same truth table [Rumfitt] |
18802 | In specifying a logical constant, use of that constant is quite unavoidable [Rumfitt] |
11212 | The sense of a connective comes from primitively obvious rules of inference [Rumfitt] |
12198 | Geometrical axioms in logic are nowadays replaced by inference rules (which imply the logical truths) [Rumfitt] |
18800 | Introduction rules give deduction conditions, and Elimination says what can be deduced [Rumfitt] |
18809 | Logical truths are just the assumption-free by-products of logical rules [Rumfitt] |
18807 | Monotonicity means there is a guarantee, rather than mere inductive support [Rumfitt] |
18842 | Maybe an ordinal is a property of isomorphic well-ordered sets, and not itself a set [Rumfitt] |
17462 | A single object must not be counted twice, which needs knowledge of distinctness (negative identity) [Rumfitt] |
18834 | Infinitesimals do not stand in a determinate order relation to zero [Rumfitt] |
18846 | Cantor and Dedekind aimed to give analysis a foundation in set theory (rather than geometry) [Rumfitt] |
17461 | Some 'how many?' answers are not predications of a concept, like 'how many gallons?' [Rumfitt] |
15658 | The hidden harmony is stronger than the visible [Heraclitus] |
13782 | Everything gives way, and nothing stands fast [Heraclitus] |
11853 | A mixed drink separates if it is not stirred [Heraclitus] |
9389 | Vague membership of sets is possible if the set is defined by its concept, not its members [Rumfitt] |
18839 | An object that is not clearly red or orange can still be red-or-orange, which sweeps up problem cases [Rumfitt] |
18838 | The extension of a colour is decided by a concept's place in a network of contraries [Rumfitt] |
427 | It is not possible to step twice into the same river [Heraclitus] |
11091 | You can bathe in the same river twice, but not in the same river stage [Quine on Heraclitus] |
2064 | If flux is continuous, then lack of change can't be a property, so everything changes in every possible way [Plato on Heraclitus] |
14532 | A distinctive type of necessity is found in logical consequence [Rumfitt, by Hale/Hoffmann,A] |
18816 | Metaphysical modalities respect the actual identities of things [Rumfitt] |
12193 | Logical necessity is when 'necessarily A' implies 'not-A is contradictory' [Rumfitt] |
12200 | A logically necessary statement need not be a priori, as it could be unknowable [Rumfitt] |
18825 | S5 is the logic of logical necessity [Rumfitt] |
12202 | Narrow non-modal logical necessity may be metaphysical, but real logical necessity is not [Rumfitt] |
18824 | Since possibilities are properties of the world, calling 'red' the determination of a determinable seems right [Rumfitt] |
18828 | If two possibilities can't share a determiner, they are incompatible [Rumfitt] |
12203 | If a world is a fully determinate way things could have been, can anyone consider such a thing? [Rumfitt] |
18821 | Possibilities are like possible worlds, but not fully determinate or complete [Rumfitt] |
18831 | Medieval logicians said understanding A also involved understanding not-A [Rumfitt] |
430 | Senses are no use if the soul is corrupt [Heraclitus] |
1500 | When we sleep, reason closes down as the senses do [Heraclitus, by Sext.Empiricus] |
18820 | In English 'evidence' is a mass term, qualified by 'little' and 'more' [Rumfitt] |
417 | Donkeys prefer chaff to gold [Heraclitus] |
426 | Sea water is life-giving for fish, but not for people [Heraclitus] |
431 | Health, feeding and rest are only made good by disease, hunger and weariness [Heraclitus] |
20653 | Six reduction levels: groups, lives, cells, molecules, atoms, particles [Putnam/Oppenheim, by Watson] |
18817 | We understand conditionals, but disagree over their truth-conditions [Rumfitt] |
18829 | The truth grounds for 'not A' are the possibilities incompatible with truth grounds for A [Rumfitt] |
11214 | We learn 'not' along with affirmation, by learning to either affirm or deny a sentence [Rumfitt] |
429 | To God (though not to humans) all things are beautiful and good and just [Heraclitus] |
12294 | Good and evil are the same thing [Heraclitus, by Aristotle] |
419 | If one does not hope, one will not find the unhoped-for, since nothing leads to it [Heraclitus] |
415 | If happiness is bodily pleasure, then oxen are happy when they have vetch to eat [Heraclitus] |
5155 | It is hard to fight against emotion, but harder still to fight against pleasure [Heraclitus] |
433 | For man character is destiny [Heraclitus] |
422 | The people should fight for the law as if for their city-wall [Heraclitus] |
614 | Heraclitus said sometimes everything becomes fire [Heraclitus, by Aristotle] |
424 | Reason tells us that all things are one [Heraclitus] |
5096 | Heraclitus says that at some time everything becomes fire [Heraclitus, by Aristotle] |
17539 | The sayings of Heraclitus are still correct, if we replace 'fire' with 'energy' [Heraclitus, by Heisenberg] |
3054 | Heraclitus said fire could be transformed to create the other lower elements [Heraclitus, by Diog. Laertius] |
15660 | Logos is the source of everything, and my theories separate and explain each nature [Heraclitus] |
12269 | All things are in a state of motion [Heraclitus, by Aristotle] |
420 | The cosmos is eternal not created, and is an ever-living and changing fire [Heraclitus] |
1499 | Heraclitus says intelligence draws on divine reason [Heraclitus, by Sext.Empiricus] |
15659 | Purifying yourself with blood is as crazy as using mud to wash off mud [Heraclitus] |
1501 | In their ignorance people pray to statues, which is like talking to a house [Heraclitus] |