104 ideas
| 8558 | One system has properties, powers, events, similarity and substance [Shoemaker] |
| 8559 | Analysis aims at internal relationships, not reduction [Shoemaker] |
| 8594 | People have had good reasons for thinking that the circle has been squared [Shoemaker] |
| 8721 | An 'impredicative' definition seems circular, because it uses the term being defined [Friend] |
| 8680 | Classical definitions attempt to refer, but intuitionist/constructivist definitions actually create objects [Friend] |
| 3678 | Reductio ad absurdum proves an idea by showing that its denial produces contradiction [Friend] |
| 8705 | Anti-realists see truth as our servant, and epistemically contrained [Friend] |
| 8713 | In classical/realist logic the connectives are defined by truth-tables [Friend] |
| 14970 | Normal system K has five axioms and rules [Cresswell] |
| 14971 | D is valid on every serial frame, but not where there are dead ends [Cresswell] |
| 14972 | S4 has 14 modalities, and always reduces to a maximum of three modal operators [Cresswell] |
| 14973 | In S5 all the long complex modalities reduce to just three, and their negations [Cresswell] |
| 14976 | Reject the Barcan if quantifiers are confined to worlds, and different things exist in other worlds [Cresswell] |
| 8708 | Double negation elimination is not valid in intuitionist logic [Friend] |
| 8694 | Free logic was developed for fictional or non-existent objects [Friend] |
| 8665 | A 'proper subset' of A contains only members of A, but not all of them [Friend] |
| 8672 | A 'powerset' is all the subsets of a set [Friend] |
| 8677 | Set theory makes a minimum ontological claim, that the empty set exists [Friend] |
| 8666 | Infinite sets correspond one-to-one with a subset [Friend] |
| 8682 | Major set theories differ in their axioms, and also over the additional axioms of choice and infinity [Friend] |
| 8709 | The law of excluded middle is syntactic; it just says A or not-A, not whether they are true or false [Friend] |
| 8711 | Intuitionists read the universal quantifier as "we have a procedure for checking every..." [Friend] |
| 15091 | Restrict 'logical truth' to formal logic, rather than including analytic and metaphysical truths [Shoemaker] |
| 8675 | Paradoxes can be solved by talking more loosely of 'classes' instead of 'sets' [Friend] |
| 8674 | The Burali-Forti paradox asks whether the set of all ordinals is itself an ordinal [Friend] |
| 8667 | The 'integers' are the positive and negative natural numbers, plus zero [Friend] |
| 8668 | The 'rational' numbers are those representable as fractions [Friend] |
| 8670 | A number is 'irrational' if it cannot be represented as a fraction [Friend] |
| 8661 | The natural numbers are primitive, and the ordinals are up one level of abstraction [Friend] |
| 8664 | Cardinal numbers answer 'how many?', with the order being irrelevant [Friend] |
| 8671 | The 'real' numbers (rationals and irrationals combined) is the Continuum, which has no gaps [Friend] |
| 8663 | Raising omega to successive powers of omega reveal an infinity of infinities [Friend] |
| 8662 | The first limit ordinal is omega (greater, but without predecessor), and the second is twice-omega [Friend] |
| 8669 | Between any two rational numbers there is an infinite number of rational numbers [Friend] |
| 8676 | Is mathematics based on sets, types, categories, models or topology? [Friend] |
| 8678 | Most mathematical theories can be translated into the language of set theory [Friend] |
| 8701 | The number 8 in isolation from the other numbers is of no interest [Friend] |
| 8702 | In structuralism the number 8 is not quite the same in different structures, only equivalent [Friend] |
| 8699 | Are structures 'ante rem' (before reality), or are they 'in re' (grounded in physics)? [Friend] |
| 8696 | Structuralist says maths concerns concepts about base objects, not base objects themselves [Friend] |
| 8695 | Structuralism focuses on relations, predicates and functions, with objects being inessential [Friend] |
| 8700 | 'In re' structuralism says that the process of abstraction is pattern-spotting [Friend] |
| 8681 | The big problem for platonists is epistemic: how do we perceive, intuit, know or detect mathematical facts? [Friend] |
| 8712 | Mathematics should be treated as true whenever it is indispensable to our best physical theory [Friend] |
| 8716 | Formalism is unconstrained, so cannot indicate importance, or directions for research [Friend] |
| 8706 | Constructivism rejects too much mathematics [Friend] |
| 8707 | Intuitionists typically retain bivalence but reject the law of excluded middle [Friend] |
| 8596 | Inability to measure equality doesn't make all lengths unequal [Shoemaker] |
| 8597 | We couldn't verify the earth's rotation if everyone simultaneously fell asleep [Shoemaker] |
| 14974 | A relation is 'Euclidean' if aRb and aRc imply bRc [Cresswell] |
| 15092 | Formerly I said properties are individuated by essential causal powers and causing instantiation [Shoemaker, by Shoemaker] |
| 15095 | A property's causal features are essential, and only they fix its identity [Shoemaker] |
| 15097 | I claim that a property has its causal features in all possible worlds [Shoemaker] |
| 8543 | Genuine properties are closely related to genuine changes [Shoemaker] |
| 8551 | Properties must be essentially causal if we can know and speak about them [Shoemaker] |
| 8557 | To ascertain genuine properties, examine the object directly [Shoemaker] |
| 15761 | We should abandon the idea that properties are the meanings of predicate expressions [Shoemaker] |
| 15756 | Some truths are not because of a thing's properties, but because of the properties of related things [Shoemaker] |
| 15758 | Things have powers in virtue of (which are entailed by) their properties [Shoemaker] |
| 8547 | One power can come from different properties; a thing's powers come from its properties [Shoemaker] |
| 8549 | Properties are functions producing powers, and powers are functions producing effects [Shoemaker] |
| 15094 | I now deny that properties are cluster of powers, and take causal properties as basic [Shoemaker] |
| 12678 | Shoemaker says all genuine properties are dispositional [Shoemaker, by Ellis] |
| 8545 | A causal theory of properties focuses on change, not (say) on abstract properties of numbers [Shoemaker] |
| 15757 | 'Square', 'round' and 'made of copper' show that not all properties are dispositional [Shoemaker] |
| 15759 | The identity of a property concerns its causal powers [Shoemaker] |
| 15760 | Properties are clusters of conditional powers [Shoemaker] |
| 15762 | Could properties change without the powers changing, or powers change without the properties changing? [Shoemaker] |
| 8552 | If properties are separated from causal powers, this invites total elimination [Shoemaker] |
| 4040 | The notions of property and of causal power are parts of a single system of related concepts [Shoemaker] |
| 15765 | Actually, properties are individuated by causes as well as effects [Shoemaker] |
| 14534 | Shoemaker moved from properties as powers to properties bestowing powers [Shoemaker, by Mumford/Anjum] |
| 8548 | Dispositional predicates ascribe powers, and the rest ascribe properties [Shoemaker] |
| 9485 | Universals concern how things are, and how they could be [Shoemaker, by Bird] |
| 8550 | Triangular and trilateral are coextensive, but different concepts; but powers and properties are the same [Shoemaker] |
| 8704 | Structuralists call a mathematical 'object' simply a 'place in a structure' [Friend] |
| 8555 | There is no subset of properties which guarantee a thing's identity [Shoemaker] |
| 14975 | A de dicto necessity is true in all worlds, but not necessarily of the same thing in each world [Cresswell] |
| 15099 | If something is possible, but not nomologically possible, we need metaphysical possibility [Shoemaker] |
| 8554 | Possible difference across worlds depends on difference across time in the actual world [Shoemaker] |
| 15101 | Once you give up necessity as a priori, causal necessity becomes the main type of necessity [Shoemaker] |
| 15764 | 'Conceivable' is either not-provably-false, or compatible with what we know? [Shoemaker] |
| 15098 | Empirical evidence shows that imagining a phenomenon can show it is possible [Shoemaker] |
| 15100 | Imagination reveals conceptual possibility, where descriptions avoid contradiction or incoherence [Shoemaker] |
| 8562 | It is possible to conceive what is not possible [Shoemaker] |
| 5691 | The adverbial account of sensation says not 'see a red image' but be 'appeared to redly' [Shoemaker] |
| 8593 | Maybe billions of changeless years have elapsed since my last meal [Shoemaker] |
| 15096 | 'Grue' only has causal features because of its relation to green [Shoemaker] |
| 8556 | Grueness is not, unlike green and blue, associated with causal potential [Shoemaker] |
| 5687 | For true introspection, must we be aware that we are aware of our mental events? [Shoemaker] |
| 5688 | Empirical foundationalism says basic knowledge is self-intimating, and incorrigible or infallible [Shoemaker] |
| 1389 | If memory is the sole criterion of identity, we ought to use it for other people too [Shoemaker] |
| 1390 | Bodily identity is one criterion and memory another, for personal identity [Shoemaker, by PG] |
| 8685 | Studying biology presumes the laws of chemistry, and it could never contradict them [Friend] |
| 8688 | Concepts can be presented extensionally (as objects) or intensionally (as a characterization) [Friend] |
| 8542 | If causality is between events, there must be reference to the properties involved [Shoemaker] |
| 8598 | If things turn red for an hour and then explode, we wouldn't say the redness was the cause [Shoemaker] |
| 15093 | We might say laws are necessary by combining causal properties with Armstrong-Dretske-Tooley laws [Shoemaker] |
| 8560 | If causal laws describe causal potentialities, the same laws govern properties in all possible worlds [Shoemaker] |
| 15763 | If properties are causal, then causal necessity is a species of logical necessity [Shoemaker] |
| 8561 | If a world has different causal laws, it must have different properties [Shoemaker] |
| 8553 | It looks as if the immutability of the powers of a property imply essentiality [Shoemaker] |
| 4226 | If three regions 'freeze' every three, four and five years, after sixty years everything stops for a year [Shoemaker, by Lowe] |
| 8595 | If three regions freeze every 3rd, 4th and 5th year, they all freeze together every 60 years [Shoemaker] |