64 ideas
2352 | The job of the philosopher is to distinguish facts about the world from conventions [Putnam] |
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] |
2345 | Semantic notions do not occur in Tarski's definitions, but assessing their correctness involves translation [Putnam] |
2347 | Asserting the truth of an indexical statement is not the same as uttering the statement [Putnam] |
8713 | In classical/realist logic the connectives are defined by truth-tables [Friend] |
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] |
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] |
2349 | Realists believe truth is correspondence, independent of humans, is bivalent, and is unique [Putnam] |
2351 | Aristotle says an object (e.g. a lamp) has identity if its parts stay together when it is moved [Putnam] |
8704 | Structuralists call a mathematical 'object' simply a 'place in a structure' [Friend] |
1556 | By nature people are close to one another, but culture drives them apart [Hippias] |
2331 | Functionalism says robots and people are the same at one level of abstraction [Putnam] |
2348 | Is there just one computational state for each specific belief? [Putnam] |
2332 | Functionalism can't explain reference and truth, which are needed for logic [Putnam] |
2071 | If concepts have external meaning, computational states won't explain psychology [Putnam] |
8685 | Studying biology presumes the laws of chemistry, and it could never contradict them [Friend] |
2344 | If we are going to eliminate folk psychology, we must also eliminate folk logic [Putnam] |
2074 | Can we give a scientific, computational account of folk psychology? [Putnam] |
2343 | Reference may be different while mental representation is the same [Putnam] |
8688 | Concepts can be presented extensionally (as objects) or intensionally (as a characterization) [Friend] |
2346 | Meaning and translation (which are needed to define truth) both presuppose the notion of reference [Putnam] |
2354 | "Meaning is use" is not a definition of meaning [Putnam] |
2336 | Holism seems to make fixed definition more or less impossible [Putnam] |
2334 | Meaning holism tried to show that you can't get fixed meanings built out of observation terms [Putnam] |
2335 | Understanding a sentence involves background knowledge and can't be done in isolation [Putnam] |
2340 | We should separate how the reference of 'gold' is fixed from its conceptual content [Putnam] |
2341 | Like names, natural kind terms have their meaning fixed by extension and reference [Putnam] |
2339 | Aristotle implies that we have the complete concepts of a language in our heads, but we don't [Putnam] |
2338 | Reference (say to 'elms') is a social phenomenon which we can leave to experts [Putnam] |
2342 | "Water" is a natural kind term, but "H2O" is a description [Putnam] |