68 ideas
18835 | Logic doesn't have a metaphysical basis, but nor can logic give rise to the metaphysics [Rumfitt] |
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] |
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] |
18815 | Logic is higher-order laws which can expand the range of any sort of deduction [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] |
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] |
18802 | In specifying a logical constant, use of that constant is quite unavoidable [Rumfitt] |
1618 | We study bound variables not to know reality, but to know what reality language asserts [Quine] |
8455 | Canonical notation needs quantification, variables and predicates, but not names [Quine, by Orenstein] |
8456 | Quine extended Russell's defining away of definite descriptions, to also define away names [Quine, by Orenstein] |
1611 | Names can be converted to descriptions, and Russell showed how to eliminate those [Quine] |
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] |
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] |
1613 | Logicists cheerfully accept reference to bound variables and all sorts of abstract entities [Quine] |
1616 | Formalism says maths is built of meaningless notations; these build into rules which have meaning [Quine] |
1615 | Intuitionism says classes are invented, and abstract entities are constructed from specified ingredients [Quine] |
1614 | Conceptualism holds that there are universals but they are mind-made [Quine] |
10241 | For Quine, there is only one way to exist [Quine, by Shapiro] |
4064 | The idea of a thing and the idea of existence are two sides of the same coin [Quine, by Crane] |
19277 | Quine rests existence on bound variables, because he thinks singular terms can be analysed away [Quine, by Hale] |
12210 | Quine's ontology is wrong; his question is scientific, and his answer is partly philosophical [Fine,K on Quine] |
8496 | What actually exists does not, of course, depend on language [Quine] |
1610 | To be is to be the value of a variable, which amounts to being in the range of reference of a pronoun [Quine] |
8459 | Fictional quantification has no ontology, so we study ontology through scientific theories [Quine, by Orenstein] |
8497 | An ontology is like a scientific theory; we accept the simplest scheme that fits disorderly experiences [Quine] |
16261 | If commitment rests on first-order logic, we obviously lose the ontology concerning predication [Maudlin on Quine] |
7698 | If to be is to be the value of a variable, we must already know the values available [Jacquette on Quine] |
1612 | Realism, conceptualism and nominalism in medieval universals reappear in maths as logicism, intuitionism and formalism [Quine] |
15402 | There is no entity called 'redness', and that some things are red is ultimate and irreducible [Quine] |
4443 | Quine has argued that predicates do not have any ontological commitment [Quine, by Armstrong] |
8498 | Treating scattered sensations as single objects simplifies our understanding of experience [Quine] |
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] |
18816 | Metaphysical modalities respect the actual identities of things [Rumfitt] |
18825 | S5 is the logic of logical necessity [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] |
8856 | Quine's indispensability argument said arguments for abstracta were a posteriori [Quine, by Yablo] |
18821 | Possibilities are like possible worlds, but not fully determinate or complete [Rumfitt] |
12443 | Can an unactualized possible have self-identity, and be distinct from other possibles? [Quine] |
18831 | Medieval logicians said understanding A also involved understanding not-A [Rumfitt] |
18209 | We can never translate our whole language of objects into phenomenalism [Quine] |
18820 | In English 'evidence' is a mass term, qualified by 'little' and 'more' [Rumfitt] |
18817 | We understand conditionals, but disagree over their truth-conditions [Rumfitt] |
1619 | There is an attempt to give a verificationist account of meaning, without the error of reducing everything to sensations [Dennett on Quine] |
1609 | I do not believe there is some abstract entity called a 'meaning' which we can 'have' [Quine] |
1617 | The word 'meaning' is only useful when talking about significance or about synonymy [Quine] |
19159 | Quine relates predicates to their objects, by being 'true of' them [Quine, by Davidson] |
18829 | The truth grounds for 'not A' are the possibilities incompatible with truth grounds for A [Rumfitt] |
16713 | Philosophers are the forefathers of heretics [Tertullian] |
6610 | I believe because it is absurd [Tertullian] |