67 ideas
21360 | Unobservant thinkers tend to dogmatise using insufficient facts [Aristotle] |
18835 | Logic doesn't have a metaphysical basis, but nor can logic give rise to the metaphysics [Rumfitt] |
21901 | 'Difference' refers to that which eludes capture [Deleuze, by May] |
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] |
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] |
13212 | Infinity is only potential, never actual [Aristotle] |
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] |
13221 | Existence is either potential or actual [Aristotle] |
21908 | Ontology can be continual creation, not to know being, but to probe the unknowable [Deleuze] |
21902 | 'Being' is univocal, but its subject matter is actually 'difference' [Deleuze] |
21903 | Ontology does not tell what there is; it is just a strange adventure [Deleuze, by May] |
21904 | Being is a problem to be engaged, not solved, and needs a new mode of thinking [Deleuze, by May] |
16100 | True change is in a thing's logos or its matter, not in its qualities [Aristotle] |
16101 | A change in qualities is mere alteration, not true change [Aristotle] |
12133 | If the substratum persists, it is 'alteration'; if it doesn't, it is 'coming-to-be' or 'passing-away' [Aristotle] |
13213 | All comings-to-be are passings-away, and vice versa [Aristotle] |
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] |
12134 | Matter is the substratum, which supports both coming-to-be and alteration [Aristotle] |
16572 | Does the pure 'this' come to be, or the 'this-such', or 'so-great', or 'somewhere'? [Aristotle] |
16573 | Philosophers have worried about coming-to-be from nothing pre-existing [Aristotle] |
13214 | The substratum changing to a contrary is the material cause of coming-to-be [Aristotle] |
13215 | If a perceptible substratum persists, it is 'alteration'; coming-to-be is a complete change [Aristotle] |
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] |
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] |
16717 | Which of the contrary features of a body are basic to it? [Aristotle] |
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] |
18829 | The truth grounds for 'not A' are the possibilities incompatible with truth grounds for A [Rumfitt] |
13216 | Matter is the limit of points and lines, and must always have quality and form [Aristotle] |
17994 | The primary matter is the substratum for the contraries like hot and cold [Aristotle] |
13224 | There couldn't be just one element, which was both water and air at the same time [Aristotle] |
16594 | The Four Elements must change into one another, or else alteration is impossible [Aristotle] |
13223 | Fire is hot and dry; Air is hot and moist; Water is cold and moist; Earth is cold and dry [Aristotle] |
13220 | Bodies are endlessly divisible [Aristotle] |
13210 | Wood is potentially divided through and through, so what is there in the wood besides the division? [Aristotle] |
13211 | If a body is endlessly divided, is it reduced to nothing - then reassembled from nothing? [Aristotle] |
13228 | There is no time without movement [Aristotle] |
16595 | If each thing can cease to be, why hasn't absolutely everything ceased to be long ago? [Aristotle] |
13227 | Being is better than not-being [Aristotle] |
13226 | An Order controls all things [Aristotle] |