71 ideas
2056 | Philosophers are always switching direction to something more interesting [Plato] |
2086 | Understanding mainly involves knowing the elements, not their combinations [Plato] |
2083 | Either a syllable is its letters (making parts as knowable as whole) or it isn't (meaning it has no parts) [Plato] |
2082 | A rational account is essentially a weaving together of things with names [Plato] |
2052 | Eristic discussion is aggressive, but dialectic aims to help one's companions in discussion [Plato] |
15854 | A primary element has only a name, and no logos, but complexes have an account, by weaving the names [Plato] |
15945 | Second-order set theory just adds a version of Replacement that quantifies over functions [Lavine] |
15914 | An 'upper bound' is the greatest member of a subset; there may be several of these, so there is a 'least' one [Lavine] |
15921 | Collections of things can't be too big, but collections by a rule seem unlimited in size [Lavine] |
15937 | Those who reject infinite collections also want to reject the Axiom of Choice [Lavine] |
15936 | The Power Set is just the collection of functions from one collection to another [Lavine] |
15899 | Replacement was immediately accepted, despite having very few implications [Lavine] |
15930 | Foundation says descending chains are of finite length, blocking circularity, or ungrounded sets [Lavine] |
15898 | The controversy was not about the Axiom of Choice, but about functions as arbitrary, or given by rules [Lavine] |
15920 | Pure collections of things obey Choice, but collections defined by a rule may not [Lavine] |
15919 | The 'logical' notion of class has some kind of definition or rule to characterise the class [Lavine] |
15900 | The iterative conception of set wasn't suggested until 1947 [Lavine] |
15931 | The iterative conception needs the Axiom of Infinity, to show how far we can iterate [Lavine] |
15932 | The iterative conception doesn't unify the axioms, and has had little impact on mathematical proofs [Lavine] |
15933 | Limitation of Size: if it's the same size as a set, it's a set; it uses Replacement [Lavine] |
15913 | A collection is 'well-ordered' if there is a least element, and all of its successors can be identified [Lavine] |
15926 | Second-order logic presupposes a set of relations already fixed by the first-order domain [Lavine] |
15934 | Mathematical proof by contradiction needs the law of excluded middle [Lavine] |
9455 | Maybe proper names have the content of fixing a thing's category [Bealer] |
9454 | The four leading theories of definite descriptions are Frege's, Russell's, Evans's, and Prior's [Bealer] |
15907 | Mathematics is nowadays (thanks to set theory) regarded as the study of structure, not of quantity [Lavine] |
15942 | Every rational number, unlike every natural number, is divisible by some other number [Lavine] |
15922 | For the real numbers to form a set, we need the Continuum Hypothesis to be true [Lavine] |
18250 | Cauchy gave a necessary condition for the convergence of a sequence [Lavine] |
15904 | The two sides of the Cut are, roughly, the bounding commensurable ratios [Lavine] |
15912 | Counting results in well-ordering, and well-ordering makes counting possible [Lavine] |
15947 | The infinite is extrapolation from the experience of indefinitely large size [Lavine] |
15949 | The theory of infinity must rest on our inability to distinguish between very large sizes [Lavine] |
15940 | The intuitionist endorses only the potential infinite [Lavine] |
15909 | 'Aleph-0' is cardinality of the naturals, 'aleph-1' the next cardinal, 'aleph-ω' the ω-th cardinal [Lavine] |
15915 | Ordinals are basic to Cantor's transfinite, to count the sets [Lavine] |
15917 | Paradox: the class of all ordinals is well-ordered, so must have an ordinal as type - giving a bigger ordinal [Lavine] |
15918 | Paradox: there is no largest cardinal, but the class of everything seems to be the largest [Lavine] |
15929 | Set theory will found all of mathematics - except for the notion of proof [Lavine] |
10216 | We master arithmetic by knowing all the numbers in our soul [Plato] |
15935 | Modern mathematics works up to isomorphism, and doesn't care what things 'really are' [Lavine] |
15928 | Intuitionism rejects set-theory to found mathematics [Lavine] |
2060 | There seem to be two sorts of change: alteration and motion [Plato] |
2084 | If a word has no parts and has a single identity, it turns out to be the same kind of thing as a letter [Plato] |
15844 | A sum is that from which nothing is lacking, which is a whole [Plato] |
15843 | The whole can't be the parts, because it would be all of the parts, which is the whole [Plato] |
2080 | Things are only knowable if a rational account (logos) is possible [Plato] |
16126 | Expertise is knowledge of the whole by means of the parts [Plato] |
2050 | It is impossible to believe something which is held to be false [Plato] |
2076 | How can a belief exist if its object doesn't exist? [Plato] |
2045 | Perception is infallible, suggesting that it is knowledge [Plato] |
2067 | Our senses could have been separate, but they converge on one mind [Plato] |
2068 | With what physical faculty do we perceive pairs of opposed abstract qualities? [Plato] |
2069 | Thought must grasp being itself before truth becomes possible [Plato] |
2078 | You might mistake eleven for twelve in your senses, but not in your mind [Plato] |
2089 | An inadequate rational account would still not justify knowledge [Plato] |
2085 | Parts and wholes are either equally knowable or equally unknowable [Plato] |
2091 | Without distinguishing marks, how do I know what my beliefs are about? [Plato] |
2087 | A rational account might be seeing an image of one's belief, like a reflection in a mirror [Plato] |
2090 | A rational account involves giving an image, or analysis, or giving a differentiating mark [Plato] |
2081 | Maybe primary elements can be named, but not receive a rational account [Plato] |
2088 | A rational account of a wagon would mean knowledge of its hundred parts [Plato] |
2047 | What evidence can be brought to show whether we are dreaming or not? [Plato] |
2054 | Clearly some people are superior to others when it comes to medicine [Plato] |
2053 | If you claim that all beliefs are true, that includes beliefs opposed to your own [Plato] |
2059 | How can a relativist form opinions about what will happen in the future? [Plato] |
9453 | Sentences saying the same with the same rigid designators may still express different propositions [Bealer] |
9452 | Propositions might be reduced to functions (worlds to truth values), or ordered sets of properties and relations [Bealer] |
9451 | Modal logic and brain science have reaffirmed traditional belief in propositions [Bealer] |
2058 | God must be the epitome of goodness, and we can only approach a divine state by being as good as possible [Plato] |
2057 | There must always be some force of evil ranged against good [Plato] |