58 ideas
23247 | The need to act produces consciousness, and practical reason is the root of all reason [Fichte] |
23232 | Sufficient reason makes the transition from the particular to the general [Fichte] |
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] |
15920 | Pure collections of things obey Choice, but collections defined by a rule may not [Lavine] |
15898 | The controversy was not about the Axiom of Choice, but about functions as arbitrary, or given by rules [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] |
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] |
15949 | The theory of infinity must rest on our inability to distinguish between very large sizes [Lavine] |
15947 | The infinite is extrapolation from the experience of indefinitely large size [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] |
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] |
23227 | Each object has a precise number of properties, each to a precise degree [Fichte] |
23228 | The principle of activity and generation is found in a self-moving basic force [Fichte] |
23241 | I am myself, but not the external object; so I only sense myself, and not the object [Fichte] |
21966 | Self-consciousness is the basis of knowledge, and knowing something is knowing myself [Fichte] |
21967 | There is nothing to say about anything which is outside my consciousness [Fichte] |
21969 | Awareness of reality comes from the free activity of consciousness [Fichte] |
23231 | I immediately know myself, and anything beyond that is an inference [Fichte] |
23246 | Faith is not knowledge; it is a decision of the will [Fichte] |
23245 | Knowledge can't be its own foundation; there has to be regress of higher and higher authorities [Fichte] |
23242 | Consciousness has two parts, passively receiving sensation, and actively causing productions [Fichte] |
23240 | We can't know by sight or hearing without realising that we are doing so [Fichte] |
23243 | Consciousness of external things is always accompanied by an unnoticed consciousness of self [Fichte] |
23244 | Forming purposes is absolutely free, and produces something from nothing [Fichte] |
23237 | The capacity for freedom is above the laws of nature, with its own power of purpose and will [Fichte] |
23235 | I want independent control of the fundamental cause of my decisions [Fichte] |
23230 | Nature contains a fundamental force of thought [Fichte] |
23233 | The will is awareness of one of our inner natural forces [Fichte] |
468 | Musical performance can reveal a range of virtues [Damon of Ath.] |
23234 | I cannot change the nature which has been determined for me [Fichte] |
23239 | The self is, apart from outward behaviour, a drive in your nature [Fichte] |
23238 | If life lacks love it becomes destruction [Fichte] |
23236 | Freedom means making yourself become true to your essential nature [Fichte] |
23229 | Nature is wholly interconnected, and the tiniest change affects everything [Fichte] |