79 ideas
12926 | Wisdom is the science of happiness [Leibniz] |
12903 | Wise people have fewer acts of will, because such acts are linked together [Leibniz] |
12914 | Metaphysics is geometrical, resting on non-contradiction and sufficient reason [Leibniz] |
12915 | Definitions can only be real if the item is possible [Leibniz] |
19333 | A truth is just a proposition in which the predicate is contained within the subject [Leibniz] |
12910 | The predicate is in the subject of a true proposition [Leibniz] |
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] |
12920 | There is no multiplicity without true units [Leibniz] |
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] |
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] |
12319 | What is not truly one being is not truly a being either [Leibniz] |
12922 | A thing 'expresses' another if they have a constant and fixed relationship [Leibniz] |
13079 | A substance contains the laws of its operations, and its actions come from its own depth [Leibniz] |
12745 | Philosophy needs the precision of the unity given by substances [Leibniz] |
12921 | Accidental unity has degrees, from a mob to a society to a machine or organism [Leibniz] |
12746 | We find unity in reason, and unity in perception, but these are not true unity [Leibniz] |
12916 | A body is a unified aggregate, unless it has an indivisible substance [Leibniz] |
12919 | Unity needs an indestructible substance, to contain everything which will happen to it [Leibniz] |
12923 | Every bodily substance must have a soul, or something analogous to a soul [Leibniz] |
12704 | Aggregates don’t reduce to points, or atoms, or illusion, so must reduce to substance [Leibniz] |
13077 | Basic predicates give the complete concept, which then predicts all of the actions [Leibniz] |
12908 | Essences exist in the divine understanding [Leibniz] |
12706 | Bodies need a soul (or something like it) to avoid being mere phenomena [Leibniz] |
12906 | Truths about species are eternal or necessary, but individual truths concern what exists [Leibniz] |
12904 | If varieties of myself can be conceived of as distinct from me, then they are not me [Leibniz] |
11981 | If someone's life went differently, then that would be another individual [Leibniz] |
12905 | I cannot think my non-existence, nor exist without being myself [Leibniz] |
19334 | I can't just know myself to be a substance; I must distinguish myself from others, which is hard [Leibniz] |
5033 | Nothing should be taken as certain without foundations [Leibniz] |
12913 | Nature is explained by mathematics and mechanism, but the laws rest on metaphysics [Leibniz] |
13089 | To fully conceive the subject is to explain the resulting predicates and events [Leibniz] |
5034 | Mind is a thinking substance which can know God and eternal truths [Leibniz] |
5032 | It seems probable that animals have souls, but not consciousness [Leibniz] |
5031 | Everything which happens is not necessary, but is certain after God chooses this universe [Leibniz] |
12911 | Concepts are what unite a proposition [Leibniz] |
12925 | Beauty increases with familiarity [Leibniz] |
12927 | Happiness is advancement towards perfection [Leibniz] |
23169 | Democratic institutions become impossible in a fanatical democracy [Russell] |
23170 | Liberal opinions are tentative rather than dogmatic, and are always responsive to new evidence [Russell] |
23171 | Empiricism is ethically superior, because dogmatism favours persecution and hatred [Russell] |
23172 | Empiricist Liberalism is the only view for someone who favours scientific evidence and happiness [Russell] |
15955 | I think the corpuscular theory, rather than forms or qualities, best explains particular phenomena [Leibniz] |
12907 | Each possible world contains its own laws, reflected in the possible individuals of that world [Leibniz] |
12924 | Motion alone is relative, but force is real, and establishes its subject [Leibniz] |
12909 | Everything, even miracles, belongs to order [Leibniz] |
5030 | Miracles are extraordinary operations by God, but are nevertheless part of his design [Leibniz] |
12912 | Immortality without memory is useless [Leibniz] |
12917 | The soul is indestructible and always self-aware [Leibniz] |
12918 | Animals have souls, but lack consciousness [Leibniz] |