100 ideas
| 14857 | The highest wisdom has the guise of simplicity [Nietzsche] |
| 14854 | Deep thinkers know that they are always wrong [Nietzsche] |
| 14833 | Comedy is a transition from fear to exuberance [Nietzsche] |
| 8721 | An 'impredicative' definition seems circular, because it uses the term being defined [Friend] |
| 8680 | Classical definitions attempt to refer, but intuitionist/constructivist definitions actually create objects [Friend] |
| 3678 | Reductio ad absurdum proves an idea by showing that its denial produces contradiction [Friend] |
| 14853 | Truth finds fewest champions not when it is dangerous, but when it is boring [Nietzsche] |
| 24075 | Convictions, more than lies, are the great enemy of truth [Nietzsche] |
| 8705 | Anti-realists see truth as our servant, and epistemically contrained [Friend] |
| 8713 | In classical/realist logic the connectives are defined by truth-tables [Friend] |
| 8708 | Double negation elimination is not valid in intuitionist logic [Friend] |
| 8694 | Free logic was developed for fictional or non-existent objects [Friend] |
| 8665 | A 'proper subset' of A contains only members of A, but not all of them [Friend] |
| 8672 | A 'powerset' is all the subsets of a set [Friend] |
| 8677 | Set theory makes a minimum ontological claim, that the empty set exists [Friend] |
| 8666 | Infinite sets correspond one-to-one with a subset [Friend] |
| 8682 | Major set theories differ in their axioms, and also over the additional axioms of choice and infinity [Friend] |
| 8709 | The law of excluded middle is syntactic; it just says A or not-A, not whether they are true or false [Friend] |
| 8711 | Intuitionists read the universal quantifier as "we have a procedure for checking every..." [Friend] |
| 8675 | Paradoxes can be solved by talking more loosely of 'classes' instead of 'sets' [Friend] |
| 8674 | The Burali-Forti paradox asks whether the set of all ordinals is itself an ordinal [Friend] |
| 8667 | The 'integers' are the positive and negative natural numbers, plus zero [Friend] |
| 8668 | The 'rational' numbers are those representable as fractions [Friend] |
| 8670 | A number is 'irrational' if it cannot be represented as a fraction [Friend] |
| 8661 | The natural numbers are primitive, and the ordinals are up one level of abstraction [Friend] |
| 8664 | Cardinal numbers answer 'how many?', with the order being irrelevant [Friend] |
| 8671 | The 'real' numbers (rationals and irrationals combined) is the Continuum, which has no gaps [Friend] |
| 8663 | Raising omega to successive powers of omega reveal an infinity of infinities [Friend] |
| 8662 | The first limit ordinal is omega (greater, but without predecessor), and the second is twice-omega [Friend] |
| 8669 | Between any two rational numbers there is an infinite number of rational numbers [Friend] |
| 8676 | Is mathematics based on sets, types, categories, models or topology? [Friend] |
| 8678 | Most mathematical theories can be translated into the language of set theory [Friend] |
| 8701 | The number 8 in isolation from the other numbers is of no interest [Friend] |
| 8702 | In structuralism the number 8 is not quite the same in different structures, only equivalent [Friend] |
| 8699 | Are structures 'ante rem' (before reality), or are they 'in re' (grounded in physics)? [Friend] |
| 8696 | Structuralist says maths concerns concepts about base objects, not base objects themselves [Friend] |
| 8695 | Structuralism focuses on relations, predicates and functions, with objects being inessential [Friend] |
| 8700 | 'In re' structuralism says that the process of abstraction is pattern-spotting [Friend] |
| 8681 | The big problem for platonists is epistemic: how do we perceive, intuit, know or detect mathematical facts? [Friend] |
| 8712 | Mathematics should be treated as true whenever it is indispensable to our best physical theory [Friend] |
| 8716 | Formalism is unconstrained, so cannot indicate importance, or directions for research [Friend] |
| 8706 | Constructivism rejects too much mathematics [Friend] |
| 8707 | Intuitionists typically retain bivalence but reject the law of excluded middle [Friend] |
| 8704 | Structuralists call a mathematical 'object' simply a 'place in a structure' [Friend] |
| 13768 | Validity can preserve certainty in mathematics, but conditionals about contingents are another matter [Edgington] |
| 13770 | There are many different conditional mental states, and different conditional speech acts [Edgington] |
| 13764 | Are conditionals truth-functional - do the truth values of A and B determine the truth value of 'If A, B'? [Edgington] |
| 13765 | 'If A,B' must entail ¬(A & ¬B); otherwise we could have A true, B false, and If A,B true, invalidating modus ponens [Edgington] |
| 14858 | Being certain presumes that there are absolute truths, and means of arriving at them [Nietzsche] |
| 14830 | Intuition only recognises what is possible, not what exists or is certain [Nietzsche] |
| 20378 | Just as skin hides the horrors of the body, vanity conceals the passions of the soul [Nietzsche] |
| 8685 | Studying biology presumes the laws of chemistry, and it could never contradict them [Friend] |
| 8688 | Concepts can be presented extensionally (as objects) or intensionally (as a characterization) [Friend] |
| 14820 | People always do what they think is right, according to the degree of their intellect [Nietzsche] |
| 14856 | Our judgment seems to cause our nature, but actually judgment arises from our nature [Nietzsche] |
| 14842 | Why are the strong tastes of other people so contagious? [Nietzsche] |
| 14835 | Artists are not especially passionate, but they pretend to be [Nietzsche] |
| 22473 | Nietzsche said the will doesn't exist, so it can't ground moral responsibility [Nietzsche, by Foot] |
| 14807 | The history of morality rests on an error called 'responsibility', which rests on an error called 'free will' [Nietzsche] |
| 14823 | Ceasing to believe in human responsibility is bitter, if you had based the nobility of humanity on it [Nietzsche] |
| 14824 | It is absurd to blame nature and necessity; we should no more praise actions than we praise plants or artworks [Nietzsche] |
| 14812 | Intellect is tied to morality, because it requires good memory and powerful imagination [Nietzsche] |
| 14810 | Originally it was the rulers who requited good for good and evil for evil who were called 'good' [Nietzsche] |
| 14831 | No one has ever done anything that was entirely for other people [Nietzsche] |
| 14855 | Simultaneous love and respect are impossible; love has no separation or rank, but respect admits power [Nietzsche] |
| 14815 | We get enormous pleasure from tales of noble actions [Nietzsche] |
| 14849 | We can only achieve happy moments, not happy eras [Nietzsche] |
| 14818 | First morality is force, then custom, then acceptance, then instinct, then a pleasure - and finally 'virtue' [Nietzsche] |
| 20103 | You are mastered by your own virtues, but you must master them, and turn them into tools [Nietzsche] |
| 14817 | The 'good' man does the moral thing as if by nature, easily and gladly, after a long inheritance [Nietzsche] |
| 14809 | All societies of good men give a priority to gratitude [Nietzsche] |
| 14816 | Justice (fairness) originates among roughly equal powers (as the Melian dialogues show) [Nietzsche] |
| 14821 | Apart from philosophers, most people rightly have a low estimate of pity [Nietzsche] |
| 20112 | Pity consoles those who suffer, because they see that they still have the power to hurt [Nietzsche] |
| 14841 | Many people are better at having good friends than being a good friend [Nietzsche] |
| 14843 | Women can be friends with men, but only some physical antipathy will maintain it [Nietzsche] |
| 14811 | In Homer it is the contemptible person, not the harmful person, who is bad [Nietzsche] |
| 20111 | We could live more naturally, relishing the spectacle, and not thinking we are special [Nietzsche] |
| 14844 | People do not experience boredom if they have never learned to work properly [Nietzsche] |
| 14808 | Over huge periods of time human character would change endlessly [Nietzsche] |
| 14822 | If self-defence is moral, then so are most expressions of 'immoral' egoism [Nietzsche] |
| 14838 | The state aims to protect individuals from one another [Nietzsche] |
| 14852 | Culture cannot do without passions and vices [Nietzsche] |
| 14846 | If we want the good life for the greatest number, we must let them decide on the good life [Nietzsche] |
| 14819 | Slavery cannot be judged by our standards, because the sense of justice was then less developed [Nietzsche] |
| 14847 | Laws that are well thought out, or laws that are easy to understand? [Nietzsche] |
| 14814 | Execution is worse than murder, because we are using the victim, and really we are the guilty [Nietzsche] |
| 14836 | People will enthusiastically pursue an unwanted war, once sacrifices have been made [Nietzsche] |
| 14845 | Don't crush girls with dull Gymnasium education, the way we have crushed boys! [Nietzsche] |
| 14848 | Education in large states is mediocre, like cooking in large kitchens [Nietzsche] |
| 14839 | Interest in education gains strength when we lose interest in God [Nietzsche] |
| 14834 | Teachers only gather knowledge for their pupils, and can't be serious about themselves [Nietzsche] |
| 14825 | In religious thought nature is a complex of arbitrary acts by conscious beings [Nietzsche] |
| 14826 | Modern man wants laws of nature in order to submit to them [Nietzsche] |
| 14827 | The Greeks saw the gods not as their masters, but as idealised versions of themselves [Nietzsche] |
| 14813 | Science rejecting the teaching of Christianity in favour of Epicurus shows the superiority of the latter [Nietzsche] |
| 14832 | The Sermon on the Mount is vanity - praying to one part of oneself, and demonising the rest [Nietzsche] |
| 14850 | Christ was the noblest human being [Nietzsche] |
| 14837 | Christ seems warm hearted, and suppressed intellect in favour of the intellectually weak [Nietzsche] |
| 14828 | Religion is tempting if your life is boring, but you can't therefore impose it on the busy people [Nietzsche] |