63 ideas
| 20678 | The Scientific Revolution was the discovery of our own ignorance [Harari] |
| 20686 | For millenia people didn't know how to convert one type of energy into another [Harari] |
| 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] |
| 21982 | I only wish I had such eyes as to see Nobody! It's as much as I can do to see real people. [Carroll,L] |
| 20692 | Money does produce happiness, but only up to a point [Harari] |
| 20663 | If a group is bound by gossip, the natural size is 150 people [Harari] |
| 20677 | Since 1500 human population has increased fourteenfold, and consumption far more [Harari] |
| 20688 | People 300m tons; domesticated animals 700m tons; larger wild animals 100m tons [Harari] |
| 20674 | The Nazi aim was to encourage progressive evolution, and avoid degeneration [Harari] |
| 20679 | We stabilise societies with dogmas, either of dubious science, or of non-scientific values [Harari] |
| 20690 | The state fostered individualism, to break the power of family and community [Harari] |
| 20689 | In 1750 losing your family and community meant death [Harari] |
| 20681 | The sacred command of capitalism is that profits must be used to increase production [Harari] |
| 20682 | The main rule of capitalism is that all other goods depend on economic growth [Harari] |
| 20683 | The progress of capitalism depends entirely on the new discoveries and gadgets of science [Harari] |
| 20687 | In capitalism the rich invest, and the rest of us go shopping [Harari] |
| 20685 | No market is free of political bias, and markets need protection of their freedoms [Harari] |
| 20693 | Freedom may work against us, as individuals can choose to leave, and make fewer commitments [Harari] |
| 20691 | Real peace is the implausibility of war (and not just its absence) [Harari] |
| 20684 | Financing is increasingly through credit rather than taxes; people prefer investing to taxation [Harari] |
| 20675 | The more you know about history, the harder it becomes to explain [Harari] |
| 20676 | History teaches us that the present was not inevitable, and shows us the possibilities [Harari] |
| 20671 | In order to explain both order and evil, a single evil creator is best, but no one favours that [Harari] |
| 20664 | Animism is belief that every part of nature is aware and feeling, and can communicate [Harari] |
| 20666 | Most polytheist recognise one supreme power or law, behind the various gods [Harari] |
| 20667 | Polytheism is open-minded, and rarely persecutes opponents [Harari] |
| 20665 | Mythologies are usual contracts with the gods, exchanging devotion for control of nature [Harari] |
| 20669 | Dualist religions see everything as a battleground of good and evil forces [Harari] |
| 20670 | Dualist religions say the cosmos is a battleground, so can’t explain its order [Harari] |
| 20673 | Manichaeans and Gnostics: good made spirit, evil made flesh [Harari] |
| 20668 | Monotheism appeared in Egypt in 1350 BCE, when the god Aten was declared supreme [Harari] |