34 ideas
| 7990 | Serene wisdom is freedom from ties, and indifference to fortune [Anon (Bhag)] |
| Full Idea: Who everywhere is free from all ties, who neither rejoices nor sorrows if fortune is good or is ill, his is a serene wisdom. | |
| From: Anon (Bhag) (The Bhagavad Gita [c.500 BCE], 2.57) | |
| A reaction: This is very similar to the 'apatheia' of the Stoics, though they are always more committed to rationality. This is quite a good strategy when times are hard, but as a general rule it offers a bogus state of 'wisdom' which is really half way to death. |
| 7989 | Seek salvation in the wisdom of reason [Anon (Bhag)] |
| Full Idea: Seek salvation in the wisdom of reason. | |
| From: Anon (Bhag) (The Bhagavad Gita [c.500 BCE], 2.49) | |
| A reaction: Quotations like this can usually be counterbalanced in eastern philosophy by wild irrationality, but they certainly felt to tug of reason. Only the Dhaoists seem really opposed to reason (e.g. Idea 7289). |
| 15924 | Predicative definitions are acceptable in mathematics if they distinguish objects, rather than creating them? [Zermelo, by Lavine] |
| Full Idea: On Zermelo's view, predicative definitions are not only indispensable to mathematics, but they are unobjectionable since they do not create the objects they define, but merely distinguish them from other objects. | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Shaughan Lavine - Understanding the Infinite V.1 | |
| A reaction: This seems to have an underlying platonism, that there are hitherto undefined 'objects' lying around awaiting the honour of being defined. Hm. |
| 17608 | We take set theory as given, and retain everything valuable, while avoiding contradictions [Zermelo] |
| Full Idea: Starting from set theory as it is historically given ...we must, on the one hand, restrict these principles sufficiently to exclude as contradiction and, on the other, take them sufficiently wide to retain all that is valuable in this theory. | |
| From: Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908], Intro) | |
| A reaction: Maddy calls this the one-step-back-from-disaster rule of thumb. Zermelo explicitly mentions the 'Russell antinomy' that blocked Frege's approach to sets. |
| 17607 | Set theory investigates number, order and function, showing logical foundations for mathematics [Zermelo] |
| Full Idea: Set theory is that branch whose task is to investigate mathematically the fundamental notions 'number', 'order', and 'function', taking them in their pristine, simple form, and to develop thereby the logical foundations of all of arithmetic and analysis. | |
| From: Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908], Intro) | |
| A reaction: At this point Zermelo seems to be a logicist. Right from the start set theory was meant to be foundational to mathematics, and not just a study of the logic of collections. |
| 10870 | ZFC: Existence, Extension, Specification, Pairing, Unions, Powers, Infinity, Choice [Zermelo, by Clegg] |
| Full Idea: Zermelo-Fraenkel axioms: Existence (at least one set); Extension (same elements, same set); Specification (a condition creates a new set); Pairing (two sets make a set); Unions; Powers (all subsets make a set); Infinity (set of successors); Choice | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Brian Clegg - Infinity: Quest to Think the Unthinkable Ch.15 |
| 13012 | Zermelo published his axioms in 1908, to secure a controversial proof [Zermelo, by Maddy] |
| Full Idea: Zermelo proposed his listed of assumptions (including the controversial Axiom of Choice) in 1908, in order to secure his controversial proof of Cantor's claim that ' we can always bring any well-defined set into the form of a well-ordered set'. | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Penelope Maddy - Believing the Axioms I §1 | |
| A reaction: This is interesting because it sometimes looks as if axiom systems are just a way of tidying things up. Presumably it is essential to get people to accept the axioms in their own right, the 'old-fashioned' approach that they be self-evident. |
| 17609 | Set theory can be reduced to a few definitions and seven independent axioms [Zermelo] |
| Full Idea: I intend to show how the entire theory created by Cantor and Dedekind can be reduced to a few definitions and seven principles, or axioms, which appear to be mutually independent. | |
| From: Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908], Intro) | |
| A reaction: The number of axioms crept up to nine or ten in subsequent years. The point of axioms is maximum reduction and independence from one another. He says nothing about self-evidence (though Boolos claimed a degree of that). |
| 13017 | Zermelo introduced Pairing in 1930, and it seems fairly obvious [Zermelo, by Maddy] |
| Full Idea: Zermelo's Pairing Axiom superseded (in 1930) his original 1908 Axiom of Elementary Sets. Like Union, its only justification seems to rest on 'limitations of size' and on the 'iterative conception'. | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Penelope Maddy - Believing the Axioms I §1.3 | |
| A reaction: Maddy says of this and Union, that they seem fairly obvious, but that their justification is of prime importance, if we are to understand what the axioms should be. |
| 13015 | Zermelo used Foundation to block paradox, but then decided that only Separation was needed [Zermelo, by Maddy] |
| Full Idea: Zermelo used a weak form of the Axiom of Foundation to block Russell's paradox in 1906, but in 1908 felt that the form of his Separation Axiom was enough by itself, and left the earlier axiom off his published list. | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Penelope Maddy - Believing the Axioms I §1.2 | |
| A reaction: Foundation turns out to be fairly controversial. Barwise actually proposes Anti-Foundation as an axiom. Foundation seems to be the rock upon which the iterative view of sets is built. Foundation blocks infinite descending chains of sets, and circularity. |
| 13486 | Not every predicate has an extension, but Separation picks the members that satisfy a predicate [Zermelo, by Hart,WD] |
| Full Idea: Zermelo assumes that not every predicate has an extension but rather that given a set we may separate out from it those of its members satisfying the predicate. This is called 'separation' (Aussonderung). | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by William D. Hart - The Evolution of Logic 3 |
| 13020 | The Axiom of Separation requires set generation up to one step back from contradiction [Zermelo, by Maddy] |
| Full Idea: The most characteristic Zermelo axiom is Separation, guided by a new rule of thumb: 'one step back from disaster' - principles of set generation should be as strong as possible short of contradiction. | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Penelope Maddy - Believing the Axioms I §1.4 | |
| A reaction: Why is there an underlying assumption that we must have as many sets as possible? We are then tempted to abolish axioms like Foundation, so that we can have even more sets! |
| 13487 | In ZF, the Burali-Forti Paradox proves that there is no set of all ordinals [Zermelo, by Hart,WD] |
| Full Idea: In Zermelo's set theory, the Burali-Forti Paradox becomes a proof that there is no set of all ordinals (so 'is an ordinal' has no extension). | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by William D. Hart - The Evolution of Logic 3 |
| 18178 | For Zermelo the successor of n is {n} (rather than n U {n}) [Zermelo, by Maddy] |
| Full Idea: For Zermelo the successor of n is {n} (rather than Von Neumann's successor, which is n U {n}). | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Penelope Maddy - Naturalism in Mathematics I.2 n8 | |
| A reaction: I could ask some naive questions about the comparison of these two, but I am too shy about revealing my ignorance. |
| 13027 | Zermelo believed, and Von Neumann seemed to confirm, that numbers are sets [Zermelo, by Maddy] |
| Full Idea: Zermelo was a reductionist, and believed that theorems purportedly about numbers (cardinal or ordinal) are really about sets, and since Von Neumann's definitions of ordinals and cardinals as sets, this has become common doctrine. | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Penelope Maddy - Believing the Axioms I §1.8 | |
| A reaction: Frege has a more sophisticated take on this approach. It may just be an updating of the Greek idea that arithmetic is about treating many things as a unit. A set bestows an identity on a group, and that is all that is needed. |
| 9627 | Different versions of set theory result in different underlying structures for numbers [Zermelo, by Brown,JR] |
| Full Idea: In Zermelo's set-theoretic definition of number, 2 is a member of 3, but not a member of 4; in Von Neumann's definition every number is a member of every larger number. This means they have two different structures. | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by James Robert Brown - Philosophy of Mathematics Ch. 4 | |
| A reaction: This refers back to the dilemma highlighted by Benacerraf, which was supposed to be the motivation for structuralism. My intuition says that the best answer is that they are both wrong. In a pattern, the nodes aren't 'members' of one another. |
| 7996 | I am all the beauty and goodness of things, says Krishna [Anon (Bhag)] |
| Full Idea: I am the beauty of all things beautiful; ...I am the goodness of those who are good, says Krishna. | |
| From: Anon (Bhag) (The Bhagavad Gita [c.500 BCE], 10.36) | |
| A reaction: Another attempt to annexe everything which is admirable to the nature of God. This sounds strikingly Platonic (c.f. Idea 7992, which seems Aristotelian). One scholar dates the text to 150 BCE. I think there is influence, one way or the other. |
| 8915 | How we refer to abstractions is much less clear than how we refer to other things [Rosen] |
| Full Idea: It is unclear how we manage to refer determinately to abstract entities in a sense in which it is not unclear how we manage to refer determinately to other things. | |
| From: Gideon Rosen (Abstract Objects [2001], 'Way of Ex') | |
| A reaction: This is where problems of abstraction overlap with problems about reference in language. Can we have a 'baptism' account of each abstraction (even very large numbers)? Will descriptions do it? Do abstractions collapse into particulars when we refer? |
| 7995 | In all living beings I am the light of consciousness, says Krishna [Anon (Bhag)] |
| Full Idea: In all living beings I am the light of consciousness, says Krishna. | |
| From: Anon (Bhag) (The Bhagavad Gita [c.500 BCE], 10.22) | |
| A reaction: Everything grand seems to be claimed for God at this stage of culture, but I am not sure how coherent this view is, unless this is pantheism. In what sense could we possibly be Krishna, when none of us (except Arjuna) is aware of it? |
| 8917 | The Way of Abstraction used to say an abstraction is an idea that was formed by abstracting [Rosen] |
| Full Idea: The simplest version of the Way of Abstraction would be to say that an object is abstract if it is a referent of an idea that was formed by abstraction, but this is wedded to an outmoded philosophy of mind. | |
| From: Gideon Rosen (Abstract Objects [2001], 'Way of Abs') | |
| A reaction: This presumably refers to Locke, who wields the highly ambiguous term 'idea'. But if we sort out that ambiguity (by using modern talk of mental events, concepts and content?) we might reclaim the view. But do we have a 'genetic fallacy' here? |
| 8912 | Nowadays abstractions are defined as non-spatial, causally inert things [Rosen] |
| Full Idea: If any characterization of the abstract deserves to be regarded as the modern standard one, it is this: an abstract entity is a non-spatial (or non-spatiotemporal) causally inert thing. This view presents a number of perplexities... | |
| From: Gideon Rosen (Abstract Objects [2001], 'Non-spat') | |
| A reaction: As indicated in other ideas, the problem is that some abstractions do seem to be located somewhere in space-time, and to have come into existence, and to pass away. I like 'to exist is to have causal powers'. See Ideas 5992 and 8300. |
| 8913 | Chess may be abstract, but it has existed in specific space and time [Rosen] |
| Full Idea: The natural view of chess is not that it is a non-spatiotemporal mathematical object, but that it was invented at a certain time and place, that it has changed over the years, and so on. | |
| From: Gideon Rosen (Abstract Objects [2001], 'Non-spat') | |
| A reaction: This strikes me as being undeniable, and being an incredibly important point. Logicians seem to want to subsume things like games into the highly abstract world of logic and numbers. In fact the direction of explanation should be reversed. |
| 8914 | Sets are said to be abstract and non-spatial, but a set of books can be on a shelf [Rosen] |
| Full Idea: It is thought that sets are abstract, abstract objects do not exist in space, so sets must not exist in space. But it is not unnatural to say that a set of books is located on a certain shelf in the library. | |
| From: Gideon Rosen (Abstract Objects [2001], 'Non-spat') | |
| A reaction: The arguments against non-spatiality of abstractions seem to me to be conclusive. Not being able to assign a location to the cosine function is on a par with not knowing where my thoughts are located in my brain. |
| 8916 | Conflating abstractions with either sets or universals is a big claim, needing a big defence [Rosen] |
| Full Idea: The Way of Conflation account of abstractions (identifying them sets or with universals) is now relatively rare. The claim sets or universals are the only abstract objects would amount to a substantive metaphysical thesis, in need of defence. | |
| From: Gideon Rosen (Abstract Objects [2001], 'Way of Con') | |
| A reaction: If you produce a concept like 'mammal' by psychological abstraction, you do seem to end up with a set of things with shared properties, so this approach is not silly. I can't think of any examples of abstractions which are not sets or universals. |
| 8918 | Functional terms can pick out abstractions by asserting an equivalence relation [Rosen] |
| Full Idea: On Frege's suggestion, functional terms that pick out abstract expressions (such as 'direction' or 'equinumeral') have a typical form of f(a) = f(b) iff aRb, where R is an equivalence relation, a relation which is reflexive, symmetric and transitive. | |
| From: Gideon Rosen (Abstract Objects [2001], 'Way of Abs') | |
| A reaction: [Wright and Hale are credited with the details] This has become the modern orthodoxy among the logically-minded. Examples of R are 'parallel' or 'just as many as'. It picks out an 'aspect', which isn't far from the old view. |
| 8919 | Abstraction by equivalence relationships might prove that a train is an abstract entity [Rosen] |
| Full Idea: It seems possible to define a train in terms of its carriages and the connection relationship, which would meet the equivalence account of abstraction, but demonstrate that trains are actually abstract. | |
| From: Gideon Rosen (Abstract Objects [2001], 'Way of Abs') | |
| A reaction: [Compressed. See article for more detail] A tricky example, but a suggestive line of criticism. If you find two physical objects which relate to one another reflexively, symmetrically and transitively, they may turn out to be abstract. |
| 7999 | All actions come from: body, lower self, perception, means of action, or Fate [Anon (Bhag)] |
| Full Idea: Whatever a man does, good or bad, in thought, word or deed, has these five sources of action: the body, the lower 'I am', the means of perception, the means of action, and Fate. | |
| From: Anon (Bhag) (The Bhagavad Gita [c.500 BCE], 18.14/15) | |
| A reaction: The 'means of action' will presumably take care of anything we haven't thought of! Nothing quite matches the idea of 'the will' here. A twitch from the first, eating from the second, a startled jump from the third, struck by lightning from the fifth. |
| 7991 | Hate and lust have their roots in man's lower nature [Anon (Bhag)] |
| Full Idea: Hate and lust for things of nature have their roots in man's lower nature. | |
| From: Anon (Bhag) (The Bhagavad Gita [c.500 BCE], 3.34) | |
| A reaction: It seems outmoded now (since Freud) to label parts of human nature as 'higher' and 'lower'. I would defend the distinction, but it is not self-evident. The basis of morality is good citizenship, and parts of our nature are detrimental to that. |
| 7988 | There is no greater good for a warrior than to fight in a just war [Anon (Bhag)] |
| Full Idea: There is no greater good for a warrior than to fight in righteous war. | |
| From: Anon (Bhag) (The Bhagavad Gita [c.500 BCE], 2.31) | |
| A reaction: What worries me now is not the urging to fight, as long as a good cause can be found, but the idea that someone should see his social role as 'warrior'. The modern 'soldier' is ready to fight, but a traditional 'warrior' is obliged to fight. |
| 7992 | The visible forms of nature are earth, water, fire, air, ether; mind, reason, and the sense of 'I' [Anon (Bhag)] |
| Full Idea: The visible forms of nature are eight: earth, water, fire, air, ether; the mind, reason, and the sense of 'I'. | |
| From: Anon (Bhag) (The Bhagavad Gita [c.500 BCE], 7.4) | |
| A reaction: Presumably there is an implication that there are also invisible forms. The Bhuddists launched an attack on 'I' as one of the categories. The first five appear to be Aristotle's, which must be of scholarly (and chronological) interest. |
| 7994 | Everything, including the gods, comes from me, says Krishna [Anon (Bhag)] |
| Full Idea: All the gods come from me, says Krishna. ...I am the one source of all | |
| From: Anon (Bhag) (The Bhagavad Gita [c.500 BCE], 10.2/8) | |
| A reaction: This seems very close to monotheism, and sounds very similar to the position that Zeus seems to occupy in later Greek religion, where he is shading off into a supreme and spiritual entity. |
| 7993 | Brahman is supreme, Atman his spirit in man, and Karma is the force of creation [Anon (Bhag)] |
| Full Idea: Brahman is supreme, the Eternal. Atman is his Spirit in man. Karma is the force of creation, wherefrom all things have their life. | |
| From: Anon (Bhag) (The Bhagavad Gita [c.500 BCE], 8.3) | |
| A reaction: I can't help wondering how they know all this stuff, but then I'm just a typical product of my culture. We seem to have a trinity here. Who's in charge? Is Atman just a servant? Is Karma totally under the control of Brahman? |
| 7997 | Only by love can men see me, know me, and come to me, says Krishna [Anon (Bhag)] |
| Full Idea: Only by love can men see me, and know me, and come unto me, says Krishna | |
| From: Anon (Bhag) (The Bhagavad Gita [c.500 BCE], 11.54) | |
| A reaction: There seems to be a paradox here, as it is unclear how you can love Krishna, if you have not already seen him in some way. This is another paradox of fideism - that faith cannot possibly be the first step in a religion, as faith needs a target. |
| 7998 | The three gates of hell are lust, anger and greed [Anon (Bhag)] |
| Full Idea: Three are the gates of this hell, the death of the soul: the gate of lust, the gate of wrath, and the gate of greed. Let a man shun the three. | |
| From: Anon (Bhag) (The Bhagavad Gita [c.500 BCE], 16.21) | |
| A reaction: Anyone who wishes to procreate, champion justice, and make a living, has to pursue all three. Wisdom consists of pursuing the three appropriately, not in shunning them. How did this bizarre puritanism ever come to grip the human race? |