40 ideas
| 14240 | The empty set is something, not nothing! [Oliver/Smiley] |
| Full Idea: Some authors need to be told loud and clear: if there is an empty set, it is something, not nothing. | |
| From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 1.2) | |
| A reaction: I'm inclined to think of a null set as a pair of brackets, so maybe that puts it into a metalanguage. |
| 14241 | We don't need the empty set to express non-existence, as there are other ways to do that [Oliver/Smiley] |
| Full Idea: The empty set is said to be useful to express non-existence, but saying 'there are no Us', or ¬∃xUx are no less concise, and certainly less roundabout. | |
| From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 1.2) |
| 14239 | The empty set is usually derived from Separation, but it also seems to need Infinity [Oliver/Smiley] |
| Full Idea: The empty set is usually derived via Zermelo's axiom of separation. But the axiom of separation is conditional: it requires the existence of a set in order to generate others as subsets of it. The original set has to come from the axiom of infinity. | |
| From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 1.2) | |
| A reaction: They charge that this leads to circularity, as Infinity depends on the empty set. |
| 14242 | Maybe we can treat the empty set symbol as just meaning an empty term [Oliver/Smiley] |
| Full Idea: Suppose we introduce Ω not as a term standing for a supposed empty set, but as a paradigm of an empty term, not standing for anything. | |
| From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 1.2) | |
| A reaction: This proposal, which they go on to explore, seems to mean that Ω (i.e. the traditional empty set symbol) is no longer part of set theory but is part of semantics. |
| 14243 | The unit set may be needed to express intersections that leave a single member [Oliver/Smiley] |
| Full Idea: Thomason says with no unit sets we couldn't call {1,2}∩{2,3} a set - but so what? Why shouldn't the intersection be the number 2? However, we then have to distinguish three different cases of intersection (common subset or member, or disjoint). | |
| From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 2.2) |
| 14234 | If you only refer to objects one at a time, you need sets in order to refer to a plurality [Oliver/Smiley] |
| Full Idea: A 'singularist', who refers to objects one at a time, must resort to the language of sets in order to replace plural reference to members ('Henry VIII's wives') by singular reference to a set ('the set of Henry VIII's wives'). | |
| From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], Intro) | |
| A reaction: A simple and illuminating point about the motivation for plural reference. Null sets and singletons give me the creeps, so I would personally prefer to avoid set theory when dealing with ontology. |
| 14237 | We can use plural language to refer to the set theory domain, to avoid calling it a 'set' [Oliver/Smiley] |
| Full Idea: Plurals earn their keep in set theory, to answer Skolem's remark that 'in order to treat of 'sets', we must begin with 'domains' that are constituted in a certain way'. We can speak in the plural of 'the objects', not a 'domain' of objects. | |
| From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], Intro) | |
| A reaction: [Skolem 1922:291 in van Heijenoort] Zermelo has said that the domain cannot be a set, because every set belongs to it. |
| 14245 | Logical truths are true no matter what exists - but predicate calculus insists that something exists [Oliver/Smiley] |
| Full Idea: Logical truths should be true no matter what exists, so true even if nothing exists. The classical predicate calculus, however, makes it logically true that something exists. | |
| From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 5.1) |
| 14246 | If mathematics purely concerned mathematical objects, there would be no applied mathematics [Oliver/Smiley] |
| Full Idea: If mathematics was purely concerned with mathematical objects, there would be no room for applied mathematics. | |
| From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 5.1) | |
| A reaction: Love it! Of course, they are using 'objects' in the rather Fregean sense of genuine abstract entities. I don't see why fictionalism shouldn't allow maths to be wholly 'pure', although we have invented fictions which actually have application. |
| 21382 | Things get smaller without end [Anaxagoras] |
| Full Idea: Of the small there is no smallest, but always a smaller. | |
| From: Anaxagoras (fragments/reports [c.460 BCE], B03), quoted by Gregory Vlastos - The Physical Theory of Anaxagoras II | |
| A reaction: Anaxagoras seems to be speaking of the physical world (and probably writing prior to the emergence of atomism, which could have been a rebellion against he current idea). |
| 14247 | Sets might either represent the numbers, or be the numbers, or replace the numbers [Oliver/Smiley] |
| Full Idea: Identifying numbers with sets may mean one of three quite different things: 1) the sets represent the numbers, or ii) they are the numbers, or iii) they replace the numbers. | |
| From: Oliver,A/Smiley,T (What are Sets and What are they For? [2006], 5.2) | |
| A reaction: Option one sounds the most plausible to me. I will take numbers to be patterns embedded in nature, and sets are one way of presenting them in shorthand form, in order to bring out what is repeated. |
| 481 | Nothing is created or destroyed; there is only mixing and separation [Anaxagoras] |
| Full Idea: No thing comes into being or passes away, but it is mixed together or separated from existing things. Thus it would be correct if coming into being was called 'mixing', and passing away 'separation-off''. | |
| From: Anaxagoras (fragments/reports [c.460 BCE], B17), quoted by Simplicius - On Aristotle's 'Physics' 163.20 | |
| A reaction: I take this to be the first axiom of the new subject of chemistry. Our world is just patterns of Being. The bigger puzzle is - why those patterns? |
| 21822 | Anaxagoras's concept of supreme Mind has a simple First and a multiple One [Anaxagoras, by Plotinus] |
| Full Idea: Anaxagoras, in his assertion of a Mind pure and unmixed, affirms a simplex First and a sundered One, though writing long ago he failed in precision. | |
| From: report of Anaxagoras (fragments/reports [c.460 BCE]) by Plotinus - The Enneads 5.1.09 | |
| A reaction: The crunch question is whether the supreme One or Mind is part of Being, or is above and beyond Being. Plotinus claims that Anaxagoras was on his side (with Plato, against Parmenides). |
| 17995 | Basic is the potentially perceptible, then comes the contrary qualities, and finally the 'elements' [Anaxagoras] |
| Full Idea: We must recognise three 'originative sources': first that which is potentially perceptible body, secondly the contrarities (e.g hot and cold), and thirdly Fire, Water, and the like. Only thirdly, however, for these bodies change into one another. | |
| From: Anaxagoras (fragments/reports [c.460 BCE]), quoted by Aristotle - The History of Animals 529a34 | |
| A reaction: The 'potentially perceptible' seems to be matter. The surprise here is that the contraries are more basic than the elements, rather than being properties of them. Reality is modes of matter, it seems. |
| 20802 | Snow is not white, and doesn't even appear white, because it is made of black water [Anaxagoras, by Cicero] |
| Full Idea: Anaxagoras not only denied that snow was white, but because he knew that the water from which it was composed was black, even denied that it appeared white to himself. | |
| From: report of Anaxagoras (fragments/reports [c.460 BCE]) by M. Tullius Cicero - Academica II.100 | |
| A reaction: Not ridiculous. Can you deny that red and yellow balls look orange from a distance? A failure of discrimination on your part. It sounds okay to say 'what I am really perceiving is red and yellow'. [see 'Anaxagoras' poem by D.H.Lawrence!] |
| 13257 | The senses are too feeble to determine the truth [Anaxagoras] |
| Full Idea: Owing to the feebleness of the sense, we are not able to determine the truth. | |
| From: Anaxagoras (fragments/reports [c.460 BCE], B21), quoted by Patricia Curd - Anaxagoras 5.1 | |
| A reaction: Anaxagoras offers a corresponding elevation of the power of mind (Idea 13256), so I now realise that he is, along with Pythagoras and Parmenides, one of the fathers of rationalism in philosophy. They probably overrate reason. |
| 22761 | We reveal unreliability in the senses when we cannot discriminate a slow change of colour [Anaxagoras, by Sext.Empiricus] |
| Full Idea: Our lack of sureness in the senses is shown if we take two colours, back and white, and pour one into the other drop by drop, we are unable to distinguish the gradual alterations although they subsist as actual facts. | |
| From: report of Anaxagoras (fragments/reports [c.460 BCE]) by Sextus Empiricus - Against the Logicians (two books) I.090 | |
| A reaction: [Sextus calls Anaxagoras 'the greatest of the physicists'] I'm not sure what this proves. People with bad eyesight can distinguish very little, but that doesn't prove scepticism. And there are things too small for anyone to see. |
| 13256 | Nous is unlimited, self-ruling and pure; it is the finest thing, with great discernment and strength [Anaxagoras] |
| Full Idea: Nous is unlimited and self-ruling and has been mixed with no thing, but is alone itself by itself. ...For it is the finest of all things and the purest, and indeed it maintains all discernment about everything and has the greatest strength. | |
| From: Anaxagoras (fragments/reports [c.460 BCE], B12), quoted by Patricia Curd - Anaxagoras 3.3 | |
| A reaction: Anaxagoras seems to have been a pioneer in elevating the status of the mind, which is a prop to the rationalist view, and encourages dualism. More naturalistic accounts are, in my view, much healthier. |
| 13784 | Mind is self-ruling, pure, ordering and ubiquitous [Anaxagoras, by Plato] |
| Full Idea: Anaxagoras says that mind is self-ruling, mixes with nothing else, orders the things that are, and travels through everything. | |
| From: report of Anaxagoras (fragments/reports [c.460 BCE]) by Plato - Cratylus 413c | |
| A reaction: This elevation of the mind in the natural scheme of things by Anaxagoras looks increasingly significant in western culture to me. Without this line of thought, Descartes and Kant are inconceivable. |
| 5118 | Anaxagoras says mind remains pure, and so is not affected by what it changes [Anaxagoras, by Aristotle] |
| Full Idea: Anaxagoras says that intellect (which is a cause of change) is not affected by or mixed in with anything else; for this is the only way in which it can cause change, while being itself changeless, and control things without mixing with them. | |
| From: report of Anaxagoras (fragments/reports [c.460 BCE]) by Aristotle - Physics 256b24 | |
| A reaction: I suggest that this is the germ of the original concept of freewill - of the mind as somehow outside the causal processes of the world, so that it can initiate change without itself being affected by other causes. Aristotle says he's right; I disagree. |
| 8122 | True works of art transmit completely new feelings [Tolstoy] |
| Full Idea: Only that is a true work of art which transmits fresh feelings not previously experienced by man. | |
| From: Leo Tolstoy (What is Art? [1898], Ch.9) | |
| A reaction: I think a great composer will probably not have any new feelings at all, but will discover new expressions which contain feelings by which even they are surprised (e.g. the Tristan chord). |
| 8121 | Art is when one man uses external signs to hand on his feelings to another man [Tolstoy] |
| Full Idea: Art is a human activity in which one man consciously by means of external signs, hands on to others feelings he has lived through, and other are infected by those feelings, and also experience them. | |
| From: Leo Tolstoy (What is Art? [1898], Ch.5) | |
| A reaction: Such definitions always work better for some art forms than for others. This may fit 'Anna Karenin' quite well, but probably not Bach's 'Art of Fugue'. Writing obscenities on someone's front door would fit this definition. |
| 8124 | The highest feelings of mankind can only be transmitted by art [Tolstoy] |
| Full Idea: The highest feelings to which mankind has attained can only be transmitted from man to man by art. | |
| From: Leo Tolstoy (What is Art? [1898], Ch.17) | |
| A reaction: We are much more nervous these days of talking about 'highest' feelings. Tolstoy obviously considers religion to be an ingredient of the highest feelings, but that prevents us from judging them purely as feelings. Music is the place to rank feelings. |
| 8123 | The purpose of art is to help mankind to evolve better, more socially beneficial feelings [Tolstoy] |
| Full Idea: The evolution of feeling proceeds by means of art - feelings less kind and less necessary for the well-being of mankind being replaced by others kinder and more needful for that end. That is the purpose of art. | |
| From: Leo Tolstoy (What is Art? [1898], Ch.16) | |
| A reaction: Underneath his superficially expressivist view of art, Tolstoy is really an old-fashioned moralist about it, like Dr Johnson. This is the moralism of the great age of the nineteenth century novel (which was, er, the greatest age of the novel!). |
| 22710 | People estimate art according to their moral values [Tolstoy] |
| Full Idea: The estimation of the value of art …depends on men's perception of the meaning of life; depends on what they hold to be the good and evil of life. | |
| From: Leo Tolstoy (What is Art? [1898]), quoted by Iris Murdoch - The Sublime and the Good p.206 | |
| A reaction: [No ref given] This is put to the test by the insightful depiction of wickedness. We condemn the wickedness and admire the insight. Every reading of a novel is a moral journey, though I'm not sure how the true psychopath reads a novel. |
| 8125 | The upper classes put beauty first, and thus freed themselves from morality [Tolstoy] |
| Full Idea: The people of the upper class, more and more frequently encountering the contradictions between beauty and goodness, put the ideal of beauty first, thus freeing themselves from the demands of morality. | |
| From: Leo Tolstoy (What is Art? [1898], Ch.17) | |
| A reaction: The rich are a great deal freer to pursue the demands of beauty than are the poor. They also have a tradition of 'immorality' (such as duels and adultery) which was in place long before they discovered art. |
| 8064 | We separate the concept of beauty from goodness, unlike the ancients [Tolstoy] |
| Full Idea: The ancients had not that conception of beauty separated from goodness which forms the basis and aim of aesthetics in our time. | |
| From: Leo Tolstoy (What is Art? [1898], Ch.3) | |
| A reaction: This is written at around the time of the Aesthetic Movement, but Tolstoy's own novels are intensely moral. This separation makes abstract painting possible. |
| 18231 | Anaxagoras said a person would choose to be born to contemplate the ordered heavens [Anaxagoras] |
| Full Idea: When Anaxagoras was asked what it was for which a person would choose to be born rather than not, he said it would be to apprehend the heavens and the order in the whole universe. | |
| From: Anaxagoras (fragments/reports [c.460 BCE], 1216), quoted by Aristotle - Eudemian Ethics 8 'Finality' | |
| A reaction: [Anaxagoras, quoted by Aristotle, quoted by Korsgaard, quoted by me, and then quoted by you, perhaps] |
| 631 | For Anaxagoras the Good Mind has no opposite, and causes all movement, for a higher reason [Anaxagoras, by Aristotle] |
| Full Idea: Anaxagoras says the good is a principle as the source of movement, in the form of Mind. However it does it for the sake of something else, which is a further factor. And he allows no opposite to the good Mind. | |
| From: report of Anaxagoras (fragments/reports [c.460 BCE]) by Aristotle - Metaphysics 1075b |
| 22727 | Mind creates the world from a mixture of pure substances [Anaxagoras, by ] |
| Full Idea: Anaxagoras assumed that Mind, which is God, is the efficient principle, and the multi-mixture of homoeomeries is the material principle. | |
| From: report of Anaxagoras (fragments/reports [c.460 BCE]) by - I.6 | |
| A reaction: The choice of homoeomeries as basic is a good one. They are much better candidates than materials which are made of parts of a quite different kind, where the parts are a better candidate than the whole. |
| 550 | Anaxagoras said that the number of principles was infinite [Anaxagoras, by Aristotle] |
| Full Idea: Anaxagoras said that the number of principles was infinite. | |
| From: report of Anaxagoras (fragments/reports [c.460 BCE]) by Aristotle - Metaphysics 984a |
| 21383 | The ultimate constituents of reality are the homoeomeries [Anaxagoras, by Vlastos] |
| Full Idea: Anaxagoras contrasts with other thinkers in the formula that his 'elements' were not the air of Anaximenes or the fire of Heraclitus or the roots of Empedocles or the atoms of Leucippus, but the infinite variety of homoiomereia. | |
| From: report of Anaxagoras (fragments/reports [c.460 BCE]) by Gregory Vlastos - The Physical Theory of Anaxagoras III | |
| A reaction: Not sure about the 'roots' of Empedocles. Anaxagoras is particularly thinking of the basic stuffs that make up the body, such as hair, bone and blood. It is plausible to reduce everything to stuffs that seem to have no further structure. |
| 13208 | Anaxagoreans regard the homoeomeries as elements, which compose earth, air, fire and water [Anaxagoras, by Aristotle] |
| Full Idea: The followers of Anaxagoras regard the 'homoeomeries' as 'simple' and elements, whilst they affirm that Earth, Fire, Water and Air are composite; for each of these is (according to them) a 'common seminary' of all the homoeomeries. | |
| From: report of Anaxagoras (fragments/reports [c.460 BCE]) by Aristotle - Coming-to-be and Passing-away (Gen/Corr) 314a28 | |
| A reaction: Compare Idea 13207. Aristotle is amused that the followers of Empedocles and of Anaxagoras have precisely opposite views on this subject. |
| 367 | Anaxagoras says mind produces order and causes everything [Anaxagoras, by Plato] |
| Full Idea: Anaxagoras asserted that it is mind that produces order and is the cause of everything. | |
| From: report of Anaxagoras (fragments/reports [c.460 BCE]) by Plato - Phaedo 097d |
| 21381 | Germs contain microscopic organs, which become visible as they grow [Anaxagoras] |
| Full Idea: In the germ there are hair, nails, arteries, sinews, bones, which are not manifest because of the smallness of their parts, but become distinct little by little as they grow. For how could hair come from not-hair, or flesh from non-flesh. | |
| From: Anaxagoras (fragments/reports [c.460 BCE], B10), quoted by Gregory Vlastos - The Physical Theory of Anaxagoras I | |
| A reaction: Compare Aristotle's apparent view that the physical world has no microscopic structure, and Democritus's view that hair can come from not-hair by the organisation of atoms. Is this the first suggestion that we need to know what is microscopic? |
| 22726 | When things were unified, Mind set them in order [Anaxagoras] |
| Full Idea: All things were together, and Mind came and set them in order. | |
| From: Anaxagoras (fragments/reports [c.460 BCE]) | |
| A reaction: This is presumably the source for the passionate belief of Plato in the importance of order. Existence seems like chaos, with order residing beneath it, but we can wonder whether if we go even deeper it is chaos again. |
| 2629 | Anaxagoras was the first to say that the universe is directed by an intelligence [Anaxagoras, by Cicero] |
| Full Idea: Anaxagoras, pupil of Anaximenes, was the first to maintain that the form and motion of the universe was determined and directed by the power and purpose of an infinite intelligence. | |
| From: report of Anaxagoras (fragments/reports [c.460 BCE]) by M. Tullius Cicero - On the Nature of the Gods ('De natura deorum') I.26 |
| 480 | Past, present and future, and the movements of the heavens, were arranged by Mind [Anaxagoras] |
| Full Idea: Whatever was then in existence which is not now, and all things that now exist, and whatever shall exist - all were arranged by Mind, as also the revolution followed now by the stars, the sun and the moon. | |
| From: Anaxagoras (fragments/reports [c.460 BCE], B12), quoted by Simplicius - On Aristotle's 'Physics' 164.24 |
| 5956 | Anaxagoras was charged with impiety for calling the sun a lump of stone [Anaxagoras, by Plutarch] |
| Full Idea: Anaxagoras was charged with impiety because he called the sun a lump of stone. | |
| From: report of Anaxagoras (fragments/reports [c.460 BCE]) by Plutarch - 14: Superstition §9 | |
| A reaction: The point is that he was supposed to say that the sun is a god. |
| 7488 | Anaxagoras was the first recorded atheist [Anaxagoras, by Watson] |
| Full Idea: Anaxagoras was the first recorded atheist. | |
| From: report of Anaxagoras (fragments/reports [c.460 BCE]) by Peter Watson - Ideas Ch.25 | |
| A reaction: He was a very lively character, right in the middle of the Athenian golden age. |