40 ideas
| 21474 | Metaphysics studies the inexplicable ends of explanation [Schopenhauer] |
| Full Idea: The plummet touches the bottom of the sea now at a greater depth, now at a less, but is bound to reach it somewhere sooner or later; the study of this inexplicable devolves upon metaphysics. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], I:1) | |
| A reaction: This definition of metapysics contains the germ of despair about the subject. Does he hope that metaphysicians can explain what nobody else can? |
| 17884 | Mathematical set theory has many plausible stopping points, such as finitism, and predicativism [Koellner] |
| Full Idea: There are many coherent stopping points in the hierarchy of increasingly strong mathematical systems, starting with strict finitism, and moving up through predicativism to the higher reaches of set theory. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], Intro) |
| 17893 | 'Reflection principles' say the whole truth about sets can't be captured [Koellner] |
| Full Idea: Roughly speaking, 'reflection principles' assert that anything true in V [the set hierarchy] falls short of characterising V in that it is true within some earlier level. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 2.1) |
| 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. |
| 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) |
| 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) |
| 17894 | We have no argument to show a statement is absolutely undecidable [Koellner] |
| Full Idea: There is at present no solid argument to the effect that a given statement is absolutely undecidable. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 5.3) |
| 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. |
| 17890 | There are at least eleven types of large cardinal, of increasing logical strength [Koellner] |
| Full Idea: Some of the standard large cardinals (in order of increasing (logical) strength) are: inaccessible, Mahlo, weakly compact, indescribable, Erdös, measurable, strong, Wodin, supercompact, huge etc. (...and ineffable). | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.4) | |
| A reaction: [I don't understand how cardinals can have 'logical strength', but I pass it on anyway] |
| 17887 | PA is consistent as far as we can accept, and we expand axioms to overcome limitations [Koellner] |
| Full Idea: To the extent that we are justified in accepting Peano Arithmetic we are justified in accepting its consistency, and so we know how to expand the axiom system so as to overcome the limitation [of Gödel's Second Theorem]. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.1) | |
| A reaction: Each expansion brings a limitation, but then you can expand again. |
| 17891 | Arithmetical undecidability is always settled at the next stage up [Koellner] |
| Full Idea: The arithmetical instances of undecidability that arise at one stage of the hierarchy are settled at the next. | |
| From: Peter Koellner (On the Question of Absolute Undecidability [2006], 1.4) |
| 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. |
| 21470 | For me the objective thing-in-itself is the will [Schopenhauer] |
| Full Idea: Thing in itself signifies that which exists independently of our perception, that which actually is; …to Kant it was '= x'; to me it is will. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], IV:61) | |
| A reaction: Does he mean his own will, which is plausible since he has direct experience of it, or is he referring will in general - whatever that is? |
| 21479 | Knowledge is not power! Ignorant people possess supreme authority [Schopenhauer] |
| Full Idea: Knowledge is power. The devil it is! One man can have a great deal of knowledge without its giving him the least power, while another possesses supreme authority but next to no knowledge. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], III:43) | |
| A reaction: He is referring to Bacon's famous adage. Bacon may be right about military affairs, but not about politics. |
| 21476 | A priori propositions are those we could never be seriously motivated to challenge [Schopenhauer] |
| Full Idea: A dictate of reason is the name we give to certain propositions which we hold to be true without investigation, and of which we think ourselves so firmly convinced we should be incapable of seriously testing them even if we wanted to. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], I:12) | |
| A reaction: This is closer to the cautious way modern thinkers are inclined to express the idea. Even Quine would be reasonably happy with this. |
| 21473 | All knowledge and explanation rests on the inexplicable [Schopenhauer] |
| Full Idea: The fundament upon which all our knowledge and learning rests is the inexplicable. It is to this that every explanation, through few or many intermediary stages, leads. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], I:1) | |
| A reaction: This is obviously true, and the only question is whether it is a necessary or a contingent truth. |
| 21478 | Half our thinking is unconscious, and we reach conclusions while unaware of premises [Schopenhauer] |
| Full Idea: One might almost believe that half our thinking takes place unconsciously.. Usually we arrive at a conclusion without having clearly thought about the premises which lead to it. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], III:40) | |
| A reaction: Schopenhauer was a major pioneer of this crucial idea. I'm beginning to think it is much greater than a half. |
| 21477 | We don't control our own thinking [Schopenhauer] |
| Full Idea: Thoughts come not when we want but when they want. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], III:37) | |
| A reaction: One of my favourite Nietzsche ideas originated in Schopenhauer! |
| 21475 | All of our concepts are borrowed from perceptual knowledge [Schopenhauer] |
| Full Idea: The entire property of a concept consists in nothing more than what has been begged and borrowed from perceptual knowledge, which is the true and inexhaustible source of all insight. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], I:9) | |
| A reaction: Schopenhauer is usually seen as a sort of idealist, but this is a full endorsement of the empirical view of concepts, to which I largely subscribe. Note that he talks of 'knowledge', rather than of 'experience'. |
| 21372 | Aesthetics concerns how we can take pleasure in an object, with no reference to the will [Schopenhauer] |
| Full Idea: The central problem of aesthetics is how satisfaction with and pleasure in an object are possible without any reference thereof to our willing. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], II:415), quoted by Christopher Janaway - Schopenhauer 6 'Aesthetic' | |
| A reaction: This does seem a good distinction. We can divide pleasures into willed and unwilled. Compare thinking that some remote stranger (in a photograph) is very beautiful, with falling in love with someone. |
| 21488 | The beautiful is a perception of Plato's Forms, which eliminates the will [Schopenhauer] |
| Full Idea: In the beautiful we always perceive the intrinsic and primary form of animate and inanimate nature, that is to say Plato's Ideas thereof. …When an aesthetic perception occurs the will completely vanishes from consciousness. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], XIX:205) | |
| A reaction: An essential Schopenauer idea. Iris Murdoch said something similar. |
| 21483 | Man is essentially a dreadful wild animal [Schopenhauer] |
| Full Idea: Man is at bottom a dreadful wild animal. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], VIII:114) | |
| A reaction: As an example he cites the slave owners in the United States. |
| 21466 | Pleasure is weaker, and pain stronger, than we expect [Schopenhauer] |
| Full Idea: As a rule we find pleasure much less pleasurable, pain much more painful than we expected. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], XII:149) | |
| A reaction: Never go on holiday with Schopenhauer. This is more accurate about pain, I think. |
| 21484 | A man's character can be learned from a single characteristic action [Schopenhauer] |
| Full Idea: As a botanist can recognise the whole plant from one leaf, …so an accurate knowledge of a man's character can be arrived at from a single characteristic action. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], VIII:118) | |
| A reaction: Very true. Great novelists specialise in such observations. One word can reveal a character, as well as one action. |
| 21481 | Buddhists wisely start with the cardinal vices [Schopenhauer] |
| Full Idea: Because of their profounder ethical and metaphysical insight, the Buddhists start not with the cardinal virtues but with cardinal vices, …which are lust, sloth, wrath and avarice (and maybe hatred). | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], VIII:110) | |
| A reaction: This may be right. Our lives are affected much more by the vices of others than by their virtues, and most virtuous behaviour aims at rectifying the bad effects of other people's vices. |
| 21482 | The five Chinese virtues: pity, justice, politeness, wisdom, honesty [Schopenhauer] |
| Full Idea: The Chinese name five cardinal virtues: pity, justice, politeness, wisdom and honesty. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], VIII:110) | |
| A reaction: I like politeness being on the list, though it seems rather superficial to be a virtue of character. Respect would be better. |
| 21480 | Boredom is only felt by those clever enough to need activity [Schopenhauer] |
| Full Idea: Only in the cleverest animals such as dogs and apes does the need for activity, and with that boredom, make itself felt. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], III:50) | |
| A reaction: But it is much more frequently young creatures, of almost any kind, that seek constant activity, and get continually restless. The most active adults need not be the cleverest. |
| 21469 | Human life is a mistake, shown by boredom, which is direct awareness of the fact [Schopenhauer] |
| Full Idea: Human life must be some kind of mistake. ...Boredom is a direct proof that existence is in itself valueless, for boredom is nothing other than the sensation of the emptiness of existence. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], XI:146) | |
| A reaction: I think it is a good advertisement for existentialism that it makes something more out of boredom than Schopenhauer does. |
| 21485 | The state only exists to defend citizens, from exterior threats, and from one another [Schopenhauer] |
| Full Idea: The state is essentially no more than an institution for the protection of the whole against attacks from without, and the protection of its individual members from attacks by one another. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], IX:123) | |
| A reaction: He then has a swipe at Hegel for his inflated idea of the importance of the state. Schopenhauer is close to Hobbes on this one. |
| 21486 | Poverty and slavery are virtually two words for the same thing [Schopenhauer] |
| Full Idea: Poverty and slavery are only two forms - on might almost say two words for - the same thing, the essence of which is that a man's energies are expended for the most part not on his own behalf but on that of others. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], IX:125) | |
| A reaction: The modern world is full of people who righteously despise slavery, but think only of the poor that it serves them right. |
| 21487 | The freedom of the press to sell poison outweighs its usefulness [Schopenhauer] |
| Full Idea: Freedom of the press must be regarded as a permit to sell poison. …I very much fear, therefore, that the dangers of press freedom outweigh its usefulness. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], IX:127) | |
| A reaction: On the whole the modern world disagrees with this view, but watching the popular press in Britain in the last twenty years has made me sympathise with Schopenhauer. |
| 21471 | If suicide was quick and easy, most people would have done it by now [Schopenhauer] |
| Full Idea: Perhaps there is no one alive who would not already have put an end to his life if this end were something purely negative, a sudden cessation of existence. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], XIII:158) | |
| A reaction: Nonsense, on the whole, but it is a nice question how many people would do it if it only took a painless instant. |
| 21467 | Would humanity still exist if sex wasn't both desired and pleasurable? [Schopenhauer] |
| Full Idea: If the act of procreation were neither the outcome of a desire nor accompanied by feelings of pleasure, but a matter to be decided on the basis of purely rational considerations, is it likely the human race would still exist? | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], XII:156) | |
| A reaction: This is almost certainly correct in the modern world. In tougher economic circumstances people seem desperate to have children who will help them survive. |
| 21472 | Only religion introduces serious issues to uneducated people [Schopenhauer] |
| Full Idea: Religion is the only means of introducing some notion of the high significance of life into the uncultivated heads of the masses. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], XV:174) | |
| A reaction: Cf Philip Larkin's poem 'Church Going'. On the whole Schopenhauer didn't actually believe that our lives had any 'high significance'. |
| 21468 | The Creator created the possibilities for worlds, so should have made a better one than this possible [Schopenhauer] |
| Full Idea: The Creator created not only the world, but also created possibility itself; therefore he should have created the possibility of a better world than this one. | |
| From: Arthur Schopenhauer (Parerga and Paralipomena [1851], XII:156) | |
| A reaction: This is explicitly a response to Leibniz's claim that the Creator selected the best of all possible worlds from the available options. The Euthyphro Question hovers here: must the Creator accept what is possible (the platonic view), or create possibility? |