50 ideas
| 10482 | The logic of ZF is classical first-order predicate logic with identity [Boolos] |
| Full Idea: The logic of ZF Set Theory is classical first-order predicate logic with identity. | |
| From: George Boolos (Must We Believe in Set Theory? [1997], p.121) | |
| A reaction: This logic seems to be unable to deal with very large cardinals, precisely those that are implied by set theory, so there is some sort of major problem hovering here. Boolos is fairly neutral. |
| 10492 | A few axioms of set theory 'force themselves on us', but most of them don't [Boolos] |
| Full Idea: Maybe the axioms of extensionality and the pair set axiom 'force themselves on us' (Gödel's phrase), but I am not convinced about the axioms of infinity, union, power or replacement. | |
| From: George Boolos (Must We Believe in Set Theory? [1997], p.130) | |
| A reaction: Boolos is perfectly happy with basic set theory, but rather dubious when very large cardinals come into the picture. |
| 18192 | Do the Replacement Axioms exceed the iterative conception of sets? [Boolos, by Maddy] |
| Full Idea: For Boolos, the Replacement Axioms go beyond the iterative conception. | |
| From: report of George Boolos (The iterative conception of Set [1971]) by Penelope Maddy - Naturalism in Mathematics I.3 |
| 7785 | The use of plurals doesn't commit us to sets; there do not exist individuals and collections [Boolos] |
| Full Idea: We should abandon the idea that the use of plural forms commits us to the existence of sets/classes… Entities are not to be multiplied beyond necessity. There are not two sorts of things in the world, individuals and collections. | |
| From: George Boolos (To be is to be the value of a variable.. [1984]), quoted by Henry Laycock - Object | |
| A reaction: The problem of quantifying over sets is notoriously difficult. Try http://plato.stanford.edu/entries/object/index.html. |
| 10485 | Naïve sets are inconsistent: there is no set for things that do not belong to themselves [Boolos] |
| Full Idea: The naïve view of set theory (that any zero or more things form a set) is natural, but inconsistent: the things that do not belong to themselves are some things that do not form a set. | |
| From: George Boolos (Must We Believe in Set Theory? [1997], p.127) | |
| A reaction: As clear a summary of Russell's Paradox as you could ever hope for. |
| 10484 | The iterative conception says sets are formed at stages; some are 'earlier', and must be formed first [Boolos] |
| Full Idea: According to the iterative conception, every set is formed at some stage. There is a relation among stages, 'earlier than', which is transitive. A set is formed at a stage if and only if its members are all formed before that stage. | |
| From: George Boolos (Must We Believe in Set Theory? [1997], p.126) | |
| A reaction: He gives examples of the early stages, and says the conception is supposed to 'justify' Zermelo set theory. It is also supposed to make the axioms 'natural', rather than just being selected for convenience. And it is consistent. |
| 13547 | Limitation of Size is weak (Fs only collect is something the same size does) or strong (fewer Fs than objects) [Boolos, by Potter] |
| Full Idea: Weak Limitation of Size: If there are no more Fs than Gs and the Gs form a collection, then Fs form a collection. Strong Limitation of Size: A property F fails to be collectivising iff there are as many Fs as there are objects. | |
| From: report of George Boolos (Iteration Again [1989]) by Michael Potter - Set Theory and Its Philosophy 13.5 |
| 10699 | Does a bowl of Cheerios contain all its sets and subsets? [Boolos] |
| Full Idea: Is there, in addition to the 200 Cheerios in a bowl, also a set of them all? And what about the vast number of subsets of Cheerios? It is haywire to think that when you have some Cheerios you are eating a set. What you are doing is: eating the Cheerios. | |
| From: George Boolos (To be is to be the value of a variable.. [1984], p.72) | |
| A reaction: In my case Boolos is preaching to the converted. I am particularly bewildered by someone (i.e. Quine) who believes that innumerable sets exist while 'having a taste for desert landscapes' in their ontology. |
| 14249 | Boolos reinterprets second-order logic as plural logic [Boolos, by Oliver/Smiley] |
| Full Idea: Boolos's conception of plural logic is as a reinterpretation of second-order logic. | |
| From: report of George Boolos (On Second-Order Logic [1975]) by Oliver,A/Smiley,T - What are Sets and What are they For? n5 | |
| A reaction: Oliver and Smiley don't accept this view, and champion plural reference differently (as, I think, some kind of metalinguistic device?). |
| 10225 | Monadic second-order logic might be understood in terms of plural quantifiers [Boolos, by Shapiro] |
| Full Idea: Boolos has proposed an alternative understanding of monadic, second-order logic, in terms of plural quantifiers, which many philosophers have found attractive. | |
| From: report of George Boolos (To be is to be the value of a variable.. [1984]) by Stewart Shapiro - Philosophy of Mathematics 3.5 |
| 10830 | Second-order logic metatheory is set-theoretic, and second-order validity has set-theoretic problems [Boolos] |
| Full Idea: The metatheory of second-order logic is hopelessly set-theoretic, and the notion of second-order validity possesses many if not all of the epistemic debilities of the notion of set-theoretic truth. | |
| From: George Boolos (On Second-Order Logic [1975], p.45) | |
| A reaction: Epistemic problems arise when a logic is incomplete, because some of the so-called truths cannot be proved, and hence may be unreachable. This idea indicates Boolos's motivation for developing a theory of plural quantification. |
| 10736 | Boolos showed how plural quantifiers can interpret monadic second-order logic [Boolos, by Linnebo] |
| Full Idea: In an indisputable technical result, Boolos showed how plural quantifiers can be used to interpret monadic second-order logic. | |
| From: report of George Boolos (To be is to be the value of a variable.. [1984], Intro) by Øystein Linnebo - Plural Quantification Exposed Intro |
| 10780 | Any sentence of monadic second-order logic can be translated into plural first-order logic [Boolos, by Linnebo] |
| Full Idea: Boolos discovered that any sentence of monadic second-order logic can be translated into plural first-order logic. | |
| From: report of George Boolos (To be is to be the value of a variable.. [1984], §1) by Øystein Linnebo - Plural Quantification Exposed p.74 |
| 10829 | A sentence can't be a truth of logic if it asserts the existence of certain sets [Boolos] |
| Full Idea: One may be of the opinion that no sentence ought to be considered as a truth of logic if, no matter how it is interpreted, it asserts that there are sets of certain sorts. | |
| From: George Boolos (On Second-Order Logic [1975], p.44) | |
| A reaction: My intuition is that in no way should any proper logic assert the existence of anything at all. Presumably interpretations can assert the existence of numbers or sets, but we should be able to identify something which is 'pure' logic. Natural deduction? |
| 10697 | Identity is clearly a logical concept, and greatly enhances predicate calculus [Boolos] |
| Full Idea: Indispensable to cross-reference, lacking distinctive content, and pervading thought and discourse, 'identity' is without question a logical concept. Adding it to predicate calculus significantly increases the number and variety of inferences possible. | |
| From: George Boolos (To be is to be the value of a variable.. [1984], p.54) | |
| A reaction: It is not at all clear to me that identity is a logical concept. Is 'existence' a logical concept? It seems to fit all of Boolos's criteria? I say that all he really means is that it is basic to thought, but I'm not sure it drives the reasoning process. |
| 10832 | '∀x x=x' only means 'everything is identical to itself' if the range of 'everything' is fixed [Boolos] |
| Full Idea: One may say that '∀x x=x' means 'everything is identical to itself', but one must realise that one's answer has a determinate sense only if the reference (range) of 'everything' is fixed. | |
| From: George Boolos (On Second-Order Logic [1975], p.46) | |
| A reaction: This is the problem now discussed in the recent book 'Absolute Generality', of whether one can quantify without specifying a fixed or limited domain. |
| 13671 | Second-order quantifiers are just like plural quantifiers in ordinary language, with no extra ontology [Boolos, by Shapiro] |
| Full Idea: Boolos proposes that second-order quantifiers be regarded as 'plural quantifiers' are in ordinary language, and has developed a semantics along those lines. In this way they introduce no new ontology. | |
| From: report of George Boolos (To be is to be the value of a variable.. [1984]) by Stewart Shapiro - Foundations without Foundationalism 7 n32 | |
| A reaction: This presumably has to treat simple predicates and relations as simply groups of objects, rather than having platonic existence, or something. |
| 10267 | We should understand second-order existential quantifiers as plural quantifiers [Boolos, by Shapiro] |
| Full Idea: Standard second-order existential quantifiers pick out a class or a property, but Boolos suggests that they be understood as a plural quantifier, like 'there are objects' or 'there are people'. | |
| From: report of George Boolos (To be is to be the value of a variable.. [1984]) by Stewart Shapiro - Philosophy of Mathematics 7.4 | |
| A reaction: This idea has potential application to mathematics, and Lewis (1991, 1993) 'invokes it to develop an eliminative structuralism' (Shapiro). |
| 10698 | Plural forms have no more ontological commitment than to first-order objects [Boolos] |
| Full Idea: Abandon the idea that use of plural forms must always be understood to commit one to the existence of sets of those things to which the corresponding singular forms apply. | |
| From: George Boolos (To be is to be the value of a variable.. [1984], p.66) | |
| A reaction: It seems to be an open question whether plural quantification is first- or second-order, but it looks as if it is a rewriting of the first-order. |
| 7806 | Boolos invented plural quantification [Boolos, by Benardete,JA] |
| Full Idea: Boolos virtually patented the new device of plural quantification. | |
| From: report of George Boolos (To be is to be the value of a variable.. [1984]) by José A. Benardete - Logic and Ontology | |
| A reaction: This would be 'there are some things such that...' |
| 10834 | Weak completeness: if it is valid, it is provable. Strong: it is provable from a set of sentences [Boolos] |
| Full Idea: A weak completeness theorem shows that a sentence is provable whenever it is valid; a strong theorem, that a sentence is provable from a set of sentences whenever it is a logical consequence of the set. | |
| From: George Boolos (On Second-Order Logic [1975], p.52) | |
| A reaction: So the weak version says |- φ → |= φ, and the strong versions says Γ |- φ → Γ |= φ. Presumably it is stronger if it can specify the source of the inference. |
| 13841 | Why should compactness be definitive of logic? [Boolos, by Hacking] |
| Full Idea: Boolos asks why on earth compactness, whatever its virtues, should be definitive of logic itself. | |
| From: report of George Boolos (On Second-Order Logic [1975]) by Ian Hacking - What is Logic? §13 |
| 10491 | Infinite natural numbers is as obvious as infinite sentences in English [Boolos] |
| Full Idea: The existence of infinitely many natural numbers seems to me no more troubling than that of infinitely many computer programs or sentences of English. There is, for example, no longest sentence, since any number of 'very's can be inserted. | |
| From: George Boolos (Must We Believe in Set Theory? [1997], p.129) | |
| A reaction: If you really resisted an infinity of natural numbers, presumably you would also resist an actual infinity of 'very's. The fact that it is unclear what could ever stop a process doesn't guarantee that the process is actually endless. |
| 10483 | Mathematics and science do not require very high orders of infinity [Boolos] |
| Full Idea: To the best of my knowledge nothing in mathematics or science requires the existence of very high orders of infinity. | |
| From: George Boolos (Must We Believe in Set Theory? [1997], p.122) | |
| A reaction: He is referring to particular high orders of infinity implied by set theory. Personally I want to wield Ockham's Razor. Is being implied by set theory a sufficient reason to accept such outrageous entities into our ontology? |
| 10833 | Many concepts can only be expressed by second-order logic [Boolos] |
| Full Idea: The notions of infinity and countability can be characterized by second-order sentences, though not by first-order sentences (as compactness and Skolem-Löwenheim theorems show), .. as well as well-ordering, progression, ancestral and identity. | |
| From: George Boolos (On Second-Order Logic [1975], p.48) |
| 10490 | Mathematics isn't surprising, given that we experience many objects as abstract [Boolos] |
| Full Idea: It is no surprise that we should be able to reason mathematically about many of the things we experience, for they are already 'abstract'. | |
| From: George Boolos (Must We Believe in Set Theory? [1997], p.129) | |
| A reaction: He has just given a list of exemplary abstract objects (Idea 10489), but I think there is a more interesting idea here - that our experience of actual physical objects is to some extent abstract, as soon as it is conceptualised. |
| 10700 | First- and second-order quantifiers are two ways of referring to the same things [Boolos] |
| Full Idea: Ontological commitment is carried by first-order quantifiers; a second-order quantifier needn't be taken to be a first-order quantifier in disguise, having special items, collections, as its range. They are two ways of referring to the same things. | |
| From: George Boolos (To be is to be the value of a variable.. [1984], p.72) | |
| A reaction: If second-order quantifiers are just a way of referring, then we can see first-order quantifiers that way too, so we could deny 'objects'. |
| 10488 | It is lunacy to think we only see ink-marks, and not word-types [Boolos] |
| Full Idea: It's a kind of lunacy to think that sound scientific philosophy demands that we think that we see ink-tracks but not words, i.e. word-types. | |
| From: George Boolos (Must We Believe in Set Theory? [1997], p.128) | |
| A reaction: This seems to link him with Armstrong's mockery of 'ostrich nominalism'. There seems to be some ambiguity with the word 'see' in this disagreement. When we look at very ancient scratches on stones, why don't we always 'see' if it is words? |
| 10487 | I am a fan of abstract objects, and confident of their existence [Boolos] |
| Full Idea: I am rather a fan of abstract objects, and confident of their existence. Smaller numbers, sets and functions don't offend my sense of reality. | |
| From: George Boolos (Must We Believe in Set Theory? [1997], p.128) | |
| A reaction: The great Boolos is rather hard to disagree with, but I disagree. Logicians love abstract objects, indeed they would almost be out of a job without them. It seems to me they smuggle them into our ontology by redefining either 'object' or 'exists'. |
| 10489 | We deal with abstract objects all the time: software, poems, mistakes, triangles.. [Boolos] |
| Full Idea: We twentieth century city dwellers deal with abstract objects all the time, such as bank balances, radio programs, software, newspaper articles, poems, mistakes, triangles. | |
| From: George Boolos (Must We Believe in Set Theory? [1997], p.129) | |
| A reaction: I find this claim to be totally question-begging, and typical of a logician. The word 'object' gets horribly stretched in these discussions. We can create concepts which have all the logical properties of objects. Maybe they just 'subsist'? |
| 3061 | Anaxarchus said that he was not even sure that he knew nothing [Anaxarchus, by Diog. Laertius] |
| Full Idea: Anaxarchus said that he was not even sure that he knew nothing. | |
| From: report of Anaxarchus (fragments/reports [c.340 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 09.10.1 |
| 8693 | An 'abstraction principle' says two things are identical if they are 'equivalent' in some respect [Boolos] |
| Full Idea: Hume's Principle has a structure Boolos calls an 'abstraction principle'. Within the scope of two universal quantifiers, a biconditional connects an identity between two things and an equivalence relation. It says we don't care about other differences. | |
| From: George Boolos (Is Hume's Principle analytic? [1997]), quoted by Michèle Friend - Introducing the Philosophy of Mathematics 3.7 | |
| A reaction: This seems to be the traditional principle of abstraction by ignoring some properties, but dressed up in the clothes of formal logic. Frege tries to eliminate psychology, but Boolos implies that what we 'care about' is relevant. |
| 23928 | Good art produces exaltation and detachment [Bell,C] |
| Full Idea: The contemplation of pure form leads to a state of extraordinary exaltation and complete detachment from the concerns of life. | |
| From: Clive Bell (Art [1913], I.III) | |
| A reaction: The last part is what gets the arts a bad name with the people who do deal with the concerns of life (which won't go away, even for an artist!). However, being totally trapped in the concerns of life is probably a recipe for misery. |
| 23922 | The word 'beauty' leads to confusion, because it denotes distinct emotions [Bell,C] |
| Full Idea: The word 'beauty' connotes objects of quite distinguishable emotions, and the term would land me in confusions and misunderstandings. | |
| From: Clive Bell (Art [1913], I.I) | |
| A reaction: His main example is a comparison of beautiful women with beautiful art. Personally I don't think the word aspires to be precise, so there is no problem. Maths has beautiful solutions, golf has beautiful shots, cooking has beautiful results. Wow! |
| 23921 | Our feeling for natural beauty is different from the aesthetic emotion of art [Bell,C] |
| Full Idea: It is not what I call an aesthetic emotion that most of us feel, generally, for natural beauty. …Most people feel a very different kind of emotion for birds, flowers and butterfly wings from that we feel for pictures, pots, temples and statues. | |
| From: Clive Bell (Art [1913], I.I) | |
| A reaction: Not convinced. I think the main difference is our awareness that art is a human production, the result of choice, whereas nature is a given. Beethoven 9 and a good sunset don't seem to me far apart in our responses. |
| 23929 | We only see landscapes as artistic if we ignore their instrumental value [Bell,C] |
| Full Idea: It is only when we cease to regard the objects in a landscape as means to anything that we can feel the landscape artistically. | |
| From: Clive Bell (Art [1913], II.I) | |
| A reaction: This sounds as if only the exploitative attitude blocks the artistic view, but I would expect the scientific view (of an ecologist, for example) to do the same. |
| 23923 | Visual form can create a sublime mental state [Bell,C] |
| Full Idea: Pure visual form transports me to an infinitely sublime state of mind. | |
| From: Clive Bell (Art [1913], I.I) | |
| A reaction: Unusual for anyone to use to term 'sublime' for works of art, and I suspect that Bell was the last to do so. Bell offers a quasi-religious role for art. I accept that being struck by something exceptionally good in art is a very distinctive experience. |
| 23932 | Art is the expression of an emotion for ultimate reality [Bell,C] |
| Full Idea: My hypothesis is that art is the expression of an emotion for ultimate reality. | |
| From: Clive Bell (Art [1913], II.II) | |
| A reaction: So later in his discussion the word 'ultimate' has crept in, after a chapter about the close relation between religious and artistic attitudes. He also sees good art as deeply 'spiritual'. It seems that religious belief is essential to his theory of art. |
| 23927 | Aestheticism invites artist to create beauty, but with no indication of how to do it [Bell,C] |
| Full Idea: The danger of aestheticism is that the artist who has got nothing to do but make something beautiful hardly knows where to begin or where to end | |
| From: Clive Bell (Art [1913], I.III) | |
| A reaction: Aestheticism strikes me as the main motivation for art nouveau artifacts, which I love. You start with beautiful lines, and then find ways to implement them. Bell has a point, though! |
| 8115 | Only artists can discern significant form; other people must look to art to find it [Bell,C, by Gardner] |
| Full Idea: Bell thinks that only artists can discern significant form directly in the natural world, and that all others must look to art for significant form. | |
| From: report of Clive Bell (Art [1913]) by Sebastian Gardner - Aesthetics 3.3 | |
| A reaction: I have a horrible feeling that 'significant' form will turn out to be the sort of form that artists can see. Presumably the form spotted by geologists won't be quite so 'significant'. Not a promising theory. |
| 23924 | Maybe significant form gives us a feeling for ultimate reality [Bell,C] |
| Full Idea: When we strip things of all associations and significance, what is left is 'the thing in itself', or 'ultimate reality'. …Artists can express an emotion felt for reality through line and colour. …So through 'significant form' we sense ultimate reality. | |
| From: Clive Bell (Art [1913], I.III) | |
| A reaction: [compressed] The thing in itself is a Kantian idea. He offers this as a speculation, rather than a fact. Maybe quantum physics gets us closer to the thing in itself? Bell knows that his faith in significant form needs more justification than an emotion. |
| 23931 | Significant form is the essence of art, which I believe expresses an emotion about reality [Bell,C] |
| Full Idea: My view that the essential quality in work of art is significant form was based on experience I am sure about. Of my view that significant form is the expression of a peculiar emotion felt for reality I am far from confident. | |
| From: Clive Bell (Art [1913], II.II) | |
| A reaction: It is hard to understand the idea of 'significant' form without a clear proposal for the nature of the significance. A detective doesn't stop at the point where evidence is seen as significant. Why should a 'peculiar' emotion matter? |
| 20434 | 'Form' is visual relations, and it is 'significant' if it moves us aesthetically; art needs both [Bell,C, by Feagin] |
| Full Idea: By 'form' Bell means the relations of lines, colours and shapes. Forms are 'significant' when the relationships of lines and so on move us aesthetically. If something is art it must have, to at least a minimum extent, significant form. | |
| From: report of Clive Bell (Art [1913], p.17) by Susan Feagin - Roger Fry and Clive Bell 3 | |
| A reaction: So art has two necessary conditions - that it move us aesthetically, and that it does so by means of its form. The obvious problem is to explain which forms are 'significant' without mentioning the aesthetic feeling they have to invoke. |
| 23934 | The only expression art could have is the emotion resulting from pure form [Bell,C] |
| Full Idea: If art expresses anything, it expresses an emotion felt for pure form and that which gives pure form its extraordinary significance. | |
| From: Clive Bell (Art [1913], III.I) | |
| A reaction: I don't think 'expresses' is the right word here. Artists express, but works just transmit. I personally doubt whether anything can have 'extraordinary significance' simply because it expresses one particular emotion. Why art, but not geometry? |
| 23925 | Mere copies of pictures are not significant - unless the copies are very exact [Bell,C] |
| Full Idea: A literal copy is seldom reckoned even by its owner a work of art. Its forms are not significant. Yet if it were an absolutely exact copy, clearly it would be as moving as the original, and a photographic reproduction of a drawing often is. | |
| From: Clive Bell (Art [1913], I.III) | |
| A reaction: What if the original artist made the copy? In 1913, Bell begins to spot this modern problem. He undermines his own theory of significant form here, if the form only becomes significant once we have checked it is an original. |
| 23926 | Art is distinguished by its aesthetic emotion, which produces appropriate form [Bell,C] |
| Full Idea: The characteristic of a work of art is its power of provoking aesthetic emotion; the expression of emotion is what gives it its power. ...Rightness of form is invariably a consequence of rightness of emotion. | |
| From: Clive Bell (Art [1913], I.III) | |
| A reaction: Bell doesn't dig very deep, because the obvious next question, not really addressed, is what makes the emotion 'right'. He suggests that significant form reveals reality, but why would an emotion do that? Does each work have a distinct emotion? |
| 23933 | Aesthetic contemplation is the best and most intense mental state [Bell,C] |
| Full Idea: Art is not only a means to good states of mind, but, perhaps, the best and most potent that we possess; …there is no state of mind more excellent or more intense than the state of aesthetic contemplation. | |
| From: Clive Bell (Art [1913], II.III) | |
| A reaction: Why does intensity make it good? It is pretty intense being involved in a road accident, but that doesn't make it good. There are many states of mind we enjoy or value highly, but we need more than that to prove them objectively 'excellent'. |
| 23935 | Aesthetic experience is an exaltation which increases the possibilities of life [Bell,C] |
| Full Idea: Those who have been thrilled by the pure aesthetic significance of a work of art …carry a state of excitement and exaltation making them more sensitive to all that is going forward about them. Thus they realise …the significance and possibility of life. | |
| From: Clive Bell (Art [1913], IV.III) | |
| A reaction: This seems like a bit of an afterthought, because he struggles to explain why his 'significant form' is so important. He shifts between it being an end - an intrinsic value - or a moral state, or now an increaser of life potential. |
| 22691 | Only artistic qualities matter in art, because they also have the highest moral value [Bell,C] |
| Full Idea: The only relevant qualities in art are artistic qualities: judged as a means to good, no other qualities are worth considering; for there are no qualities of greater moral value than artistic qualities, since there is no greater means to good than art. | |
| From: Clive Bell (Art [1913], II.III) | |
| A reaction: Wishful thinking, I suspect. I can't see anyone acquiring a moral education just by looking a Cezannes. This seems to be a late manifesto for the aesthetic movement. |
| 23930 | Religion sees infinite value in some things, and irrelevance in the rest [Bell,C] |
| Full Idea: The essence of religion is a conviction that because some things are of infinite value most are profoundly unimportant. | |
| From: Clive Bell (Art [1913], II.I) | |
| A reaction: The aspect of religion which most worries atheists like Nietzsche. You can end up with a rather cool and detached view of genocide, if you really believe that worldly matters are unimportant. Do souls in heaven worry about the next life after that? |