47 ideas
| 8623 | Proof reveals the interdependence of truths, as well as showing their certainty [Euclid, by Frege] |
| Full Idea: Euclid gives proofs of many things which anyone would concede to him without question. ...The aim of proof is not merely to place the truth of a proposition beyond doubt, but also to afford us insight into the dependence of truths upon one another. | |
| From: report of Euclid (Elements of Geometry [c.290 BCE]) by Gottlob Frege - Grundlagen der Arithmetik (Foundations) §02 | |
| A reaction: This connects nicely with Shoemaker's view of analysis (Idea 8559), which I will adopt as my general view. I've always thought of philosophy as the aspiration to wisdom through the cartography of concepts. |
| 13907 | If you pick an arbitrary triangle, things proved of it are true of all triangles [Euclid, by Lemmon] |
| Full Idea: Euclid begins proofs about all triangles with 'let ABC be a triangle', but ABC is not a proper name. It names an arbitrarily selected triangle, and if that has a property, then we can conclude that all triangles have the property. | |
| From: report of Euclid (Elements of Geometry [c.290 BCE]) by E.J. Lemmon - Beginning Logic 3.2 | |
| A reaction: Lemmon adds the proviso that there must be no hidden assumptions about the triangle we have selected. You must generalise the properties too. Pick a triangle, any triangle, say one with three angles of 60 degrees; now generalise from it. |
| 1618 | We study bound variables not to know reality, but to know what reality language asserts [Quine] |
| Full Idea: We look to bound variables in connection with ontology not in order to know what there is, but in order to know what a given remark or doctrine, ours or someone else's, says there is. | |
| From: Willard Quine (On What There Is [1948], p.15) |
| 8455 | Canonical notation needs quantification, variables and predicates, but not names [Quine, by Orenstein] |
| Full Idea: Quine says that names need not be part of one's canonical notation; in fact, whatever scientific purposes are accomplished by names can be carried out just as well by the devices of quantification, variables and predicates. | |
| From: report of Willard Quine (On What There Is [1948]) by Alex Orenstein - W.V. Quine Ch.2 | |
| A reaction: This is part of Quine's analysis of where the ontological commitment of a language is to be found. Kripke's notion that a name baptises an item comes as a challenge to this view. |
| 8456 | Quine extended Russell's defining away of definite descriptions, to also define away names [Quine, by Orenstein] |
| Full Idea: Quine extended Russell's theory for defining away definite descriptions, so that he could also define away names. | |
| From: report of Willard Quine (On What There Is [1948]) by Alex Orenstein - W.V. Quine Ch.2 | |
| A reaction: Quine also gets rid of universals and properties, so his ontology is squeezed from both the semantic and the metaphysical directions. Quine seems to be the key figure in modern ontology. If you want to expand it (E.J. Lowe), justify yourself to Quine. |
| 1611 | Names can be converted to descriptions, and Russell showed how to eliminate those [Quine] |
| Full Idea: I have shown that names can be converted to descriptions, and Russell has shown that descriptions can be eliminated. | |
| From: Willard Quine (On What There Is [1948], p.12) |
| 6297 | Euclid's geometry is synthetic, but Descartes produced an analytic version of it [Euclid, by Resnik] |
| Full Idea: Euclid's geometry is a synthetic geometry; Descartes supplied an analytic version of Euclid's geometry, and we now have analytic versions of the early non-Euclidean geometries. | |
| From: report of Euclid (Elements of Geometry [c.290 BCE]) by Michael D. Resnik - Maths as a Science of Patterns One.4 | |
| A reaction: I take it that the original Euclidean axioms were observations about the nature of space, but Descartes turned them into a set of pure interlocking definitions which could still function if space ceased to exist. |
| 9603 | An assumption that there is a largest prime leads to a contradiction [Euclid, by Brown,JR] |
| Full Idea: Assume a largest prime, then multiply the primes together and add one. The new number isn't prime, because we assumed a largest prime; but it can't be divided by a prime, because the remainder is one. So only a larger prime could divide it. Contradiction. | |
| From: report of Euclid (Elements of Geometry [c.290 BCE]) by James Robert Brown - Philosophy of Mathematics Ch.1 | |
| A reaction: Not only a very elegant mathematical argument, but a model for how much modern logic proceeds, by assuming that the proposition is false, and then deducing a contradiction from it. |
| 9894 | A unit is that according to which each existing thing is said to be one [Euclid] |
| Full Idea: A unit is that according to which each existing thing is said to be one. | |
| From: Euclid (Elements of Geometry [c.290 BCE], 7 Def 1) | |
| A reaction: See Frege's 'Grundlagen' §29-44 for a sustained critique of this. Frege is good, but there must be something right about the Euclid idea. If I count stone, paper and scissors as three, each must first qualify to be counted as one. Psychology creeps in. |
| 8738 | Postulate 2 says a line can be extended continuously [Euclid, by Shapiro] |
| Full Idea: Euclid's Postulate 2 says the geometer can 'produce a finite straight line continuously in a straight line'. | |
| From: report of Euclid (Elements of Geometry [c.290 BCE]) by Stewart Shapiro - Thinking About Mathematics 4.2 | |
| A reaction: The point being that this takes infinity for granted, especially if you start counting how many points there are on the line. The Einstein idea that it might eventually come round and hit you on the back of the head would have charmed Euclid. |
| 22278 | Euclid relied on obvious properties in diagrams, as well as on his axioms [Potter on Euclid] |
| Full Idea: Euclid's axioms were insufficient to derive all the theorems of geometry: at various points in his proofs he appealed to properties that are obvious from the diagrams but do not follow from the stated axioms. | |
| From: comment on Euclid (Elements of Geometry [c.290 BCE]) by Michael Potter - The Rise of Analytic Philosophy 1879-1930 03 'aim' | |
| A reaction: I suppose if the axioms of a system are based on self-evidence, this would licence an appeal to self-evidence elsewhere in the system. Only pedants insist on writing down what is obvious to everyone! |
| 8673 | Euclid's parallel postulate defines unique non-intersecting parallel lines [Euclid, by Friend] |
| Full Idea: Euclid's fifth 'parallel' postulate says if there is an infinite straight line and a point, then there is only one straight line through the point which won't intersect the first line. This axiom is independent of Euclid's first four (agreed) axioms. | |
| From: report of Euclid (Elements of Geometry [c.290 BCE]) by Michèle Friend - Introducing the Philosophy of Mathematics 2.2 | |
| A reaction: This postulate was challenged in the nineteenth century, which was a major landmark in the development of modern relativist views of knowledge. |
| 10250 | Euclid needs a principle of continuity, saying some lines must intersect [Shapiro on Euclid] |
| Full Idea: Euclid gives no principle of continuity, which would sanction an inference that if a line goes from the outside of a circle to the inside of circle, then it must intersect the circle at some point. | |
| From: comment on Euclid (Elements of Geometry [c.290 BCE]) by Stewart Shapiro - Philosophy of Mathematics 6.1 n2 | |
| A reaction: Cantor and Dedekind began to contemplate discontinuous lines. |
| 10302 | Euclid says we can 'join' two points, but Hilbert says the straight line 'exists' [Euclid, by Bernays] |
| Full Idea: Euclid postulates: One can join two points by a straight line; Hilbert states the axiom: Given any two points, there exists a straight line on which both are situated. | |
| From: report of Euclid (Elements of Geometry [c.290 BCE]) by Paul Bernays - On Platonism in Mathematics p.259 |
| 14157 | Modern geometries only accept various parts of the Euclid propositions [Russell on Euclid] |
| Full Idea: In descriptive geometry the first 26 propositions of Euclid hold. In projective geometry the 1st, 7th, 16th and 17th require modification (as a straight line is not a closed series). Those after 26 depend on the postulate of parallels, so aren't assumed. | |
| From: comment on Euclid (Elements of Geometry [c.290 BCE]) by Bertrand Russell - The Principles of Mathematics §388 |
| 1600 | Euclid's common notions or axioms are what we must have if we are to learn anything at all [Euclid, by Roochnik] |
| Full Idea: The best known example of Euclid's 'common notions' is "If equals are subtracted from equals the remainders are equal". These can be called axioms, and are what "the man who is to learn anything whatever must have". | |
| From: report of Euclid (Elements of Geometry [c.290 BCE], 72a17) by David Roochnik - The Tragedy of Reason p.149 |
| 1613 | Logicists cheerfully accept reference to bound variables and all sorts of abstract entities [Quine] |
| Full Idea: The logicism of Frege, Russell, Whitehead, Church and Carnap condones the use of bound variables or reference to abstract entities known and unknown, specifiable and unspecifiable, indiscriminately. | |
| From: Willard Quine (On What There Is [1948], p.14) |
| 1616 | Formalism says maths is built of meaningless notations; these build into rules which have meaning [Quine] |
| Full Idea: The formalism of Hilbert keeps classical maths as a play of insignificant notations. Agreement is found among the rules which, unlike the notations, are quite significant and intelligible. | |
| From: Willard Quine (On What There Is [1948], p.15) |
| 1615 | Intuitionism says classes are invented, and abstract entities are constructed from specified ingredients [Quine] |
| Full Idea: The intuitionism of Poincaré, Brouwer, Weyl and others holds that classes are invented, and accepts reference to abstract entities only if they are constructed from pre-specified ingredients. | |
| From: Willard Quine (On What There Is [1948], p.14) |
| 1614 | Conceptualism holds that there are universals but they are mind-made [Quine] |
| Full Idea: Conceptualism holds that there are universals but they are mind-made. | |
| From: Willard Quine (On What There Is [1948], p.14) |
| 10241 | For Quine, there is only one way to exist [Quine, by Shapiro] |
| Full Idea: Quine takes 'existence' to be univocal, with a single ontology for his entire 'web of belief'. | |
| From: report of Willard Quine (On What There Is [1948]) by Stewart Shapiro - Philosophy of Mathematics 4.9 | |
| A reaction: Thus, there can be no 'different way of existing' (such as 'subsisting') for abstract objects such as those of mathematics. I presume that Quine's low-key physicalism is behind this. |
| 4064 | The idea of a thing and the idea of existence are two sides of the same coin [Quine, by Crane] |
| Full Idea: According to Quine's conception of existence, the idea of a thing and the idea of existence are two sides of the same coin. | |
| From: report of Willard Quine (On What There Is [1948]) by Tim Crane - Elements of Mind 1.5 | |
| A reaction: I suspect that Quine's ontology is too dependent on language, but this thought seems profoundly right |
| 19277 | Quine rests existence on bound variables, because he thinks singular terms can be analysed away [Quine, by Hale] |
| Full Idea: It is because Quine holds constant singular terms to be always eliminable by an extension of Russell's theory of definite descriptions that he takes the bound variables of first-order quantification to be the sole means by which we refer to objects. | |
| From: report of Willard Quine (On What There Is [1948]) by Bob Hale - Necessary Beings 01.2 | |
| A reaction: Hale defends a Fregean commitment to existence based on the reference of singular terms in true statements. I think they're both wrong. If you want to know what I am committed to, ask me. Don't infer it from my use of English, or logic. |
| 12210 | Quine's ontology is wrong; his question is scientific, and his answer is partly philosophical [Fine,K on Quine] |
| Full Idea: Quine's approach to ontology asks the wrong question, a scientific rather than philosophical question, and answers it in the wrong way, by appealing to philosophical considerations in addition to ordinary scientific considerations. | |
| From: comment on Willard Quine (On What There Is [1948]) by Kit Fine - The Question of Ontology p.161 | |
| A reaction: He goes on to call Quine's procedure 'cockeyed'. Presumably Quine would reply with bafflement that scientific and philosophical questions could be considered as quite different from one another. |
| 8496 | What actually exists does not, of course, depend on language [Quine] |
| Full Idea: Ontological controversy tends into controversy over language, but we must not jump to the conclusion that what there is depends on words. | |
| From: Willard Quine (On What There Is [1948], p.16) | |
| A reaction: An important corrective to my constant whinge against philosophers who treat ontology as if it were semantics, of whom Quine is the central villain. Quine was actually quite a sensible chap. |
| 1610 | To be is to be the value of a variable, which amounts to being in the range of reference of a pronoun [Quine] |
| Full Idea: To be assumed as an entity is to be reckoned as the value of a variable. This amounts roughly to saying that to be is to be in the range of reference of a pronoun. | |
| From: Willard Quine (On What There Is [1948], p.13) | |
| A reaction: Cf. Idea 7784. |
| 8459 | Fictional quantification has no ontology, so we study ontology through scientific theories [Quine, by Orenstein] |
| Full Idea: In fiction, 'Once upon a time there was an F who...' obviously does not make an ontological commitment, so Quine says the question of which ontology we accept must be dealt with in terms of the role an ontology plays in a scientific worldview. | |
| From: report of Willard Quine (On What There Is [1948]) by Alex Orenstein - W.V. Quine Ch.3 | |
| A reaction: This seems to invite questions about the ontology of people who don't espouse a scientific worldview. If your understanding of the outside world and of the past is created for you by storytellers, you won't be a Quinean. |
| 8497 | An ontology is like a scientific theory; we accept the simplest scheme that fits disorderly experiences [Quine] |
| Full Idea: Our acceptance of ontology is similar in principle to our acceptance of a scientific theory; we adopt the simplest conceptual scheme into which the disordered fragments of raw experience can be fitted and arranged. | |
| From: Willard Quine (On What There Is [1948], p.16) | |
| A reaction: Quine (who says he likes 'desert landscapes') is the modern hero for anyone who loves Ockham's Razor, and seeks extreme simplicity. And yet he finds himself committed to the existence of sets to achieve this. |
| 16261 | If commitment rests on first-order logic, we obviously lose the ontology concerning predication [Maudlin on Quine] |
| Full Idea: If Quine restricts himself to first-order predicate calculus, then the ontological implications concern the subjects of predicates. The nature of predicates, and what must be true for the predication, have disappeared from the radar screen. | |
| From: comment on Willard Quine (On What There Is [1948]) by Tim Maudlin - The Metaphysics within Physics 3.1 | |
| A reaction: Quine's response, I presume, is that the predicates can all be covered extensionally (red is a list of the red objects), and so a simpler logic will do the whole job. I agree with Maudlin though. |
| 7698 | If to be is to be the value of a variable, we must already know the values available [Jacquette on Quine] |
| Full Idea: To apply Quine's criterion that to be is to be the value of a quantifier-bound variable, we must already know the values of bound variables, which is to say that we must already be in possession of a preferred existence domain. | |
| From: comment on Willard Quine (On What There Is [1948], Ch.6) by Dale Jacquette - Ontology | |
| A reaction: [A comment on Idea 1610]. Very nice to accuse Quine, of all people, of circularity, given his attack on analytic-synthetic with the same strategy! The values will need to be known extra-lingistically, to avoid more circularity. |
| 1612 | Realism, conceptualism and nominalism in medieval universals reappear in maths as logicism, intuitionism and formalism [Quine] |
| Full Idea: The three medieval views on universals (realism, conceptualism and nominalism) reappear in the philosophy of maths as logicism, intuitionism and formalism. | |
| From: Willard Quine (On What There Is [1948], p.14) |
| 15402 | There is no entity called 'redness', and that some things are red is ultimate and irreducible [Quine] |
| Full Idea: There is not any entity whatever, individual or otherwise, which is named by the word 'redness'. ...That the houses and roses and sunsets are all of them red may be taken as ultimate and irreducible. | |
| From: Willard Quine (On What There Is [1948], p.10) | |
| A reaction: This seems to invite the 'ostrich' charge (Armstrong), that there is something left over that needs explaining. If the reds are ultimate and irreducible, that seems to imply that they have no relationship at all to one another. |
| 4443 | Quine has argued that predicates do not have any ontological commitment [Quine, by Armstrong] |
| Full Idea: Quine has attempted to bypass the problem of universals by arguing for the ontological innocence of predicates, since it is the application conditions of predicates which furnish the Realists with much of their case. | |
| From: report of Willard Quine (On What There Is [1948]) by David M. Armstrong - Universals p.503 | |
| A reaction: Presumably this would be a claim that predicates appear to commit us to properties, but that properties are not natural features, and can be reduced to something else. Tricky.. |
| 8498 | Treating scattered sensations as single objects simplifies our understanding of experience [Quine] |
| Full Idea: By bringing together scattered sense events and treating them as perceptions of one object, we reduce the complexity of our stream of experience to a manageable conceptual simplicity. | |
| From: Willard Quine (On What There Is [1948], p.17) | |
| A reaction: If, however, our consideration of tricky cases, such as vague objects, or fast-changing objects, or spatially coinciding objects made it all seem too complex, then Quine's argument would be grounds for abandoning objects. See Merricks. |
| 16078 | Clay is intrinsically and atomically the same as statue (and that lacks 'modal properties') [Rudder Baker] |
| Full Idea: Arguments for statue being the clay are: that the clay is intrinsically like the statue, that the clay has the same atoms as the statue', that objects don't have modal properties such as being necessarily F, and the reference of 'property' changes. | |
| From: Lynne Rudder Baker (Why Constitution is not Identity [1997], II) | |
| A reaction: [my summary of the arguments she identifies - see text for details] Rudder Baker attempts to refute all four of these arguments, in defence of constitution as different from identity. |
| 16077 | The clay is not a statue - it borrows that property from the statue it constitutes [Rudder Baker] |
| Full Idea: I argue that a lump of clay borrows the property of being a statue from the statue. The lump is a statue because, and only because, there is something that the lump constitutes that is a statue. | |
| From: Lynne Rudder Baker (Why Constitution is not Identity [1997], n9) | |
| A reaction: It is skating on very thin metaphysical ice to introduce the concept of 'borrowing' a property. I've spent the last ten minutes trying to 'borrow' some properties, but without luck. |
| 16080 | Is it possible for two things that are identical to become two separate things? [Rudder Baker] |
| Full Idea: A strong intuition shared by many philosophers is that some things that are in fact identical might not have been identical. | |
| From: Lynne Rudder Baker (Why Constitution is not Identity [1997], IV) | |
| A reaction: This flies in the face of the Kripkean view that if Hesperus=Phosphorus then the identity is necessary. I don't think I have an intuition that some given thing might have been two things - indeed the thought seems totally weird. Amoeba? Statue/clay? |
| 16076 | Constitution is not identity, as consideration of essential predicates shows [Rudder Baker] |
| Full Idea: I want to resuscitate an essentialist argument against the view that constitution is identity, of the form 'x is essentially F, y is not essentially F, so x is not y'. | |
| From: Lynne Rudder Baker (Why Constitution is not Identity [1997], Intro) | |
| A reaction: The point is that x might be essentially F and y only accidentally F. Thus a statue is essentially so, but a lump if clay is not essentially a statue. Another case where 'necessary' would do instead of 'essentially'. |
| 16081 | The constitution view gives a unified account of the relation of persons/bodies, statues/bronze etc [Rudder Baker] |
| Full Idea: Constitution-without-identity is superior to constitution-as-identity in that it provides a unified view of the relation between persons and bodies, statues and pieces of bronze, and so on. | |
| From: Lynne Rudder Baker (Why Constitution is not Identity [1997], IV) | |
| A reaction: I have a problem with the intrinsic dualism of this whole picture. Clay needs shape, statues need matter - there aren't two 'things' here which have a 'relation'. |
| 16082 | Statues essentially have relational properties lacked by lumps [Rudder Baker] |
| Full Idea: The statue has relational properties which the lump of clay does not have essentially. | |
| From: Lynne Rudder Baker (Why Constitution is not Identity [1997], V) | |
| A reaction: She has in mind relations to the community of artistic life. I don't think this is convincing. Is something only a statue if it is validated by an artistic community? That sounds like relative identity, which she doesn't like. |
| 8856 | Quine's indispensability argument said arguments for abstracta were a posteriori [Quine, by Yablo] |
| Full Idea: Fifty years ago, Quine convinced everyone who cared that the argument for abstract objects, if there were going to be one, would have to be a posteriori in nature; an argument that numbers, for example, are indispensable entities for 'total science'. | |
| From: report of Willard Quine (On What There Is [1948], §1) by Stephen Yablo - Apriority and Existence | |
| A reaction: This sets the scene for the modern debate on the a priori. The claim that abstractions are indispensable for a factual account of the physical world strikes me as highly implausible. |
| 12443 | Can an unactualized possible have self-identity, and be distinct from other possibles? [Quine] |
| Full Idea: Is the concept of identity simply inapplicable to unactualized possibles? But what sense can be found in talking of entities which cannot meaningfully be said to be identical with themselve and distinct from one another. | |
| From: Willard Quine (On What There Is [1948], p.4) | |
| A reaction: Can he seriously mean that we are not allowed to talk about possible objects? If I design a house, it is presumably identical to the house I am designing, and distinct from houses I'm not designing. |
| 18209 | We can never translate our whole language of objects into phenomenalism [Quine] |
| Full Idea: There is no likelihood that each sentence about physical objects can actually be translated, however deviously and complexly, into the phenomenalistic language. | |
| From: Willard Quine (On What There Is [1948], p.18), quoted by Penelope Maddy - Naturalism in Mathematics III.2 |
| 1619 | There is an attempt to give a verificationist account of meaning, without the error of reducing everything to sensations [Dennett on Quine] |
| Full Idea: This essay offered a verificationist account of language without the logical positivist error of supposing that verification could be reduced to a mere sequence of sense-experiences. | |
| From: comment on Willard Quine (On What There Is [1948]) by Daniel C. Dennett - works | |
| A reaction: This is because of Quine's holistic view of theory, so that sentences are not tested individually, where sense-data might be needed as support, but as whole teams which need to be simple, coherent etc. |
| 1609 | I do not believe there is some abstract entity called a 'meaning' which we can 'have' [Quine] |
| Full Idea: Some philosophers construe meaningfulness as the having (in some sense of 'having') of some abstract entity which he calls a meaning, whereas I do not. | |
| From: Willard Quine (On What There Is [1948], p.11) | |
| A reaction: To call a meaning an 'entity' is to put a spin on it that makes it very implausible. Introspection shows us a gap between grasping a word and grasping its meaning. |
| 1617 | The word 'meaning' is only useful when talking about significance or about synonymy [Quine] |
| Full Idea: The useful ways in which ordinary people talk about meanings boil down to two: the having of meanings, which is significance, and sameness of meaning, or synonymy. | |
| From: Willard Quine (On What There Is [1948], p.11) | |
| A reaction: If the Fregean criterion for precise existence is participation in an identity relation, then synonymy does indeed pinpoint what we mean by 'meaning. |
| 19159 | Quine relates predicates to their objects, by being 'true of' them [Quine, by Davidson] |
| Full Idea: Quine relates predicates to the things of which they can be predicated ...and hence predicates are 'true of' each and every thing of which the predicate can be truly predicated. | |
| From: report of Willard Quine (On What There Is [1948]) by Donald Davidson - Truth and Predication 5 | |
| A reaction: Davidson comments that the virtue of Quine's view is negative, in avoiding a regress in the explanation of predication. I'm not sure about true 'of' as an extra sort of truth, but I like dropping predicates from ontology, and sticking to truths. |