| 9607 | The greatest discovery in human thought is Plato's discovery of abstract objects [Brown,JR on Plato] |
| Full Idea: The greatest discovery in the history of human thought is Plato's discovery of abstract objects. | |
| From: comment on Plato (works [c.375 BCE]) by James Robert Brown - Philosophy of Mathematics Ch. 2 | |
| A reaction: Compare Idea 2860! Given the diametrically opposed views, it is clearly likely that Plato's central view is the most important idea in the history of human thought, even if it is wrong. |
| 16086 | Objects lacking matter are intrinsic unities [Aristotle] |
| Full Idea: With things that do not have matter, they are all unities of a kind simpliciter. | |
| From: Aristotle (Metaphysics [c.324 BCE], 1045b24) | |
| A reaction: Are all abstract objects unities? Are all sets Aristotelian unities? Only the brackets unify a disparate bunch of things. Are the primes one object or many? If many, each one needs an intrinsic unity to pick it out. The group of primes lacks matter. |
| 12990 | Real (non-logical) abstract terms are either essences or accidents [Leibniz] |
| Full Idea: Real (as opposed to logical) abstract terms, or at least those which are conceived as real, are either essences or parts of essences, or else accidents (i.e. beings added to a substance). | |
| From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.08) | |
| A reaction: Interesting to refer to accidents as 'beings'. This seems to fit abstraction by ignoring, since you can either ignore the accidents to get the essence, or ignore the essence to get the accidents. |
| 8647 | Not all objects are spatial; 4 can still be an object, despite lacking spatial co-ordinates [Frege] |
| Full Idea: To give spatial co-ordinates for the number four makes no sense; but the only conclusion to be drawn from that is, that 4 is not a spatial object, not that it is not an object at all. Not every object has a place. | |
| From: Gottlob Frege (Grundlagen der Arithmetik (Foundations) [1884], §61) | |
| A reaction: This is the modern philosophical concept of an 'object', though I find such talk very peculiar. It sounds like extreme Platonism, though this is usually denied. This is how logicians seem to see the world. |
| 10545 | Abstract objects may not cause changes, but they can be the subject of change [Dummett] |
| Full Idea: To say that an abstract object cannot be the cause of change seems plausible enough, but the thesis that it cannot be the subject of change is problematic. The shape of an object can change, or the number of sheep on a hill. | |
| From: Michael Dummett (Frege Philosophy of Language (2nd ed) [1973], Ch.14) | |
| A reaction: This seems a pretty crucial difficulty for the standard notion of abstracta as non-causal. I would say that it is an acid which could eat away the whole edifice if you thought about it for long enough. He shifts shape-change to the physical object. |
| 9885 | The existence of abstract objects is a pseudo-problem [Dummett] |
| Full Idea: The existence of abstract objects is a pseudo-problem. | |
| From: Michael Dummett (Frege philosophy of mathematics [1991], Ch.18) | |
| A reaction: This remark follows after Idea 9884, which says the abstract/concrete distinction is a sliding scale. Personally I take the distinction to be fairly sharp, and it is therefore probably the single most important problem in the whole of human thought. |
| 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'. |
| 10414 | Abstract objects are constituted by encoded collections of properties [Zalta, by Swoyer] |
| Full Idea: In Zalta's view abstract objects are correlated with collections of properties. ..They encode, as well as exemplify, properties; indeed, an abstract object (such as a Euclidean triangle) is constituted by the properties it encodes. | |
| From: report of Edward N. Zalta (Abstract Objects:intro to Axiomatic Metaphysics [1983]) by Chris Swoyer - Properties 6.3 | |
| A reaction: If we are going to explain abstract objects with properties, then properties had better not be abstract objects. Zalta has a promising idea if we start from a nominalist and naturalistic view of properties (built from physical powers). 'Encode'? |
| 10558 | Abstract objects are actually constituted by the properties by which we conceive them [Zalta] |
| Full Idea: Where for ordinary objects one can discover the properties they exemplify, abstract objects are actually constituted or determined by the properties by which we conceive them. I use the technical term 'x encodes F' for this idea. | |
| From: Edward N. Zalta (Deriving Kripkean Claims with Abstract Objects [2006], 2 n2) | |
| A reaction: One might say that whereas concrete objects can be dubbed (in the Kripke manner), abstract objects can only be referred to by descriptions. See 10557 for more technicalities about Zalta's idea. |
| 17785 | Real numbers as abstracted objects are now treated as complete ordered fields [Mayberry] |
| Full Idea: The abstractness of the old fashioned real numbers has been replaced by generality in the modern theory of complete ordered fields. | |
| From: John Mayberry (What Required for Foundation for Maths? [1994], p.408-2) | |
| A reaction: In philosophy, I'm increasingly thinking that we should talk much more of 'generality', and a great deal less about 'universals'. (By which I don't mean that redness is just the set of red things). |
| 10403 | If properties are abstract objects, then their being abstract exemplifies being abstract [Swoyer] |
| Full Idea: If properties are abstract objects, then the property of being abstract should itself exemplify the property of being abstract. | |
| From: Chris Swoyer (Properties [2000], 2.2) | |
| A reaction: Swoyer links this observation with Plato's views on self-predication, and his Third Man Argument (which I bet originated with Aristotle in the Academy!). Do we have a regress of objects, as well as a regress of properties? |
| 10513 | Many abstract objects, such as chess, seem non-spatial, but are not atemporal [Hale] |
| Full Idea: There are many plausible example of abstract objects which, though non-spatial, do not appear to satisfy the suggested requirement of atemporality, such as chess, or the English language. | |
| From: Bob Hale (Abstract Objects [1987], Ch.3.1) | |
| A reaction: Given the point that modern physics is committed to 'space-time', with no conceivable separation of them, this looks dubious. Though I think the physics could be challenged. Try Idea 7621, for example. |
| 10514 | If the mental is non-spatial but temporal, then it must be classified as abstract [Hale] |
| Full Idea: If mental events are genuinely non-spatial, but not atemporal, its effect is to classify them as abstract; the distinction between the abstract and the mental simply collapses. | |
| From: Bob Hale (Abstract Objects [1987], Ch.3.1) | |
| A reaction: This is important. You can't discuss this sort of metaphysics in isolation from debates about the ontology of mind. Functionalists do treat mental events as abstractions. |
| 10518 | Shapes and directions are of something, but games and musical compositions are not [Hale] |
| Full Idea: While a shape or a direction is necessarily of something, games, musical compositions or dance routines are not of anything at all. | |
| From: Bob Hale (Abstract Objects [1987], Ch.3.II) | |
| A reaction: This seems important, because Frege's abstraction principle works nicely for abstractions 'of' some objects, but is not so clear for abstracta that are sui generis. |
| 10523 | Being abstract is based on a relation between things which are spatially separated [Hale] |
| Full Idea: The abstract/concrete distinction is, roughly, between those sortals whose grounding relations can hold between abstract things which are spatially but not temporally separated, those concrete things whose grounding relations cannot so hold. | |
| From: Bob Hale (Abstract Objects [1987], Ch.3.III) | |
| A reaction: Thus being a father is based on 'begat', which does not involve spatial separation, and so is concrete. The relation is one of equivalence. |
| 8704 | Structuralists call a mathematical 'object' simply a 'place in a structure' [Friend] |
| Full Idea: What the mathematician labels an 'object' in her discipline, is called 'a place in a structure' by the structuralist. | |
| From: Michèle Friend (Introducing the Philosophy of Mathematics [2007], 4.5) | |
| A reaction: This is a strategy for dispersing the idea of an object in the world of thought, parallel to attempts to eliminate them from physical ontology (e.g. Idea 614). |