14 ideas
| 17824 | The master science is physical objects divided into sets [Maddy] |
| Full Idea: The master science can be thought of as the theory of sets with the entire range of physical objects as ur-elements. | |
| From: Penelope Maddy (Sets and Numbers [1981], II) | |
| A reaction: This sounds like Quine's view, since we have to add sets to our naturalistic ontology of objects. It seems to involve unrestricted mereology to create normal objects. |
| 13007 | Archimedes defined a straight line as the shortest distance between two points [Archimedes, by Leibniz] |
| Full Idea: Archimedes gave a sort of definition of 'straight line' when he said it is the shortest line between two points. | |
| From: report of Archimedes (fragments/reports [c.240 BCE]) by Gottfried Leibniz - New Essays on Human Understanding 4.13 | |
| A reaction: Commentators observe that this reduces the purity of the original Euclidean axioms, because it involves distance and measurement, which are absent from the purest geometry. |
| 17825 | Set theory (unlike the Peano postulates) can explain why multiplication is commutative [Maddy] |
| Full Idea: If you wonder why multiplication is commutative, you could prove it from the Peano postulates, but the proof offers little towards an answer. In set theory Cartesian products match 1-1, and n.m dots when turned on its side has m.n dots, which explains it. | |
| From: Penelope Maddy (Sets and Numbers [1981], II) | |
| A reaction: 'Turning on its side' sounds more fundamental than formal set theory. I'm a fan of explanation as taking you to the heart of the problem. I suspect the world, rather than set theory, explains the commutativity. |
| 17826 | Standardly, numbers are said to be sets, which is neat ontology and epistemology [Maddy] |
| Full Idea: The standard account of the relationship between numbers and sets is that numbers simply are certain sets. This has the advantage of ontological economy, and allows numbers to be brought within the epistemology of sets. | |
| From: Penelope Maddy (Sets and Numbers [1981], III) | |
| A reaction: Maddy votes for numbers being properties of sets, rather than the sets themselves. See Yourgrau's critique. |
| 17828 | Numbers are properties of sets, just as lengths are properties of physical objects [Maddy] |
| Full Idea: I propose that ...numbers are properties of sets, analogous, for example, to lengths, which are properties of physical objects. | |
| From: Penelope Maddy (Sets and Numbers [1981], III) | |
| A reaction: Are lengths properties of physical objects? A hole in the ground can have a length. A gap can have a length. Pure space seems to contain lengths. A set seems much more abstract than its members. |
| 17827 | Sets exist where their elements are, but numbers are more like universals [Maddy] |
| Full Idea: A set of things is located where the aggregate of those things is located, ...but a number is simultaneously located at many different places (10 in my hand, and a baseball team) ...so numbers seem more like universals than particulars. | |
| From: Penelope Maddy (Sets and Numbers [1981], III) | |
| A reaction: My gut feeling is that Maddy's master idea (of naturalising sets by building them from ur-elements of natural objects) won't work. Sets can work fine in total abstraction from nature. |
| 17830 | Number theory doesn't 'reduce' to set theory, because sets have number properties [Maddy] |
| Full Idea: I am not suggesting a reduction of number theory to set theory ...There are only sets with number properties; number theory is part of the theory of finite sets. | |
| From: Penelope Maddy (Sets and Numbers [1981], V) |
| 17823 | If mathematical objects exist, how can we know them, and which objects are they? [Maddy] |
| Full Idea: The popular challenges to platonism in philosophy of mathematics are epistemological (how are we able to interact with these objects in appropriate ways) and ontological (if numbers are sets, which sets are they). | |
| From: Penelope Maddy (Sets and Numbers [1981], I) | |
| A reaction: These objections refer to Benacerraf's two famous papers - 1965 for the ontology, and 1973 for the epistemology. Though he relied too much on causal accounts of knowledge in 1973, I'm with him all the way. |
| 17829 | Number words are unusual as adjectives; we don't say 'is five', and numbers always come first [Maddy] |
| Full Idea: Number words are not like normal adjectives. For example, number words don't occur in 'is (are)...' contexts except artificially, and they must appear before all other adjectives, and so on. | |
| From: Penelope Maddy (Sets and Numbers [1981], IV) | |
| A reaction: [She is citing Benacerraf's arguments] |
| 6387 | A minimum requirement for a theory of meaning is that it include an account of truth [Davidson] |
| Full Idea: Whatever else it embraces, a theory of meaning must include an account of truth - a statement of the conditions under which an arbitrary sentence of the language is true. | |
| From: Donald Davidson (Reality without Reference [1977], p.132) | |
| A reaction: It is a moot point whether we can define meaning if we assume truth, or if we can define truth by assuming meaning. Tarski seems to presuppose meaning when he defines truth (Idea 2345). I like Davidson's taking of truth as basic. |
| 6391 | A theory of truth tells us how communication by language is possible [Davidson] |
| Full Idea: A theory of truth lets us answer the underlying question how communication by language is possible. | |
| From: Donald Davidson (Reality without Reference [1977], p.137) | |
| A reaction: If, instead, you explain communication by understood intentions (á la Grice), you have to say more about what sort of intentions are meant. If you use reference, you still have more to say about the meaning of sentences. Davidson looks good. |
| 6388 | Is reference the key place where language and the world meet? [Davidson] |
| Full Idea: The essential question is whether reference is the, or at least one, place where there is direct contact between linguistic theory and events, actions, or objects described in nonlinguistic terms. | |
| From: Donald Davidson (Reality without Reference [1977], p.134) | |
| A reaction: How do you 'describe objects in nonlinguistic terms'? The causal theory of reference (e.g. Idea 4957) is designed to plug language straight into the world via reference. It simplifies things nicely, but I don't quite believe it. |
| 6390 | With a holistic approach, we can give up reference in empirical theories of language [Davidson] |
| Full Idea: I defend a version of the holistic approach, and urge that we must give up the concept of reference as basic to an empirical theory of language. | |
| From: Donald Davidson (Reality without Reference [1977], p.136) | |
| A reaction: He proposes to connect language to the world via the concept of truth, rather than of reference. It is a brilliant idea, and is the key issue in philosophy of language. I go back to animals, which seem to care about situations rather than things. |
| 6389 | To explain the reference of a name, you must explain its sentence-role, so reference can't be defined nonlinguistically [Davidson] |
| Full Idea: It is inconceivable that one should be able to explain the relationship between 'Kilimanjiro' and Kilimanjiro without first explaining the role of the word in sentences; hence there is no chance of explaining reference directly in nonlinguistic terms. | |
| From: Donald Davidson (Reality without Reference [1977], p.135) | |
| A reaction: I point at the mountain, and a local says 'Kilimanjiro'? There is a 'gavagai'-type problem with that. The prior question might be 'what is it about this word that enables it to have a role in sentences?' Unlike whimpering or belching. |