25 ideas
| 10017 | Truth in a model is more tractable than the general notion of truth [Hodes] |
| Full Idea: Truth in a model is interesting because it provides a transparent and mathematically tractable model - in the 'ordinary' rather than formal sense of the term 'model' - of the less tractable notion of truth. | |
| From: Harold Hodes (Logicism and Ontological Commits. of Arithmetic [1984], p.131) | |
| A reaction: This is an important warning to those who wish to build their entire account of truth on Tarski's rigorously formal account of the term. Personally I think we should start by deciding whether 'true' can refer to the mental state of a dog. I say it can. |
| 10018 | Truth is quite different in interpreted set theory and in the skeleton of its language [Hodes] |
| Full Idea: There is an enormous difference between the truth of sentences in the interpreted language of set theory and truth in some model for the disinterpreted skeleton of that language. | |
| From: Harold Hodes (Logicism and Ontological Commits. of Arithmetic [1984], p.132) | |
| A reaction: This is a warning to me, because I thought truth and semantics only entered theories at the stage of 'interpretation'. I must go back and get the hang of 'skeletal' truth, which sounds rather charming. [He refers to set theory, not to logic.] |
| 10015 | Higher-order logic may be unintelligible, but it isn't set theory [Hodes] |
| Full Idea: Brand higher-order logic as unintelligible if you will, but don't conflate it with set theory. | |
| From: Harold Hodes (Logicism and Ontological Commits. of Arithmetic [1984], p.131) | |
| A reaction: [he gives Boolos 1975 as a further reference] This is simply a corrective, because the conflation of second-order logic with set theory is an idea floating around in the literature. |
| 10011 | Identity is a level one relation with a second-order definition [Hodes] |
| Full Idea: Identity should he considered a logical notion only because it is the tip of a second-order iceberg - a level 1 relation with a pure second-order definition. | |
| From: Harold Hodes (Logicism and Ontological Commits. of Arithmetic [1984]) |
| 10016 | When an 'interpretation' creates a model based on truth, this doesn't include Fregean 'sense' [Hodes] |
| Full Idea: A model is created when a language is 'interpreted', by assigning non-logical terms to objects in a set, according to a 'true-in' relation, but we must bear in mind that this 'interpretation' does not associate anything like Fregean senses with terms. | |
| From: Harold Hodes (Logicism and Ontological Commits. of Arithmetic [1984], p.131) | |
| A reaction: This seems like a key point (also made by Hofweber) that formal accounts of numbers, as required by logic, will not give an adequate account of the semantics of number-terms in natural languages. |
| 10027 | Mathematics is higher-order modal logic [Hodes] |
| Full Idea: I take the view that (agreeing with Aristotle) mathematics only requires the notion of a potential infinity, ...and that mathematics is higher-order modal logic. | |
| From: Harold Hodes (Logicism and Ontological Commits. of Arithmetic [1984]) | |
| A reaction: Modern 'modal' accounts of mathematics I take to be heirs of 'if-thenism', which seems to have been Russell's development of Frege's original logicism. I'm beginning to think it is right. But what is the subject-matter of arithmetic? |
| 10026 | Arithmetic must allow for the possibility of only a finite total of objects [Hodes] |
| Full Idea: Arithmetic should be able to face boldly the dreadful chance that in the actual world there are only finitely many objects. | |
| From: Harold Hodes (Logicism and Ontological Commits. of Arithmetic [1984], p.148) | |
| A reaction: This seems to be a basic requirement for any account of arithmetic, but it was famously a difficulty for early logicism, evaded by making the existence of an infinity of objects into an axiom of the system. |
| 10021 | It is claimed that numbers are objects which essentially represent cardinality quantifiers [Hodes] |
| Full Idea: The mathematical object-theorist says a number is an object that represents a cardinality quantifier, with the representation relation as the entire essence of the nature of such objects as cardinal numbers like 4. | |
| From: Harold Hodes (Logicism and Ontological Commits. of Arithmetic [1984]) | |
| A reaction: [compressed] This a classic case of a theory beginning to look dubious once you spell it our precisely. The obvious thought is to make do with the numerical quantifiers, and dispense with the objects. Do other quantifiers need objects to support them? |
| 10022 | Numerical terms can't really stand for quantifiers, because that would make them first-level [Hodes] |
| Full Idea: The dogmatic Frege is more right than wrong in denying that numerical terms can stand for numerical quantifiers, for there cannot be a language in which object-quantifiers and objects are simultaneously viewed as level zero. | |
| From: Harold Hodes (Logicism and Ontological Commits. of Arithmetic [1984], p.142) | |
| A reaction: Subtle. We see why Frege goes on to say that numbers are level zero (i.e. they are objects). We are free, it seems, to rewrite sentences containing number terms to suit whatever logical form appeals. Numbers are just quantifiers? |
| 10023 | Talk of mirror images is 'encoded fictions' about real facts [Hodes] |
| Full Idea: Talk about mirror images is a sort of fictional discourse. Statements 'about' such fictions are not made true or false by our whims; rather they 'encode' facts about the things reflected in mirrors. | |
| From: Harold Hodes (Logicism and Ontological Commits. of Arithmetic [1984], p.146) | |
| A reaction: Hodes's proposal for how we should view abstract objects (c.f. Frege and Dummett on 'the equator'). The facts involved are concrete, but Hodes is offering 'encoding fictionalism' as a linguistic account of such abstractions. He applies it to numbers. |
| 14064 | If a statue is identical with the clay of which it is made, that identity is contingent [Gibbard] |
| Full Idea: Under certain conditions a clay statue is identical with the piece of clay of which it is made, and if this is so then the identity is contingent. | |
| From: Allan Gibbard (Contingent Identity [1975], Intro) | |
| A reaction: This initiated the modern debate about statues, and it is an attack on Kripke's claim that if two things are identical, then they are necessarily identical. Kripke seems right about Hesperus and Phosphorus, but not about the statue. |
| 14066 | A 'piece' of clay begins when its parts stick together, separately from other clay [Gibbard] |
| Full Idea: A 'piece' of clay is a portion of clay which comes into existence when all of its parts come to be stuck to each other, and cease to be stuck to any clay which is not a part of the portion. | |
| From: Allan Gibbard (Contingent Identity [1975], I) | |
| A reaction: The sort of gormlessly elementary things that philosophers find themselves having to say, but this is a good basic assertion for a discussion of statue and clay, and I can't think of an objection to it. |
| 14067 | Clay and statue are two objects, which can be named and reasoned about [Gibbard] |
| Full Idea: The piece of clay and the statue are 'objects' - that is to say, they can be designated with proper names, and the logic we ordinarily use will still apply. | |
| From: Allan Gibbard (Contingent Identity [1975], I) | |
| A reaction: An interesting indication of the way that 'object' is used in modern analytic philosophy, which may not be the way that it is used in ordinary English. The number 'seven', for example, seems to be an object by this criterion. |
| 14069 | We can only investigate the identity once we have designated it as 'statue' or as 'clay' [Gibbard] |
| Full Idea: To ask meaningfully what that thing would be, we must designate it either as a statue or as a piece of clay. What that thing would be, apart from the way it is designated, is a question without meaning. | |
| From: Allan Gibbard (Contingent Identity [1975], III) | |
| A reaction: He obviously has a powerful point, but to suggest that we can only investigate a mysterious object once we have designated it as something sounds daft. It would ruin the fun of archaeology. |
| 14076 | Essentialism is the existence of a definite answer as to whether an entity fulfils a condition [Gibbard] |
| Full Idea: Essentialism for a class of entities is that for one entity and a condition which it fulfills, the question of whether it necessarily fulfills the condition has a definite answer apart from the way the entity is specified. | |
| From: Allan Gibbard (Contingent Identity [1975], VII) | |
| A reaction: Yet another definition of essentialism, but resting, as usual in modern discussions, entirely on the notion of necessity. Kit Fine's challenge is that if you investigate the source of the necessity, it turns out to be an essence. |
| 14077 | Essentialism for concreta is false, since they can come apart under two concepts [Gibbard] |
| Full Idea: Essentialism for the class of concrete things is false, since a statue necessarily fulfils a condition as 'Goliath', but only contingently fulfils it as 'lumpl'. On the other hand, essentialism for the class of individual concepts can be true. | |
| From: Allan Gibbard (Contingent Identity [1975], VII) | |
| A reaction: This rests on his definition of essentialism in Idea 14076. He rests his essentialism about concepts on an account given by Carnap ('Meaning and Necessity' §41). The essence of a statue and the essence of a lump of clay do seem distinct. |
| 14070 | A particular statue has sortal persistence conditions, so its origin defines it [Gibbard] |
| Full Idea: A proper name like 'Goliath' denotes a thing in the actual world, and invokes a sortal with certain persistence criteria. Hence its origin makes a statue the statue that it is, and if statues in different worlds have the same beginning, they are the same. | |
| From: Allan Gibbard (Contingent Identity [1975], III) | |
| A reaction: Too neat. There are vague, ambiguous and duplicated origins. Persistence criteria can shift during the existence of a thing (like a club which changes its own constitution). In replicated statues, what is the status of the mould? |
| 14073 | Claims on contingent identity seem to violate Leibniz's Law [Gibbard] |
| Full Idea: The most prominent objection to contingent identity (as in the case of the statue and its clay) is that it violates Leibniz's Law. | |
| From: Allan Gibbard (Contingent Identity [1975], V) | |
| A reaction: Depends what you mean by a property. The trickiest one would be that the statue has (right now) a disposition to be worth a lot, but the clay doesn't. But I don't think that is really a property of the statue. Properties are a muddle. |
| 14065 | Two identical things must share properties - including creation and destruction times [Gibbard] |
| Full Idea: For two things to be strictly identical, they must have all properties in common. That means, among other things, that they must start to exist at the same time and cease to exist at the same time. | |
| From: Allan Gibbard (Contingent Identity [1975], I) | |
| A reaction: I don't accept that coming into existence at time t is a 'property' of a thing. Coincident objects give you the notion of 'existing as' something, which complicates the whole story. |
| 14074 | Leibniz's Law isn't just about substitutivity, because it must involve properties and relations [Gibbard] |
| Full Idea: As a general law of substitutivity of identicals, Leibniz's Law is false. It is a law about properties and relations, that if two things are identical, they have the same properties and relations. It only works in contexts which attribute those. | |
| From: Allan Gibbard (Contingent Identity [1975], V) | |
| A reaction: I'm not convinced about relations, which are not intrinsic properties. Under different descriptions, the relations to human minds might differ. |
| 14072 | Possible worlds identity needs a sortal [Gibbard] |
| Full Idea: Identity across possible worlds makes sense only with respect to a sortal | |
| From: Allan Gibbard (Contingent Identity [1975], IV) | |
| A reaction: See Gibbard's other ideas from this paper. I fear that the sortal invoked is too uncertain and slippery to do any useful job, and I can't see any principled difficulty with naming something before you can think of a sortal for it. |
| 14078 | Only concepts, not individuals, can be the same across possible worlds [Gibbard] |
| Full Idea: It is meaningless to talk of the same concrete thing in different possible worlds, ...but it makes sense to speak of the same individual concept, which is just a function which assigns to each possible world in a set an individual in that world. | |
| From: Allan Gibbard (Contingent Identity [1975], VII) | |
| A reaction: A lovely bold response to the problem of transworld identity, but one which needs investigation. It sounds very promising to me. 'Aristotle' is a cocept, not a name. There is no separate category of 'names'. Wow. (Attach dispositions to concepts?). |
| 14079 | Kripke's semantics needs lots of intuitions about which properties are essential [Gibbard] |
| Full Idea: To use Kripke's semantics, one needs extensive intuitions that certain properties are essential and others accidental. | |
| From: Allan Gibbard (Contingent Identity [1975], X) | |
| A reaction: As usual, we could substitute the word 'necessary' for 'essential' without changing his meaning. If we are always referring to 'our' Hubert Humphrey is speculations about him, then nearly all of his properties will be necessary ones. |
| 20653 | Six reduction levels: groups, lives, cells, molecules, atoms, particles [Putnam/Oppenheim, by Watson] |
| Full Idea: There are six 'reductive levels' in science: social groups, (multicellular) living things, cells, molecules, atoms, and elementary particles. | |
| From: report of H.Putnam/P.Oppenheim (Unity of Science as a Working Hypothesis [1958]) by Peter Watson - Convergence 10 'Intro' | |
| A reaction: I have the impression that fields are seen as more fundamental that elementary particles. What is the status of the 'laws' that are supposed to govern these things? What is the status of space and time within this picture? |
| 14071 | Naming a thing in the actual world also invokes some persistence criteria [Gibbard] |
| Full Idea: The reference of a name in the actual world is fixed partly by invoking a set of persistence criteria which determine what thing it names. | |
| From: Allan Gibbard (Contingent Identity [1975], III) | |
| A reaction: This is offered as a modification to Kripke, to deal with the statue and clay. I fear that the 'persistence criteria' may be too vague, and too subject to possible change after the origin, to do the job required. |