17 ideas
| 15647 | Truth definitions don't produce a good theory, because they go beyond your current language [Halbach] |
| Full Idea: It is far from clear that a definition of truth can lead to a philosophically satisfactory theory of truth. Tarski's theorem on the undefinability of the truth predicate needs resources beyond those of the language for which it is being defined. | |
| From: Volker Halbach (Axiomatic Theories of Truth (2005 ver) [2005], 1) | |
| A reaction: The idea is that you need a 'metalanguage' for the definition. If I say 'p' is a true sentence in language 'L', I am not making that observation from within language L. The dream is a theory confined to the object language. |
| 15649 | In semantic theories of truth, the predicate is in an object-language, and the definition in a metalanguage [Halbach] |
| Full Idea: In semantic theories of truth (Tarski or Kripke), a truth predicate is defined for an object-language. This definition is carried out in a metalanguage, which is typically taken to include set theory or another strong theory or expressive language. | |
| From: Volker Halbach (Axiomatic Theories of Truth (2005 ver) [2005], 1) | |
| A reaction: Presumably the metalanguage includes set theory because that connects it with mathematics, and enables it to be formally rigorous. Tarski showed, in his undefinability theorem, that the meta-language must have increased resources. |
| 15655 | Should axiomatic truth be 'conservative' - not proving anything apart from implications of the axioms? [Halbach] |
| Full Idea: If truth is not explanatory, truth axioms should not allow proof of new theorems not involving the truth predicate. It is hence said that axiomatic truth should be 'conservative' - not implying further sentences beyond what the axioms can prove. | |
| From: Volker Halbach (Axiomatic Theories of Truth (2005 ver) [2005], 1.3) | |
| A reaction: [compressed] |
| 15654 | If truth is defined it can be eliminated, whereas axiomatic truth has various commitments [Halbach] |
| Full Idea: If truth can be explicitly defined, it can be eliminated, whereas an axiomatized notion of truth may bring all kinds of commitments. | |
| From: Volker Halbach (Axiomatic Theories of Truth (2005 ver) [2005], 1.3) | |
| A reaction: The general principle that anything which can be defined can be eliminated (in an abstract theory, presumably, not in nature!) raises interesting questions about how many true theories there are which are all equivalent to one another. |
| 15650 | Axiomatic theories of truth need a weak logical framework, and not a strong metatheory [Halbach] |
| Full Idea: Axiomatic theories of truth can be presented within very weak logical frameworks which require very few resources, and avoid the need for a strong metalanguage and metatheory. | |
| From: Volker Halbach (Axiomatic Theories of Truth (2005 ver) [2005], 1) |
| 15648 | Instead of a truth definition, add a primitive truth predicate, and axioms for how it works [Halbach] |
| Full Idea: The axiomatic approach does not presuppose that truth can be defined. Instead, a formal language is expanded by a new primitive predicate of truth, and axioms for that predicate are then laid down. | |
| From: Volker Halbach (Axiomatic Theories of Truth (2005 ver) [2005], 1) | |
| A reaction: Idea 15647 explains why Halbach thinks the definition route is no good. |
| 15656 | Deflationists say truth merely serves to express infinite conjunctions [Halbach] |
| Full Idea: According to many deflationists, truth serves merely the purpose of expressing infinite conjunctions. | |
| From: Volker Halbach (Axiomatic Theories of Truth (2005 ver) [2005], 1.3) | |
| A reaction: That is, it asserts sentences that are too numerous to express individually. It also seems, on a deflationist view, to serve for anaphoric reference to sentences, such as 'what she just said is true'. |
| 8250 | So-called 'free logic' operates without existence assumptions [Meinong, by George/Van Evra] |
| Full Idea: Meinong has recently been credited with inspiring 'free logic': a logic without existence assumptions. | |
| From: report of Alexius Meinong (The Theory of Objects [1904]) by George / Van Evra - The Rise of Modern Logic 8 | |
| A reaction: This would appear to be a bold escape from the quandries concerning the existential implications of quantifiers. I immediately find it very appealing. It seems to spell disaster for the Quinean program of deducing ontology from language. |
| 15657 | To prove the consistency of set theory, we must go beyond set theory [Halbach] |
| Full Idea: The consistency of set theory cannot be established without assumptions transcending set theory. | |
| From: Volker Halbach (Axiomatic Theories of Truth (2005 ver) [2005], 2.1) |
| 15652 | We can use truth instead of ontologically loaded second-order comprehension assumptions about properties [Halbach] |
| Full Idea: The reduction of 2nd-order theories (of properties or sets) to axiomatic theories of truth may be conceived as a form of reductive nominalism, replacing existence assumptions (for comprehension axioms) by ontologically innocent truth assumptions. | |
| From: Volker Halbach (Axiomatic Theories of Truth (2005 ver) [2005], 1.1) | |
| A reaction: I like this very much, as weeding properties out of logic (without weeding them out of the world). So-called properties in logic are too abundant, so there is a misfit with their role in science. |
| 15651 | Instead of saying x has a property, we can say a formula is true of x - as long as we have 'true' [Halbach] |
| Full Idea: Quantification over (certain) properties can be mimicked in a language with a truth predicate by quantifying over formulas. Instead of saying that Tom has the property of being a poor philosopher, we can say 'x is a poor philosopher' is true of Tom. | |
| From: Volker Halbach (Axiomatic Theories of Truth (2005 ver) [2005], 1.1) | |
| A reaction: I love this, and think it is very important. He talks of 'mimicking' properties, but I see it as philosophers mistakenly attributing properties, when actually what they were doing is asserting truths involving certain predicates. |
| 8719 | There can be impossible and contradictory objects, if they can have properties [Meinong, by Friend] |
| Full Idea: Meinong (and Priest) leave room for impossible objects (like a mountain made entirely of gold), and even contradictory objects (such as a round square). This would have a property, of 'being a contradictory object'. | |
| From: report of Alexius Meinong (The Theory of Objects [1904]) by Michèle Friend - Introducing the Philosophy of Mathematics 6.8 | |
| A reaction: This view is only possible with a rather lax view of properties. Personally I don't take 'being a pencil' to be a property of a pencil. It might be safer to just say that 'round squares' are possible linguistic subjects of predication. |
| 8971 | There are objects of which it is true that there are no such objects [Meinong] |
| Full Idea: There are objects of which it is true that there are no such objects. | |
| From: Alexius Meinong (The Theory of Objects [1904]), quoted by Peter van Inwagen - Existence,Ontological Commitment and Fictions p.131 | |
| A reaction: Van Inwagen say this idea is 'infamous', but Meinong is undergoing a revival, and commitment to non-existent objects may be the best explanation of some ways of talking. |
| 8718 | Meinong says an object need not exist, but must only have properties [Meinong, by Friend] |
| Full Idea: Meinong distinguished between 'existing objects' and 'subsisting objects', and being an object does not imply existence, but only 'having properties'. | |
| From: report of Alexius Meinong (The Theory of Objects [1904]) by Michèle Friend - Introducing the Philosophy of Mathematics 6.8 | |
| A reaction: Meinong is treated as a joke (thanks to Russell), but this is good. "Father Christmas does not exist, but he has a red coat". He'd better have some sort of existy aspect if he is going to have a property. So he's 'an object'. 'Insubstantial'? |
| 7756 | Meinong said all objects of thought (even self-contradictions) have some sort of being [Meinong, by Lycan] |
| Full Idea: Meinong insisted (à la Anselm) that any possible object of thought - even a self-contradictory one - has being of a sort even though only a few such things are so lucky as to exist in reality as well. | |
| From: report of Alexius Meinong (The Theory of Objects [1904]) by William Lycan - Philosophy of Language Ch.1 | |
| A reaction: ['This idea gave Russell fits' says Lycan]. In the English-speaking world this is virtually the only idea for which Meinong is remembered. Russell (Idea 5409) was happy for some things to merely 'subsist' as well as others which could 'exist'. |
| 15781 | The objects of knowledge are far more numerous than objects which exist [Meinong] |
| Full Idea: The totality of what exists, including what has existed and what will exist, is infinitely small in comparison with the totality of Objects of knowledge. | |
| From: Alexius Meinong (The Theory of Objects [1904]), quoted by William Lycan - The Trouble with Possible Worlds 01 | |
| A reaction: This is rather profound, but the word 'object' doesn't help. I would say 'What we know concerns far more than what merely exists'. |
| 22628 | Substance has to exist, with no intrinsic qualities or relations [McTaggart] |
| Full Idea: Something must exist, then, and have qualities, without being itself either a quality or a relation. And this is Substance. | |
| From: J.M.E. McTaggart (The Nature of Existence vol.1 [1921], §67), quoted by R.D. Ingthorsson - A Powerful Particulars View of Causation 7.2 | |
| A reaction: Ingthorsson quotes this as 'the most extreme analytic view', which is a long way from the Aristotelian view. This is the implausible bare substrate. |