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'. |
| 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. |
| 6417 | In 1921 Russell abandoned sense-data, and the gap between sensation and object [Russell, by Grayling] |
| Full Idea: In 'The Analysis of Mind' Russell gave up talk of 'sense-data', and ceased to distinguish between the act of sensing and what is sensed. | |
| From: report of Bertrand Russell (The Analysis of Mind [1921]) by A.C. Grayling - Russell Ch.2 | |
| A reaction: This seems to lead towards the modern 'adverbial' account of sensing, where I don't sense 'data', but where qualia (such as redness) are our particular mode of directly perceiving objects, where insects might directly perceive them in a different mode. |
| 6474 | Seeing is not in itself knowledge, but is separate from what is seen, such as a patch of colour [Russell] |
| Full Idea: Undeniably, knowledge comes through seeing, but it is a mistake to regard the mere seeing itself as knowledge; if we are so to regard it, we must distinguish the seeing from what is seen; a patch of colour is one thing, and our seeing it is another. | |
| From: Bertrand Russell (The Analysis of Mind [1921], Lec. VIII) | |
| A reaction: This is Russell's 1921 explanation of why he adopted sense-data (but he rejects them later in this paragraph). This gives a simplistic impression of what he intended, which has three components: the object, the 'sensibile', and the sense-datum. |
| 6476 | We cannot assume that the subject actually exists, so we cannot distinguish sensations from sense-data [Russell] |
| Full Idea: If we are to avoid a perfectly gratuitous assumption, we must dispense with the subject as one of the actual ingredients of the world; but when we do this, the possibility of distinguishing the sensation from the sense-datum vanishes. | |
| From: Bertrand Russell (The Analysis of Mind [1921], Lec. VIII) | |
| A reaction: This is the reason why Russell himself rejected sense-data. It is more normal, I think, to reject them simply as being superfluous. If the subject can simply perceive the sense-data, why can't they just perceive the object more directly? |
| 2792 | It is possible the world came into existence five minutes ago, complete with false memories [Russell] |
| Full Idea: There is no logical impossibility in the hypothesis that the world sprang into being five minutes ago, exactly as it then was, with a population that "remembered" a wholly unreal past. | |
| From: Bertrand Russell (The Analysis of Mind [1921], p.159) | |
| A reaction: One of the great sceptical arguments! At a stroke it undermines forever any dreams that memories are totally certain. This is an extra scepticism, which arises if you decide that current experience IS totally certain. |
| 22326 | Knowledge needs more than a sensitive response; the response must also be appropriate [Russell] |
| Full Idea: Accuracy of response to stimulus does not alone show knowledge, but must be reinforced by appropriateness, i.e. suitability of realising one's purpose. | |
| From: Bertrand Russell (The Analysis of Mind [1921], p.261), quoted by Michael Potter - The Rise of Analytic Philosophy 1879-1930 66 'Rel' | |
| A reaction: The aim of 'realising one's purpose' puts a very pragmatist spin on this. The point is a good one, and seems to apply particularly to Nozick's accurate 'tracking' account of knowledge. |
| 6475 | In perception, the self is just a logical fiction demanded by grammar [Russell] |
| Full Idea: In perception, the idea of the subject appears to be a logical fiction, like mathematical points and instants; it is introduced, not because observation reveals it, but because it is linguistically convenient and apparently demanded by grammar. | |
| From: Bertrand Russell (The Analysis of Mind [1921], Lec. VIII) | |
| A reaction: In 1912, Russell had felt that both the Cogito, and the experience of meta-thought, had confirmed the existence of a non-permanent ego, but here he offers a Humean rejection. His notion of a 'logical fiction' is behaviouristic. I believe in the Self. |
| 20746 | One is not born, but rather becomes a woman [Beauvoir] |
| Full Idea: One is not born, but rather becomes a woman. | |
| From: Simone de Beauvoir (The Second Sex [1952], p.301 (or 267)), quoted by Kevin Aho - Existentialism: an introduction 2 'Phenomenology' | |
| A reaction: This has become the principle idea in modern discussions of gender. It divides gender from sex, rather as Locke divided person from human being. It is an abstraction. It is part of the Hegelian-Marxist idea that persons are moulded by culture. |