23 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. |
| 19527 | We don't acquire evidence and then derive some knowledge, because evidence IS knowledge [Williamson] |
| Full Idea: When we acquire new evidence in perception, we do not first acquire unknown evidence and then somehow base knowledge on it later. Rather, acquiring new is evidence IS acquiring new knowledge. | |
| From: Timothy Williamson (Knowledge First (and reply) [2014], p.4) | |
| A reaction: This makes his point much better than Idea 19526 does. |
| 19528 | Knowledge is prior to believing, just as doing is prior to trying to do [Williamson] |
| Full Idea: Knowing corresponds to doing, believing to trying. Just as trying is naturally understood in relation to doing, so believing is naturally understood in relation to knowing. | |
| From: Timothy Williamson (Knowledge First (and reply) [2014], p.4) | |
| A reaction: An interesting analogy. You might infer that there can be no concept of 'belief' without the concept of 'knowledge', but we could say that it is 'truth' which is indispensible, and leave out knowledge entirely. Belief is to truth as trying is to doing? |
| 19529 | Belief explains justification, and knowledge explains belief, so knowledge explains justification [Williamson] |
| Full Idea: If justification is the fundamental epistemic norm of belief, and a belief ought to constitute knowledge, then justification should be understood in terms of knowledge too. | |
| From: Timothy Williamson (Knowledge First (and reply) [2014], p.5) | |
| A reaction: If we are looking for the primitive norm which motivates the whole epistemic game, then I am thinking that truth might well play that role better than knowledge. TW would have to reply that it is the 'grasped truth', rather than the 'theoretical truth'. |
| 19530 | A neutral state of experience, between error and knowledge, is not basic; the successful state is basic [Williamson] |
| Full Idea: A neutral state covering both perceiving and misperceiving (or remembering and misrembering) is not somehow more basic than perceiving, for what unifies the case of each neutral state is their relation to the successful state. | |
| From: Timothy Williamson (Knowledge First (and reply) [2014], p.5-6) | |
| A reaction: An alternative is Disjunctivism, which denies the existence of a single neutral state, so that there is nothing to unite the two states, and they don't have a dependence relation. Why can't there be a prior family of appearances, some of them successful? |
| 19531 | Internalism about mind is an obsolete view, and knowledge-first epistemology develops externalism [Williamson] |
| Full Idea: A postulated underlying layer of narrow mental states is a myth, whose plausibility derives from a comfortingly familiar but obsolescent philosophy of mind. Knowledge-first epistemology is a further step in the development of externalism. | |
| From: Timothy Williamson (Knowledge First (and reply) [2014], p.6) | |
| A reaction: Williamson is a real bruiser, isn't he? I don't take internalism about mind to be obsolescent at all, but now I feel so inferior for clinging to such an 'obsolescent' belief. ...But then I cling to Aristotle, who is (no doubt) an obsolete philosopher. |
| 19536 | Knowledge-first says your total evidence IS your knowledge [Williamson] |
| Full Idea: Knowledge-first equate one's total evidence with one's total knowledge. | |
| From: Timothy Williamson (Knowledge First (and reply) [2014], p.8) | |
| A reaction: Couldn't lots of evidence which merely had a high probability be combined together to give a state we would call 'knowledge'? Many dubious witnesses confirm the truth, as long as they are independent, and agree. |
| 19526 | Surely I am acquainted with physical objects, not with appearances? [Williamson] |
| Full Idea: When I ask myself what I am acquainted with, the physical objects in front of me are far more natural candidates than their appearances. | |
| From: Timothy Williamson (Knowledge First (and reply) [2014], p.3) | |
| A reaction: Not very impressive. The word 'acquainted' means the content of the experience, not the phenomena. Do I 'experience' the objects, or the appearances? The answer there is less obvious. If you apply it to colours, it is even less obvious. |
| 18699 | Carnap tried to define all scientific predicates in terms of primitive relations, using type theory [Carnap, by Button] |
| Full Idea: Carnap's ultimate ambition in the Aufbau is to provide a constitution-system within which any predicate of any scientific vocabulary can be explicitly defined in terms of primitive relations holding among basic elements, using type theory. | |
| From: report of Rudolph Carnap (The Logical Structure of the World (Aufbau) [1928]) by Tim Button - The Limits of Reason 05.2 | |
| A reaction: David Chalmers has a modern shot at the same project in 'Constructing the World'. Ramsey sentences seem to be part of the same game. |
| 12131 | All concepts can be derived from a few basics, making possible one science of everything [Carnap, by Brody] |
| Full Idea: In the 'Aufbau', Carnap tried to show how all of our concepts can be derived from a few basic concepts. ..Consequently there can be one science which studied all that existed, the science of the objects corresponding to the basic concepts. | |
| From: report of Rudolph Carnap (The Logical Structure of the World (Aufbau) [1928]) by Baruch Brody - Identity and Essence 2.2 | |
| A reaction: This is Carnap's Constructionist programme. |
| 19534 | How does inferentialism distinguish the patterns of inference that are essential to meaning? [Williamson] |
| Full Idea: Inferentialism faces the grave problem of separating patterns of inference that are to count as essential to the meaning of an expression from those that will count as accidental (a form of the analytic/synthetic distinction). | |
| From: Timothy Williamson (Knowledge First (and reply) [2014], p.6) | |
| A reaction: This sounds like a rather persuasive objection to inferentialism, though I don't personally take that as a huge objection to all internalist semantics. |
| 19535 | Internalist inferentialism has trouble explaining how meaning and reference relate [Williamson] |
| Full Idea: The internalist version of inferentialist semantics has particular difficulty in establishing an adequate relation between meaning and reference. | |
| From: Timothy Williamson (Knowledge First (and reply) [2014], p.6) | |
| A reaction: I would have thought that this was a big problem for referentialist semantics too, though evidently Williamson doesn't think so. If he is saying that the meaning is in the external world, dream on. |
| 19533 | Inferentialist semantics relies on internal inference relations, not on external references [Williamson] |
| Full Idea: On internalist inferential (or conceptual role) semantics, the inferential relations of an expression do not depend on what, if anything, it refers to, ...rather, the meaning is something like its place in a web of inferential relations. | |
| From: Timothy Williamson (Knowledge First (and reply) [2014], p.6) | |
| A reaction: Williamson says the competition is between externalist truth-conditional referential semantics (which he favours), and this internalist inferential semantics. He is, like, an expert, of course, but I doubt whether that is the only internalist option. |
| 19532 | Truth-conditional referential semantics is externalist, referring to worldly items [Williamson] |
| Full Idea: Truth-conditional referential semantics is an externalist programme. In a context of utterance the atomic expressions of a language refer to worldly items, from which the truth-conditions of sentences are compositionally determined. | |
| From: Timothy Williamson (Knowledge First (and reply) [2014], p.6) | |
| A reaction: I just don't see how a physical object can be part of the contents of a sentence. 'Dragons fly' is atomic, and meaningful, but its reference fails. 'The cat is asleep' is just words - it doesn't contain a live animal. |