20 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. |
| 2590 | Dispositions need mental terms to define them [Putnam] |
| Full Idea: The chief difficulty with the behaviour-disposition account is the virtual impossibility of specifying a disposition except as a 'disposition of x to behave as though x were in pain'. | |
| From: Hilary Putnam (The Nature of Mental States [1968], p.57) | |
| A reaction: This has become the best-known objection to behaviourism - that you can't specify a piece of behaviour clearly unless you mention the mental state which it is expressing. The defence is to go on endlessly mentioning further behaviour. |
| 3161 | If mind is just an explanation, the explainer must have beliefs [Rey on Dennett] |
| Full Idea: If something has beliefs only if something else is disposed to "treat it" (i.e. think of it) as though it does, then we seem at least to have an infinite regress of appeals to believers. | |
| From: comment on Daniel C. Dennett (works [1985]) by Georges Rey - Contemporary Philosophy of Mind 3.2.1 | |
| A reaction: This sounds like a serious difficulty for behaviourists, but is not insurmountable. We need a community of interlocking behaviours, with a particular pattern of behaviour being labelled (for instrumental convenience) as 'beliefs'. |
| 2591 | Total paralysis would mean that there were mental states but no behaviour at all [Putnam] |
| Full Idea: Two animals with all motor nerves cut will have the same actual and potential behaviour (i.e. none), but if only one has uncut pain fibres, it will feel pain where the other won't. | |
| From: Hilary Putnam (The Nature of Mental States [1968], p.57) | |
| A reaction: This is a splendidly literal and practical argument against behaviourism - if you prevent all the behaviour, you don't thereby prevent the experience. Clearly we have to say something about what is inside the 'black box' of the mind. |
| 2588 | Is pain a functional state of a complete organism? [Putnam] |
| Full Idea: I propose the hypothesis that pain, or the state of being in pain, is a functional state of a whole organism. | |
| From: Hilary Putnam (The Nature of Mental States [1968], p.54) | |
| A reaction: This sounds wrong right from the start. Pain hurts. The fact that it leads to avoidance behaviour etc. seems much more like a by-product of pain than its essence. |
| 2589 | Functionalism is compatible with dualism, as pure mind could perform the functions [Putnam] |
| Full Idea: The functional-state hypothesis is not incompatible with dualism, as a system consisting of a body and a soul could meet the required conditions. | |
| From: Hilary Putnam (The Nature of Mental States [1968], p.55) | |
| A reaction: He doesn't really believe this, of course. This claim led to all the weak objections to functionalism involving silly implementations of minds. A brain is the only plausible way to implement our mental functions. |
| 2592 | Functional states correlate with AND explain pain behaviour [Putnam] |
| Full Idea: The presence of a certain functional state is not merely 'correlated with' but actually explains the pain behaviour on the part of the organism. | |
| From: Hilary Putnam (The Nature of Mental States [1968], p.58) | |
| A reaction: Does it offer any further explanation beyond saying that it is the brain state that causes the behaviour? The pain is just a link between damage and avoidance. I wish that is all that pain was. |
| 2587 | Temperature is mean molecular kinetic energy, but they are two different concepts [Putnam] |
| Full Idea: The concept of temperature is not the same as the concept of mean molecular kinetic energy. But temperature is mean molecular kinetic energy. | |
| From: Hilary Putnam (The Nature of Mental States [1968], p.52) | |
| A reaction: This is the standard analogy for mind-brain identity, and it seems fair enough to me. The mind is the activity of the brain. It is rather unhelpful to think of weather in terms of chemistry, but it is actions of chemicals. |
| 6376 | Neuroscience does not support multiple realisability, and tends to support identity [Polger on Putnam] |
| Full Idea: Putnam was too quick to assert neuroscientific support for multiple realizability; current evidence does not reveal it, and there is some reason to think the enterprises of neuroscience are premised on the hypothesis of brain-state identity. | |
| From: comment on Hilary Putnam (The Nature of Mental States [1968]) by Thomas W. Polger - Natural Minds Ch.1.4 | |
| A reaction: I have always been suspicious of the glib claim that mental states were multiply realisable. I see no reason to think that octupi see colours as we do, or experience fear as we do, even though their behaviour has to be similar, for survival. |
| 2330 | If humans and molluscs both feel pain, it can't be a single biological state [Putnam, by Kim] |
| Full Idea: Mental states have vastly diverse physical/biological realizations in different species and structures (e.g. pain in humans and in molluscs), so no mental state can be identified with any single physical/biological state. | |
| From: report of Hilary Putnam (The Nature of Mental States [1968]) by Jaegwon Kim - Mind in a Physical World n p.120 | |
| A reaction: But maybe mollusc and human nervous systems ARE the same in the respects that matter. We don't know enough about pain to deny that possibility. |
| 3177 | You couldn't drive a car without folk psychology [Dennett] |
| Full Idea: Folk psychology is indispensable for driving a car, which would be terrifying if we didn't assume there were psychologically normal people behind the wheels. | |
| From: Daniel C. Dennett (works [1985]), quoted by Georges Rey - Contemporary Philosophy of Mind p.133 n35 | |
| A reaction: Nice example. If someone is approaching you from the front on your side of the road, should you assume that they are 'psychologically normal'? Does psychology imply behaviour, or vice versa? |