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. |
| 14330 | To be realists about dispositions, we can only discuss them through their categorical basis [Armstrong] |
| Full Idea: It is only to the extent that we relate disposition to 'categorical basis', and difference of disposition to difference of 'categorical basis', that we can speak of dispositions. We must be Realists, not Phenomenalists, about dispositions. | |
| From: David M. Armstrong (A Materialist Theory of Mind (Rev) [1968], 6.VI) | |
| A reaction: It is Armstrong's realism which motivates this claim, because he thinks only categorical properties are real. But categorical properties seem to be passive, and the world is active. |
| 22142 | In future, only logical limits can be placed on divine omnipotence [Anon (Par), by Boulter] |
| Full Idea: The Condemnation stipulated that all portions of the ancient intellectual heritage that placed non-logical limits on divine omnipotence were no longer to be tolerated. ...Philosophers now had to entertain the wildest ideas with all seriousness. | |
| From: report of Anon (Par) (The Condemnation of 1277 [1277]) by Stephen Boulter - Why Medieval Philosophy Matters 3 | |
| A reaction: Boulter identifies this as 'the ultimate source of Hume's philosophical delirium'. Presumably the angels-on-a-pinhead stuff originated with this. It is crazy to think that the only limit on possible existence is logic. Can God make a planet of uranium? |
| 6498 | Armstrong suggests secondary qualities are blurred primary qualities [Armstrong, by Robinson,H] |
| Full Idea: According to D.M. Armstrong and others, when we perceive secondary qualities we are in fact perceiving primary qualities in a confused, indistinct or blurred way. | |
| From: report of David M. Armstrong (A Materialist Theory of Mind (Rev) [1968], 270-90) by Howard Robinson - Perception III.1 | |
| A reaction: This is obviously an attempt to fit secondary qualities into a reductive physicalist account of the mind. Personally I favour Armstrong's project, but doubt whether this strategy is necessary. I just don't think there is anything 'primary' about redness. |
| 16716 | It is heresy to require self-evident foundational principles in order to be certain [Anon (Par)] |
| Full Idea: Heresy 151: 'To have certainty regarding any conclusion, it must be founded on self-evident principles'. | |
| From: Anon (Par) (The Condemnation of 1277 [1277], 151), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 20.3 | |
| A reaction: The correct view is obviously to found certainty on faith and authority. It is one thing to be told that foundationalism is a poor theory, but another to be told it is a heresy, and thus a potential capital crime! |
| 5690 | A mental state without belief refutes self-intimation; a belief with no state refutes infallibility [Armstrong, by Shoemaker] |
| Full Idea: For Armstrong, introspection involves a belief, and mental states and their accompanying beliefs are 'distinct existences', so a state without belief shows states are not self-intimating, and the belief without the state shows beliefs aren't infallible. | |
| From: report of David M. Armstrong (A Materialist Theory of Mind (Rev) [1968]) by Sydney Shoemaker - Introspection | |
| A reaction: I agree with Armstrong. Introspection is a two-level activity, which animals probably can't do, and there is always the possibility of a mismatch between the two levels, so introspection is neither self-intimating nor infallibe (though incorrigible). |
| 5493 | If pains are defined causally, and research shows that the causal role is physical, then pains are physical [Armstrong, by Lycan] |
| Full Idea: Armstrong and Lewis said that mental items were defined in terms of typical causes and effects; if, as seems likely, research reveals that a particular causal niche is occupied by a physical state, it follows that pain is a physical state. | |
| From: report of David M. Armstrong (A Materialist Theory of Mind (Rev) [1968]) by William Lycan - Introduction - Ontology p.5 | |
| A reaction: I am not fully convinced of the first step in the argument. It sounds like the epistemology and the ontology have got muddled (as usual). We define mental states as we define electrons, in terms of observed behaviour, but what are they? |
| 4600 | Armstrong and Lewis see functionalism as an identity of the function and its realiser [Armstrong, by Heil] |
| Full Idea: The Armstrong/Lewis version of functionalism takes mental properties to be functional properties, but identifies these with what other functionalists would regard as their realisers. | |
| From: report of David M. Armstrong (A Materialist Theory of Mind (Rev) [1968]) by John Heil - Philosophy of Mind Ch.4 | |
| A reaction: Heil rejects this, but I am beginning to think that this is the answer. If functions do not have an ontological life of their own (the 'ringing' of the bell), then functionalist mental states can't either. Function is not an ontological category. |
| 1866 | It is heresy to teach that history repeats every 36,000 years [Anon (Par)] |
| Full Idea: It is heresy to teach that with all the heavenly bodies coming back to the same point after a period of thirty-six thousand years, the same effects as now exist will reappear. | |
| From: Anon (Par) (The Condemnation of 1277 [1277], §92) |
| 1865 | It is heresy to teach that natural impossibilities cannot even be achieved by God [Anon (Par)] |
| Full Idea: It is heresy to teach that what is absolutely impossible according to nature cannot be brought about by God or another agent. | |
| From: Anon (Par) (The Condemnation of 1277 [1277], §17) |
| 1864 | It is heresy to teach that we can know God by his essence in this mortal life [Anon (Par)] |
| Full Idea: It is heresy to teach that we can know God by his essence in this mortal life. | |
| From: Anon (Par) (The Condemnation of 1277 [1277], §9) |