18 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'. |
| 17990 | Instances of minimal truth miss out propositions inexpressible in current English [Hofweber] |
| Full Idea: A standard objection to minimalist truth is the 'incompleteness objection'. Since there are propositions inexpressible in present English the concept of truth isn't captured by all the instances of the Tarski biconditional. | |
| From: Thomas Hofweber (Inexpressible Properties and Propositions [2006], 5.3) | |
| A reaction: Sounds like a good objection. |
| 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. |
| 17988 | Quantification can't all be substitutional; some reference is obviously to objects [Hofweber] |
| Full Idea: The view that all quantification is substitutional is not very plausible in general. Some uses of quantifiers clearly seem to have the function to make a claim about a domain of objects out there, no matter how they relate to the terms in our language. | |
| From: Thomas Hofweber (Inexpressible Properties and Propositions [2006], 2.1) | |
| A reaction: Robust realists like myself are hardly going to say that quantification is just an internal language game. |
| 17989 | Since properties have properties, there can be a typed or a type-free theory of them [Hofweber] |
| Full Idea: Since properties themselves can have properties there is a well-known division in the theory of properties between those who take a typed and those who take a type-free approach. | |
| From: Thomas Hofweber (Inexpressible Properties and Propositions [2006], 2.2) | |
| A reaction: A typed approach would imply restrictions on what it can be a property of. 'Green' is a property of surfaces, 'dark' is a property of colours. My first reaction is to opt for type-free. |
| 17991 | Holism says language can't be translated; the expressibility hypothesis says everything can [Hofweber] |
| Full Idea: Holism says that nothing that can be said in one language can be said in another one. The expressibility hypothesis says that everything that can be said in one language can be said in every other one. | |
| From: Thomas Hofweber (Inexpressible Properties and Propositions [2006], 6.4) | |
| A reaction: Obviously expressibility would only refer to reasonably comprehensive languages (with basic logical connectives, for example). Personally I vote for the expressibility hypothesis, which Hofweber seems to favour. |
| 4581 | Virtues and vices are like secondary qualities in perception, found in observers, not objects [Hume] |
| Full Idea: Vice and virtue may be compared to sounds, colours, heat and cold, which, according to modern philosophy, are not qualities in objects but perceptions in the mind. | |
| From: David Hume (Letters [1739], to Hutcheson 1740) | |
| A reaction: Very revealing about the origin of the is/ought idea, but this is an assertion rather than an argument. Most Greeks treat value as a primary quality of things (e.g. life, harmony, beauty, health). |
| 4580 | All virtues benefit either the public, or the individual who possesses them [Hume] |
| Full Idea: I desire you to consider if there be any quality that is virtuous, without having a tendency either to the public good or to the good of the person who possesses it. | |
| From: David Hume (Letters [1739], to Hutcheson 1739) | |
| A reaction: Obviously this is generally true. How, though, does it benefit the individual to secretly preserve their integrity? I go round to visit a friend to repay a debt; I am told they have died; I quietly leave some money on the table and leave. Why? |
| 4579 | The idea of a final cause is very uncertain and unphilosophical [Hume] |
| Full Idea: Your sense of 'natural' is founded on final causes, which is a consideration that appears to me pretty uncertain and unphilosophical. | |
| From: David Hume (Letters [1739], to Hutcheson 1739) | |
| A reaction: This is the rejection of Aristotelian teleology by modern science. I agree that the notion of utterly ultimate final cause is worse than 'uncertain' - it is an impossible concept. Nevertheless, I prefer Aristotle to Hume. Nature can teach us lessons. |
| 20705 | That events could be uncaused is absurd; I only say intuition and demonstration don't show this [Hume] |
| Full Idea: I never asserted so absurd a proposition as that anything might arise without a cause: I only maintained that our certainty of the falsehood of that proposition proceeded neither from intuition nor from demonstration, but from another source. | |
| From: David Hume (Letters [1739], 1754), quoted by Brian Davies - Introduction to the Philosophy of Religion 5 'God' | |
| A reaction: Since the other source is habit, he is being a bit disingenuous. While rational intuition and demonstration give a fairly secure basis for the universality of causation, mere human habits of expectation give very feeble grounds. |