19125
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If we define truth, we can eliminate it [Halbach/Leigh]
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Full Idea:
If truth can be explicitly defined, it can be eliminated.
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From:
Halbach,V/Leigh,G.E. (Axiomatic Theories of Truth (2013 ver) [2013], 1.3)
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A reaction:
That we could just say p corresponds to the facts, or p coheres with our accepted beliefs, or p is the aim of our enquiries, and never mention the word 'true'. Definition is a strategy for reduction or elimination.
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19076
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Coherence theories differ over the coherence relation, and over the set of proposition with which to cohere [Young,JO]
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Full Idea:
Coherence theories of truth differ on their accounts of the coherence relation, and on their accounts of the set (or sets) of propositions with which true propositions occur (the 'specified set').
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From:
James O. Young (The Coherence Theory of Truth [2013], §1)
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A reaction:
Coherence is clearly more than consistency or mutual entailment, and I like to invoke explanation. The set has to be large, or the theory is absurd (as two absurdities can 'cohere'). So very large, or very very large, or maximally large?
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19077
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Two propositions could be consistent with your set, but inconsistent with one another [Young,JO]
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Full Idea:
It is unsatisfactory for the coherence relation to be consistency, because two propositions could be consistent with a 'specified set', and yet be inconsistent with each other. That would imply they are both true, which is impossible.
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From:
James O. Young (The Coherence Theory of Truth [2013], §1)
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A reaction:
I'm not convinced by this. You first accept P because it is consistent with the set; then Q turns up, which is consistent with everything in the set except P. So you have to choose between them, and might eject P. Your set was too small.
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19078
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Coherence with actual beliefs, or our best beliefs, or ultimate ideal beliefs? [Young,JO]
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Full Idea:
One extreme for the specified set is the largest consistent set of propositions currently believed by actual people. A moderate position makes it the limit of people's enquiries. The other extreme is what would be believed by an omniscient being.
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From:
James O. Young (The Coherence Theory of Truth [2013], §1)
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A reaction:
One not considered is the set of propositions believed by each individual person. Thoroughgoing relativists might well embrace that one. Peirce and Putnam liked the moderate one. I'm taken with the last one, since truth is an ideal, not a phenomenon.
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19127
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The T-sentences are deductively weak, and also not deductively conservative [Halbach/Leigh]
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Full Idea:
Although the theory is materially adequate, Tarski thought that the T-sentences are deductively too weak. …Also it seems that the T-sentences are not conservative, because they prove in PA that 0=0 and ¬0=0 are different, so at least two objects exist.
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From:
Halbach,V/Leigh,G.E. (Axiomatic Theories of Truth (2013 ver) [2013], 3.2)
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A reaction:
They are weak because they can't prove completeness. This idea give two reasons for looking for a better theory of truth.
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19124
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A natural theory of truth plays the role of reflection principles, establishing arithmetic's soundness [Halbach/Leigh]
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Full Idea:
If a natural theory of truth is added to Peano Arithmetic, it is not necessary to add explicity global reflection principles to assert soundness, as the truth theory proves them. Truth theories thus prove soundess, and allows its expression.
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From:
Halbach,V/Leigh,G.E. (Axiomatic Theories of Truth (2013 ver) [2013], 1.2)
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A reaction:
This seems like a big attraction of axiomatic theories of truth for students of metamathematics.
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19126
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If deflationary truth is not explanatory, truth axioms should be 'conservative', proving nothing new [Halbach/Leigh]
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Full Idea:
If truth does not have any explanatory force, as some deflationists claim, the axioms of truth should not allow us to prove any new theorems that do not involve the truth predicate. That is, a deflationary axiomatisation of truth should be 'conservative'.
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From:
Halbach,V/Leigh,G.E. (Axiomatic Theories of Truth (2013 ver) [2013], 1.3)
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A reaction:
So does truth have 'explanatory force'? These guys are interested in explaining theorems of arithmetic, but I'm more interested in real life. People do daft things because they have daft beliefs. Logic should be neutral, but truth has values?
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19129
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The FS axioms use classical logical, but are not fully consistent [Halbach/Leigh]
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Full Idea:
It is a virtue of the Friedman-Sheard axiomatisation that it is thoroughly classical in its logic. Its drawback is that it is ω-inconsistent. That is, it proves &exists;x¬φ(x), but proves also φ(0), φ(1), φ(2), …
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From:
Halbach,V/Leigh,G.E. (Axiomatic Theories of Truth (2013 ver) [2013], 4.3)
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A reaction:
It seems the theory is complete (and presumably sound), yet not fully consistent. FS also proves the finite levels of Tarski's hierarchy, but not the transfinite levels.
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19130
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KF is formulated in classical logic, but describes non-classical truth, which allows truth-value gluts [Halbach/Leigh]
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Full Idea:
KF is formulated in classical logic, but describes a non-classical notion of truth. It allow truth-value gluts, making some sentences (such as the Liar) both true and not-true. Some authors add an axiom ruling out such gluts.
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From:
Halbach,V/Leigh,G.E. (Axiomatic Theories of Truth (2013 ver) [2013], 4.4)
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A reaction:
[summary, which I hope is correct! Stanford is not wholly clear]
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19121
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We can reduce properties to true formulas [Halbach/Leigh]
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Full Idea:
One might say that 'x is a poor philosopher' is true of Tom instead of saying that Tom has the property of being a poor philosopher. We quantify over formulas instead of over definable properties, and thus reduce properties to truth.
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From:
Halbach,V/Leigh,G.E. (Axiomatic Theories of Truth (2013 ver) [2013], 1.1)
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A reaction:
[compressed] This stuff is difficult (because the axioms are complex and hard to compare), but I am excited (yes!) about this idea. Their point is that you need a truth predicate within the object language for this, which disquotational truth forbids.
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19074
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Are truth-condtions other propositions (coherence) or features of the world (correspondence)? [Young,JO]
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Full Idea:
For the coherence theory of truth, the truth conditions of propositions consist in other propositions. The correspondence theory, in contrast, states that the truth conditions of propositions are ... objective features of the world.
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From:
James O. Young (The Coherence Theory of Truth [2013], Intro)
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A reaction:
It is obviously rather important for your truth-conditions theory of meaning that you are clear about your theory of truth. A correspondence theory is evidently taken for granted, even in possible worlds versions.
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19082
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Coherence truth suggests truth-condtions are assertion-conditions, which need knowledge of justification [Young,JO]
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Full Idea:
Coherence theorists can argue that the truth conditions of a proposition are those under which speakers tend to assert it, ...and that speakers can only make a practice of asserting a proposition under conditions they can recognise as justifying it.
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From:
James O. Young (The Coherence Theory of Truth [2013], §2.2)
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A reaction:
[compressed] This sounds rather verificationist, and hence wrong, since if you then asserted anything for which you didn't know the justification, that would remove its truth, and thus make it meaningless.
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