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All the ideas for 'Mathematical Methods in Philosophy', 'Continuity and Irrational Numbers' and 'Truth (2nd edn)'

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25 ideas

3. Truth / A. Truth Problems / 1. Truth
The function of the truth predicate? Understanding 'true'? Meaning of 'true'? The concept of truth? A theory of truth? [Horwich]
     Full Idea: We must distinguish the function of the truth predicate, what it is to understand 'true', the meaning of 'true', grasping the concept of truth, and a theory of truth itself.
     From: Paul Horwich (Truth (2nd edn) [1990], Ch.2.8)
     A reaction: It makes you feel tired to think about it. Presumably every other philosophical analysis has to do this many jobs. Clearly Horwich wants to propose one account which will do all five jobs. Personally I don't believe these five are really distinct.
3. Truth / C. Correspondence Truth / 1. Correspondence Truth
Some correspondence theories concern facts; others are built up through reference and satisfaction [Horwich]
     Full Idea: One correspondence theory (e.g. early Wittgenstein) concerns representations and facts; alternatively (Tarski, Davidson) the category of fact is eschewed, and the truth of sentences or propositions is built out of relations of reference and satisfaction.
     From: Paul Horwich (Truth (2nd edn) [1990], Ch.7.35)
     A reaction: A helpful distinction. Clearly the notion of a 'fact' is an elusive one ("how many facts are there in this room?"), so it seems quite promising to say that the parts of the sentence correspond, rather than the whole thing.
3. Truth / C. Correspondence Truth / 3. Correspondence Truth critique
The common-sense theory of correspondence has never been worked out satisfactorily [Horwich]
     Full Idea: The common-sense notion that truth is a kind of 'correspondence with the facts' has never been worked out to anyone's satisfaction.
     From: Paul Horwich (Truth (2nd edn) [1990], Ch.1)
     A reaction: I've put this in to criticise it. Philosophy can't work by rejecting theories which can't be 'worked out', and accepting theories (like Tarski's) because they can be 'worked out'. All our theories will end up minimal, and defiant of common sense.
3. Truth / H. Deflationary Truth / 1. Redundant Truth
The redundancy theory cannot explain inferences from 'what x said is true' and 'x said p', to p [Horwich]
     Full Idea: The redundancy theory is unable to account for the inference from "Oscar's claim is true" and "Oscar's claim is that snow is white" to "the proposition 'that snow is white' is true", and hence to "snow is white".
     From: Paul Horwich (Truth (2nd edn) [1990], Ch.2.9)
     A reaction: Earlier objections appealed to the fact that the word 'true' seemed to have a use in ordinary speech, but this seems a much stronger one. In general, showing the role of a term in making inferences pins it down better than ordinary speech does.
3. Truth / H. Deflationary Truth / 2. Deflationary Truth
Horwich's deflationary view is novel, because it relies on propositions rather than sentences [Horwich, by Davidson]
     Full Idea: Horwich's brave and striking move is to make the primary bearers of truth propositions - not exactly a new idea in itself, but new in the context of a serious attempt to defend deflationism.
     From: report of Paul Horwich (Truth (2nd edn) [1990]) by Donald Davidson - The Folly of Trying to Define Truth p.30
     A reaction: Davidson rejects propositions because they can't be individuated, but I totally accept propositions. I'm puzzled why this would produce a deflationist theory, since I think it points to a much more robust view.
No deflationary conception of truth does justice to the fact that we aim for truth [Horwich]
     Full Idea: It has been suggested that no deflationary conception of truth could do justice to the fact that we aim for the truth.
     From: Paul Horwich (Truth (2nd edn) [1990], Ch.2.11)
     A reaction: (He mentions Dummett and Wright). People don't only aim for it - they become very idealistic about it, and sometimes die for it. Personally I think that any study of truth should use as its example police investigations, not philosophical analysis.
The deflationary picture says believing a theory true is a trivial step after believing the theory [Horwich]
     Full Idea: According to the deflationary picture, believing that a theory is true is a trivial step beyond believing the theory.
     From: Paul Horwich (Truth (2nd edn) [1990], Ch.2.17)
     A reaction: What has gone wrong with this picture is that you cannot (it seems to me) give a decent account of belief without mentioning truth. To believe a proposition is to hold it true. Hume's emotional account (Idea 2208) makes belief bewildering.
Truth is a useful concept for unarticulated propositions and generalisations about them [Horwich]
     Full Idea: All uses of the truth predicate are explained by the hypothesis that its entire raison d'ętre is to help us say things about unarticulated propositions, and in particular to express generalisations about them.
     From: Paul Horwich (Truth (2nd edn) [1990], Concl)
     A reaction: This certain is a very deflationary notion of truth. Articulated propositions are considered to stand on their own two feet, without need of 'is true'. He makes truth sound like a language game, though. Personally I prefer to mention reality.
5. Theory of Logic / A. Overview of Logic / 9. Philosophical Logic
Three stages of philosophical logic: syntactic (1905-55), possible worlds (1963-85), widening (1990-) [Horsten/Pettigrew]
     Full Idea: Three periods can be distinguished in philosophical logic: the syntactic stage, from Russell's definite descriptions to the 1950s, the dominance of possible world semantics from the 50s to 80s, and a current widening of the subject.
     From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 1)
     A reaction: [compressed] I've read elsewhere that the arrival of Tarski's account of truth in 1933, taking things beyond the syntactic, was also a landmark.
5. Theory of Logic / E. Structures of Logic / 1. Logical Form
Logical form is the aspects of meaning that determine logical entailments [Horwich]
     Full Idea: The logical forms of the sentences in a language are those aspects of their meanings that determine the relations of deductive entailment holding amongst them.
     From: Paul Horwich (Truth (2nd edn) [1990], Ch.6.30)
     A reaction: A helpful definition. Not all sentences, therefore, need to have a 'logical form'. Is the logical form the same as the underlying proposition. The two must converge, given that propositions lack the ambiguity that is often found in sentences.
Logical formalization makes concepts precise, and also shows their interrelation [Horsten/Pettigrew]
     Full Idea: Logical formalization forces the investigator to make the central philosophical concepts precise. It can also show how some philosophical concepts and objects can be defined in terms of others.
     From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 2)
     A reaction: This is the main rationale of the highly formal and mathematical approach to such things. The downside is when you impose 'precision' on language that was never intended to be precise.
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
Models are sets with functions and relations, and truth built up from the components [Horsten/Pettigrew]
     Full Idea: A (logical) model is a set with functions and relations defined on it that specify the denotation of the non-logical vocabulary. A series of recursive clauses explicate how truth values of complex sentences are compositionally determined from the parts.
     From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 3)
     A reaction: See the ideas on 'Functions in logic' and 'Relations in logic' (in the alphabetical list) to expand this important idea.
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / g. Real numbers
We want the essence of continuity, by showing its origin in arithmetic [Dedekind]
     Full Idea: It then only remained to discover its true origin in the elements of arithmetic and thus at the same time to secure a real definition of the essence of continuity.
     From: Richard Dedekind (Continuity and Irrational Numbers [1872], Intro)
     A reaction: [He seeks the origin of the theorem that differential calculus deals with continuous magnitude, and he wants an arithmetical rather than geometrical demonstration; the result is his famous 'cut'].
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / i. Reals from cuts
A cut between rational numbers creates and defines an irrational number [Dedekind]
     Full Idea: Whenever we have to do a cut produced by no rational number, we create a new, an irrational number, which we regard as completely defined by this cut.
     From: Richard Dedekind (Continuity and Irrational Numbers [1872], §4)
     A reaction: Fine quotes this to show that the Dedekind Cut creates the irrational numbers, rather than hitting them. A consequence is that the irrational numbers depend on the rational numbers, and so can never be identical with any of them. See Idea 10573.
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / f. Arithmetic
Arithmetic is just the consequence of counting, which is the successor operation [Dedekind]
     Full Idea: I regard the whole of arithmetic as a necessary, or at least natural, consequence of the simplest arithmetic act, that of counting, and counting itself is nothing else than the successive creation of the infinite series of positive integers.
     From: Richard Dedekind (Continuity and Irrational Numbers [1872], §1)
     A reaction: Thus counting roots arithmetic in the world, the successor operation is the essence of counting, and the Dedekind-Peano axioms are built around successors, and give the essence of arithmetic. Unfashionable now, but I love it. Intransitive counting?
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / l. Limits
If x changes by less and less, it must approach a limit [Dedekind]
     Full Idea: If in the variation of a magnitude x we can for every positive magnitude δ assign a corresponding position from and after which x changes by less than δ then x approaches a limiting value.
     From: Richard Dedekind (Continuity and Irrational Numbers [1872], p.27), quoted by Philip Kitcher - The Nature of Mathematical Knowledge 10.7
     A reaction: [Kitcher says he 'showed' this, rather than just stating it]
7. Existence / A. Nature of Existence / 1. Nature of Existence
If 'exist' doesn't express a property, we can hardly ask for its essence [Horsten/Pettigrew]
     Full Idea: If there is indeed no property of existence that is expressed by the word 'exist', then it makes no sense to ask for its essence.
     From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 2)
     A reaction: As far as I can tell, this was exactly Aristotle's conclusion, so he skirted round the question of 'being qua being', and focused on the nature of objects instead. Grand continental talk of 'Being' doesn't sound very interesting.
10. Modality / E. Possible worlds / 1. Possible Worlds / a. Possible worlds
A Tarskian model can be seen as a possible state of affairs [Horsten/Pettigrew]
     Full Idea: A Tarskian model can in a sense be seen as a model of a possible state of affairs.
     From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 3)
     A reaction: I include this remark to show how possible worlds semantics built on the arrival of model theory.
The 'spheres model' was added to possible worlds, to cope with counterfactuals [Horsten/Pettigrew]
     Full Idea: The notion of a possible worlds model was extended (resulting in the concept of a 'spheres model') in order to obtain a satisfactory logical treatment of counterfactual conditional sentences.
     From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 4)
     A reaction: Thus we add 'centred' worlds, and an 'actual' world, to the loose original model. It is important to remember when we discuss 'close' worlds that we are then committed to these presuppositions.
10. Modality / E. Possible worlds / 1. Possible Worlds / b. Impossible worlds
Epistemic logic introduced impossible worlds [Horsten/Pettigrew]
     Full Idea: The idea of 'impossible worlds' was introduced into epistemic logic.
     From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 4)
     A reaction: Nathan Salmon seems interested in their role in metaphysics (presumably in relation to Meinongian impossible objects, like circular squares, which must necessarily be circular).
10. Modality / E. Possible worlds / 1. Possible Worlds / e. Against possible worlds
Possible worlds models contain sets of possible worlds; this is a large metaphysical commitment [Horsten/Pettigrew]
     Full Idea: Each possible worlds model contains a set of possible worlds. For this reason, possible worlds semantics is often charged with smuggling in heavy metaphysical commitments.
     From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 3)
     A reaction: To a beginner it looks very odd that you should try to explain possibility by constructing a model of it in terms of 'possible' worlds.
Using possible worlds for knowledge and morality may be a step too far [Horsten/Pettigrew]
     Full Idea: When the possible worlds semantics were further extended to model notions of knowledge and of moral obligation, the application was beginning to look distinctly forced and artificial.
     From: Horsten,L/Pettigrew,R (Mathematical Methods in Philosophy [2014], 5)
     A reaction: They accept lots of successes in modelling necessity and time.
19. Language / A. Nature of Meaning / 4. Meaning as Truth-Conditions
We could know the truth-conditions of a foreign sentence without knowing its meaning [Horwich]
     Full Idea: Someone who does not understand German and is told 'Schnee ist weiss' is true if frozen H2O is white, does not understand the German sentence, even though he knows the truth-conditions.
     From: Paul Horwich (Truth (2nd edn) [1990], Ch.5.22 n1)
     A reaction: This sounds like a powerful objection to Davidson's well-known claim that meaning is truth-conditions. Horwich likes the idea that meaning is use, but I think a similar objection arises - you can use a sentence well without knowing its meaning.
19. Language / D. Propositions / 1. Propositions
There are Fregean de dicto propositions, and Russellian de re propositions, or a mixture [Horwich]
     Full Idea: There are pure, Fregean, abstract, de dicto propositions, in which a compositional structure is filled only with senses; there are pure, Russellian, concrete, de re propositions, which are filled with referents; and there are mixed propositions.
     From: Paul Horwich (Truth (2nd edn) [1990], Ch.6.31)
     A reaction: Once Frege has distinguished sense from reference, this distinction of propositions is likely to follow. The current debate over the internalist and externalist accounts of concepts seems to continue the debate. A mixed strategy sounds good.
19. Language / F. Communication / 6. Interpreting Language / b. Indeterminate translation
Right translation is a mapping of languages which preserves basic patterns of usage [Horwich]
     Full Idea: The right translation between words of two languages is the mapping that preserves basic patterns of usage - where usage is characterised non-semantically, in terms of circumstances of application, assertibility conditions and inferential role.
     From: Paul Horwich (Truth (2nd edn) [1990], Ch.6.32)
     A reaction: It still strikes me that if you ask why a piece of language is used in a certain way, you find yourself facing something deeper about meaning than mere usage. Horwich cites Wittgenstein and Quine in his support. Could a machine pass his test?