84 ideas
| 15357 | Philosophy is the most general intellectual discipline [Horsten] |
| Full Idea: Philosophy is the most general intellectual discipline. | |
| From: Leon Horsten (The Tarskian Turn [2011], 05.1) | |
| A reaction: Very simple, but exactly how I see the subject. It is continuous with the sciences, and tries to give an account of nature, but operating at an extreme level of generality. It must respect the findings of science, but offer bold interpretations. |
| 6161 | Structuralism is neo-Kantian idealism, with language playing the role of categories of understanding [Rowlands] |
| Full Idea: Structuralism is a form of neo-Kantian idealism, in which the job of creating Kant's phenomenal world has been taken over by language instead of forms of sensibility and categories of the understanding. | |
| From: Mark Rowlands (Externalism [2003], Ch.3) | |
| A reaction: A helpful connection, which explains my aversion to any attempt at understanding the world simply by analysing language, either in its ordinary usage, or in its underlying logical form. |
| 15352 | A definition should allow the defined term to be eliminated [Horsten] |
| Full Idea: A definition allows a defined term to be eliminated in every context in which it appears. | |
| From: Leon Horsten (The Tarskian Turn [2011], 04.2) | |
| A reaction: To do that, a definition had better be incredibly comprehensive, so that no nice nuance of the original term is thrown out. |
| 10882 | Predicative definitions only refer to entities outside the defined collection [Horsten] |
| Full Idea: Definitions are called 'predicative', and are considered sound, if they only refer to entities which exist independently from the defined collection. | |
| From: Leon Horsten (Philosophy of Mathematics [2007], §2.4) |
| 15324 | Semantic theories of truth seek models; axiomatic (syntactic) theories seek logical principles [Horsten] |
| Full Idea: There are semantical theories of truth, concerned with models for languages containing the truth predicate, and axiomatic (or syntactic) theories, interested in basic logical principles governing the concept of truth. | |
| From: Leon Horsten (The Tarskian Turn [2011], 01.1) | |
| A reaction: This is the map of contemporary debates, which seem now to have given up talking about 'correspondence', 'coherence' etc. |
| 15323 | Truth is a property, because the truth predicate has an extension [Horsten] |
| Full Idea: I take truth to be a property because the truth predicate has an extension - the collection of all true sentences - and this collection does not (unlike the 'extension' of 'exists') consist of everything, or even of all sentences. | |
| From: Leon Horsten (The Tarskian Turn [2011], 01.1) | |
| A reaction: He concedes that it may be an 'uninteresting' property. My problem is always that I am unconvinced that truth is tied to sentences. I can make perfect sense of animal thoughts being right or wrong. Extension of mental propositions? |
| 15374 | Truth has no 'nature', but we should try to describe its behaviour in inferences [Horsten] |
| Full Idea: We should not aim at describing the nature of truth because there is no such thing. Rather, we should aim at describing the inferential behaviour of truth. | |
| From: Leon Horsten (The Tarskian Turn [2011], 10.2.3) |
| 15348 | Propositions have sentence-like structures, so it matters little which bears the truth [Horsten] |
| Full Idea: It makes little difference, at least in extensional contexts, whether the truth bearers are propositions or sentences (or assertions). Even if the bearers are propositions rather than sentences, propositions are structured rather like sentences. | |
| From: Leon Horsten (The Tarskian Turn [2011], 02.4) | |
| A reaction: The 'extensional' context means you are only talking about the things that are referred to, and not about the way this is expressed. I prefer propositions, but this is an interesting point. |
| 15333 | Modern correspondence is said to be with the facts, not with true propositions [Horsten] |
| Full Idea: Modern correspondence theorists no longer take things to correspond to true propositions; they consider facts to be the truthmakers of propositions. | |
| From: Leon Horsten (The Tarskian Turn [2011], 02.1) | |
| A reaction: If we then define facts as the way certain things are, independently from our thinking about it, at least we seem to be avoiding circularity. Not much point in correspondence accounts if you are not a robust realist (like me). [14,000th idea, 23/4/12!] |
| 15337 | The correspondence 'theory' is too vague - about both 'correspondence' and 'facts' [Horsten] |
| Full Idea: The principle difficulty of the correspondence theory of truth is its vagueness. It is too vague to be called a theory until more information is given about what is meant by the terms 'correspondence' and 'fact'. Facts can involve a heavy ontology. | |
| From: Leon Horsten (The Tarskian Turn [2011], 02.1) | |
| A reaction: I see nothing here to make me give up my commitment to the correspondence view of truth, though it sounds as if I will have to give up the word 'theory' in that context. Truth is so obviously about thought fitting reality that there is nothing to discuss. |
| 15334 | The coherence theory allows multiple coherent wholes, which could contradict one another [Horsten] |
| Full Idea: The coherence theory seems too liberal. It seems there can be more than one systematic whole which, while being internally coherent, contradict each other, and thus cannot all be true. Coherence is a necessary but not sufficient condition for truth. | |
| From: Leon Horsten (The Tarskian Turn [2011], 02.1) | |
| A reaction: This is a modern post-Tarski axiomatic truth theorist making very short work indeed of the coherence theory of truth. I take Horsten to be correct. |
| 15336 | The pragmatic theory of truth is relative; useful for group A can be useless for group B [Horsten] |
| Full Idea: The pragmatic theory is unsatisfactory because usefulness is a relative notion. One theory can be useful to group A while being thoroughly impractical for group B. This would make the theory both truth and false. | |
| From: Leon Horsten (The Tarskian Turn [2011], 02.1) | |
| A reaction: This objection, along with the obvious fact that certain falsehoods can be very useful, would seem to rule pragmatism out as a theory of truth. It is, in fact, an abandonment of truth. |
| 15354 | Tarski's hierarchy lacks uniform truth, and depends on contingent factors [Horsten] |
| Full Idea: According to the Tarskian hierarchical conception, truth is not a uniform notion. ...Also Kripke has emphasised that the level of a token of the truth predicate can depend on contingent factors, such as what else has been said by a speaker. | |
| From: Leon Horsten (The Tarskian Turn [2011], 04.5) |
| 15340 | Tarski Bi-conditional: if you'll assert φ you'll assert φ-is-true - and also vice versa [Horsten] |
| Full Idea: The axiom schema 'Sentence "phi;" is true iff φ' is the (unrestricted) Tarski-Biconditional, and is motivated by the thought that if you are willing to assume or outright assert that φ, you will assert that φ is true - and also vice versa. | |
| From: Leon Horsten (The Tarskian Turn [2011], 02.2) | |
| A reaction: Very helpful! Most people are just bewildered by the Tarski bi-conditional ('"Snow is white"...), but this formulation nicely shows its minimal character while showing that it really does say something. It says what truths and truth-claims commit you to. |
| 15345 | Semantic theories have a regress problem in describing truth in the languages for the models [Horsten] |
| Full Idea: Semantic theories give a class of models with a truth predicate, ...but Tarski taught us that this needs a more encompassing framework than its language...so how is the semantics of the framework expressed? The model route has a regress. | |
| From: Leon Horsten (The Tarskian Turn [2011], 02.3) | |
| A reaction: [compressed] So this regress problem, of endless theories of truth going up the hierarchy, is Horsten's main reason for opting for axiomatic theories, which he then tries to strengthen, so that they are not quite so deflated. |
| 15373 | Axiomatic approaches avoid limiting definitions to avoid the truth predicate, and limited sizes of models [Horsten] |
| Full Idea: An adequate definition of truth can only be given for the fragment of our language that does not contain the truth predicate. A model can never encompass the whole of the domain of discourse of our language. The axiomatic approach avoids these problems. | |
| From: Leon Horsten (The Tarskian Turn [2011], 10.1) |
| 15346 | Axiomatic approaches to truth avoid the regress problem of semantic theories [Horsten] |
| Full Idea: The axiomatic approach to truth does not suffer from the regress problem. | |
| From: Leon Horsten (The Tarskian Turn [2011], 02.3) | |
| A reaction: See Idea 15345 for the regress problem. The difficulty then seems to be that axiomatic approaches lack expressive power, so the hunt is on for a set of axioms which will do a decent job. Fun work, if you can cope with it. |
| 15371 | An axiomatic theory needs to be of maximal strength, while being natural and sound [Horsten] |
| Full Idea: The challenge is to find the arithmetically strongest axiomatical truth theory that is both natural and truth-theoretically sound. | |
| From: Leon Horsten (The Tarskian Turn [2011], 07.7) |
| 15332 | 'Reflexive' truth theories allow iterations (it is T that it is T that p) [Horsten] |
| Full Idea: A theory of truth is 'reflexive' if it allows us to prove truth-iterations ("It is true that it is true that so-and-so"). | |
| From: Leon Horsten (The Tarskian Turn [2011], 01.4) |
| 15361 | A good theory of truth must be compositional (as well as deriving biconditionals) [Horsten] |
| Full Idea: Deriving many Tarski-biconditionals is not a sufficient condition for being a good theory of truth. A good theory of truth must in addition do justice to the compositional nature of truth. | |
| From: Leon Horsten (The Tarskian Turn [2011], 06.1) |
| 15350 | The Naïve Theory takes the bi-conditionals as axioms, but it is inconsistent, and allows the Liar [Horsten] |
| Full Idea: The Naïve Theory of Truth collects all the Tarski bi-conditionals of a language and takes them as axioms. But no consistent theory extending Peano arithmetic can prove all of them. It is inconsistent, and even formalises the liar paradox. | |
| From: Leon Horsten (The Tarskian Turn [2011], 03.5.2) | |
| A reaction: [compressed] This looks to me like the account of truth that Davidson was working with, since he just seemed to be compiling bi-conditionals for tricky cases. (Wrong! He championed the Compositional Theory, Horsten p.71) |
| 15351 | Axiomatic theories take truth as primitive, and propose some laws of truth as axioms [Horsten] |
| Full Idea: In the axiomatic approach we take the truth predicate to express an irreducible, primitive notion. The meaning of the truth predicate is partially explicated by proposing certain laws of truth as basic principles, as axioms. | |
| From: Leon Horsten (The Tarskian Turn [2011], 04.2) | |
| A reaction: Judging by Horsten's book, this is a rather fruitful line of enquiry, but it still seems like a bit of a defeat to take truth as 'primitive'. Presumably you could add some vague notion of correspondence as the background picture. |
| 15367 | By adding truth to Peano Arithmetic we increase its power, so truth has mathematical content! [Horsten] |
| Full Idea: It is surprising that just by adding to Peano Arithmetic principles concerning the notion of truth, we increase the mathematical strength of PA. So, contrary to expectations, the 'philosophical' notion of truth has real mathematical content. | |
| From: Leon Horsten (The Tarskian Turn [2011], 06.4) | |
| A reaction: Horsten invites us to be really boggled by this. All of this is in the Compositional Theory TC. It enables a proof of the consistency of arithmetic (but still won't escape Gödel's Second). |
| 15330 | Friedman-Sheard theory keeps classical logic and aims for maximum strength [Horsten] |
| Full Idea: The Friedman-Sheard theory of truth holds onto classical logic and tries to construct a theory that is as strong as possible. | |
| From: Leon Horsten (The Tarskian Turn [2011], 01.4) |
| 15331 | Kripke-Feferman has truth gaps, instead of classical logic, and aims for maximum strength [Horsten] |
| Full Idea: If we abandon classical logic in favour of truth-value gaps and try to strengthen the theory, this leads to the Kripke-Feferman theory of truth, and variants of it. | |
| From: Leon Horsten (The Tarskian Turn [2011], 01.4) |
| 15325 | Inferential deflationism says truth has no essence because no unrestricted logic governs the concept [Horsten] |
| Full Idea: According to 'inferential deflationism', truth is a concept without a nature or an essence. This is betrayed by the fact that there are no unrestricted logical laws that govern the concept of truth. | |
| From: Leon Horsten (The Tarskian Turn [2011], 01.1) |
| 15344 | Deflationism skips definitions and models, and offers just accounts of basic laws of truth [Horsten] |
| Full Idea: Contemporary deflationism about truth does not attempt to define truth, and does not rely on models containing the truth predicate. Instead they are interpretations of axiomatic theories of truth, containing only basic laws of truth. | |
| From: Leon Horsten (The Tarskian Turn [2011], 02.3) |
| 15356 | Deflationism concerns the nature and role of truth, but not its laws [Horsten] |
| Full Idea: Deflationism is not a theory of the laws of truth. It is a view on the nature and role of the concept of truth. | |
| From: Leon Horsten (The Tarskian Turn [2011], 05 Intro) |
| 15368 | This deflationary account says truth has a role in generality, and in inference [Horsten] |
| Full Idea: On the conception of deflationism developed in this book, the prime positive role of the truth predicate is to serve as a device for expressing generalities, and an inferential tool. | |
| From: Leon Horsten (The Tarskian Turn [2011], 07.5) |
| 15358 | Deflationism says truth isn't a topic on its own - it just concerns what is true [Horsten] |
| Full Idea: Deflationism says the theory of truth does not have a substantial domain of its own. The domain of the theory of truth consists of the bearers of truth. | |
| From: Leon Horsten (The Tarskian Turn [2011], 05.1) | |
| A reaction: The immediate thought is that truth also concerns falsehoods, which would be inexplicable without it. If physics just concerns the physical, does that mean that physics lacks its own 'domain'? Generalising about the truths is a topic. |
| 15359 | Deflation: instead of asserting a sentence, we can treat it as an object with the truth-property [Horsten] |
| Full Idea: The Deflationary view just says that instead of asserting a sentence, we can turn the sentence into an object and assert that this object has the property of truth. | |
| From: Leon Horsten (The Tarskian Turn [2011], 05.2.2) | |
| A reaction: That seems to leave a big question hanging, which concerns the nature of the property that is being attributed to this object. Quine 1970:10-13 says it is just a 'device'. Surely you can rest content with that as an account of truth? |
| 15329 | Nonclassical may accept T/F but deny applicability, or it may deny just T or F as well [Horsten] |
| Full Idea: Some nonclassical logic stays close to classical, assuming two mutually exclusive truth values T and F, but some sentences fail to have one. Others have further truth values such as 'half truth', or dialethists allow some T and F at the same time. | |
| From: Leon Horsten (The Tarskian Turn [2011], 01.2) | |
| A reaction: I take that to say that the first lot accept bivalence but reject excluded middle (allowing 'truth value gaps'), while the second lot reject both. Bivalence gives the values available, and excluded middle says what has them. |
| 15326 | Doubt is thrown on classical logic by the way it so easily produces the liar paradox [Horsten] |
| Full Idea: Aside from logic, so little is needed to generate the liar paradox that one wonders whether the laws of classical logic are unrestrictedly valid after all. (Many theories of truth have therefore been formulated in nonclassical logic.) | |
| From: Leon Horsten (The Tarskian Turn [2011], 01.2) | |
| A reaction: Kripke uses Strong Kleene logic for his theory. The implication is that debates discussed by Horsten actually have the status of classical logic at stake, as well as the nature of truth. |
| 15341 | Deduction Theorem: ψ only derivable from φ iff φ→ψ are axioms [Horsten] |
| Full Idea: The Deduction Theorem says ψ is derivable in classical predicate logic from ψ iff the sentence φ→ψ is a theorem of classical logic. Hence inferring φ to ψ is truth-preserving iff the axiom scheme φ→ψ is provable. | |
| From: Leon Horsten (The Tarskian Turn [2011], 02.2) | |
| A reaction: Horsten offers this to show that the Tarski bi-conditionals can themselves be justified, and not just the rule of inference involved. Apparently you can only derive something if you first announce that you have the ability to derive it. Odd. |
| 6163 | If bivalence is rejected, then excluded middle must also be rejected [Rowlands] |
| Full Idea: If you reject the principle of bivalence (that a proposition is either determinately true or false), then statements are also not subject to the Law of Excluded Middle (P or not-P). | |
| From: Mark Rowlands (Externalism [2003], Ch.3) | |
| A reaction: I think Rowlands is wrong about this. Excluded Middle could be purely syntacti, or its semantics could be 'True or Not-True'. Only bivalent excluded middle introduces 'True or False'. Compare Idea 4752. |
| 15328 | A theory is 'non-conservative' if it facilitates new mathematical proofs [Horsten] |
| Full Idea: A theory is 'non-conservative' if it allows us to prove mathematical facts that go beyond what the background mathematical theory can prove on its own. | |
| From: Leon Horsten (The Tarskian Turn [2011], 01.4) | |
| A reaction: This is an instance of the relationship with mathematics being used as the test case for explorations of logic. It is a standard research method, because it is so precise, but should not be mistaken for the last word about a theory. |
| 15349 | It is easier to imagine truth-value gaps (for the Liar, say) than for truth-value gluts (both T and F) [Horsten] |
| Full Idea: It is easier to imagine what it is like for a sentence to lack a truth value than what it is like for a sentence to be both truth and false. So I am grudgingly willing to entertain the possibility that certain sentences (like the Liar) lack a truth value. | |
| From: Leon Horsten (The Tarskian Turn [2011], 02.5) | |
| A reaction: Fans of truth value gluts are dialethists like Graham Priest. I'm with Horsten on this one. But in what way can a sentence be meaningful if it lacks a truth-value? He mentions unfulfilled presuppositions and indicative conditionals as gappy. |
| 15366 | Satisfaction is a primitive notion, and very liable to semantical paradoxes [Horsten] |
| Full Idea: Satisfaction is a more primitive notion than truth, and it is even more susceptible to semantical paradoxes than the truth predicate. | |
| From: Leon Horsten (The Tarskian Turn [2011], 06.3) | |
| A reaction: The Liar is the best known paradox here. Tarski bases his account of truth on this primitive notion, so Horsten is pointing out the difficulties. |
| 10884 | A theory is 'categorical' if it has just one model up to isomorphism [Horsten] |
| Full Idea: If a theory has, up to isomorphism, exactly one model, then it is said to be 'categorical'. | |
| From: Leon Horsten (Philosophy of Mathematics [2007], §5.2) |
| 15353 | The first incompleteness theorem means that consistency does not entail soundness [Horsten] |
| Full Idea: It is a lesson of the first incompleteness theorem that consistency does not entail soundness. If we add the negation of the gödel sentence for PA as an extra axiom to PA, the result is consistent. This negation is false, so the theory is unsound. | |
| From: Leon Horsten (The Tarskian Turn [2011], 04.3) |
| 15355 | Strengthened Liar: 'this sentence is not true in any context' - in no context can this be evaluated [Horsten] |
| Full Idea: The Strengthened Liar sentence says 'this sentence is not true in any context'. It is not hard to figure out that there is no context in which the sentence can be coherently evaluated. | |
| From: Leon Horsten (The Tarskian Turn [2011], 04.6) |
| 15364 | English expressions are denumerably infinite, but reals are nondenumerable, so many are unnameable [Horsten] |
| Full Idea: The number of English expressions is denumerably infinite. But Cantor's theorem can be used to show that there are nondenumerably many real numbers. So not every real number has a (simple or complex name in English). | |
| From: Leon Horsten (The Tarskian Turn [2011], 06.3) | |
| A reaction: This really bothers me. Are we supposed to be committed to the existence of entities which are beyond our powers of naming? How precise must naming be? If I say 'pick a random real number', might that potentially name all of them? |
| 10885 | Computer proofs don't provide explanations [Horsten] |
| Full Idea: Mathematicians are uncomfortable with computerised proofs because a 'good' proof should do more than convince us that a certain statement is true. It should also explain why the statement in question holds. | |
| From: Leon Horsten (Philosophy of Mathematics [2007], §5.3) |
| 10881 | The concept of 'ordinal number' is set-theoretic, not arithmetical [Horsten] |
| Full Idea: The notion of an ordinal number is a set-theoretic, and hence non-arithmetical, concept. | |
| From: Leon Horsten (Philosophy of Mathematics [2007], §2.3) |
| 15360 | ZFC showed that the concept of set is mathematical, not logical, because of its existence claims [Horsten] |
| Full Idea: One of the strengths of ZFC is that it shows that the concept of set is a mathematical concept. Many originally took it to be a logical concept. But ZFC makes mind-boggling existence claims, which should not follow if it was a logical concept. | |
| From: Leon Horsten (The Tarskian Turn [2011], 05.2.3) | |
| A reaction: This suggests that set theory is not just a way of expressing mathematics (see Benacerraf 1965), but that some aspect of mathematics has been revealed by it - maybe even its essential nature. |
| 15369 | Set theory is substantial over first-order arithmetic, because it enables new proofs [Horsten] |
| Full Idea: The nonconservativeness of set theory over first-order arithmetic has done much to establish set theory as a substantial theory indeed. | |
| From: Leon Horsten (The Tarskian Turn [2011], 07.5) | |
| A reaction: Horsten goes on to point out the price paid, which is the whole new ontology which has to be added to the arithmetic. Who cares? It's all fictions anyway! |
| 15370 | Predicativism says mathematical definitions must not include the thing being defined [Horsten] |
| Full Idea: Predicativism has it that a mathematical object (such as a set of numbers) cannot be defined by quantifying over a collection that includes that same mathematical object. To do so would be a violation of the vicious circle principle. | |
| From: Leon Horsten (The Tarskian Turn [2011], 07.7) | |
| A reaction: In other words, when you define an object you are obliged to predicate something new, and not just recycle the stuff you already have. |
| 6155 | Supervenience is a one-way relation of dependence or determination between properties [Rowlands] |
| Full Idea: Supervenience is essentially a one-way relation of dependence or determination, …which holds, in the first instance, between properties. | |
| From: Mark Rowlands (Externalism [2003], Ch.2) | |
| A reaction: This definition immediately shows why supervenient properties are in danger of being epiphenomenal (i.e. causally irrelevant). Carefully thought about the notion of a 'one-way' relation will, I think, make it more obscure rather than clearer. |
| 15338 | We may believe in atomic facts, but surely not complex disjunctive ones? [Horsten] |
| Full Idea: While positive and perhaps even negative atomic facts may be unproblematic, it seems excessive to commit oneself to the existence of logically complex facts such as disjunctive facts. | |
| From: Leon Horsten (The Tarskian Turn [2011], 02.1) | |
| A reaction: Presumably it is hard to deny that very complex statements involving massive disjunctions can be true or false. But why does commitment to real facts have to involve a huge ontology? The ontology is just the ingredients of the fact, isn't it? |
| 15363 | In the supervaluationist account, disjunctions are not determined by their disjuncts [Horsten] |
| Full Idea: If 'Britain is large' and 'Italy is large' lack truth values, then so must 'Britain or Italy is large' - so on the supervaluationist account the truth value of a disjunction is not determined by the truth values of its disjuncts. | |
| From: Leon Horsten (The Tarskian Turn [2011], 06.2) | |
| A reaction: Compare Idea 15362 to get the full picture here. |
| 15362 | If 'Italy is large' lacks truth, so must 'Italy is not large'; but classical logic says it's large or it isn't [Horsten] |
| Full Idea: If 'Italy is a large country' lacks a truth value, then so too, presumably, does 'Italy is not a large country'. But 'Italy is or is not a large country' is true, on the supervaluationist account, because it is a truth of classical propositional logic. | |
| From: Leon Horsten (The Tarskian Turn [2011], 06.2) | |
| A reaction: See also Idea 15363. He cites Fine 1975. |
| 6154 | It is argued that wholes possess modal and counterfactual properties that parts lack [Rowlands] |
| Full Idea: Some have argued that a mereological whole should not be identified with the sum of its parts on the grounds that the former possess certain properties - specifically modal and (perhaps) counterfactual properties - that the latter lacks. | |
| From: Mark Rowlands (Externalism [2003], Ch.2) | |
| A reaction: I am not convinced that modal and counterfactual claims should count as properties. If my pen is heated it melts (a property), but if my pen were intelligent it could do philosophy. Intelligence is a property, but the situation isn't. |
| 6157 | Tokens are dated, concrete particulars; types are their general properties or kinds [Rowlands] |
| Full Idea: Tokens are dated, concrete, particular occurrences or instances; types are the general properties that these occurrences exemplify or the kinds to which they belong. | |
| From: Mark Rowlands (Externalism [2003], Ch.2) | |
| A reaction: It might be said that types are sets, of which tokens are the members. The question of 'general properties' raises the question of whether universals must exist to make kinds possible. |
| 15372 | Some claim that indicative conditionals are believed by people, even though they are not actually held true [Horsten] |
| Full Idea: In the debate about doxastic attitudes towards indicative conditional sentences, one finds philosophers who claim that conditionals can be believed even though they have no truth value (and thus are not true). | |
| From: Leon Horsten (The Tarskian Turn [2011], 09.3) |
| 6159 | Strong idealism is the sort of mess produced by a Cartesian separation of mind and world [Rowlands] |
| Full Idea: Neo-Kantian idealism, and the excesses of recent versions of it, are precisely the sort of mess one can get oneself into through an uncritical acceptance of the dichotomizing of mind and world along Cartesian internalist lines. | |
| From: Mark Rowlands (Externalism [2003], Ch.3) | |
| A reaction: I am unconvinced that internalism about the mind (that its contents can be defined without reference to anything external) leads to this disastrous split. We don't have to abandon the links between an internal mind and the world. |
| 6152 | Minds are rational, conscious, subjective, self-knowing, free, meaningful and self-aware [Rowlands] |
| Full Idea: The apparent features of mind which are not obviously physical include: rationality, thought, consciousness, subjectivity, infallible first-person knowledge, freedom, meaning and self-awareness. | |
| From: Mark Rowlands (Externalism [2003], Ch.2) | |
| A reaction: A helpful list, some of which can be challenged. Ryle challenges first-person infallibility. Hume challenges self-awareness. Quine challenges meaning. Lots of people (e.g. Spinoza) challenge freedom. The Churchlands seem to challenge consciousness. |
| 6173 | Content externalism implies that we do not have privileged access to our own minds [Rowlands] |
| Full Idea: Content externalism threatens the idea of first-person authority in all its forms, and does so because it calls into question the idea that the access we have to our own mental states is privileged in the way required for such authority. | |
| From: Mark Rowlands (Externalism [2003], Ch.7) | |
| A reaction: I am inclined to respond by saying that since we clearly have privileged access to our own minds, that means there must be something wrong with content externalism. |
| 6174 | If someone is secretly transported to Twin Earth, others know their thoughts better than they do [Rowlands] |
| Full Idea: If someone knew that a thinker had, without realising it, been transported to Twin Earth, they would almost certainly be a higher authority on the content of the thinker's thoughts than would the thinker. | |
| From: Mark Rowlands (Externalism [2003], Ch.8) | |
| A reaction: They would certainly be a higher authority on the truth of the thinker's thoughts, but only in the way that you might think I hold a diamond when I know it is a club. If the thinker believes it is H2O, the fact that it isn't is irrelevant to content. |
| 6158 | Supervenience of mental and physical properties often comes with token-identity of mental and physical particulars [Rowlands] |
| Full Idea: One often finds a supervenience thesis concerning the relation between mental and physical properties combined with a token identity theory concerning the relation between mental and physical particulars. | |
| From: Mark Rowlands (Externalism [2003], Ch.2) | |
| A reaction: This brings out the important clarifying point that supervenience is said to be between properties, not substances. The point is that supervenience will always cry out for an explanation, preferably a sensible one. |
| 6168 | The content of a thought is just the meaning of a sentence [Rowlands] |
| Full Idea: The content of the thought that the sky is blue is simply the meaning of the sentence "The sky is blue". | |
| From: Mark Rowlands (Externalism [2003], Ch.5) | |
| A reaction: This seems to imply that it is logically impossible for a non-language-speaker, such as a chimpanzee, to think that the sky is the same colour as the water. If we allow propositions, we might be able to keep meanings without the sentences. |
| 15347 | A theory of syntax can be based on Peano arithmetic, thanks to the translation by Gödel coding [Horsten] |
| Full Idea: A notion of formal provability can be articulated in Peano arithmetic. ..This is surprisingly 'linguistic' rather than mathematical, but the key is in the Gödel coding. ..Hence we use Peano arithmetic as a theory of syntax. | |
| From: Leon Horsten (The Tarskian Turn [2011], 02.4) | |
| A reaction: This is the explanation of why issues in formal semantics end up being studied in systems based on formal arithmetic. And I had thought it was just because they were geeks who dream in numbers, and can't speak language properly... |
| 6167 | Action is bodily movement caused by intentional states [Rowlands] |
| Full Idea: An action is a bodily movement that is caused by intentional states such as beliefs, desires and so on. | |
| From: Mark Rowlands (Externalism [2003], Ch.5) | |
| A reaction: A useful definition, and clearly one that has no truck with attempts at giving behaviourist definitions of action. The definition of a 'moral action' needs to be built on this one. Particular types of belief and desire, presumably. |
| 6177 | Moral intuition seems unevenly distributed between people [Rowlands] |
| Full Idea: The faculty of moral intuition seems to be unevenly distributed between people. | |
| From: Mark Rowlands (Externalism [2003], Ch.11) | |
| A reaction: This would be a good argument if it was thought that the source of moral intuitions was divine, but people vary enormously in their intuitions about maths, about character, about danger. If you believe in any intuition at all, you must accept its variety. |
| 6156 | The 17th century reintroduced atoms as mathematical modes of Euclidean space [Rowlands] |
| Full Idea: The seventeenth century revolution reintroduced the classical concept of the atom in somewhat new attire as an essentially mathematical entity whose primary qualities could be precisely quantified as modes or aspects of Euclidean space. | |
| From: Mark Rowlands (Externalism [2003], Ch.2) | |
| A reaction: Obviously this very abstract view of atoms didn't last, once they began to identify specific physical atoms, such as oxygen. This view fits in with Newton's use of pure (abstract) points such as the 'centre of gravity'. |
| 6170 | Natural kinds are defined by their real essence, as in gold having atomic number 79 [Rowlands] |
| Full Idea: Part of what it means to be a natural kind is that they are defined by a real essence, a constitution that marks them out as the substance they are (as water is essentially H2O, and gold essentially has atomic number 79). | |
| From: Mark Rowlands (Externalism [2003], Ch.6) | |
| A reaction: A 'real essence' would be the opposite of a 'conventional essence', which is just a human way of seeing things. |
| 20624 | Work degrades into heat, but not vice versa [Close] |
| Full Idea: William Thomson, Lord Kelvin, declared (in 1865) the second law of thermodynamics: mechanical work inevitably tends to degrade into heat, but not vice versa. | |
| From: Frank Close (Theories of Everything [2017], 3 'Perpetual') | |
| A reaction: The basis of entropy, which makes time an essential part of physics. Might this be the single most important fact about the physical world? |
| 20623 | First Law: energy can change form, but is conserved overall [Close] |
| Full Idea: The first law of thermodynamics : energy can be changed from one form to another, but is always conserved overall. | |
| From: Frank Close (Theories of Everything [2017], 3 'Perpetual') | |
| A reaction: So we have no idea what energy is, but we know it's conserved. (Daniel Bernoulli showed the greater the mean energy, the higher the temperature. James Joule showed the quantitative equivalence of heat and work p.26-7) |
| 20625 | Third Law: total order and minimum entropy only occurs at absolute zero [Close] |
| Full Idea: The third law of thermodynamics says that a hypothetical state of total order and minimum entropy can be attained only at the absolute zero temperature, minus 273 degrees Celsius. | |
| From: Frank Close (Theories of Everything [2017], 3 'Arrow') | |
| A reaction: If temperature is energetic movement of atoms (or whatever), then obviously zero movement is the coldest it can get. So is absolute zero an energy state, or an absence of energy? I have no idea what 'total order' means. |
| 20622 | All motions are relative and ambiguous, but acceleration is the same in all inertial frames [Close] |
| Full Idea: There is no absolute state of rest; only relative motions are unambiguous. Contrast this with acceleration, however, which has the same magnitude in all inertial frames. | |
| From: Frank Close (Theories of Everything [2017], 3 'Newton's') | |
| A reaction: It seems important to remember this, before we start trumpeting about the whole of physics being relative. ....But see Idea 20634! |
| 20628 | The electric and magnetic are tightly linked, and viewed according to your own motion [Close] |
| Full Idea: Electric and magnetic phenomena are profoundly intertwined; what you interpret as electric or magnetic thus depends on your own motion. | |
| From: Frank Close (Theories of Everything [2017], 3 'Light!') | |
| A reaction: This sounds like an earlier version of special relativity. |
| 20635 | The general relativity equations relate curvature in space-time to density of energy-momentum [Close] |
| Full Idea: The essence of general relativity relates 'curvature in space-time' on one side of the equation to the 'density of momentum and energy' on the other. ...In full, Einstein required ten equations of this type. | |
| From: Frank Close (Theories of Everything [2017], 5 'Gravity') | |
| A reaction: Momentum involves mass, and energy is equivalent to mass (e=mc^2). |
| 20642 | Photon exchange drives the electro-magnetic force [Close] |
| Full Idea: The exchange of photons drives the electro-magnetic force. | |
| From: Frank Close (Theories of Everything [2017], 6 'Superstrings') | |
| A reaction: So light, which we just think of as what is visible, is a mere side-effect of the engine room of nature - the core mechanism of the whole electro-magnetic field. |
| 20627 | Electric fields have four basic laws (two by Gauss, one by Ampère, one by Faraday) [Close] |
| Full Idea: Four basic laws of electric and magnetic fields: Gauss's Law (about the flux produced by a field), Gauss's law of magnets (there can be no monopoles), Ampère's Law (fields on surfaces), and Farday's Law (accelerated magnets produce fields). | |
| From: Frank Close (Theories of Everything [2017], 3 'Light!') | |
| A reaction: [Highly compressed, for an overview. Close explains them] |
| 20630 | Light isn't just emitted in quanta called photons - light is photons [Close] |
| Full Idea: Planck had assumed that light is emitted in quanta called photons. Einstein went further - light is photons. | |
| From: Frank Close (Theories of Everything [2017], 3 'Light!') | |
| A reaction: The point is that light travels as entities which are photons, rather than the emissions being quantized packets of some other stuff. |
| 20637 | In general relativity the energy and momentum of photons subjects them to gravity [Close] |
| Full Idea: In Einstein's general theory, gravity acts also on energy and momentum, not simply on mass. For example, massless photons of light feel the gravitational attraction of the Sun and can be deflected. | |
| From: Frank Close (Theories of Everything [2017], 5 'Planck') | |
| A reaction: Ah, a puzzle solved. How come massless photons are bent by gravity? |
| 20629 | Electro-magnetic waves travel at light speed - so light is electromagnetism! [Close] |
| Full Idea: Faradays' measurements predicted the speed of electro-magnetic waves, which happened to be the speed of light, so Maxwell made an inspired leap: light is an electromagnetic wave! | |
| From: Frank Close (Theories of Everything [2017], 3 'Light!') | |
| A reaction: Put that way, it doesn't sound like an 'inspired' leap, because travelling at exactly the same speed seems a pretty good indication that they are the same sort of thing. (But I'm not denying that Maxwell was a special guy!) |
| 20632 | In QED, electro-magnetism exists in quantum states, emitting and absorbing electrons [Close] |
| Full Idea: Dirac created quantum electrodynamics (QED): the universal electro-magnetic field can exist in discreet states of energy (with photons appearing and disappearing by energy excitations. This combined classical ideas, quantum theory and special relativity. | |
| From: Frank Close (Theories of Everything [2017], 3 'Light!') | |
| A reaction: Close says this is the theory of everything in atomic structure, but not in nuclei (which needs QCD and QFD). So if there are lots of other 'fields' (e.g. gravitational, weak, strong, Higgs), how do they all fit together? Do they talk to one another? |
| 20639 | Quantum fields contain continual rapid creation and disappearance [Close] |
| Full Idea: Quantum field theory implies that the vacuum of space is filled with particles and antiparticles which bubble in and out of existence on faster and faster timescales over shorter and shorter distances. | |
| From: Frank Close (Theories of Everything [2017], 6 'Intro') | |
| A reaction: Ponder this sentence until you head aches. Existence, but not as we know it, Jim. Close says calculations in QED about the electron confirm this. |
| 20641 | Electrons get their mass by interaction with the Higgs field [Close] |
| Full Idea: The electron gets its mass by interaction with the ubiquitous Higgs field. | |
| From: Frank Close (Theories of Everything [2017], 6 'Hierarchy') | |
| A reaction: I thought I understood mass until I read this. Is it just wrong to say the mass of a table is the 'amount of stuff' in it? |
| 20631 | Dirac showed how electrons conform to special relativity [Close] |
| Full Idea: In 1928 Paul Dirac discovered the quantum equation that describes the electron and conforms to the requirements special relativity theory. | |
| From: Frank Close (Theories of Everything [2017], 3 'Light!') | |
| A reaction: This sounds like a major step in the unification of physics. Quantum theory and General relativity remain irreconcilable. |
| 20626 | Modern theories of matter are grounded in heat, work and energy [Close] |
| Full Idea: The link between temperature, heat, work and energy is at the root of our historical ability to construct theories of matter, such as Newton's dynamics, while ignoring, and indeed being ignorant of - atomic dimensions. | |
| From: Frank Close (Theories of Everything [2017], 3 'Arrow') | |
| A reaction: That is, presumably, that even when you fill in the atoms, and the standard model of physics, these aspects of matter do the main explaiining (of the behaviour, rather than of the structure). |
| 20633 | The Higgs field is an electroweak plasma - but we don't know what stuff it consists of [Close] |
| Full Idea: In 2012 it was confirmed that we are immersed in an electroweak plasma - the Higgs field. We curently have no knowledge of what this stuff might consist of. | |
| From: Frank Close (Theories of Everything [2017], 4 'Higgs') | |
| A reaction: The second sentence has my full attention. So we don't understand a field properly until we understand the 'stuff' it is made of? So what are all the familiar fields made of? Tell me more! |
| 20640 | Space-time is indeterminate foam over short distances [Close] |
| Full Idea: At very short distances, space-time itself becomes some indeterminate foam. | |
| From: Frank Close (Theories of Everything [2017], 6 'Intro') | |
| A reaction: [see Close for a bit more detail of this weird idea] |
| 6178 | It is common to see the value of nature in one feature, such as life, diversity, or integrity [Rowlands] |
| Full Idea: In recent environmental philosophy it is common to see the value of nature identified with one or another natural feature of the environment: life, diversity, ecosystemic integrity and so on. | |
| From: Mark Rowlands (Externalism [2003], Ch.11) | |
| A reaction: This thought seems to be asking for the Open Question argument. What is so good about life, or diversity? Our strongest intuition must be that the survival of the ecosystem, and whatever makes that possible, is the highest value. |