32 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. |
| 21544 | It seems that when a proposition is false, something must fail to subsist [Russell] |
| Full Idea: It seems that when a proposition is false, something does not subsist which would subsist if the proposition were true. | |
| From: Bertrand Russell (Meinong on Complexes and Assumptions [1904], p.76) | |
| A reaction: This looks to me like a commitment by Russell to the truthmaker principle. The negations of false propositions are made true by some failure of existence in the world. |
| 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. |
| 21539 | Excluded middle can be stated psychologically, as denial of p implies assertion of not-p [Russell] |
| Full Idea: The law of excluded middle may be stated in the form: If p is denied, not-p must be asserted; this form is too psychological to be ultimate, but the point is that it is significant and not a mere tautology. | |
| From: Bertrand Russell (Meinong on Complexes and Assumptions [1904], p.41) | |
| A reaction: 'Psychology' is, of course, taboo, post-Frege, though I think it is interesting. Stated in this form the law looks more false than usual. I can be quite clear than p is unacceptable, but unclear about its contrary. |
| 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. |
| 21538 | If two people perceive the same object, the object of perception can't be in the mind [Russell] |
| Full Idea: If two people can perceive the same object, as the possibility of any common world requires, then the object of an external perception is not in the mind of the percipient. | |
| From: Bertrand Russell (Meinong on Complexes and Assumptions [1904], p.33) | |
| A reaction: This is merely an assertion of the realist view, rather than an argument. I take representative realism to tell a perfectly good story that permits two subjective representations of the same object. |
| 21534 | The only thing we can say about relations is that they relate [Russell] |
| Full Idea: It may be doubted whether relations can be adequately characterised by anything except the fact that they relate. | |
| From: Bertrand Russell (Meinong on Complexes and Assumptions [1904], p.27) | |
| A reaction: We can characterise a rope that ties things together. If I say 'stand to his left', do I assume the existence of one of the relata and the relation, but without the second relata? How about 'you two stand over there, with him on the left'? |
| 21540 | Relational propositions seem to be 'about' their terms, rather than about the relation [Russell] |
| Full Idea: In some sense which it would be very desirable to define, a relational proposition seems to be 'about' its terms, in a way in which it is not about the relation. | |
| From: Bertrand Russell (Meinong on Complexes and Assumptions [1904], p.53) | |
| A reaction: Identifying how best to specify what a proposition is actually 'about' is a very illuminating mode of enquiry. You can't define 'underneath' without invoking a pair of objects to illustrate it. A proposition can still focus on the relation. |
| 21536 | When I perceive a melody, I do not perceive the notes as existing [Russell] |
| Full Idea: When, after hearing the notes of a melody, I perceive the melody, the notes are not presented as still existing. | |
| From: Bertrand Russell (Meinong on Complexes and Assumptions [1904], p.31) | |
| A reaction: This is a good example, supporting Meinong's idea that we focus on 'intentional objects', rather than actual objects. |
| 21535 | Objects only exist if they 'occupy' space and time [Russell] |
| Full Idea: Only those objects exist which have to particular parts of space and time the special relation of 'occupying' them. | |
| From: Bertrand Russell (Meinong on Complexes and Assumptions [1904], p.29) | |
| A reaction: He excepts space and time themselves. Clearly this doesn't advance our understanding much, but it points to a priority in our normal conceptual scheme. Is Russell assuming absolute space and time? |
| 21533 | Contingency arises from tensed verbs changing the propositions to which they refer [Russell] |
| Full Idea: Contingency derives from the fact that a sentence containing a verb in the present tense - or sometimes in the past or the future - changes its meaning continually as the present changes, and stands for different propositions at different times. | |
| From: Bertrand Russell (Meinong on Complexes and Assumptions [1904], p.26) | |
| A reaction: This immediately strikes me as a bad example of the linguistic approach to philosophy. As if we (like any animal) didn't have an apprehension prior to any language that most parts of experience are capable of change. |
| 21537 | I assume we perceive the actual objects, and not their 'presentations' [Russell] |
| Full Idea: I prefer to advocate ...that the object of a presentation is the actual external object itself, and not any part of the presentation at all. | |
| From: Bertrand Russell (Meinong on Complexes and Assumptions [1904], p.33) | |
| A reaction: Although I am a fan of the robust realism usually favoured by Russell, I think he is wrong. I take Russell to be frightened that once you take perception to be of 'presentations' rather than things, there is a slippery slope to anti-realism. Not so. |
| 21532 | Full empiricism is not tenable, but empirical investigation is always essential [Russell] |
| Full Idea: Although empiricism as a philosophy does not appear to be tenable, there is an empirical manner of investigating, which should be applied in every subject-matter | |
| From: Bertrand Russell (Meinong on Complexes and Assumptions [1904], p.22) | |
| A reaction: Given that early Russell loads his ontology with properties and propositions, this should come as no surprise, even if J.S. Mill was his godfather. |
| 7647 | The imagination alone perceives all objects; it is the soul, playing all its roles [La Mettrie] |
| Full Idea: The imagination alone perceives; it forms an idea of all objects, with the words and figures that characterise them; thus the imagination is the soul, because it plays all its roles. | |
| From: Julien Offray de La Mettrie (Machine Man [1747], p.15) | |
| A reaction: This is not just a big claim for the importance of imagination, in strong opposition to Descartes's rather dismissive view (Idea 1399), but also appears to be the germ of an interesting theory about the nature of personal identity. |
| 7645 | When falling asleep, the soul becomes paralysed and weak, just like the body [La Mettrie] |
| Full Idea: The soul and body fall asleep together. The soul slowly becomes paralysed, together with all the body's muscles. They can no longer hold up the weight of the head, while the soul can no longer bear the burden of thought. | |
| From: Julien Offray de La Mettrie (Machine Man [1747], p.6) | |
| A reaction: A very nice observation, to place alongside other evidence such as drunkenness and blushing. Personally I find it hard to see why anyone ever believed dualism. You don't need modern brain scans and brain lesion research to see the problem. |
| 23225 | The soul's faculties depend on the brain, and are simply the brain's organisation [La Mettrie] |
| Full Idea: All the soul's faculties depend so much on the specific organisation of the brain and of the whole body that they are clearly nothing but that organisation. | |
| From: Julien Offray de La Mettrie (Machine Man [1747], p.26) | |
| A reaction: An interesting idea because it suggests that La Mettrie is a functionalist, rather than simply a reductive physicalist. |
| 7652 | Man is a machine, and there exists only one substance, diversely modified [La Mettrie] |
| Full Idea: Let us conclude boldly that man is a machine and that there is in the whole universe only one diversely modified substance. | |
| From: Julien Offray de La Mettrie (Machine Man [1747], p.39) | |
| A reaction: What courage it must have taken to write what now seems a perfectly acceptable and normal view. One day there should be a collective monument to Hobbes, Gassendi, Spinoza, La Mettrie and Hume, who thought so boldly. |
| 7650 | All thought is feeling, and rationality is the sensitive soul contemplating reasoning [La Mettrie] |
| Full Idea: Thought is only a capacity to feel, and the rational soul is only the sensitive soul applied to the contemplation of ideas and to reasoning. | |
| From: Julien Offray de La Mettrie (Machine Man [1747], p.33) | |
| A reaction: What a very nice idea. La Mettrie wants to bring us closer to animals. Because we can pursue a train of rational thought, it does not follow that we have a faculty called 'rationality'. A dog can follow a clever series of clues that lead to food. |
| 21542 | Do incorrect judgements have non-existent, or mental, or external objects? [Russell] |
| Full Idea: Correct judgements have a transcendent object; but with regard to incorrect judgements, it remains to examine whether 1) the object is immanent, 2) there is no object, or 3) the object is transcendent. | |
| From: Bertrand Russell (Meinong on Complexes and Assumptions [1904], p.67) | |
| A reaction: Why is it that only Russell seems to have taken this problem seriously? Its solution gives the clearest possible indicator of how the mind relates to the world. |
| 7651 | With wonderful new machines being made, a speaking machine no longer seems impossible [La Mettrie] |
| Full Idea: If wonderful machines like Huygens's planetary clock can be made, it would take even more cogs and springs to make a speaking machine, which can no longer be considered impossible, particularly at the hands of a new Prometheus. | |
| From: Julien Offray de La Mettrie (Machine Man [1747], p.34) | |
| A reaction: Compare Descartes in Idea 3614. The idea of artificial intelligence does not arise with the advent of computers; it follows naturally from the materialist view of the mind, along with a bit of ambition to build complex machines. |
| 21541 | The complexity of the content correlates with the complexity of the object [Russell] |
| Full Idea: Every property of the object seems to demand a strictly correlative property of the content, and the content, therefore, must have every complexity belonging to the object. | |
| From: Bertrand Russell (Meinong on Complexes and Assumptions [1904], p.55) | |
| A reaction: This claim gives a basis for his 'congruence' account of the correspondence theory of truth. It strikes me as false. If I talk of the 'red red robin', I don't mention the robin's feet. He ignores the psychological selection we make in abstraction. |
| 21543 | If p is false, then believing not-p is knowing a truth, so negative propositions must exist [Russell] |
| Full Idea: If p is a false affirmative proposition ...then it seems obvious that if we believe not-p we do know something true, so belief in not-p must be something which is not mere disbelief. This proves that there are negative propositions. | |
| From: Bertrand Russell (Meinong on Complexes and Assumptions [1904], p.75) | |
| A reaction: This evidently assumes excluded middle, but is none the worse for that. But it sounds suspiciously like believing there is no rhinoceros in the room. Does such a belief require a fact? |
| 7648 | The sun and rain weren't made for us; they sometimes burn us, or spoil our seeds [La Mettrie] |
| Full Idea: The sun was not made in order to heat the earth and all its inhabitants - whom it sometimes burns - any more than the rain was created in order to grow seeds - which it often spoils. | |
| From: Julien Offray de La Mettrie (Machine Man [1747]) | |
| A reaction: This denial of Aristotelian (and divine) teleology is as much part of the movement against religion, as are concerns about natural evil, and about the weakness of arguments for God's existence. These facts were obvious long before La Mettrie. |
| 7646 | There is no abrupt transition from man to animal; only language has opened a gap [La Mettrie] |
| Full Idea: From animals to man there is no abrupt transition. What was man before he invented words and learnt languages? An animal of a particular species, with much less natural instinct than the others. | |
| From: Julien Offray de La Mettrie (Machine Man [1747], p.13) | |
| A reaction: This shows how strongly the evolutionary idea was in the air, a century before Darwin proposed a mechanism for it. This thought is the beginning of a very new view of man, and also of a very new view of animals. |
| 7649 | There is no clear idea of the soul, which should only refer to our thinking part [La Mettrie] |
| Full Idea: The soul is merely a vain term of which we have no idea and which a good mind should use only to refer to that part of us which thinks. | |
| From: Julien Offray de La Mettrie (Machine Man [1747]) | |
| A reaction: I have always found the concept of the soul particularly baffling. It seems that it is only believed in to make immortality possible, with no other purpose to the belief, let alone evidence. I suspect that Descartes agreed with La Mettrie on this. |