28 ideas
| 22285 | Impredicative definitions are circular, but fine for picking out, rather than creating something [Potter] |
| Full Idea: The circularity in a definition where the property being defined is used in the definition is now known as 'impredicativity'. ...Some cases ('the tallest man in the room') are unproblematic, as they pick him out, and don't conjure him into existence. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 07 'Impred') | |
| A reaction: [part summary] |
| 22301 | The Identity Theory says a proposition is true if it coincides with what makes it true [Potter] |
| Full Idea: The Identity Theory of truth says a proposition is true just in case it coincides with what makes it true. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 23 'Abs') | |
| A reaction: The obvious question is how 'there are trees in the wood' can somehow 'coincide with' or 'be identical to' the situation outside my window. The theory is sort of right, but we will never define the relationship, which is no better than 'corresponds'. |
| 22324 | It has been unfortunate that externalism about truth is equated with correspondence [Potter] |
| Full Idea: There has been an unfortunate tendency in the secondary literature to equate externalism about truth with the correspondence theory. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 65 'Truth') | |
| A reaction: Quite helpful to distinguish internalist from externalist theories of truth. It is certainly the case that robust externalist views of truth have unfortunately been discredited merely because the correspondence account is inadequate. |
| 22279 | Frege's sign |--- meant judgements, but the modern |- turnstile means inference, with intecedents [Potter] |
| Full Idea: Natural deduction systems generally depend on conditional proof, but for Frege everything is asserted unconditionally. The modern turnstile |- is allowed to have antecedents, and hence to represent inference rather than Frege's judgement sign |---. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 03 'Axioms') | |
| A reaction: [compressed] Shockingly, Frege's approach seems more psychological than the modern approach. I would say that the whole point of logic is that it has to be conditional, because the truth of the antecedents is irrelevant. |
| 22291 | Deductivism can't explain how the world supports unconditional conclusions [Potter] |
| Full Idea: Deductivism is a good account of large parts of mathematics, but stumbles where mathematics is directly applicable to the world. It fails to explain how we detach the antecedent so as to arrive at unconditional conclusions. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 12 'Deduc') | |
| A reaction: I suppose the reply would be that we have designed deductive structures which fit our understanding of reality - so it is all deductive, but selected pragmatically. |
| 22295 | Modern logical truths are true under all interpretations of the non-logical words [Potter] |
| Full Idea: In the modern definition, a 'logical truth' is true under every interpretation of the non-logical words it contains. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 19 'Frege's') | |
| A reaction: What if the non-logical words are nonsense, or are used inconsistently ('good'), or ambiguously ('bank'), or vaguely ('bald'), or with unsure reference ('the greatest philosopher' becomes 'Bentham')? What qualifies as an 'interpretation'? |
| 22310 | The formalist defence against Gödel is to reject his metalinguistic concept of truth [Potter] |
| Full Idea: Gödel's theorem does not refute formalism outright, because the committed formalist need not recognise the metalinguistic notion of truth to which the theorem appeals. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 45 'Log') | |
| A reaction: The theorem was prior to Tarski's account of truth. Potter says Gödel avoided explicit mention of truth because of this problem. In general Gödel showed that there are truths outside the formal system (which is all provable). |
| 22298 | Why is fictional arithmetic applicable to the real world? [Potter] |
| Full Idea: Fictionalists struggle to explain why arithmetic is applicable to the real world in a way that other stories are not. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 21 'Math') | |
| A reaction: We know why some novels are realistic and others just the opposite. If a novel aimed to 'model' the real world it would be even closer to it. Fictionalists must explain why some fictions are useful. |
| 22287 | If 'concrete' is the negative of 'abstract', that means desires and hallucinations are concrete [Potter] |
| Full Idea: The word 'concrete' is often used as the negative of 'abstract', with the slightly odd consequence that desires and hallucinations are thereby classified as concrete. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 12 'Numb') | |
| A reaction: There is also the even more baffling usage of 'abstract' for the most highly generalised mathematics, leaving lower levels as 'concrete'. I favour the use of 'generalised' wherever possible, rather than 'abstract'. |
| 22284 | 'Greater than', which is the ancestral of 'successor', strictly orders the natural numbers [Potter] |
| Full Idea: From the successor function we can deduce its ancestral, the 'greater than' relation, which is a strict total ordering of the natural numbers. (Frege did not mention this, but Dedekind worked it out, when expounding definition by recursion). | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 07 'Def') | |
| A reaction: [compressed] |
| 22281 | A material conditional cannot capture counterfactual reasoning [Potter] |
| Full Idea: What the material conditional most significantly fails to capture is counterfactual reasoning. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 04 'Sem') | |
| A reaction: The point is that counterfactuals say 'if P were the case (which it isn't), then Q'. But that means P is false, and in the material conditional everything follows from a falsehood. A reinterpretation of the conditional might embrace counterfactuals. |
| 22327 | Knowledge from a drunken schoolteacher is from a reliable and unreliable process [Potter] |
| Full Idea: Knowledge might result from a reliable and an unreliable process. ...Is something knowledge if you were told it by a drunken schoolteacher? | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 66 'Rel') | |
| A reaction: Nice example. The listener must decide which process to rely on. But how do you decide that, if not by assessing the likely truth of what you are being told? It could be a bad teacher who is inspired by drink. |
| 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. |
| 22273 | Traditionally there are twelve categories of judgement, in groups of three [Potter] |
| Full Idea: The traditional categorisation of judgements (until at least 1800) was as universal, particular or singular; as affirmative, negative or infinite; as categorical, hypothetical or disjunctive; or as problematic, assertoric or apodictic. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 02 'Trans') | |
| A reaction: Arranging these things in neat groups of three seems to originate with the stoics. Making distinctions like this is very much the job of a philosopher, but arranging them in neat equinumerous groups is intellectual tyranny. |
| 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. |
| 22290 | The phrase 'the concept "horse"' can't refer to a concept, because it is saturated [Potter] |
| Full Idea: Frege's mirroring principle (that the structure of thoughts mirrors that of language) has the uncomfortable consequence that since the phrase 'the concept "horse"' is saturated, it cannot refer to something unsaturated, which includes concepts. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 16 'Conc') |
| 22283 | Compositionality should rely on the parsing tree, which may contain more than sentence components [Potter] |
| Full Idea: Compositionality is best seen as saying the semantic value of a string is explained by the strings lower down its parsing tree. It is unimportant whether a string is always parsed in terms of its own substrings. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 05 'Sem') | |
| A reaction: That is, the analysis must explain the meaning, but the analysis can contain more than the actual ingredients of the sentence (which would be too strict). |
| 22282 | 'Direct compositonality' says the components wholly explain a sentence meaning [Potter] |
| Full Idea: Some authors urge the strong notion of 'direct compositionality', which requires that the content of a sentence be explained in terms of the contents of the component parts of that very sentence. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 05 'Sem') | |
| A reaction: The alternative is that meaning is fully explained by an analysis, but that may contain more than the actual components of the sentence. |
| 22296 | Compositionality is more welcome in logic than in linguistics (which is more contextual) [Potter] |
| Full Idea: The principle of compositionality is more popular among philosophers of logic than of language, because the subtle context-sensitivity or ordinary language makes providing a compositional semantics for it a daunting challenge. | |
| From: Michael Potter (The Rise of Analytic Philosophy 1879-1930 [2020], 21 'Lang') | |
| A reaction: Logicians love breaking complex entities down into simple atomic parts. Linguistics tries to pin down something much more elusive. |
| 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. |
| 1748 | Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius] |
| Full Idea: Archelaus was the first person to say that the universe is boundless. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 02.Ar.3 |
| 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. |
| 5989 | Archelaus said life began in a primeval slime [Archelaus, by Schofield] |
| Full Idea: Archelaus wrote that life on Earth began in a primeval slime. | |
| From: report of Archelaus (fragments/reports [c.450 BCE]) by Malcolm Schofield - Archelaus | |
| A reaction: This sounds like a fairly clearcut assertion of the production of life by evolution. Darwin's contribution was to propose the mechanism for achieving it. We should honour the name of Archelaus for this idea. |
| 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. |