42 ideas
9108 | From an impossibility anything follows [William of Ockham] |
Full Idea: From an impossibility anything follows ('quod ex impossibili sequitur quodlibet'). | |
From: William of Ockham (Summa totius logicae [1323], III.c.xxxvi) | |
A reaction: The hallmark of a true logician, I suspect, is that this opinion is really meaningful and important to them. They yearn to follow the logic wherever it leads. Common sense would seem to say that absolutely nothing follows from an impossibility. |
5784 | In its primary and formal sense, 'true' applies to propositions, not beliefs [Russell] |
Full Idea: We call a belief true when it is belief in a true proposition, ..but it is to propositions that the primary formal meanings of 'truth' and 'falsehood' apply. | |
From: Bertrand Russell (On Propositions: What they are, and Meaning [1919], §IV) | |
A reaction: I think this is wrong. A proposition such as 'it is raining' would need a date-and-time stamp to be a candidate for truth, and an indexical statement such as 'I am ill' would need to be asserted by a person. Of course, books can contain unread truths. |
5777 | The truth or falsehood of a belief depends upon a fact to which the belief 'refers' [Russell] |
Full Idea: I take it as evident that the truth or falsehood of a belief depends upon a fact to which the belief 'refers'. | |
From: Bertrand Russell (On Propositions: What they are, and Meaning [1919], p.285) | |
A reaction: A nice bold commitment to a controversial idea. The traditional objection is to ask how you are going to formulate the 'facts' except in terms of more beliefs, so you ending up comparing beliefs. Facts are a metaphysical commitment, not an acquaintance. |
9107 | A proposition is true if its subject and predicate stand for the same thing [William of Ockham] |
Full Idea: If in the proposition 'This is an angel' subject and predicate stand for the same thing, the proposition is true. | |
From: William of Ockham (Summa totius logicae [1323], II.c.ii) | |
A reaction: An interesting statement of what looks like a correspondence theory, employing the idea that both the subject and the predicate have a reference. I think Frege would say that 'x is an angel' is unsaturated, and so lacks reference. |
5783 | Propositions of existence, generalities, disjunctions and hypotheticals make correspondence tricky [Russell] |
Full Idea: The correspondence of proposition and fact grows increasingly complicated as we pass to more complicated types of propositions: existence-propositions, general propositions, disjunctive and hypothetical propositions, and so on. | |
From: Bertrand Russell (On Propositions: What they are, and Meaning [1919], §IV) | |
A reaction: An important point. Truth must not just work for 'it is raining', but also for maths, logic, tautologies, laws etc. This is why so many modern philosophers have retreated to deflationary and minimal accounts of truth, which will cover all cases. |
16300 | Ockham had an early axiomatic account of truth [William of Ockham, by Halbach] |
Full Idea: Theories structurally very similar to axiomatic compositional theories of truth can be found in Ockham's 'Summa Logicae'. | |
From: report of William of Ockham (Summa totius logicae [1323]) by Volker Halbach - Axiomatic Theories of Truth 3 |
9106 | The word 'every' only signifies when added to a term such as 'man', referring to all men [William of Ockham] |
Full Idea: The syncategorematic word 'every' does not signify any fixed thing, but when added to 'man' it makes the term 'man' stand for all men actually. | |
From: William of Ockham (Summa totius logicae [1323], I.c.iv) | |
A reaction: Although quantifiers may have become a part of formal logic with Frege, their importance is seen from Aristotle onwards, and it is clearly a key part of William's understanding of logic. |
9113 | Just as unity is not a property of a single thing, so numbers are not properties of many things [William of Ockham] |
Full Idea: Number is nothing but the actual numbered things themselves. Hence just as unity is not an accident added to the thing which is one, so number is not an accident of the things which are numbered. | |
From: William of Ockham (Summa totius logicae [1323], I.c.xliv) | |
A reaction: [William does not necessarily agree with this view] It strikes me as a key point here that any account of the numbers had better work for 'one', though 'zero' might be treated differently. Some people seem to think unity is a property of things. |
9110 | The words 'thing' and 'to be' assert the same idea, as a noun and as a verb [William of Ockham] |
Full Idea: The words 'thing' and 'to be' (esse) signify one and the same thing, but the one in the manner of a noun and the other in the manner of a verb. | |
From: William of Ockham (Summa totius logicae [1323], III,II,c,xxvii) | |
A reaction: Well said - as you would expect from a thoroughgoing nominalist. I would have thought that this was the last word on the subject of Being, thus rendering any need for me to read Heidegger quite superfluous. Or am I missing something? |
15388 | Universals are single things, and only universal in what they signify [William of Ockham] |
Full Idea: Every universal is one particular thing and it is not a universal except in its signification, in its signifying many thing. | |
From: William of Ockham (Summa totius logicae [1323]), quoted by Claude Panaccio - Medieval Problem of Universals 'William' | |
A reaction: Sounds as if William might have liked tropes. It seems to leave the problem unanswered (the 'ostrich' problem?). How are they able to signify in this universal way, if each thing is just distinct and particular? |
9109 | If essence and existence were two things, one could exist without the other, which is impossible [William of Ockham] |
Full Idea: If essence and existence were two things, then no contradiction would be involved if God preserved the essence of a thing in the world without its existence, or vice versa, its existence without its essence; both of which are impossible. | |
From: William of Ockham (Summa totius logicae [1323], III,II,c,xxvii) | |
A reaction: Not that William is using the concept of a supreme mind as a tool in argument. His denial of essence as something separable is presumably his denial of the Aristotelian view of universals, as well as of the Platonic view. |
5780 | The three questions about belief are its contents, its success, and its character [Russell] |
Full Idea: There are three issues about belief: 1) the content which is believed, 2) the relation of the content to its 'objective' - the fact which makes it true or false, and 3) the element which is belief, as opposed to consideration or doubt or desire. | |
From: Bertrand Russell (On Propositions: What they are, and Meaning [1919], §III) | |
A reaction: The correct answers to the questions (trust me) are that propositions are the contents, the relation aimed at is truth, which is a 'metaphysical ideal' of correspondence to facts, and belief itself is an indefinable feeling. See Hume, Idea 2208. |
17979 | Research shows perceptual discrimination is sharper at category boundaries [Murphy] |
Full Idea: Goldstone's research has shown how learning concepts can change perceptual units. For example, perceptual discrimination is heightened along category boundaries. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch.13) | |
A reaction: [Goldstone 1994, 2000] This is just the sort of research which throws a spanner into the simplistic a priori thinking of many philosophers. |
18690 | Induction is said to just compare properties of categories, but the type of property also matters [Murphy] |
Full Idea: Most theories of induction claim that it should depend primarily on the similarity of the categories involved, but then the type of property should not matter, yet research shows that it does. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 6) | |
A reaction: I take this to be good empirical support for Gilbert Harman's view that induction is really inference to the best explanation. The thought (which strikes me as obviously correct) is that we bring nested domains of knowledge to bear in induction. |
5778 | If we object to all data which is 'introspective' we will cease to believe in toothaches [Russell] |
Full Idea: If privacy is the main objection to introspective data, we shall have to include among such data all sensations; a toothache, for example, is essentially private; a dentist may see the bad condition of your tooth, but does not feel your ache. | |
From: Bertrand Russell (On Propositions: What they are, and Meaning [1919], §II) | |
A reaction: Russell was perhaps the first to see why eliminative behaviourism is a non-starter as a theory of mind. Mental states are clearly a cause of behaviour, so they can't be the same thing. We might 'eliminate' mental states by reducing them, though. |
5779 | There are distinct sets of psychological and physical causal laws [Russell] |
Full Idea: There do seem to be psychological and physical causal laws which are distinct from each other. | |
From: Bertrand Russell (On Propositions: What they are, and Meaning [1919], §II) | |
A reaction: This sounds like the essence of 'property dualism'. Reductive physicalists (like myself) say there is no distinction. Davidson, usually considered a property dualist, claims there are no psycho-physical laws. Russell notes that reduction may be possible. |
17980 | The main theories of concepts are exemplar, prototype and knowledge [Murphy] |
Full Idea: The three main theories of concepts under consideration are the exemplar, the prototype and the knowledge approaches. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch.13) |
17973 | The theoretical and practical definitions for the classical view are very hard to find [Murphy] |
Full Idea: It has been extremely difficult to find definitions for most natural categories, and even harder to find definitions that are plausible psychological representations that people of all ages would be likely to use. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 2) |
17969 | The classical definitional approach cannot distinguish typical and atypical category members [Murphy] |
Full Idea: The early psychological approaches to concepts took a definitional approach. ...but this view does not have any way of distinguishing typical and atypical category members (...as when a trout is a typical fish and an eel an atypical one). | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 2) | |
A reaction: [pp. 12 and 22] Eleanor Rosch in the 1970s is said to have largely killed off the classical view. |
17970 | Classical concepts follow classical logic, but concepts in real life don't work that way [Murphy] |
Full Idea: The classical view of concepts has been tied to traditional logic. 'Fido is a dog and a pet' is true if it has the necessary and sufficient conditions for both, ...but there is empirical evidence that people do not follow that rule. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 2) | |
A reaction: Examples given are classifying chess as a sport and/or game, and classifying a tree house (which is agreed to be both a building and not a building!). |
17971 | Classical concepts are transitive hierarchies, but actual categories may be intransitive [Murphy] |
Full Idea: The classical view of concepts explains hierarchical order, where categories form nested sets. But research shows that categories are often not transitive. Research shows that a seat is furniture, and a car seat is a seat, but it is not furniture. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 2) | |
A reaction: [compressed] Murphy adds that the nesting of definitions is classically used to match the nesting of hierarchies. This is a nice example of the neatness of the analytic philosopher breaking down when it meets the mess of the world. |
17972 | The classical core is meant to be the real concept, but actually seems unimportant [Murphy] |
Full Idea: A problem with the revised classical view is that the concept core does not seem to be an important part of the concept, despite its name and theoretical intention as representing the 'real' concept. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 2) | |
A reaction: Apparently most researchers feel they can explain their results without reference to any core. Not so fast, I would say (being an essentialist). Maybe people acknowledge an implicit core without knowing what it is. See Susan Gelman. |
17975 | There is no 'ideal' bird or dog, and prototypes give no information about variability [Murphy] |
Full Idea: Is there really an 'ideal bird' that could represent all birds? ...Furthermore a single prototype would give no information about the variability of a category. ...Compare the incredible variety of dogs to the much smaller diversity of cats. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 3) | |
A reaction: The point about variability is particularly noteworthy. You only grasp the concept of 'furniture' when you understand its range, as well as its typical examples. What structure is needed in a concept to achieve this? |
17976 | Prototypes are unified representations of the entire category (rather than of members) [Murphy] |
Full Idea: In the prototype view the entire category is represented by a unified representation rather than separate representations for each member, or for different classes of members. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 3) | |
A reaction: This is the improved prototype view, as opposed to the implausible idea that there is one ideal exemplar. The new theory still have the problem of how to represent diversity within the category, while somehow remaining 'unified'. |
18691 | The prototype theory uses observed features, but can't include their construction [Murphy] |
Full Idea: Nothing in the prototype model says the shape of an animal is more important than its location in identifying its kind. The theory does not provide a way the features can be constructed, rather than just observed. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 6) | |
A reaction: This makes some kind of mental modelling central to thought, and not just a bonus once you have empirically acquired the concepts. We bring our full range of experience to bear on even the most instantaneous observations. |
17983 | The prototype theory handles hierarchical categories and combinations of concepts well [Murphy] |
Full Idea: The prototype view has no trouble with either hierarchical structure or explaining categories. ...Meaning and conceptual combination provide strong evidence for prototypes. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch.13) | |
A reaction: Prototypes are not vague, making clearer classification possible. A 'mountain lion' is clear, because its components are clear. |
17985 | Prototypes theory of concepts is best, as a full description with weighted typical features [Murphy] |
Full Idea: Our theory of concepts must be primarily prototype-based. That is, it must be a description of an entire concept, with its typical features (presumably weighted by their importance). | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch.13) | |
A reaction: This is to be distinguished from the discredited 'classical' view of concepts, that the concept consists of its definition. I take Aristotle's account of definition to be closer to a prototype description than to a dictionary definition. |
17986 | Learning concepts is forming prototypes with a knowledge structure [Murphy] |
Full Idea: My proposal is that people attempt to form prototypes as part of a larger knowledge structure when they learn concepts. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch.13) | |
A reaction: This combines theory theory (knowledge) with the prototype view, and sounds rather persuasive. The formation of prototypes fits with the explanatory account of essentialism I am defending. He later calls prototype formation 'abstraction' (494). |
17974 | The most popular theories of concepts are based on prototypes or exemplars [Murphy] |
Full Idea: The most popular theories of concepts are based on prototype or exemplar theories that are strongly unclassical. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 2) |
17977 | The exemplar view of concepts says 'dogs' is the set of dogs I remember [Murphy] |
Full Idea: In the exemplar view of concepts, the idea that people have a representation that somehow encompasses an entire concept is rejected. ...Instead a person's concept of dogs is the set of dogs that the person remembers. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 3) | |
A reaction: [The theory was introduced by Medin and Schaffer 1978] I think I have finally met a plausible theory of concepts. When I think 'dog' I conjure up a fuzz of dogs that exhibit the range I have encountered (e.g. tiny to very big). Individuals come first! |
17982 | Exemplar theory struggles with hierarchical classification and with induction [Murphy] |
Full Idea: The exemplar view has trouble with hierarchical classification and with induction in adults. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch.13) | |
A reaction: To me these both strongly support essentialism - that you form the concept 'dog' from seeing some dogs, but you then extrapolate to large categories and general truths about dogs, on the assumption of the natures of the dogs you have seen. |
17981 | Children using knowing and essentialist categories doesn't fit the exemplar view [Murphy] |
Full Idea: The findings showing that children use knowledge and may be essentialist about category membership do not comport well with the exemplar view. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch.13) | |
A reaction: Tricky, because Gelman persuaded me of the essentialism, but the exemplar view of concepts looks the most promising. Clearly they must be forced to coexist.... |
17984 | Conceptual combination must be compositional, and can't be built up from exemplars [Murphy] |
Full Idea: The exemplar accounts of conceptual combination are demonstrably wrong, because the meaning of a phrase has to be composed from the meaning of its parts (plus broader knowledge), and it cannot be composed as a function of exemplars. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch.13) | |
A reaction: This sounds quite persuasive, and I begin to see that my favoured essentialism fits the prototype view of concepts best, though this mustn't be interpreted too crudely. We change our prototypes with experience. 'Bird' is a tricky case. |
17987 | The concept of birds from exemplars must also be used in inductions about birds [Murphy] |
Full Idea: We don't have one concept of birds formed by learning from exemplars, and another concept of birds that is used in induction. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch.13) | |
A reaction: In other words exemplar concepts break down when we generalise using the concept. The exemplars must be unified, to be usable in thought and language. |
17978 | We do not learn concepts in isolation, but as an integrated part of broader knowledge [Murphy] |
Full Idea: The knowledge approach argues that concepts are part of our general knowledge about the world. We do not learn concepts in isolation, ...but as part of our overall understanding of the world. Animal concepts are integrated with biology, behaviour etc. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 3) | |
A reaction: This is one of the leading theories of concepts among psychologists. It seems to be an aspect of the true theory, but it needs underpinning with some account of isolated individual concepts. This is also known as the 'theory theory'. |
18687 | Concepts with familiar contents are easier to learn [Murphy] |
Full Idea: A concept's content influences how easy it is to learn. If the concept is grossly incompatible with what people know prior to the experiment, it will be difficult to acquire. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 6) | |
A reaction: This is a preliminary fact which leads towards the 'knowledge' theory of concepts (aka 'theory theory'). The point being that the knowledge involved is integral to the concept. Fits my preferred mental files approach. |
18688 | Some knowledge is involved in instant use of categories, other knowledge in explanations [Murphy] |
Full Idea: Some kinds of knowledge are probably directly incorporated into the category representation and used in normal, fast decisions about objects. Other kinds of knowledge, however, may come into play only when it has been solicited. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 6) | |
A reaction: This is a summary of empirical research, but seems to fit our normal experience. If you see a hawk, you have some instant understanding, but if you ask what the hawk is doing here, you draw more widely. |
18689 | People categorise things consistent with their knowledge, even rejecting some good evidence [Murphy] |
Full Idea: People tend to positively categorise items that are consistent with their knowledge and to exclude items that are inconsistent, sometimes even overruling purely empirical sources of information. | |
From: Gregory L. Murphy (The Big Book of Concepts [2004], Ch. 6) | |
A reaction: The main rival to 'theory theory' is the purely empirical account of how concepts are acquired. This idea reports empirical research in favour of the theory theory (or 'knowledge') approach. |
5781 | Our important beliefs all, if put into words, take the form of propositions [Russell] |
Full Idea: The important beliefs, even if they are not the only ones, are those which, if rendered into explicit words, take the form of a proposition. | |
From: Bertrand Russell (On Propositions: What they are, and Meaning [1919], §III) | |
A reaction: This assertion is close to the heart of the twentieth century linking of ontology and epistemology to language. It is open to challenges. Why is non-propositional belief unimportant? Do dogs have important beliefs? Can propositions exist non-verbally? |
5782 | A proposition expressed in words is a 'word-proposition', and one of images an 'image-proposition' [Russell] |
Full Idea: I shall distinguish a proposition expressed in words as a 'word-proposition', and one consisting of images as an 'image-proposition'. | |
From: Bertrand Russell (On Propositions: What they are, and Meaning [1919], §III) | |
A reaction: This, I think, is good, though it raises the question of what exactly an 'image' is when it is non-visual, as when a dog believes its owner called. This distinction prevents us from regarding all knowledge and ontology as verbal in form. |
5776 | A proposition is what we believe when we believe truly or falsely [Russell] |
Full Idea: A proposition may be defined as: what we believe when we believe truly or falsely. | |
From: Bertrand Russell (On Propositions: What they are, and Meaning [1919], p.285) | |
A reaction: If we define belief as 'commitment to truth', Russell's last six words become redundant. "Propositions are the contents of beliefs", it being beliefs which are candidates for truth, not propositions. (Russell agrees, on p.308!) |
9105 | Some concepts for propositions exist only in the mind, and in no language [William of Ockham] |
Full Idea: Conceptual terms and the propositions formed by them are those mental words which do not belong to any language; they remain only in the mind and cannot be uttered exteriorly, though signs subordinated to these can be exteriorly uttered. | |
From: William of Ockham (Summa totius logicae [1323], I.c.i) | |
A reaction: [He cites Augustine] A glimmer of the idea of Mentalese, and is probably an integral part of any commitment to propositions. Quine would hate it, but I like it. Logicians seem to dislike anything that cannot be articulated, but brains are like that. |