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Ideas of Gregory L. Murphy, by Text

[American, fl. 2004, Professor of Psychology at New York University.]

2004 The Big Book of Concepts
Ch. 2 p.12 The classical definitional approach cannot distinguish typical and atypical category members
     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.
Ch. 2 p.26 Classical concepts follow classical logic, but concepts in real life don't work that way
     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!).
Ch. 2 p.27 Classical concepts are transitive hierarchies, but actual categories may be intransitive
     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.
Ch. 2 p.28 The classical core is meant to be the real concept, but actually seems unimportant
     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.
Ch. 2 p.38 The theoretical and practical definitions for the classical view are very hard to find
     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)
Ch. 2 p.40 The most popular theories of concepts are based on prototypes or exemplars
     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)
Ch. 3 p.42 There is no 'ideal' bird or dog, and prototypes give no information about variability
     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 must 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?
Ch. 3 p.42 Prototypes are unified representations of the entire category (rather than of members)
     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'.
Ch. 3 p.49 The exemplar view of concepts says 'dogs' is the set of dogs I remember
     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!
Ch. 3 p.60 We do not learn concepts in isolation, but as an integrated part of broader knowledge
     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'.
Ch. 6 p.148 Concepts with familiar contents are easier to learn
     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.
Ch. 6 p.168 Some knowledge is involved in instant use of categories, other knowledge in explanations
     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.
Ch. 6 p.173 People categorise things consistent with their knowledge, even rejecting some good evidence
     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.
Ch. 6 p.181 Induction is said to just compare properties of categories, but the type of property also matters
     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.
Ch. 6 p.183 The prototype theory uses observed features, but can't include their construction
     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.
Ch.13 p.479 Research shows perceptual discrimination is sharper at category boundaries
     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.
Ch.13 p.483 The main theories of concepts are exemplar, prototype and knowledge
     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)
Ch.13 p.485 Children using knowing and essentialist categories doesn't fit the exemplar view
     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....
Ch.13 p.485 Exemplar theory struggles with hierarchical classification and with induction
     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.
Ch.13 p.487 The prototype theory handles hierarchical categories and combinations of concepts well
     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.
Ch.13 p.487 Conceptual combination must be compositional, and can't be built up from exemplars
     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.
Ch.13 p.488 Prototypes theory of concepts is best, as a full description with weighted typical features
     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.
Ch.13 p.492 Learning concepts is forming prototypes with a knowledge structure
     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).
Ch.13 p.496 The concept of birds from exemplars must also be used in inductions about birds
     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.