23 ideas
| 21704 | 'Impredictative' definitions fix a class in terms of the greater class to which it belongs [Linsky,B] |
| Full Idea: The ban on 'impredicative' definitions says you can't define a class in terms of a totality to which that class must be seen as belonging. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 1) | |
| A reaction: So that would be defining 'citizen' in terms of the community to which the citizen belongs? If you are asked to define 'community' and 'citizen' together, where do you start? But how else can it be done? Russell's Reducibility aimed to block this. |
| 21705 | Reducibility says any impredicative function has an appropriate predicative replacement [Linsky,B] |
| Full Idea: The Axiom of Reducibility avoids impredicativity, by asserting that for any predicate of given arguments defined by quantifying over higher-order functions or classes, there is another co-extensive but predicative function of the same type of arguments. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 1) | |
| A reaction: Eventually the axiom seemed too arbitrary, and was dropped. Linsky's book explores it. |
| 21727 | Definite descriptions theory eliminates the King of France, but not the Queen of England [Linsky,B] |
| Full Idea: The theory of definite descriptions may eliminate apparent commitment to such entities as the present King of France, but certainly not to the present Queen of England. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 7.3) |
| 21719 | Extensionalism means what is true of a function is true of coextensive functions [Linsky,B] |
| Full Idea: With the principle of extensionality anything true of one propositional functions will be true of every coextensive one. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 6.3) |
| 21723 | The task of logicism was to define by logic the concepts 'number', 'successor' and '0' [Linsky,B] |
| Full Idea: The problem for logicism was to find definitions of the primitive notions of Peano's theory, number, successor and 0, in terms of logical notions, so that the postulates could then be derived by logic alone. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 7) | |
| A reaction: Both Frege and Russell defined numbers as equivalence classes. Successor is easily defined (in various ways) in set theory. An impossible set can exemplify zero. The trouble for logicism is this all relies on sets. |
| 21721 | Higher types are needed to distinguished intensional phenomena which are coextensive [Linsky,B] |
| Full Idea: The higher types are needed for intensional phenomena, cases where the same class is picked out by distinct propositional functions. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 6.4) | |
| A reaction: I take it that in this way 'x is renate' can be distinguished from 'x is cordate', a task nowadays performed by possible worlds. |
| 21703 | Types are 'ramified' when there are further differences between the type of quantifier and its range [Linsky,B] |
| Full Idea: The types is 'ramified' because there are further differences between the type of a function defined in terms of a quantifier ranging over other functions and the type of those other functions, despite the functions applying to the same simple type. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 1) | |
| A reaction: Not sure I understand this, but it evidently created difficulties for dealing with actual mathematics, and Ramsey showed how you could manage without the ramifications. |
| 21714 | The ramified theory subdivides each type, according to the range of the variables [Linsky,B] |
| Full Idea: The original ramified theory of types ...furthern subdivides each of the types of the 'simple' theory according to the range of the bound variables used in the definition of each propositional function. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 6) | |
| A reaction: For a non-intiate like me it certainly sounds disappointing that such a bold and neat theory because a tangle of complications. Ramsey and Russell in the 1920s seem to have dropped the ramifications. |
| 21713 | Did logicism fail, when Russell added three nonlogical axioms, to save mathematics? [Linsky,B] |
| Full Idea: It is often thought that Logicism was a failure, because after Frege's contradiction, Russell required obviously nonlogical principles, in order to develop mathematics. The axioms of Reducibility, Infinity and Choice are cited. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 6) | |
| A reaction: Infinity and Choice remain as axioms of the standard ZFC system of set theory, which is why set theory is always assumed to be 'up to its neck' in ontological commitments. Linsky argues that Russell saw ontology in logic. |
| 21715 | For those who abandon logicism, standard set theory is a rival option [Linsky,B] |
| Full Idea: ZF set theory is seen as a rival to logicism as a foundational scheme. Set theory is for those who have given up the project of reducing mathematics to logic. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 6.1) | |
| A reaction: Presumably there are other rivals. Set theory has lots of ontological commitments. One could start at the other end, and investigate the basic ontological commitments of arithmetic. I have no idea what those might be. |
| 3509 | Externalism may be the key idea in philosophical naturalism [Papineau] |
| Full Idea: Some people view an externalist approach to epistemology as the essence of philosophical naturalism. | |
| From: David Papineau (Philosophical Naturalism [1993], Intro) | |
| A reaction: I suspect philosophers avoid psychology and mental events, simply because they are elusive. Externalism is a theory about justification, and independent of naturalism as a metaphysic. |
| 21729 | Construct properties as sets of objects, or say an object must be in the set to have the property [Linsky,B] |
| Full Idea: Rather than directly constructing properties as sets of objects and proving neat facts about properties by proxy, we can assert biconditionals, such as that an object has a property if and only if it is in a certain set. | |
| From: Bernard Linsky (Russell's Metaphysical Logic [1999], 7.6) | |
| A reaction: Linsky is describing Russell's method of logical construction. I'm not clear what is gained by this move, but at least it is a variant of the usual irritating expression of properties as sets of objects. |
| 22049 | Transcendental idealism aims to explain objectivity through subjectivity [Bowie] |
| Full Idea: The aim of transcendental idealism is to give a basis for objectivity in terms of subjectivity. | |
| From: Andrew Bowie (German Philosophy: a very short introduction [2010], 1) | |
| A reaction: Hume used subjectivity to undermine the findings of objectivity. There was then no return to naive objectivity. Kant's aim then was to thwart global scepticism. Post-Kantians feared that he had failed. |
| 22055 | The Idealists saw the same unexplained spontaneity in Kant's judgements and choices [Bowie] |
| Full Idea: The Idealist saw in Kant that knowledge, which depends on the spontaneity of judgement, and self-determined spontaneous action, can be seen as sharing the same source, which is not accessible to scientific investigation. | |
| From: Andrew Bowie (German Philosophy: a very short introduction [2010]) | |
| A reaction: This is the 'spontaneity' of judgements and choices which was seen as the main idea in Kant. It inspired romantic individualism. The judgements are the rule-based application of concepts. |
| 22054 | German Idealism tried to stop oppositions of appearances/things and receptivity/spontaneity [Bowie] |
| Full Idea: A central aim of German Idealism is to overcome Kant's oppositions between appearances and thing in themselves, and between receptivity and spontaneity. | |
| From: Andrew Bowie (German Philosophy: a very short introduction [2010], 2) | |
| A reaction: I have the impression that there were two strategies: break down the opposition within the self (Fichte), or break down the opposition in the world (Spinozism). |
| 22056 | Crucial to Idealism is the idea of continuity between receptivity and spontaneous judgement [Bowie] |
| Full Idea: A crucial idea for German Idealism (from Hamann) is that apparently passive receptivity and active spontaneity are in fact different degrees of the same 'activity, and the gap between subject and world can be closed. | |
| From: Andrew Bowie (German Philosophy: a very short introduction [2010], 3) | |
| A reaction: The 'passive' bit seems to be Hume's 'impressions', which are Kant's 'intuitions', which need 'spontaneous' interpretation to become experiences. Critics of Kant said this implied a dualism. |
| 3513 | How does a dualist mind represent, exist outside space, and be transparent to itself? [Papineau] |
| Full Idea: Even dualists must explain how the mind represents things, but then their mind-stuff has so many special powers already (being outside space but in time, being transparent to itself etc.) that one more scarcely seems worth worrying about. | |
| From: David Papineau (Philosophical Naturalism [1993], 3.1 n1) | |
| A reaction: I share the exasperation. It is hard to see how a dualist could even begin to formulate a theory about HOW the mind does so many different things. Could Descartes get a research grant for it? Would we understand God if he tried to explain it to us? |
| 3514 | Functionalism needs causation and intentionality to explain actions [Papineau] |
| Full Idea: The functionalist approach to the mind needs to invoke assumptions about what desires are for and beliefs are about, in order to infer what agents will do. | |
| From: David Papineau (Philosophical Naturalism [1993], 3.2) | |
| A reaction: Isn't the idea that you discover what desires are for and what beliefs are about by examining their function, and what the agent does? Which end should we start? |
| 3511 | Supervenience requires all mental events to have physical effects [Papineau] |
| Full Idea: The argument for supervenience rests on the principle that any mental difference must be capable of showing itself in differential physical consequences. | |
| From: David Papineau (Philosophical Naturalism [1993], 1.8) | |
| A reaction: With our current knowledge of the brain, to assume anything less than this sort of correlation would be crazy. |
| 3510 | Epiphenomenalism is supervenience without physicalism [Papineau] |
| Full Idea: Supervenience is a necessary condition for physicalism, but it is not sufficient. Epiphenomenalism rules out mental variation without physical variation, but says mental properties are quite distinct from physical properties. | |
| From: David Papineau (Philosophical Naturalism [1993], 1.2) | |
| A reaction: I take full epiphenomenalism about mind to be incoherent, and not worth even mentioning (see Idea 7379). Papineau seems to be thinking of so-called property dualism (which may also be incoherent!). |
| 3515 | Knowing what it is like to be something only involves being (physically) that thing [Papineau] |
| Full Idea: Physicalism does not deny that there are conscious experiences, nor that 'it is like something to have them'. The claim is only that this is nothing different from what it is to be a physical system of the relevant kind. | |
| From: David Papineau (Philosophical Naturalism [1993], 4.2) | |
| A reaction: The implication is that no physicalist is an extreme eliminativist about consciousness, which seems to be correct. We all concede that weather exists, but have a reductive view of it. The key question is whether mind is reducible to physics. |
| 3512 | If a mental state is multiply realisable, why does it lead to similar behaviour? [Papineau] |
| Full Idea: If functionalism implies that there is nothing physically in common among the realisations of a given mental state, then there is no possibility of any uniform explanation of why they all give rise to a common physical result. | |
| From: David Papineau (Philosophical Naturalism [1993], 2.2) | |
| A reaction: This is the well known interaction problem for dualism. The standard reply is to accept interaction as a given (with no apparent explanation). A miracle, if you like. |
| 3516 | The Private Language argument only means people may misjudge their experiences [Papineau] |
| Full Idea: I take the moral of the Private Language argument to be that there must be room for error in people's judgements about their experiences, not that those judgements must necessarily be expressed in a language used by a community. | |
| From: David Papineau (Philosophical Naturalism [1993], 4.4 n10) | |
| A reaction: These two readings don't seem to be in conflict, and the argument must have something to say about the communal nature of thought expressed in language. Language imposes introspection on us? |