26 ideas
| 18005 | Philosophy aims to become more disciplined about categories [Ryle] |
| Full Idea: Philosophy is the replacement of category-habits by category-disciplines. | |
| From: Gilbert Ryle (The Concept of Mind [1949], Intro p.8), quoted by Ofra Magidor - Category Mistakes 1.2 | |
| A reaction: I rather like this. It fits the view the idea that metaphysics aims to give the structure of reality. If there are not reasonably uniform categories for things, then reality is indescribable. Improving our categories seems a thoroughly laudable aim. |
| 15924 | Predicative definitions are acceptable in mathematics if they distinguish objects, rather than creating them? [Zermelo, by Lavine] |
| Full Idea: On Zermelo's view, predicative definitions are not only indispensable to mathematics, but they are unobjectionable since they do not create the objects they define, but merely distinguish them from other objects. | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Shaughan Lavine - Understanding the Infinite V.1 | |
| A reaction: This seems to have an underlying platonism, that there are hitherto undefined 'objects' lying around awaiting the honour of being defined. Hm. |
| 17608 | We take set theory as given, and retain everything valuable, while avoiding contradictions [Zermelo] |
| Full Idea: Starting from set theory as it is historically given ...we must, on the one hand, restrict these principles sufficiently to exclude as contradiction and, on the other, take them sufficiently wide to retain all that is valuable in this theory. | |
| From: Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908], Intro) | |
| A reaction: Maddy calls this the one-step-back-from-disaster rule of thumb. Zermelo explicitly mentions the 'Russell antinomy' that blocked Frege's approach to sets. |
| 17607 | Set theory investigates number, order and function, showing logical foundations for mathematics [Zermelo] |
| Full Idea: Set theory is that branch whose task is to investigate mathematically the fundamental notions 'number', 'order', and 'function', taking them in their pristine, simple form, and to develop thereby the logical foundations of all of arithmetic and analysis. | |
| From: Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908], Intro) | |
| A reaction: At this point Zermelo seems to be a logicist. Right from the start set theory was meant to be foundational to mathematics, and not just a study of the logic of collections. |
| 10870 | ZFC: Existence, Extension, Specification, Pairing, Unions, Powers, Infinity, Choice [Zermelo, by Clegg] |
| Full Idea: Zermelo-Fraenkel axioms: Existence (at least one set); Extension (same elements, same set); Specification (a condition creates a new set); Pairing (two sets make a set); Unions; Powers (all subsets make a set); Infinity (set of successors); Choice | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Brian Clegg - Infinity: Quest to Think the Unthinkable Ch.15 |
| 13012 | Zermelo published his axioms in 1908, to secure a controversial proof [Zermelo, by Maddy] |
| Full Idea: Zermelo proposed his listed of assumptions (including the controversial Axiom of Choice) in 1908, in order to secure his controversial proof of Cantor's claim that ' we can always bring any well-defined set into the form of a well-ordered set'. | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Penelope Maddy - Believing the Axioms I §1 | |
| A reaction: This is interesting because it sometimes looks as if axiom systems are just a way of tidying things up. Presumably it is essential to get people to accept the axioms in their own right, the 'old-fashioned' approach that they be self-evident. |
| 17609 | Set theory can be reduced to a few definitions and seven independent axioms [Zermelo] |
| Full Idea: I intend to show how the entire theory created by Cantor and Dedekind can be reduced to a few definitions and seven principles, or axioms, which appear to be mutually independent. | |
| From: Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908], Intro) | |
| A reaction: The number of axioms crept up to nine or ten in subsequent years. The point of axioms is maximum reduction and independence from one another. He says nothing about self-evidence (though Boolos claimed a degree of that). |
| 13017 | Zermelo introduced Pairing in 1930, and it seems fairly obvious [Zermelo, by Maddy] |
| Full Idea: Zermelo's Pairing Axiom superseded (in 1930) his original 1908 Axiom of Elementary Sets. Like Union, its only justification seems to rest on 'limitations of size' and on the 'iterative conception'. | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Penelope Maddy - Believing the Axioms I §1.3 | |
| A reaction: Maddy says of this and Union, that they seem fairly obvious, but that their justification is of prime importance, if we are to understand what the axioms should be. |
| 13015 | Zermelo used Foundation to block paradox, but then decided that only Separation was needed [Zermelo, by Maddy] |
| Full Idea: Zermelo used a weak form of the Axiom of Foundation to block Russell's paradox in 1906, but in 1908 felt that the form of his Separation Axiom was enough by itself, and left the earlier axiom off his published list. | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Penelope Maddy - Believing the Axioms I §1.2 | |
| A reaction: Foundation turns out to be fairly controversial. Barwise actually proposes Anti-Foundation as an axiom. Foundation seems to be the rock upon which the iterative view of sets is built. Foundation blocks infinite descending chains of sets, and circularity. |
| 13020 | The Axiom of Separation requires set generation up to one step back from contradiction [Zermelo, by Maddy] |
| Full Idea: The most characteristic Zermelo axiom is Separation, guided by a new rule of thumb: 'one step back from disaster' - principles of set generation should be as strong as possible short of contradiction. | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Penelope Maddy - Believing the Axioms I §1.4 | |
| A reaction: Why is there an underlying assumption that we must have as many sets as possible? We are then tempted to abolish axioms like Foundation, so that we can have even more sets! |
| 13486 | Not every predicate has an extension, but Separation picks the members that satisfy a predicate [Zermelo, by Hart,WD] |
| Full Idea: Zermelo assumes that not every predicate has an extension but rather that given a set we may separate out from it those of its members satisfying the predicate. This is called 'separation' (Aussonderung). | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by William D. Hart - The Evolution of Logic 3 |
| 13487 | In ZF, the Burali-Forti Paradox proves that there is no set of all ordinals [Zermelo, by Hart,WD] |
| Full Idea: In Zermelo's set theory, the Burali-Forti Paradox becomes a proof that there is no set of all ordinals (so 'is an ordinal' has no extension). | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by William D. Hart - The Evolution of Logic 3 |
| 18178 | For Zermelo the successor of n is {n} (rather than n U {n}) [Zermelo, by Maddy] |
| Full Idea: For Zermelo the successor of n is {n} (rather than Von Neumann's successor, which is n U {n}). | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Penelope Maddy - Naturalism in Mathematics I.2 n8 | |
| A reaction: I could ask some naive questions about the comparison of these two, but I am too shy about revealing my ignorance. |
| 13027 | Zermelo believed, and Von Neumann seemed to confirm, that numbers are sets [Zermelo, by Maddy] |
| Full Idea: Zermelo was a reductionist, and believed that theorems purportedly about numbers (cardinal or ordinal) are really about sets, and since Von Neumann's definitions of ordinals and cardinals as sets, this has become common doctrine. | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by Penelope Maddy - Believing the Axioms I §1.8 | |
| A reaction: Frege has a more sophisticated take on this approach. It may just be an updating of the Greek idea that arithmetic is about treating many things as a unit. A set bestows an identity on a group, and that is all that is needed. |
| 9627 | Different versions of set theory result in different underlying structures for numbers [Zermelo, by Brown,JR] |
| Full Idea: In Zermelo's set-theoretic definition of number, 2 is a member of 3, but not a member of 4; in Von Neumann's definition every number is a member of every larger number. This means they have two different structures. | |
| From: report of Ernst Zermelo (Investigations in the Foundations of Set Theory I [1908]) by James Robert Brown - Philosophy of Mathematics Ch. 4 | |
| A reaction: This refers back to the dilemma highlighted by Benacerraf, which was supposed to be the motivation for structuralism. My intuition says that the best answer is that they are both wrong. In a pattern, the nodes aren't 'members' of one another. |
| 14297 | A dispositional property is not a state, but a liability to be in some state, given a condition [Ryle] |
| Full Idea: To possess a dispositional property is not to be in a particular state;..it is to be bound or liable to be in a particular state, or undergo a particular change, when a particular condition is realized. | |
| From: Gilbert Ryle (The Concept of Mind [1949], II (7)) | |
| A reaction: Whether this view is correct is the central question about dispositions. Ryle's view is tied in with Humean regularities and behaviourism about mind. The powers view, which I favour, says a disposition is a drawn bow, an actual state of power. |
| 14300 | No physical scientist now believes in an occult force-exerting agency [Ryle] |
| Full Idea: The old error treating the term 'Force' as denoting an occult force-exerting agency has been given up in the physical sciences. | |
| From: Gilbert Ryle (The Concept of Mind [1949], V (1)) | |
| A reaction: Since 1949 they seem to have made a revival, once they are divested of their religious connotations. The word 'agency' is the misleading bit. Even Leibniz's monads weren't actual agents - he always said that was 'an analogy'. |
| 2622 | Can one movement have a mental and physical cause? [Ryle] |
| Full Idea: The dogma of the Ghost in the Machine maintains that there exist both minds and bodies; that there are mechanical causes of corporeal movements, and mental causes of corporeal movements. | |
| From: Gilbert Ryle (The Concept of Mind [1949], I (3)) | |
| A reaction: This nicely identifies the problem of double causation, which can be found in Spinoza (Idea 4862). The dualists have certainly got a problem here, but they can deny a conflict. The initiation of a hand movement is not mechanical at all. |
| 21799 | We just use the word 'faculty' when we don't know the psychological cause [Galen] |
| Full Idea: So long as we are ignorant of the true essence of the cause which is operating, we call it a 'faculty'. | |
| From: Galen (On the Natural Faculties [c.170], I.iv), quoted by Dominik Perler - Intro to The Faculties: a History 2 | |
| A reaction: This is probably the view of most modern neuroscientists. I want to defend the idea that we need the concept of a faculty in philosophy, even if the psychologists and neuroscientists say it is too vague for their purposes. |
| 1353 | Reporting on myself has the same problems as reporting on you [Ryle] |
| Full Idea: My reports on myself are subject to the same kinds of defects as are my reports on you. | |
| From: Gilbert Ryle (The Concept of Mind [1949], Ch.6) | |
| A reaction: This may be true of memories or of motives, but it hardly seems to apply to being in pain, where you might be totally lying, where the worst I could do to myself is exaggerate. "You're fine; how am I?" |
| 1354 | We cannot introspect states of anger or panic [Ryle] |
| Full Idea: No one could introspectively scrutinize the state of panic or fury. | |
| From: Gilbert Ryle (The Concept of Mind [1949], Ch.6) | |
| A reaction: It depends what you mean by 'scrutinize'. No human being ever loses their temper or panics without a background thought of "Oh dear, I'm losing it - it would probably be better if I didn't" (or, as Aristotle might say, "I'm angry, and so I should be"). |
| 2624 | I cannot prepare myself for the next thought I am going to think [Ryle] |
| Full Idea: One thing that I cannot prepare myself for is the next thought that I am going to think. | |
| From: Gilbert Ryle (The Concept of Mind [1949], VI (7)) |
| 2620 | Dualism is a category mistake [Ryle] |
| Full Idea: The official theory of mind (as private, non-spatial, outside physical laws) I call 'the dogma of the Ghost in the Machine'. I hope to prove it entirely false, and show that it is one big mistake, namely a 'category mistake'. | |
| From: Gilbert Ryle (The Concept of Mind [1949], I (2)) | |
| A reaction: This is the essence of Ryle's eliminitavist behaviourism. Personally I agree that the idea of a separate 'ghost' running the machine is utterly implausible, but it isn't a 'category mistake'. The mind clearly exists, but the confusion is about what it is. |
| 2388 | Behaviour depends on desires as well as beliefs [Chalmers on Ryle] |
| Full Idea: Another problem for Ryle (from Chisholm and Geach) is that no mental state could be defined by a single range of behavioural dispositions, independent of any other mental states. (Behaviour depends upon desires as well as beliefs). | |
| From: comment on Gilbert Ryle (The Concept of Mind [1949]) by David J.Chalmers - The Conscious Mind 1.1.2 | |
| A reaction: The defence of behaviourism is to concede this point, but suggest that behavioural dispositions come in large groups of interdependent sets, some relating to beliefs, others relating to desires, and each group leads to a behaviour. |
| 3354 | You can't explain mind as dispositions, if they aren't real [Benardete,JA on Ryle] |
| Full Idea: Ryle is tough-minded to the point of incoherence when he combines a dispositional account of the mind with an anti-realist account of dispositions. | |
| From: comment on Gilbert Ryle (The Concept of Mind [1949]) by José A. Benardete - Metaphysics: the logical approach Ch.22 | |
| A reaction: A nice point, but it strikes me that Ryle was, by temperament at least, an eliminativist about the mind, so the objection would not bother him. Maybe a disposition and a property are the same thing? |
| 2387 | How can behaviour be the cause of behaviour? [Chalmers on Ryle] |
| Full Idea: A problem for Ryle is that mental states may cause behaviour, but if mental states are themselves behavioural or behavioural dispositions, as opposed to internal states, then it is hard to see how they could do the job. | |
| From: comment on Gilbert Ryle (The Concept of Mind [1949]) by David J.Chalmers - The Conscious Mind 1.1.2 | |
| A reaction: I strongly approve of this, as an objection to any form of behaviourism or functionalism. If you identify something by its related behaviour, or its apparent function, this leaves the question 'WHY does it behave or function in this way?' |