82 ideas
| 15901 | Trying to represent curves, we study arbitrary functions, leading to the ordinals, which produces set theory [Cantor, by Lavine] |
| Full Idea: The notion of a function evolved gradually from wanting to see what curves can be represented as trigonometric series. The study of arbitrary functions led Cantor to the ordinal numbers, which led to set theory. | |
| From: report of George Cantor (works [1880]) by Shaughan Lavine - Understanding the Infinite I |
| 13444 | Cantor's Theorem: for any set x, its power set P(x) has more members than x [Cantor, by Hart,WD] |
| Full Idea: Cantor's Theorem says that for any set x, its power set P(x) has more members than x. | |
| From: report of George Cantor (works [1880]) by William D. Hart - The Evolution of Logic 1 |
| 18098 | Cantor proved that all sets have more subsets than they have members [Cantor, by Bostock] |
| Full Idea: Cantor's diagonalisation argument generalises to show that any set has more subsets than it has members. | |
| From: report of George Cantor (works [1880]) by David Bostock - Philosophy of Mathematics 4.5 | |
| A reaction: Thus three members will generate seven subsets. This means that 'there is no end to the series of cardinal numbers' (Bostock p.106). |
| 15505 | If a set is 'a many thought of as one', beginners should protest against singleton sets [Cantor, by Lewis] |
| Full Idea: Cantor taught that a set is 'a many, which can be thought of as one'. ...After a time the unfortunate beginner student is told that some classes - the singletons - have only a single member. Here is a just cause for student protest, if ever there was one. | |
| From: report of George Cantor (works [1880]) by David Lewis - Parts of Classes 2.1 | |
| A reaction: There is a parallel question, almost lost in the mists of time, of whether 'one' is a number. 'Zero' is obviously dubious, but if numbers are for counting, that needs units, so the unit is the precondition of counting, not part of it. |
| 10701 | Cantor showed that supposed contradictions in infinity were just a lack of clarity [Cantor, by Potter] |
| Full Idea: Cantor's theories exhibited the contradictions others had claimed to derive from the supposition of infinite sets as confusions resulting from the failure to mark the necessary distinctions with sufficient clarity. | |
| From: report of George Cantor (works [1880]) by Michael Potter - Set Theory and Its Philosophy Intro 1 |
| 10865 | The continuum is the powerset of the integers, which moves up a level [Cantor, by Clegg] |
| Full Idea: Cantor discovered that the continuum is the powerset of the integers. While adding or multiplying infinities didn't move up a level of complexity, multiplying a number by itself an infinite number of times did. | |
| From: report of George Cantor (works [1880]) by Brian Clegg - Infinity: Quest to Think the Unthinkable Ch.14 |
| 13016 | The Axiom of Union dates from 1899, and seems fairly obvious [Cantor, by Maddy] |
| Full Idea: Cantor first stated the Union Axiom in a letter to Dedekind in 1899. It is nearly too obvious to deserve comment from most commentators. Justifications usually rest on 'limitation of size' or on the 'iterative conception'. | |
| From: report of George Cantor (works [1880]) by Penelope Maddy - Believing the Axioms I §1.3 | |
| A reaction: Surely someone can think of some way to challenge it! An opportunity to become notorious, and get invited to conferences. |
| 14199 | Cantor's sets were just collections, but Dedekind's were containers [Cantor, by Oliver/Smiley] |
| Full Idea: Cantor's definition of a set was a collection of its members into a whole, but within a few years Dedekind had the idea of a set as a container, enclosing its members like a sack. | |
| From: report of George Cantor (works [1880]) by Oliver,A/Smiley,T - What are Sets and What are they For? Intro | |
| A reaction: As the article goes on to show, these two view don't seem significantly different until you start to ask about the status of the null set and of singletons. I intuitively vote for Dedekind. Set theory is the study of brackets. |
| 3005 | 'Jocasta' needs to be distinguished from 'Oedipus's mother' because they are connected by different properties [Fodor] |
| Full Idea: If the concept 'Jocasta' needs to be distinguished from the concept 'Oedipus's mother', that's all right because the two concepts are connected with different properties. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 84) |
| 10082 | There are infinite sets that are not enumerable [Cantor, by Smith,P] |
| Full Idea: Cantor's Theorem (1874) says there are infinite sets that are not enumerable. This is proved by his 1891 'diagonal argument'. | |
| From: report of George Cantor (works [1880]) by Peter Smith - Intro to Gödel's Theorems 2.3 | |
| A reaction: [Smith summarises the diagonal argument] |
| 13483 | Cantor's Paradox: the power set of the universe must be bigger than the universe, yet a subset of it [Cantor, by Hart,WD] |
| Full Idea: The problem of Cantor's Paradox is that the power set of the universe has to be both bigger than the universe (by Cantor's theorem) and not bigger (since it is a subset of the universe). | |
| From: report of George Cantor (works [1880]) by William D. Hart - The Evolution of Logic 3 | |
| A reaction: Russell eliminates the 'universe' in his theory of types. I don't see why you can't just say that the members of the set are hypothetical rather than real, and that hypothetically the universe might contain more things than it does. |
| 8710 | The powerset of all the cardinal numbers is required to be greater than itself [Cantor, by Friend] |
| Full Idea: Cantor's Paradox says that the powerset of a set has a cardinal number strictly greater than the original set, but that means that the powerset of the set of all the cardinal numbers is greater than itself. | |
| From: report of George Cantor (works [1880]) by Michèle Friend - Introducing the Philosophy of Mathematics | |
| A reaction: Friend cites this with the Burali-Forti paradox and the Russell paradox as the best examples of the problems of set theory in the early twentieth century. Did this mean that sets misdescribe reality, or that we had constructed them wrongly? |
| 15910 | Cantor named the third realm between the finite and the Absolute the 'transfinite' [Cantor, by Lavine] |
| Full Idea: Cantor believed he had discovered that between the finite and the 'Absolute', which is 'incomprehensible to the human understanding', there is a third category, which he called 'the transfinite'. | |
| From: report of George Cantor (works [1880]) by Shaughan Lavine - Understanding the Infinite III.4 |
| 15905 | Cantor proved the points on a plane are in one-to-one correspondence to the points on a line [Cantor, by Lavine] |
| Full Idea: In 1878 Cantor published the unexpected result that one can put the points on a plane, or indeed any n-dimensional space, into one-to-one correspondence with the points on a line. | |
| From: report of George Cantor (works [1880]) by Shaughan Lavine - Understanding the Infinite III.1 |
| 9983 | Cantor took the ordinal numbers to be primary [Cantor, by Tait] |
| Full Idea: Cantor took the ordinal numbers to be primary: in his generalization of the cardinals and ordinals into the transfinite, it is the ordinals that he calls 'numbers'. | |
| From: report of George Cantor (works [1880]) by William W. Tait - Frege versus Cantor and Dedekind VI | |
| A reaction: [Tait says Dedekind also favours the ordinals] It is unclear how the matter might be settled. Humans cannot give the cardinality of large groups without counting up through the ordinals. A cardinal gets its meaning from its place in the ordinals? |
| 17798 | Cantor presented the totality of natural numbers as finite, not infinite [Cantor, by Mayberry] |
| Full Idea: Cantor taught us to regard the totality of natural numbers, which was formerly thought to be infinite, as really finite after all. | |
| From: report of George Cantor (works [1880]) by John Mayberry - What Required for Foundation for Maths? p.414-2 | |
| A reaction: I presume this is because they are (by definition) countable. |
| 9971 | Cantor introduced the distinction between cardinals and ordinals [Cantor, by Tait] |
| Full Idea: Cantor introduced the distinction between cardinal and ordinal numbers. | |
| From: report of George Cantor (works [1880]) by William W. Tait - Frege versus Cantor and Dedekind Intro | |
| A reaction: This seems remarkably late for what looks like a very significant clarification. The two concepts coincide in finite cases, but come apart in infinite cases (Tait p.58). |
| 9892 | Cantor showed that ordinals are more basic than cardinals [Cantor, by Dummett] |
| Full Idea: Cantor's work revealed that the notion of an ordinal number is more fundamental than that of a cardinal number. | |
| From: report of George Cantor (works [1880]) by Michael Dummett - Frege philosophy of mathematics Ch.23 | |
| A reaction: Dummett makes it sound like a proof, which I find hard to believe. Is the notion that I have 'more' sheep than you logically prior to how many sheep we have? If I have one more, that implies the next number, whatever that number may be. Hm. |
| 14136 | A cardinal is an abstraction, from the nature of a set's elements, and from their order [Cantor] |
| Full Idea: The cardinal number of M is the general idea which, by means of our active faculty of thought, is deduced from the collection M, by abstracting from the nature of its diverse elements and from the order in which they are given. | |
| From: George Cantor (works [1880]), quoted by Bertrand Russell - The Principles of Mathematics §284 | |
| A reaction: [Russell cites 'Math. Annalen, XLVI, §1'] See Fine 1998 on this. |
| 15906 | Cantor tried to prove points on a line matched naturals or reals - but nothing in between [Cantor, by Lavine] |
| Full Idea: Cantor said he could show that every infinite set of points on the line could be placed into one-to-one correspondence with either the natural numbers or the real numbers - with no intermediate possibilies (the Continuum hypothesis). His proof failed. | |
| From: report of George Cantor (works [1880]) by Shaughan Lavine - Understanding the Infinite III.1 |
| 11015 | Cantor's diagonal argument proved you can't list all decimal numbers between 0 and 1 [Cantor, by Read] |
| Full Idea: Cantor's diagonal argument showed that all the infinite decimals between 0 and 1 cannot be written down even in a single never-ending list. | |
| From: report of George Cantor (works [1880]) by Stephen Read - Thinking About Logic Ch.6 |
| 15903 | A real is associated with an infinite set of infinite Cauchy sequences of rationals [Cantor, by Lavine] |
| Full Idea: Cantor's theory of Cauchy sequences defines a real number to be associated with an infinite set of infinite sequences of rational numbers. | |
| From: report of George Cantor (works [1880]) by Shaughan Lavine - Understanding the Infinite II.6 | |
| A reaction: This sounds remarkably like the endless decimals we use when we try to write down an actual real number. |
| 18251 | Irrational numbers are the limits of Cauchy sequences of rational numbers [Cantor, by Lavine] |
| Full Idea: Cantor introduced irrationals to play the role of limits of Cauchy sequences of rational numbers. | |
| From: report of George Cantor (works [1880]) by Shaughan Lavine - Understanding the Infinite 4.2 |
| 15902 | Irrationals and the Dedekind Cut implied infinite classes, but they seemed to have logical difficulties [Cantor, by Lavine] |
| Full Idea: From the very nature of an irrational number, it seems necessary to understand the mathematical infinite thoroughly before an adequate theory of irrationals is possible. Infinite classes are obvious in the Dedekind Cut, but have logical difficulties | |
| From: report of George Cantor (works [1880]) by Shaughan Lavine - Understanding the Infinite II Intro | |
| A reaction: Almost the whole theory of analysis (calculus) rested on the irrationals, so a theory of the infinite was suddenly (in the 1870s) vital for mathematics. Cantor wasn't just being eccentric or mystical. |
| 15908 | It was Cantor's diagonal argument which revealed infinities greater than that of the real numbers [Cantor, by Lavine] |
| Full Idea: Cantor's 1891 diagonal argument revealed there are infinitely many infinite powers. Indeed, it showed more: it shows that given any set there is another of greater power. Hence there is an infinite power strictly greater than that of the set of the reals. | |
| From: report of George Cantor (works [1880]) by Shaughan Lavine - Understanding the Infinite III.2 |
| 13464 | Cantor proposes that there won't be a potential infinity if there is no actual infinity [Cantor, by Hart,WD] |
| Full Idea: What we might call 'Cantor's Thesis' is that there won't be a potential infinity of any sort unless there is an actual infinity of some sort. | |
| From: report of George Cantor (works [1880]) by William D. Hart - The Evolution of Logic 1 | |
| A reaction: This idea is nicely calculated to stop Aristotle in his tracks. |
| 10112 | The naturals won't map onto the reals, so there are different sizes of infinity [Cantor, by George/Velleman] |
| Full Idea: Cantor showed that the complete totality of natural numbers cannot be mapped 1-1 onto the complete totality of the real numbers - so there are different sizes of infinity. | |
| From: report of George Cantor (works [1880]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.4 |
| 8733 | The Continuum Hypothesis says there are no sets between the natural numbers and reals [Cantor, by Shapiro] |
| Full Idea: Cantor's 'continuum hypothesis' is the assertion that there are no infinite cardinalities strictly between the size of the natural numbers and the size of the real numbers. | |
| From: report of George Cantor (works [1880]) by Stewart Shapiro - Thinking About Mathematics 2.4 | |
| A reaction: The tricky question is whether this hypothesis can be proved. |
| 17889 | CH: An infinite set of reals corresponds 1-1 either to the naturals or to the reals [Cantor, by Koellner] |
| Full Idea: Cantor's Continuum Hypothesis (CH) says that for every infinite set X of reals there is either a one-to-one correspondence between X and the natural numbers, or between X and the real numbers. | |
| From: report of George Cantor (works [1880]) by Peter Koellner - On the Question of Absolute Undecidability 1.2 | |
| A reaction: Every single writer I read defines this differently, which drives me crazy, but is also helpfully illuminating. There is a moral there somewhere. |
| 13447 | Cantor: there is no size between naturals and reals, or between a set and its power set [Cantor, by Hart,WD] |
| Full Idea: Cantor conjectured that there is no size between those of the naturals and the reals - called the 'continuum hypothesis'. The generalized version says that for no infinite set A is there a set larger than A but smaller than P(A). | |
| From: report of George Cantor (works [1880]) by William D. Hart - The Evolution of Logic 1 | |
| A reaction: Thus there are gaps between infinite numbers, and the power set is the next size up from any infinity. Much discussion as ensued about whether these two can be proved. |
| 10883 | Cantor's Continuum Hypothesis says there is a gap between the natural and the real numbers [Cantor, by Horsten] |
| Full Idea: Cantor's Continuum Hypothesis states that there are no sets which are too large for there to be a one-to-one correspondence between the set and the natural numbers, but too small for there to exist a one-to-one correspondence with the real numbers. | |
| From: report of George Cantor (works [1880]) by Leon Horsten - Philosophy of Mathematics §5.1 |
| 13528 | Continuum Hypothesis: there are no sets between N and P(N) [Cantor, by Wolf,RS] |
| Full Idea: Cantor's conjecture (the Continuum Hypothesis) is that there are no sets between N and P(N). The 'generalized' version replaces N with an arbitrary infinite set. | |
| From: report of George Cantor (works [1880]) by Robert S. Wolf - A Tour through Mathematical Logic 2.2 | |
| A reaction: The initial impression is that there is a single gap in the numbers, like a hole in ozone layer, but the generalised version implies an infinity of gaps. How can there be gaps in the numbers? Weird. |
| 9555 | Continuum Hypothesis: no cardinal greater than aleph-null but less than cardinality of the continuum [Cantor, by Chihara] |
| Full Idea: Cantor's Continuum Hypothesis was that there is no cardinal number greater than aleph-null but less than the cardinality of the continuum. | |
| From: report of George Cantor (works [1880]) by Charles Chihara - A Structural Account of Mathematics 05.1 | |
| A reaction: I have no view on this (have you?), but the proposal that there are gaps in the number sequences has to excite all philosophers. |
| 18174 | Cantor extended ordinals into the transfinite, and they can thus measure infinite cardinalities [Cantor, by Maddy] |
| Full Idea: Cantor's second innovation was to extend the sequence of ordinal numbers into the transfinite, forming a handy scale for measuring infinite cardinalities. | |
| From: report of George Cantor (works [1880]) by Penelope Maddy - Naturalism in Mathematics I.1 | |
| A reaction: Struggling with this. The ordinals seem to locate the cardinals, but in what sense do they 'measure' them? |
| 15893 | Cantor's theory concerns collections which can be counted, using the ordinals [Cantor, by Lavine] |
| Full Idea: Cantor's set theory was not of collections in some familiar sense, but of collections that can be counted using the indexes - the finite and transfinite ordinal numbers. ..He treated infinite collections as if they were finite. | |
| From: report of George Cantor (works [1880]) by Shaughan Lavine - Understanding the Infinite I |
| 18173 | Cardinality strictly concerns one-one correspondence, to test infinite sameness of size [Cantor, by Maddy] |
| Full Idea: Cantor's first innovation was to treat cardinality as strictly a matter of one-to-one correspondence, so that the question of whether two infinite sets are or aren't of the same size suddenly makes sense. | |
| From: report of George Cantor (works [1880]) by Penelope Maddy - Naturalism in Mathematics I.1 | |
| A reaction: It makes sense, except that all sets which are infinite but countable can be put into one-to-one correspondence with one another. What's that all about, then? |
| 10232 | Property extensions outstrip objects, so shortage of objects caused the Caesar problem [Cantor, by Shapiro] |
| Full Idea: Cantor's theorem entails that there are more property extensions than objects. So there are not enough objects in any domain to serve as extensions for that domain. So Frege's view that numbers are objects led to the Caesar problem. | |
| From: report of George Cantor (works [1880]) by Stewart Shapiro - Philosophy of Mathematics 4.6 | |
| A reaction: So the possibility that Caesar might have to be a number arises because otherwise we are threatening to run out of numbers? Is that really the problem? |
| 18176 | Pure mathematics is pure set theory [Cantor] |
| Full Idea: Pure mathematics ...according to my conception is nothing other than pure set theory. | |
| From: George Cantor (works [1880], I.1), quoted by Penelope Maddy - Naturalism in Mathematics I.1 | |
| A reaction: [an unpublished paper of 1884] So right at the beginning of set theory this claim was being made, before it was axiomatised, and so on. Zermelo endorsed the view, and it flourished unchallenged until Benacerraf (1965). |
| 8631 | Cantor says that maths originates only by abstraction from objects [Cantor, by Frege] |
| Full Idea: Cantor calls mathematics an empirical science in so far as it begins with consideration of things in the external world; on his view, number originates only by abstraction from objects. | |
| From: report of George Cantor (works [1880]) by Gottlob Frege - Grundlagen der Arithmetik (Foundations) §21 | |
| A reaction: Frege utterly opposed this view, and he seems to have won the day, but I am rather thrilled to find the great Cantor endorsing my own intuitions on the subject. The difficulty is to explain 'abstraction'. |
| 7014 | A particle and a coin heads-or-tails pick out to perfectly well-defined predicates and properties [Fodor] |
| Full Idea: 'Is a particle and my coin is heads' and 'is a particle and my coin is tails' are perfectly well defined predicates and they pick out perfectly well defined (relational) properties of physical particles. | |
| From: Jerry A. Fodor (Psychosemantics [1987], Ch.2) | |
| A reaction: (Somewhat paraphrased). This is a very nice offering for the case that all predicates are properties, and hence that 'properties' is an entirely conventional category. It strikes me as self-evident that Fodor is not picking out 'natural' properties. |
| 2990 | Contrary to commonsense, most of what is in the mind seems to be unlearned [Fodor] |
| Full Idea: Contrary to commonsense, it looks as though much of what is in the mind is unlearned. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 15) |
| 3009 | Sticklebacks have an innate idea that red things are rivals [Fodor] |
| Full Idea: God gave the male stickleback the idea that whatever is red is a rival. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p.133) |
| 3008 | Evolution suggests that innate knowledge of human psychology would be beneficial [Fodor] |
| Full Idea: If I had to design homo sapiens, I would have made commonsense knowledge of homo sapiens psychology innate; that way nobody would have to spend time learning it. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p.132) |
| 2994 | In CRTT thought may be represented, content must be [Fodor] |
| Full Idea: In the Representation Theory of Mind, programs (the 'laws of thought') may be explicitly represented, but data structures (the 'contents of thought') have to be. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 25) | |
| A reaction: Presumably this is because content is where mental events actually meet up with the reality being considered. It may be an abstract procedure, but if it doesn't plug into reality then it isn't thought, but merely activity, like that of the liver. |
| 15494 | We can't use propositions to explain intentional attitudes, because they would need explaining [Fodor] |
| Full Idea: It's not clear what the point would be of an explanation of the intentionality of attitudes which presupposes objects that are intentional intrinsically. Why not just say that the attitudes are? | |
| From: Jerry A. Fodor (Psychosemantics [1987], Ch.3) |
| 7326 | Intentionality doesn't go deep enough to appear on the physicists' ultimate list of things [Fodor] |
| Full Idea: Sooner or later the physicists will complete the catalogue of ultimate and irreducible things, with the likes of spin, charm and charge. But aboutness won't be on the list; intentionality simply doesn't go that deep. | |
| From: Jerry A. Fodor (Psychosemantics [1987], 4 Intro) | |
| A reaction: I totally agree with this, which I take to be a warning to John Searle against including something called 'intrinsic intentionality' into his ontology. Intentionality 'emerges' out of certain complex brain activity. |
| 3001 | Behaviourism has no theory of mental causation [Fodor] |
| Full Idea: Behaviourists had trouble providing a robust construal of mental causation (and hence had no logical space for a psychology of mental processes). | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 67) | |
| A reaction: If they could reduce all mental events to stimulus-response, that seems to fall within the normal procedures of physical causation. There is no problem of mental causation if your ontology is entirely physical. |
| 2993 | Any piece of software can always be hard-wired [Fodor] |
| Full Idea: For any machine that computes a function by executing an explicit algorithm, there exists a hard-wired machine that computes the same function by not executing an explicit algorithm. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 23) | |
| A reaction: It is certainly vital for functionalists to understand that software can be hardwired. Presumably we should understand a hardwired alogirthm as 'implicit'? |
| 3011 | Causal powers must be a crucial feature of mental states [Fodor] |
| Full Idea: Everybody is a functionalist, in that we all hold that mental states are individuated, at least in part, by reference to their causal powers. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p.138) | |
| A reaction: I might individuate the Prime Minister by the carnation in his buttonhole. However, even a dualist must concede that we individuate mental faculties by their role within the mind. |
| 5498 | Mind is a set of hierarchical 'homunculi', which are made up in turn from subcomponents [Fodor, by Lycan] |
| Full Idea: Fodor sees behaviour as manifestations of psychological capacities, which result from the subject being a set of interconnected 'homunculi', which in turn have subcomponents, all of it arranged in a hierarchy. | |
| From: report of Jerry A. Fodor (Psychosemantics [1987]) by William Lycan - Introduction - Ontology p.9 | |
| A reaction: This may well miss out the most interesting parts of a mind (such as awareness, and personal identity), but it sounds basically right, especially when an evolutionary history is added to the system. Parts of my mind intrude into my trains of thought. |
| 2995 | Supervenience gives good support for mental causation [Fodor] |
| Full Idea: Mind/brain supervenience is the best idea anyone has had so far about how mental causation is possible. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 30) | |
| A reaction: I would have thought that mind brain identity was a much better idea (see Idea 3440). Supervenience seems to prove that 'mental causation' occurs, but doesn't explain it. |
| 2991 | Hume's associationism offers no explanation at all of rational thought [Fodor] |
| Full Idea: With Associationism there proved to be no way to get a rational mental life to emerge from the sorts of causal relations among thoughts that the 'laws of association' recognised. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 18) | |
| A reaction: This might not be true if you add the concept of evolution, which has refined the associations to generate truth (which is vital for survival). |
| 3002 | If mind is just physical, how can it follow the rules required for intelligent thought? [Fodor] |
| Full Idea: Central state identity theorists had trouble providing for the nomological possibility of rational machines (and hence no space for a non-biological, e.g. computational, theory of intelligence). | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 67) | |
| A reaction: I surmise that a more externalist account of the physical mind might do the trick, by explaining intelligence in terms of an evolved relationship between brain and environment. |
| 2992 | We may be able to explain rationality mechanically [Fodor] |
| Full Idea: We are on the verge of solving a great mystery about the mind: how is rationality mechanically possible? | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 20) | |
| A reaction: Optimistic, given that AI has struggled to implement natural languages, mainly because common sense knowledge seems too complex to encode. Can a machine determine logical forms of sentences? |
| 2988 | Folk psychology is the only explanation of behaviour we have [Fodor] |
| Full Idea: Commonsense belief/desire psychology explains vastly more of the facts about behaviour than any of the alternative theories available. It could hardly fail to; there are no alternative theories available. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p.x) | |
| A reaction: The alternative view wouldn't expect a clear-cut theory, because it deals with the endless complexity of brain events. The charge is that Fodor and co oversimplify their account, in their desperation for a 'theory'. |
| 3010 | Belief and desire are structured states, which need mentalese [Fodor] |
| Full Idea: A defence of the language of thought has to be an argument that believing and desiring are typically structured states. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p.136) | |
| A reaction: A structure is one thing, and a language is another. Both believings and desirings can be extremely vague, to the point where the owner is unsure what is believed or desired. They can, of course, be extremely precise. |
| 2999 | Obsession with narrow content leads to various sorts of hopeless anti-realism [Fodor] |
| Full Idea: People who ask what the narrow content of the thought that water is wet is (for example) get what they deserve: phenomenalism, verificationism, 'procedural' semantics, or scepticism, according to temperament. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 51) | |
| A reaction: The question is whether content IS narrow. We could opt for broad content because then we wouldn't have to worry about scepticism, but I doubt whether we would then sleep well at night. |
| 3012 | Do identical thoughts have identical causal roles? [Fodor] |
| Full Idea: If thoughts have their causal roles in virtue of their contents, then two thoughts with identical contents ought to be identical in their causal roles. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p.140) | |
| A reaction: A pencil would presumably have the same causal role if it wrote a love poem or hate mail. But a pencil is also good for scratching your back. 'Causal role' can be a rather vacuous idea. |
| 8715 | Infinities expand the bounds of the conceivable; we explore concepts to explore conceivability [Cantor, by Friend] |
| Full Idea: Cantor (in his exploration of infinities) pushed the bounds of conceivability further than anyone before him. To discover what is conceivable, we have to enquire into the concept. | |
| From: report of George Cantor (works [1880]) by Michèle Friend - Introducing the Philosophy of Mathematics 6.5 | |
| A reaction: This remark comes during a discussion of Husserl's phenomenology. Intuitionists challenge Cantor's claim, and restrict what is conceivable to what is provable. Does possibility depend on conceivability? |
| 13454 | Cantor says (vaguely) that we abstract numbers from equal sized sets [Hart,WD on Cantor] |
| Full Idea: Cantor thought that we abstract a number as something common to all and only those sets any one of which has as many members as any other. ...However one wants to see the logic of the inference. The irony is that set theory lays out this logic. | |
| From: comment on George Cantor (works [1880]) by William D. Hart - The Evolution of Logic 1 | |
| A reaction: The logic Hart has in mind is the notion of an equivalence relation between sets. This idea sums up the older and more modern concepts of abstraction, the first as psychological, the second as logical (or trying very hard to be!). Cf Idea 9145. |
| 2998 | Grice thinks meaning is inherited from the propositional attitudes which sentences express [Fodor] |
| Full Idea: According to Gricean theories of meaning, the meaning of a sentence is inherited from the propositional attitudes that the sentence is conventionally used to express. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 50) | |
| A reaction: Since the propositional attitudes contain propositions, this seems like a very plausible idea. If an indexical like 'I' is involved, the meaning of the sentence is not the same as its 'conventional' use. |
| 3006 | Whatever in the mind delivers falsehood is parasitic on what delivers truth [Fodor] |
| Full Idea: The mechanisms that deliver falsehoods are somehow parasitic on the ones that deliver truths. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p.107) | |
| A reaction: In the case of a sentence and its negation it is not clear which one is 'parasitic', because that can usually be reversed by paraphrasing. Historically, I very much hope that truth-speaking came first. |
| 3007 | Many different verification procedures can reach 'star', but it only has one semantic value [Fodor] |
| Full Idea: Verification procedures connect terms with their denotations in too many ways. Different routes to 'star' do not determine different semantic values for 'star'. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p.125) | |
| A reaction: This fairly conclusively shows that meaning is not 'the method of verification' - but that wasn't a difficult target to hit. |
| 3004 | The meaning of a sentence derives from its use in expressing an attitude [Fodor] |
| Full Idea: The meaning of a sentence derives from its use in expressing an attitude. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 79) | |
| A reaction: Among other things. It can also arrive from a desire to remember something. A sentence can also acquire meaning compositionally (by assembling) with no use or aim. |
| 3000 | Meaning holism is a crazy doctrine [Fodor] |
| Full Idea: Meaning holism really is a crazy doctrine. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 60) | |
| A reaction: Yes. What is not crazy is a contextualist account of utterances, and a recognition of the contextual and relational ingredient in the meanings of most of our sentences. |
| 3003 | Very different mental states can share their contents, so content doesn't seem to be constructed from functional role [Fodor] |
| Full Idea: It's an embarrassment for attempts to construct content from functional role that quite different sorts of mental states can nevertheless share their contents. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 70) | |
| A reaction: That is, presumably, one content having two different roles. Two contents with the same role is 'multiple realisability'. Pain can tell me I'm damaged, or reveal that my damaged nerves are healing. Problem? |
| 2996 | Mental states may have the same content but different extensions [Fodor] |
| Full Idea: The identity of the content of mental states does not ensure the identity of their extensions. | |
| From: Jerry A. Fodor (Psychosemantics [1987], p. 45) | |
| A reaction: Obviously if I am thinking each day about 'my sheep', that won't change if I am unaware that one of them died this morning. …Because I didn’t have the precise number of sheep in mind. |
| 10863 | Cantor proved that three dimensions have the same number of points as one dimension [Cantor, by Clegg] |
| Full Idea: Cantor proved that one-dimensional space has exactly the same number of points as does two dimensions, or our familiar three-dimensional space. | |
| From: report of George Cantor (works [1880]) by Brian Clegg - Infinity: Quest to Think the Unthinkable Ch.14 |
| 13465 | Only God is absolutely infinite [Cantor, by Hart,WD] |
| Full Idea: Cantor said that only God is absolutely infinite. | |
| From: report of George Cantor (works [1880]) by William D. Hart - The Evolution of Logic 1 | |
| A reaction: We are used to the austere 'God of the philosophers', but this gives us an even more austere 'God of the mathematicians'. |
| 20712 | God is 'eternal' either by being non-temporal, or by enduring forever [Davies,B] |
| Full Idea: Saying 'God is eternal' means either that God is non-temporal or timeless, or that God has no beginning and no end. The first ('classical') view is found in Anselm, Augustine, Boethius, Aquinas, Calvin and Descartes. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 8 'Meaning') | |
| A reaction: A God who is outside of time but performs actions is a bit of a puzzle. It seems that Augustine started the idea of a timeless God. |
| 20701 | Can God be good, if he has not maximised goodness? [Davies,B] |
| Full Idea: We may wonder whether God can be good since he has not produced more moral goodness than he has. We may wonder whether God is guilty by neglect. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 3 'Freedom') | |
| A reaction: The orthodox response is that we cannot possibly know what the maximum of moral goodness would look like, so we can't make this judgement. Atheists say that God fails by human standards, which are not particularly high. |
| 20702 | The goodness of God may be a higher form than the goodness of moral agents [Davies,B] |
| Full Idea: If we can know that God exists and if God's goodness is not moral goodness, then moral goodness is not the highest form of goodness we know. There is the goodness of God to be reckoned with. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 3 'Goodness') | |
| A reaction: This idea is to counter the charge that God fails to meet human standards for an ideal moral agent. But it sounds hand-wavy, since we presumably cannot comprehend the sort of goodness that is postulated here. |
| 20703 | How could God have obligations? What law could possibly impose them? [Davies,B] |
| Full Idea: We have good reason for resisting the suggestion that God has any duties or obligations. …What can oblige God in relation to his creatures? Could there be a law saying God has such obligations? Where does such a law come from? | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 3 'Goodness') | |
| A reaction: Plato can answer this question. Greek gods are not so supreme that nothing could put them under an obligation, but 'God' has to be supreme in every respect. |
| 20694 | 'Natural theology' aims to prove God to anyone (not just believers) by reason or argument [Davies,B] |
| Full Idea: 'Natural theology' is the attempt to show that belief in God's existence can be defended with reference to reason or argument which ought to be acceptable to anyone, not simply to those who believe in God's existence. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 1 'Other') | |
| A reaction: I assume by 'reason or argument' he primarily means evidence (plus the ontological argument). He cites Karl Barth as objecting to the assumption of natural theology (preferring revelation). Presumably Kierkegaard offers a rival view too. |
| 20706 | A distinct cause of the universe can't be material (which would be part of the universe) [Davies,B] |
| Full Idea: If the universe was caused to come into being, it presumably could not have been caused to do so by anything material. For a material object would be part of the universe, and we are now asking for a cause distinct from the universe. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 5 'God') | |
| A reaction: We're out of our depth here. We only have two modes of existence to offer, material and spiritual, and 'spiritual' means little more than non-material. |
| 20707 | The universe exhibits design either in its sense of purpose, or in its regularity [Davies,B] |
| Full Idea: The design argument offers two lines: the first states that the universe displays design in the sense of purpose; the second that it displays design in the sense of regularity. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 6 'Versions') | |
| A reaction: I would have thought that you would infer the purpose from the regularity. How could you see purpose in a totally chaotic universe? |
| 20708 | If God is an orderly being, he cannot be the explanation of order [Davies,B] |
| Full Idea: If God is an instance of something orderly, how can he serve to account for the order of orderly things? | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 6 'b Has') | |
| A reaction: You can at least explain the tidiness of a house by the tidiness of its owner, but obviously that won't explain the phenomenon of tidiness. |
| 20710 | Maybe an abnormal state of mind is needed to experience God? [Davies,B] |
| Full Idea: Might it not be possible that experience of God requires an unusual state or psychological abnormality, just as an aerial view of Paris requires that one be in the unusual state of being abnormally elevated? | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 7 'Are the') | |
| A reaction: That would make sense if it were analogous to great mathematical or musical ability, but it sounds more like ouija boards in darkened rooms. Talent has a wonderful output, but people in mystical states don't return with proofs. |
| 20711 | A believer can experience the world as infused with God [Davies,B] |
| Full Idea: Maybe someone who believes in God can be regarded as experiencing everything as something behind which God lies. Believers see the world as a world in which God is present. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 7 'Experiencing') | |
| A reaction: [Attributed to John Hick] This would count as supporting evidence for God, perhaps, if seeing reality as infused with God produces a consistent and plausible picture. But seeing reality as infused with other things might pass the same test. |
| 20709 | The experiences of God are inconsistent, not universal, and untestable [Davies,B] |
| Full Idea: A proclaimed experience of God must be rejected because a) there is no agreed test that it is such an experience, b) some people experience God's absence, and c) there is no uniformity of testimony about the experience. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 7 'Objections') | |
| A reaction: [compressed] I'm not sure that absence of an experience is experience of an absence. Compare it with experiencing the greatness of Beethoven's Ninth. |
| 20697 | One does not need a full understanding of God in order to speak of God [Davies,B] |
| Full Idea: In order to speak meaningfully about God, it is not necessary that one should understand exactly the import of one's statements about him. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 2 'Sayng') | |
| A reaction: Perfectly reasonable. To insist that all discussion of a thing requires exact understanding of the thing is ridiculous. Equally, though, to discuss God while denying all understanding of God is just as ridiculous. |
| 20699 | Paradise would not contain some virtues, such as courage [Davies,B] |
| Full Idea: There are virtues (such as courage) that would not be present in a paradise. | |
| From: Brian Davies (Introduction to the Philosophy of Religion [1982], 3 'Evil') | |
| A reaction: Part of a suggestion that morality would be entirely inapplicable in paradise, and so we need dangers etc in the world. |