45 ideas
| 6405 | Moore's 'The Nature of Judgement' (1898) marked the rejection (with Russell) of idealism [Moore,GE, by Grayling] |
| Full Idea: The rejection of idealism by Moore and Russell was marked in 1898 by the publication of Moore's article 'The Nature of Judgement'. | |
| From: report of G.E. Moore (The Nature of Judgement [1899]) by A.C. Grayling - Russell Ch.2 | |
| A reaction: This now looks like a huge landmark in the history of British philosophy. |
| 17992 | The main aim of philosophy is to describe the whole Universe. [Moore,GE] |
| Full Idea: It seems to me that the most important and interesting thing which philosophers have tried to do ...is to give a general description of the whole of the Universe. | |
| From: G.E. Moore (Some Main Problems of Philosophy [1911], Ch. 1) | |
| A reaction: He adds that they aim to show what is in it, and what might be in it, and how the two relate. This sort of big view is the one I favour. I think the hallmark of philosophical thought is a high level of generality. He next proceeds to defend common sense. |
| 7527 | Analysis for Moore and Russell is carving up the world, not investigating language [Moore,GE, by Monk] |
| Full Idea: For Moore and Russell analysis is not - as is commonly understood now - a linguistic activity, but an ontological one. To analyse a proposition is not to investigate language, but to carve up the world so that it begins to make some sort of sense. | |
| From: report of G.E. Moore (The Nature of Judgement [1899]) by Ray Monk - Bertrand Russell: Spirit of Solitude Ch.4 | |
| A reaction: A thought dear to my heart. The twentieth century got horribly side-tracked into thinking that ontology was an entirely linguistic problem. I suggest that physicists analyse physical reality, and philosophers analyse abstract reality. |
| 17926 | Rejecting double negation elimination undermines reductio proofs [Colyvan] |
| Full Idea: The intuitionist rejection of double negation elimination undermines the important reductio ad absurdum proof in classical mathematics. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 1.1.3) |
| 17925 | Showing a disproof is impossible is not a proof, so don't eliminate double negation [Colyvan] |
| Full Idea: In intuitionist logic double negation elimination fails. After all, proving that there is no proof that there can't be a proof of S is not the same thing as having a proof of S. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 1.1.3) | |
| A reaction: I do like people like Colyvan who explain things clearly. All of this difficult stuff is understandable, if only someone makes the effort to explain it properly. |
| 17924 | Excluded middle says P or not-P; bivalence says P is either true or false [Colyvan] |
| Full Idea: The law of excluded middle (for every proposition P, either P or not-P) must be carefully distinguished from its semantic counterpart bivalence, that every proposition is either true or false. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 1.1.3) | |
| A reaction: So excluded middle makes no reference to the actual truth or falsity of P. It merely says P excludes not-P, and vice versa. |
| 17929 | Löwenheim proved his result for a first-order sentence, and Skolem generalised it [Colyvan] |
| Full Idea: Löwenheim proved that if a first-order sentence has a model at all, it has a countable model. ...Skolem generalised this result to systems of first-order sentences. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 2.1.2) |
| 17930 | Axioms are 'categorical' if all of their models are isomorphic [Colyvan] |
| Full Idea: A set of axioms is said to be 'categorical' if all models of the axioms in question are isomorphic. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 2.1.2) | |
| A reaction: The best example is the Peano Axioms, which are 'true up to isomorphism'. Set theory axioms are only 'quasi-isomorphic'. |
| 17928 | Ordinal numbers represent order relations [Colyvan] |
| Full Idea: Ordinal numbers represent order relations. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 1.2.3 n17) |
| 17923 | Intuitionists only accept a few safe infinities [Colyvan] |
| Full Idea: For intuitionists, all but the smallest, most well-behaved infinities are rejected. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 1.1.3) | |
| A reaction: The intuitionist idea is to only accept what can be clearly constructed or proved. |
| 17941 | Infinitesimals were sometimes zero, and sometimes close to zero [Colyvan] |
| Full Idea: The problem with infinitesimals is that in some places they behaved like real numbers close to zero but in other places they behaved like zero. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 7.1.2) | |
| A reaction: Colyvan gives an example, of differentiating a polynomial. |
| 17922 | Reducing real numbers to rationals suggested arithmetic as the foundation of maths [Colyvan] |
| Full Idea: Given Dedekind's reduction of real numbers to sequences of rational numbers, and other known reductions in mathematics, it was tempting to see basic arithmetic as the foundation of mathematics. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 1.1.1) | |
| A reaction: The reduction is the famous Dedekind 'cut'. Nowadays theorists seem to be more abstract (Category Theory, for example) instead of reductionist. |
| 17936 | Transfinite induction moves from all cases, up to the limit ordinal [Colyvan] |
| Full Idea: Transfinite inductions are inductive proofs that include an extra step to show that if the statement holds for all cases less than some limit ordinal, the statement also holds for the limit ordinal. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 5.2.1 n11) |
| 17940 | Most mathematical proofs are using set theory, but without saying so [Colyvan] |
| Full Idea: Most mathematical proofs, outside of set theory, do not explicitly state the set theory being employed. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 7.1.1) |
| 17931 | Structuralism say only 'up to isomorphism' matters because that is all there is to it [Colyvan] |
| Full Idea: Structuralism is able to explain why mathematicians are typically only interested in describing the objects they study up to isomorphism - for that is all there is to describe. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 3.1.2) |
| 17932 | If 'in re' structures relies on the world, does the world contain rich enough structures? [Colyvan] |
| Full Idea: In re structuralism does not posit anything other than the kinds of structures that are in fact found in the world. ...The problem is that the world may not provide rich enough structures for the mathematics. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 3.1.2) | |
| A reaction: You can perceive a repeating pattern in the world, without any interest in how far the repetitions extend. |
| 21342 | A relation is internal if two things possessing the relation could not fail to be related [Moore,GE, by Heil] |
| Full Idea: Moore characterises internal relations modally, as those essential to their relata. If a and b are related R-wise, and R is an internal relation, a and b could not fail to be so related; otherwise R is external. | |
| From: report of G.E. Moore (External and Internal Relations [1919]) by John Heil - Relations 'Internal' | |
| A reaction: I don't think of Moore as an essentialist, but this fits the essentialist picture nicely, and is probably best paraphrased in terms of powers. Integers are the standard example of internal relations. |
| 6672 | Moore's Paradox: you can't assert 'I believe that p but p is false', but can assert 'You believe p but p is false' [Moore,GE, by Lowe] |
| Full Idea: Moore's Paradox says it makes no sense to assert 'I believe that p, but p is false', even though it makes perfectly good sense to assert 'I used to believe p, but p is false' or 'You believe p, but p is false'. | |
| From: report of G.E. Moore (works [1905]) by E.J. Lowe - Introduction to the Philosophy of Mind Ch.10 | |
| A reaction: I'm not sure if this really deserves the label of 'paradox'. I take it as drawing attention to the obvious fact that belief is commitment to truth. I think my assessment that p is true is correct, but your assessment is wrong. ('True' is not redundant!) |
| 20147 | Arguments that my finger does not exist are less certain than your seeing my finger [Moore,GE] |
| Full Idea: This really is a finger ...and you all know it. ...I can safely challenge anyone to give an argument that it is not true, which does not rest upon some premise which is less certain than is the proposition which it is designed to attack. | |
| From: G.E. Moore (Some Judgements of Perception [1922], p.228), quoted by John Kekes - The Human Condition 01.3 | |
| A reaction: [In Moore's 'Philosophical Studies'] This is a particularly clear statement from Moore of his famous claim. I'm not sure what to make of an attempt to compare a sceptical argument (dreams, demons) with the sight of a finger. |
| 6349 | I can prove a hand exists, by holding one up, pointing to it, and saying 'here is one hand' [Moore,GE] |
| Full Idea: I can prove now that two human hands exist. How? By holding up my two hands, and saying, as I make a certain gesture with the right hand, 'Here is one hand', and adding, as I gesture with the left, 'and here is another'. | |
| From: G.E. Moore (Proof of an External World [1939], p.1) | |
| A reaction: The words need to be spoken, presumably, so that what he is doing fits into the linguistic conventions of what will normally be accepted as a proof. In fact, just holding the hand up seems enough. The proof begs the question of virtual reality. |
| 3061 | Anaxarchus said that he was not even sure that he knew nothing [Anaxarchus, by Diog. Laertius] |
| Full Idea: Anaxarchus said that he was not even sure that he knew nothing. | |
| From: report of Anaxarchus (fragments/reports [c.340 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 09.10.1 |
| 17943 | Probability supports Bayesianism better as degrees of belief than as ratios of frequencies [Colyvan] |
| Full Idea: Those who see probabilities as ratios of frequencies can't use Bayes's Theorem if there is no objective prior probability. Those who accept prior probabilities tend to opt for a subjectivist account, where probabilities are degrees of belief. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 9.1.8) | |
| A reaction: [compressed] |
| 17939 | Mathematics can reveal structural similarities in diverse systems [Colyvan] |
| Full Idea: Mathematics can demonstrate structural similarities between systems (e.g. missing population periods and the gaps in the rings of Saturn). | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 6.3.2) | |
| A reaction: [Colyvan expounds the details of his two examples] It is these sorts of results that get people enthusiastic about the mathematics embedded in nature. A misunderstanding, I think. |
| 17938 | Mathematics can show why some surprising events have to occur [Colyvan] |
| Full Idea: Mathematics can show that under a broad range of conditions, something initially surprising must occur (e.g. the hexagonal structure of honeycomb). | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 6.3.2) |
| 17934 | Proof by cases (by 'exhaustion') is said to be unexplanatory [Colyvan] |
| Full Idea: Another style of proof often cited as unexplanatory are brute-force methods such as proof by cases (or proof by exhaustion). | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 5.2.1) |
| 17933 | Reductio proofs do not seem to be very explanatory [Colyvan] |
| Full Idea: One kind of proof that is thought to be unexplanatory is the 'reductio' proof. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 5.2.1) | |
| A reaction: Presumably you generate a contradiction, but are given no indication of why the contradiction has arisen? Tracking back might reveal the source of the problem? Colyvan thinks reductio can be explanatory. |
| 17935 | If inductive proofs hold because of the structure of natural numbers, they may explain theorems [Colyvan] |
| Full Idea: It might be argued that any proof by induction is revealing the explanation of the theorem, namely, that it holds by virtue of the structure of the natural numbers. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 5.2.1) | |
| A reaction: This is because induction characterises the natural numbers, in the Peano Axioms. |
| 17942 | Can a proof that no one understands (of the four-colour theorem) really be a proof? [Colyvan] |
| Full Idea: The proof of the four-colour theorem raises questions about whether a 'proof' that no one understands is a proof. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 9.1.6) | |
| A reaction: The point is that the theorem (that you can colour countries on a map with just four colours) was proved with the help of a computer. |
| 17937 | Mathematical generalisation is by extending a system, or by abstracting away from it [Colyvan] |
| Full Idea: One type of generalisation in mathematics extends a system to go beyond what is was originally set up for; another kind involves abstracting away from some details in order to capture similarities between different systems. | |
| From: Mark Colyvan (Introduction to the Philosophy of Mathematics [2012], 5.2.2) |
| 22302 | Moor bypassed problems of correspondence by saying true propositions ARE facts [Moore,GE, by Potter] |
| Full Idea: Moore avoided the problematic correspondence between propositions and reality by identifying the former with the latter; the world consists of true propositions, and there is no difference between a true proposition and the fact that makes it true. | |
| From: report of G.E. Moore (The Nature of Judgement [1899]) by Michael Potter - The Rise of Analytic Philosophy 1879-1930 28 'Refut' | |
| A reaction: This is "the most platonic system of modern times", he wrote (letter 14.8.1898). He then added platonist ethics. This is a pernicious and absurd doctrine. The obvious problem is that false propositions can be indistinguishable, but differ in ontology. |
| 7526 | Hegelians say propositions defy analysis, but Moore says they can be broken down [Moore,GE, by Monk] |
| Full Idea: Moore rejected the Hegelian view, that a proposition is a unity that defies analysis; instead, it is a complex that positively cries out to be broken up into its constituent parts, which parts Moore called 'concepts'. | |
| From: report of G.E. Moore (The Nature of Judgement [1899]) by Ray Monk - Bertrand Russell: Spirit of Solitude Ch.4 | |
| A reaction: Russell was much influenced by this idea, though it may be found in Frege. Anglophone philosophers tend to side instantly with Moore, but the Hegel view must be pondered. An idea comes to us in a unified flash, before it is articulated. |
| 21233 | The beautiful is whatever it is intrinsically good to admire [Moore,GE] |
| Full Idea: The beautiful should be defined as that of which the admiring contemplation is good in itself. | |
| From: G.E. Moore (Principia Ethica [1903], p.210), quoted by Graham Farmelo - The Strangest Man | |
| A reaction: To work, this definition must exclude anything else which it is intrinsically good to admire. Good deeds obviously qualify for that, so good deeds must be intrinsically beautiful (which would be agreed by ancient Greeks). We can't ask WHY it is good! |
| 8039 | Moore tries to show that 'good' is indefinable, but doesn't understand what a definition is [MacIntyre on Moore,GE] |
| Full Idea: Moore tries to show that 'good' is indefinable by relying on a bad dictionary definition of 'definition'. | |
| From: comment on G.E. Moore (Principia Ethica [1903]) by Alasdair MacIntyre - After Virtue: a Study in Moral Theory Ch.2 | |
| A reaction: An interesting remark, with no further explanation offered. If Moore has this problem, then Plato had it too (see Idea 3032). I would have thought that any definition MacIntyre could offer would either be naturalistic, or tautological. |
| 22151 | The Open Question argument leads to anti-realism and the fact-value distinction [Boulter on Moore,GE] |
| Full Idea: Moore's Open Question argument led, however unintentionally, to the rise of anti-realism in meta-ethics (which leads to distinguishing values from facts). | |
| From: comment on G.E. Moore (Principia Ethica [1903]) by Stephen Boulter - Why Medieval Philosophy Matters 4 | |
| A reaction: I presume that Moore proves that the Good is not natural, and after that no one knows what it is, so it seems to be arbitrary or non-existent (rather than the platonic fact that Moore had hoped for). I vote for naturalistic ethics. |
| 11056 | The naturalistic fallacy claims that natural qualties can define 'good' [Moore,GE] |
| Full Idea: The naturalistic fallacy ..consists in the contention that good means nothing but some simple or complex notion, that can be defined in terms of natural qualities. | |
| From: G.E. Moore (Principia Ethica [1903], §044) | |
| A reaction: Presumably aimed at those who think morality is pleasure and pain. We could hardly attribute morality to non-human qualities. I connect morality to human deliberative functions. |
| 8033 | Moore cannot show why something being good gives us a reason for action [MacIntyre on Moore,GE] |
| Full Idea: Moore's account leaves it entirely unexplained and inexplicable why something's being good should ever furnish us with a reason for action. | |
| From: comment on G.E. Moore (Principia Ethica [1903]) by Alasdair MacIntyre - A Short History of Ethics Ch.18 | |
| A reaction: The same objection can be raised to Plato's Form of the Good, but Plato's answer seems to be that the Good is partly a rational entity, and partly that the Good just has a natural magnetism that makes it quasi-religious. |
| 8032 | Can learning to recognise a good friend help us to recognise a good watch? [MacIntyre on Moore,GE] |
| Full Idea: How could having learned to recognize a good friend help us to recognize a good watch? Yet is Moore is right, the same simple property is present in both cases? | |
| From: comment on G.E. Moore (Principia Ethica [1903]) by Alasdair MacIntyre - A Short History of Ethics Ch.18 | |
| A reaction: It begins to look as if what they have in common is just that they both make you feel good. However, I like the Aristotelian idea that they both function succesfully, one as a timekeeper, the other as a citizen or companion. |
| 11050 | Moore's combination of antinaturalism with strong supervenience on the natural is incoherent [Hanna on Moore,GE] |
| Full Idea: Moore incoherently combines his antinaturalism with the thesis that intrinsic-value properties are logically strongly supervenient on (or explanatorily reducible to) natural facts. | |
| From: comment on G.E. Moore (Principia Ethica [1903]) by Robert Hanna - Rationality and Logic Ch.1 | |
| A reaction: I take this to be Moore fighting shy of the strongly Platonist view of values which his arguments all seemed to imply. |
| 23726 | Despite Moore's caution, non-naturalists incline towards intuitionism [Moore,GE, by Smith,M] |
| Full Idea: Although Moore was reluctant to adopt it, the epistemology the non-naturalists tended to favour was intuitionism. | |
| From: report of G.E. Moore (Principia Ethica [1903]) by Michael Smith - The Moral Problem 2.2 | |
| A reaction: Moore was presumably reluctant because intuitionism had been heavily criticised in the past for its inability to settle moral disputes. But if you insist that goodness is outside nature, what other means of knowing it is available? Reason? |
| 18676 | We should ask what we would judge to be good if it existed in absolute isolation [Moore,GE] |
| Full Idea: It is necessary to consider what things are such that, if they existed by themselves, in absolute isolation, we should yet judge their existence to be good. | |
| From: G.E. Moore (Principia Ethica [1903], §112) | |
| A reaction: This is known as the 'isolation test'. The test has an instant appeal, but looks a bit odd after a little thought. The value of most things drains out of them if they are totally isolated. The MS of the Goldberg Variations floating in outer space? |
| 11057 | It is always an open question whether anything that is natural is good [Moore,GE] |
| Full Idea: Good does not, by definition, mean anything that is natural; and it is therefore always an open question whether anything that is natural is good. | |
| From: G.E. Moore (Principia Ethica [1903], §027) | |
| A reaction: This is the best known modern argument for Platonist idealised ethics. But maybe there is no end to questioning anywhere, so each theory invites a further question, and nothing is ever fully explained? Next stop - pragmatism. |
| 5925 | The three main values are good, right and beauty [Moore,GE, by Ross] |
| Full Idea: Moore describes rightness and beauty as the two main value-attributes, apart from goodness. | |
| From: report of G.E. Moore (Principia Ethica [1903]) by W. David Ross - The Right and the Good §IV | |
| A reaction: This was a last-throw of the Platonic ideal, before we plunged into the value-free world of Darwin and the physicists. It is hard to agree with Moore, but also hard to disagree. Why do many people despise or ignore these values? |
| 5902 | For Moore, 'right' is what produces good [Moore,GE, by Ross] |
| Full Idea: Moore claims that 'right' means 'productive of the greatest possible good'. | |
| From: report of G.E. Moore (Principia Ethica [1903]) by W. David Ross - The Right and the Good §I | |
| A reaction: Ross is at pains to keep 'right' and 'good' as quite distinct notions. Some actions are right but very unpleasant, and seem to produce no real good at all. |
| 5903 | 'Right' means 'cause of good result' (hence 'useful'), so the end does justify the means [Moore,GE] |
| Full Idea: 'Right' does and can mean nothing but 'cause of a good result', and is thus identical with 'useful', whence it follows that the end always will justify the means. | |
| From: G.E. Moore (Principia Ethica [1903], §089) | |
| A reaction: Of course, Moore does not identify utility with pleasure, as his notion of what is good concerns fairly Platonic ideals. Would Stalin's murders have been right if Russia were now the happiest nation on Earth? |
| 5907 | Relationships imply duties to people, not merely the obligation to benefit them [Ross on Moore,GE] |
| Full Idea: Moore's 'Ideal Utilitarianism' seems to unduly simplify our relations to our fellows. My neighbours are merely possible beneficiaries by my action. But they also stand to me as promiser, creditor, husband, friend, which entails prima facie duties. | |
| From: comment on G.E. Moore (Principia Ethica [1903]) by W. David Ross - The Right and the Good §II | |
| A reaction: Perhaps it is better to say that we have obligations to benefit particular people, because of our obligations, and that we are confined to particular benefits which meet those obligations - not just any old benefit to any old person. |