69 ideas
| 5515 | Imaginary cases are good for revealing our beliefs, rather than the truth [Parfit] |
| Full Idea: I believe it is worth considering imaginary cases (such as Teletransportation), as we can use them to discover, not what the truth is, but what we believe. | |
| From: Derek Parfit (The Unimportance of Identity [1995], p.293) | |
| A reaction: The trouble is that we might say that IF I were suddenly turned into a pig, then I would come to believe in dualism, but that will not and cannot happen, because dualism is false. It seems essential to accept the natural possibility of the case. |
| 15716 | If axioms and their implications have no contradictions, they pass my criterion of truth and existence [Hilbert] |
| Full Idea: If the arbitrarily given axioms do not contradict each other with all their consequences, then they are true and the things defined by the axioms exist. For me this is the criterion of truth and existence. | |
| From: David Hilbert (Letter to Frege 29.12.1899 [1899]), quoted by R Kaplan / E Kaplan - The Art of the Infinite 2 'Mind' | |
| A reaction: If an axiom says something equivalent to 'fairies exist, but they are totally undetectable', this would seem to avoid contradiction with anything, and hence be true. Hilbert's idea sounds crazy to me. He developed full Formalism later. |
| 15879 | The Square of Opposition has two contradictory pairs, one contrary pair, and one sub-contrary pair [Harré] |
| Full Idea: Square of Opposition: 'all A are B' and 'no A are B' are contraries; 'some A are B' and 'some A are not B' are sub-contraries; the pairs 'all A are B'/'some A are B' and 'no A are B'/'some A are B' are contradictories. | |
| From: Rom Harré (Laws of Nature [1993], 3) | |
| A reaction: [the reader may construct his own diagram from this description!] The contraries are at the extremes of contradiction, but the sub-contraries are actual compatible. You could add possible worlds to this picture. |
| 18844 | You would cripple mathematics if you denied Excluded Middle [Hilbert] |
| Full Idea: Taking the principle of Excluded Middle away from the mathematician would be the same, say, as prohibiting the astronomer from using the telescope or the boxer from using his fists. | |
| From: David Hilbert (The Foundations of Mathematics [1927], p.476), quoted by Ian Rumfitt - The Boundary Stones of Thought 9.4 | |
| A reaction: [p.476 in Van Heijenoort] |
| 15891 | Traditional quantifiers combine ordinary language generality and ontology assumptions [Harré] |
| Full Idea: The generalising function and the ontological function of discourse are elided in the traditional quantifier. | |
| From: Rom Harré (Laws of Nature [1993], 5) | |
| A reaction: This simple point strikes me as helping enormously to disentangle the mess created by over-emphasis on formal logic in ontology, and especially in the Quinean concept of 'ontological commitment'. |
| 15878 | Some quantifiers, such as 'any', rule out any notion of order within their range [Harré] |
| Full Idea: The quantifier 'any' unambiguously rules out any presupposition of order in the members of the range of individuals quantified. | |
| From: Rom Harré (Laws of Nature [1993], 3) | |
| A reaction: He contrasts this with 'all', 'each' and 'every', which are ambiguous in this respect. |
| 17963 | The facts of geometry, arithmetic or statics order themselves into theories [Hilbert] |
| Full Idea: The facts of geometry order themselves into a geometry, the facts of arithmetic into a theory of numbers, the facts of statics, electrodynamics into a theory of statics, electrodynamics, or the facts of the physics of gases into a theory of gases. | |
| From: David Hilbert (Axiomatic Thought [1918], [03]) | |
| A reaction: This is the confident (I would say 'essentialist') view of axioms, which received a bit of a setback with Gödel's Theorems. I certainly agree that the world proposes an order to us - we don't just randomly invent one that suits us. |
| 17966 | Axioms must reveal their dependence (or not), and must be consistent [Hilbert] |
| Full Idea: If a theory is to serve its purpose of orienting and ordering, it must first give us an overview of the independence and dependence of its propositions, and second give a guarantee of the consistency of all of the propositions. | |
| From: David Hilbert (Axiomatic Thought [1918], [09]) | |
| A reaction: Gödel's Second theorem showed that the theory can never prove its own consistency, which made the second Hilbert requirement more difficult. It is generally assumed that each of the axioms must be independent of the others. |
| 8717 | Hilbert wanted to prove the consistency of all of mathematics (which realists take for granted) [Hilbert, by Friend] |
| Full Idea: Hilbert wanted to derive ideal mathematics from the secure, paradox-free, finite mathematics (known as 'Hilbert's Programme'). ...Note that for the realist consistency is not something we need to prove; it is a precondition of thought. | |
| From: report of David Hilbert (works [1900], 6.7) by Michčle Friend - Introducing the Philosophy of Mathematics | |
| A reaction: I am an intuitive realist, though I am not so sure about that on cautious reflection. Compare the claims that there are reasons or causes for everything. Reality cannot contain contradicitions (can it?). Contradictions would be our fault. |
| 12456 | I aim to establish certainty for mathematical methods [Hilbert] |
| Full Idea: The goal of my theory is to establish once and for all the certitude of mathematical methods. | |
| From: David Hilbert (On the Infinite [1925], p.184) | |
| A reaction: This is the clearest statement of the famous Hilbert Programme, which is said to have been brought to an abrupt end by Gödel's Incompleteness Theorems. |
| 12461 | We believe all mathematical problems are solvable [Hilbert] |
| Full Idea: The thesis that every mathematical problem is solvable - we are all convinced that it really is so. | |
| From: David Hilbert (On the Infinite [1925], p.200) | |
| A reaction: This will include, for example, Goldbach's Conjecture (every even is the sum of two primes), which is utterly simple but with no proof anywhere in sight. |
| 13472 | Hilbert aimed to eliminate number from geometry [Hilbert, by Hart,WD] |
| Full Idea: One of Hilbert's aims in 'The Foundations of Geometry' was to eliminate number [as measure of lengths and angles] from geometry. | |
| From: report of David Hilbert (Foundations of Geometry [1899]) by William D. Hart - The Evolution of Logic 2 | |
| A reaction: Presumably this would particularly have to include the elimination of ratios (rather than actual specific lengths). |
| 9633 | No one shall drive us out of the paradise the Cantor has created for us [Hilbert] |
| Full Idea: No one shall drive us out of the paradise the Cantor has created for us. | |
| From: David Hilbert (On the Infinite [1925], p.191), quoted by James Robert Brown - Philosophy of Mathematics | |
| A reaction: This is Hilbert's famous refusal to accept any account of mathematics, such as Kant's, which excludes actual infinities. Cantor had laid out a whole glorious hierarchy of different infinities. |
| 12460 | We extend finite statements with ideal ones, in order to preserve our logic [Hilbert] |
| Full Idea: To preserve the simple formal rules of ordinary Aristotelian logic, we must supplement the finitary statements with ideal statements. | |
| From: David Hilbert (On the Infinite [1925], p.195) | |
| A reaction: I find very appealing the picture of mathematics as rooted in the physical world, and then gradually extended by a series of 'idealisations', which should perhaps be thought of as fictions. |
| 12462 | Only the finite can bring certainty to the infinite [Hilbert] |
| Full Idea: Operating with the infinite can be made certain only by the finitary. | |
| From: David Hilbert (On the Infinite [1925], p.201) | |
| A reaction: See 'Compactness' for one aspect of this claim. I think Hilbert was fighting a rearguard action, and his idea now has few followers. |
| 12455 | The idea of an infinite totality is an illusion [Hilbert] |
| Full Idea: Just as in the limit processes of the infinitesimal calculus, the infinitely large and small proved to be a mere figure of speech, so too we must realise that the infinite in the sense of an infinite totality, used in deductive methods, is an illusion. | |
| From: David Hilbert (On the Infinite [1925], p.184) | |
| A reaction: This is a very authoritative rearguard action. I no longer think the dispute matters much, it being just a dispute over a proposed new meaning for the word 'number'. |
| 12457 | There is no continuum in reality to realise the infinitely small [Hilbert] |
| Full Idea: A homogeneous continuum which admits of the sort of divisibility needed to realise the infinitely small is nowhere to be found in reality. | |
| From: David Hilbert (On the Infinite [1925], p.186) | |
| A reaction: He makes this remark as a response to Planck's new quantum theory (the year before the big works of Heisenberg and Schrödinger). Personally I don't see why infinities should depend on the physical world, since they are imaginary. |
| 17967 | To decide some questions, we must study the essence of mathematical proof itself [Hilbert] |
| Full Idea: It is necessary to study the essence of mathematical proof itself if one wishes to answer such questions as the one about decidability in a finite number of operations. | |
| From: David Hilbert (Axiomatic Thought [1918], [53]) |
| 9546 | Euclid axioms concerns possibilities of construction, but Hilbert's assert the existence of objects [Hilbert, by Chihara] |
| Full Idea: Hilbert's geometrical axioms were existential in character, asserting the existence of certain geometrical objects (points and lines). Euclid's postulates do not assert the existence of anything; they assert the possibility of certain constructions. | |
| From: report of David Hilbert (Foundations of Geometry [1899]) by Charles Chihara - A Structural Account of Mathematics 01.1 | |
| A reaction: Chihara says geometry was originally understood modally, but came to be understood existentially. It seems extraordinary to me that philosophers of mathematics can have become more platonist over the centuries. |
| 18742 | Hilbert's formalisation revealed implicit congruence axioms in Euclid [Hilbert, by Horsten/Pettigrew] |
| Full Idea: In his formal investigation of Euclidean geometry, Hilbert uncovered congruence axioms that implicitly played a role in Euclid's proofs but were not explicitly recognised. | |
| From: report of David Hilbert (Foundations of Geometry [1899]) by Horsten,L/Pettigrew,R - Mathematical Methods in Philosophy 2 | |
| A reaction: The writers are offering this as a good example of the benefits of a precise and formal approach to foundational questions. It's hard to disagree, but dispiriting if you need a PhD in maths before you can start doing philosophy. |
| 18217 | Hilbert's geometry is interesting because it captures Euclid without using real numbers [Hilbert, by Field,H] |
| Full Idea: Hilbert's formulation of the Euclidean theory is of special interest because (besides being rigorously axiomatised) it does not employ the real numbers in the axioms. | |
| From: report of David Hilbert (Foundations of Geometry [1899]) by Hartry Field - Science without Numbers 3 | |
| A reaction: Notice that this job was done by Hilbert, and not by the fictionalist Hartry Field. |
| 17965 | The whole of Euclidean geometry derives from a basic equation and transformations [Hilbert] |
| Full Idea: The linearity of the equation of the plane and of the orthogonal transformation of point-coordinates is completely adequate to produce the whole broad science of spatial Euclidean geometry purely by means of analysis. | |
| From: David Hilbert (Axiomatic Thought [1918], [05]) | |
| A reaction: This remark comes from the man who succeeded in producing modern axioms for geometry (in 1897), so he knows what he is talking about. We should not be wholly pessimistic about Hilbert's ambitious projects. He had to dig deeper than this idea... |
| 17964 | Number theory just needs calculation laws and rules for integers [Hilbert] |
| Full Idea: The laws of calculation and the rules of integers suffice for the construction of number theory. | |
| From: David Hilbert (Axiomatic Thought [1918], [05]) | |
| A reaction: This is the confident Hilbert view that the whole system can be fully spelled out. Gödel made this optimism more difficult. |
| 17697 | The existence of an arbitrarily large number refutes the idea that numbers come from experience [Hilbert] |
| Full Idea: The standpoint of pure experience seems to me to be refuted by the objection that the existence, possible or actual, of an arbitrarily large number can never be derived through experience, that is, through experiment. | |
| From: David Hilbert (On the Foundations of Logic and Arithmetic [1904], p.130) | |
| A reaction: Alternatively, empiricism refutes infinite numbers! No modern mathematician will accept that, but you wonder in what sense the proposed entities qualify as 'numbers'. |
| 17698 | Logic already contains some arithmetic, so the two must be developed together [Hilbert] |
| Full Idea: In the traditional exposition of the laws of logic certain fundamental arithmetic notions are already used, for example in the notion of set, and to some extent also of number. Thus we turn in a circle, and a partly simultaneous development is required. | |
| From: David Hilbert (On the Foundations of Logic and Arithmetic [1904], p.131) | |
| A reaction: If the Axiom of Infinity is meant, it may be possible to purge the arithmetic from the logic. Then the challenge to derive arithmetic from it becomes rather tougher. |
| 10113 | The grounding of mathematics is 'in the beginning was the sign' [Hilbert] |
| Full Idea: The solid philosophical attitude that I think is required for the grounding of pure mathematics is this: In the beginning was the sign. | |
| From: David Hilbert (works [1900]), quoted by A.George / D.J.Velleman - Philosophies of Mathematics Ch.6 | |
| A reaction: Why did people invent those particular signs? Presumably they were meant to designate something, in the world or in our experience. |
| 10115 | Hilbert substituted a syntactic for a semantic account of consistency [Hilbert, by George/Velleman] |
| Full Idea: Hilbert replaced a semantic construal of inconsistency (that the theory entails a statement that is necessarily false) by a syntactic one (that the theory formally derives the statement (0 =1 ∧ 0 not-= 1). | |
| From: report of David Hilbert (works [1900]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.6 | |
| A reaction: Finding one particular clash will pinpoint the notion of inconsistency, but it doesn't seem to define what it means, since the concept has very wide application. |
| 22293 | Hilbert said (to block paradoxes) that mathematical existence is entailed by consistency [Hilbert, by Potter] |
| Full Idea: Hilbert proposed to circuvent the paradoxes by means of the doctrine (already proposed by Poincaré) that in mathematics consistency entails existence. | |
| From: report of David Hilbert (On the Concept of Number [1900], p.183) by Michael Potter - The Rise of Analytic Philosophy 1879-1930 19 'Exist' | |
| A reaction: Interesting. Hilbert's idea has struck me as weird, but it makes sense if its main motive is to block the paradoxes. Roughly, the idea is 'it exists if it isn't paradoxical'. A low bar for existence (but then it is only in mathematics!). |
| 12459 | The subject matter of mathematics is immediate and clear concrete symbols [Hilbert] |
| Full Idea: The subject matter of mathematics is the concrete symbols themselves whose structure is immediately clear and recognisable. | |
| From: David Hilbert (On the Infinite [1925], p.192) | |
| A reaction: I don't think many people will agree with Hilbert here. Does he mean token-symbols or type-symbols? You can do maths in your head, or with different symbols. If type-symbols, you have to explain what a type is. |
| 10116 | Hilbert aimed to prove the consistency of mathematics finitely, to show infinities won't produce contradictions [Hilbert, by George/Velleman] |
| Full Idea: Hilbert's project was to establish the consistency of classical mathematics using just finitary means, to convince all parties that no contradictions will follow from employing the infinitary notions and reasoning. | |
| From: report of David Hilbert (works [1900]) by A.George / D.J.Velleman - Philosophies of Mathematics Ch.6 | |
| A reaction: This is the project which was badly torpedoed by Gödel's Second Incompleteness Theorem. |
| 18112 | Mathematics divides in two: meaningful finitary statements, and empty idealised statements [Hilbert] |
| Full Idea: We can conceive mathematics to be a stock of two kinds of formulas: first, those to which the meaningful communications of finitary statements correspond; and secondly, other formulas which signify nothing and which are ideal structures of our theory. | |
| From: David Hilbert (On the Infinite [1925], p.196), quoted by David Bostock - Philosophy of Mathematics 6.1 |
| 5516 | Reduction can be by identity, or constitution, or elimination [Parfit, by PG] |
| Full Idea: We can distinguish Identifying Reductionism (as in 'persons are bodies'), or Constitutive Reductionism (as in 'persons are distinct, but consist of thoughts etc.'), or Eliminative Reductionism (as in 'there are no persons, only thoughts etc.'). | |
| From: report of Derek Parfit (The Unimportance of Identity [1995], p.295) by PG - Db (ideas) | |
| A reaction: Constitutive Reductionism seems the most common one, as in 'chemistry just consists of lots of complicated physics'. He doesn't mention bridge laws, which are presumably only required in more complicated cases of constitutive reduction. |
| 15874 | Scientific properties are not observed qualities, but the dispositions which create them [Harré] |
| Full Idea: The properties of material things with which the sciences deal are not the qualities we observe them to have, but the dispositions of those things to engender the states and qualities we observe. | |
| From: Rom Harré (Laws of Nature [1993], 2) | |
| A reaction: I take this to be the correct use of the word 'qualities', so that properties are not qualities (in the way Heil would like). |
| 15884 | Laws of nature remain the same through any conditions, if the underlying mechanisms are unchanged [Harré] |
| Full Idea: A statement is a law of nature if it is true in all those worlds which differ only as to their initial conditions, that is in which the underlying mechanisms of nature are the same. | |
| From: Rom Harré (Laws of Nature [1993], 4) | |
| A reaction: Harré takes it that laws of nature have to be necessary, by definition. I like this way of expressing natural necessity, in terms of 'mechanisms' rather than of 'laws'. Where do the mechanisms get their necessity? |
| 9636 | My theory aims at the certitude of mathematical methods [Hilbert] |
| Full Idea: The goal of my theory is to establish once and for all the certitude of mathematical methods. | |
| From: David Hilbert (On the Infinite [1925], p.184), quoted by James Robert Brown - Philosophy of Mathematics Ch.5 | |
| A reaction: This dream is famous for being shattered by Gödel's Incompleteness Theorem a mere six years later. Neverless there seem to be more limited certainties which are accepted in mathematics. The certainty of the whole of arithmetic is beyond us. |
| 15880 | In physical sciences particular observations are ordered, but in biology only the classes are ordered [Harré] |
| Full Idea: In the physical sciences the particular observations and experimental results are usually orderable, while in the biological sciences it is the classes of organism which are ordered, not the particular organisms. | |
| From: Rom Harré (Laws of Nature [1993], 3) | |
| A reaction: Harré is interesting on the role of ordering in science. Functions can be defined by an order. Maths feeds on orderings. Physics, he notes, focuses on things which vary together. |
| 15869 | Reports of experiments eliminate the experimenter, and present results as the behaviour of nature [Harré] |
| Full Idea: In accounts of experiments, by Faraday and others, the role of the guiding hand of the actual experimenter is written out in successive accounts. The effect is to display the phenomenon as a natural occurrence, existing independently of the experiments. | |
| From: Rom Harré (Laws of Nature [1993], 1) | |
| A reaction: He records three stages in Faraday's reports. The move from active to passive voice is obviously part of it. The claim of universality is thus implicit rather than explicit. |
| 15881 | We can save laws from counter-instances by treating the latter as analytic definitions [Harré] |
| Full Idea: When we come upon a counter-instance to a generalisation we can save the putative law, by treating it as potentially analytic and claiming it as a definition. ...Thus magnetism doesn't hold for phosphorus, so we say phosphorus is not a magnetic substance. | |
| From: Rom Harré (Laws of Nature [1993], 3) | |
| A reaction: He notes this as being particularly true when the laws concern the dispositions of substances, rather than patterns of events. |
| 15882 | Since there are three different dimensions for generalising laws, no one system of logic can cover them [Harré] |
| Full Idea: Since there are three different dimensions of generality into which every law of nature is generalised, there can be no one system of logic which will govern inference to or from every law of every kind. | |
| From: Rom Harré (Laws of Nature [1993], 3) | |
| A reaction: This is aimed at the covering-law approach, which actually aims to output observations as logical inferences from laws. Wrong. |
| 15888 | The grue problem shows that natural kinds are central to science [Harré] |
| Full Idea: The grue problem illustrates the enormous importance that the concept of a natural-kind plays in real science. | |
| From: Rom Harré (Laws of Nature [1993], 5) | |
| A reaction: The point is that we took emeralds to be a natural kind, but 'grue' proposes that they aren't, since stability is the hallmark of a natural kind. |
| 15887 | 'Grue' introduces a new causal hypothesis - that emeralds can change colour [Harré] |
| Full Idea: In introducing the predicate 'grue' we also introduce an additional causal hypothesis into our chemistry and physics; namely, that when observed grue emeralds change from blue to green. | |
| From: Rom Harré (Laws of Nature [1993], 5) | |
| A reaction: [The 'when observered' is a Harré addition] I hate 'grue'. Only people who think our predicates have very little to do with reality are impressed by it. Grue is a behaviour, not a colour. |
| 15889 | It is because ravens are birds that their species and their colour might be connected [Harré] |
| Full Idea: It is because ravens are birds that it makes sense to contemplate the possibility of a lawful relation between their species and their colour. | |
| From: Rom Harré (Laws of Nature [1993], 5) | |
| A reaction: Compare the 'laws' concerning leaf colour in autumn, and the 'laws' concerning packaging colour in supermarkets. Harré's underlying point is that raven colour concerns mechanism. |
| 15890 | Non-black non-ravens just aren't part of the presuppositions of 'all ravens are black' [Harré] |
| Full Idea: Non-black non-ravens have no role to play in assessing the plausibility of 'All ravens are black' because their existence is not among the existential presuppositions of that statement. | |
| From: Rom Harré (Laws of Nature [1993], 5) | |
| A reaction: [He cites Strawson for the 'presupposition' approach] |
| 15885 | The necessity of Newton's First Law derives from the nature of material things, not from a mechanism [Harré] |
| Full Idea: The 'must' of Newton's First Law is different. There is no deeper level relative to the processes described to give a mechanism which generates uniform motion. There is no such mechanism. ..It specifies what it is for something to be a material thing. | |
| From: Rom Harré (Laws of Nature [1993], 4) | |
| A reaction: Harré says the law can only exist as part of a network of other ideas. |
| 15868 | Idealisation idealises all of a thing's properties, but abstraction leaves some of them out [Harré] |
| Full Idea: An 'idealisation' preserves all the properties of the source but it possesses these properties in some ideal or perfect form. ...An 'abstraction', on the other hand, lacks certain features of its source. | |
| From: Rom Harré (Laws of Nature [1993], 1) | |
| A reaction: Yet another example in contemporary philosophy of a clear understanding of the sort of abstraction which Geach and others have poured scorn on. |
| 3539 | Personal identity is just causally related mental states [Parfit, by Maslin] |
| Full Idea: For Parfit all personal identity really amounts to is a chain of experiences and other psychological features causally related to each other in 'direct' sorts of ways. | |
| From: report of Derek Parfit (Personal Identity [1971]) by Keith T. Maslin - Introduction to the Philosophy of Mind 10.5 | |
| A reaction: When summarised like this, it strikes me that Parfit is just false to our experience, whatever Hume may say. I suspect that Parfit (and those like him) concentrate too much on rather passive perceptual experience, and neglect the will. |
| 5514 | Psychologists are interested in identity as a type of person, but philosophers study numerical identity [Parfit] |
| Full Idea: When psychologists discuss identity, they are typically concerned with the kind of person someone is, or wants to be (as in an 'identity crisis'). But when philosophers discuss identity, it is numerical identity they mean. | |
| From: Derek Parfit (The Unimportance of Identity [1995], p.293) | |
| A reaction: I think it is important to note that the philosophical problem breaks down into two areas: whether I have numerical identity with myself over time, and whether other people have it. It may be that two different sets of criteria will emerge. |
| 1393 | One of my future selves will not necessarily be me [Parfit] |
| Full Idea: If I say 'It will not be me, but one of my future selves', I do not imply that I will be that future self. He is one of my later selves, and I am one of his earlier selves. There is no underlying person we both are. | |
| From: Derek Parfit (Personal Identity [1971], §5) | |
| A reaction: The problem here seems to be explaining why I should care about my later self, if it isn't me. If the answer is only that it will be psychologically very similar to me, then I would care more about my current identical twin than about my future self. |
| 5521 | If my brain-halves are transplanted into two bodies, I have continuity, and don't need identity [Parfit] |
| Full Idea: If the two halves of my brain are transplanted into different bodies just like mine, they cannot both be me, since that would make them the same person. ..But my relation to these two contains everything that matters, so identity is not what matters. | |
| From: Derek Parfit (The Unimportance of Identity [1995], p.314) | |
| A reaction: I challenge his concept of what 'matters'. He has a rather solipsistic view of the problem, and I take Parfit to be a rather unsociable person, since his friends and partner will be keenly interested in the identities of the new beings. |
| 5522 | Over a period of time what matters is not that 'I' persist, but that I have psychological continuity [Parfit] |
| Full Idea: We should revise our view about identity over time: what matters isn't that there will be someone alive who will be me; it is rather that there should be at least one living person who will be psychologically continuous with me as I am now. | |
| From: Derek Parfit (The Unimportance of Identity [1995], p.316) | |
| A reaction: Parfit and Locke seem to agree on this, and it is no accident that they both like 'science fiction' examples. Apparently Parfit wouldn't bat an eyelid if someone threatened to cut his corpus callosum. I rate it as a catastrophe for my current existence. |
| 1392 | If we split like amoeba, we would be two people, neither of them being us [Parfit] |
| Full Idea: In the case of the man who, like an amoeba, divides….we can suggest that he survives as two different people without implying that he is those people. | |
| From: Derek Parfit (Personal Identity [1971], §1) | |
| A reaction: Maybe an amoeba is a homogeneous substance for which splitting is insignificant, but when a person has certain parts that are totally crucial, splitting them is catastrophic, and quite different. I'm not sure that splitting a self would leave persons. |
| 5519 | It is fine to save two dying twins by merging parts of their bodies into one, and identity is irrelevant [Parfit] |
| Full Idea: If I am largely paralysed, and my twin brother is dying of brain disease, then if the operation to graft my head onto his body is offered, I should accept the operation, and it is irrelevant whether this person would be me. | |
| From: Derek Parfit (The Unimportance of Identity [1995], p.308) | |
| A reaction: Parfit notes that the brain is a particularly significant part of the process. The fact that I might cheerfully accept this offer without philosophical worries doesn't get rid of the question 'who is this person?' Who should they remain married to? |
| 5520 | If two humans are merged surgically, the new identity is a purely verbal problem [Parfit] |
| Full Idea: If there is someone with my head and my brother's body, it is a merely verbal question whether that person will be me, and that is why, even if it won't be me, that doesn't matter. ..What matters is not identity, but the facts of which identity consists. | |
| From: Derek Parfit (The Unimportance of Identity [1995], p.310) | |
| A reaction: It strikes me that from the subjective psychological point of view identity is of little interest, but from the objective external viewpoint (e.g. the forensic one) such questions are highly significant, and rightly so. |
| 1391 | Concern for our own lives isn't the source of belief in identity, it is the result of it [Parfit] |
| Full Idea: Egoism, and the fear not of near but of distant death, and the regret that so much of one's life should have gone by - these are not, I think, wholly natural or instinctive. They are strengthened by a false belief in stable identity. | |
| From: Derek Parfit (Personal Identity [1971], §6) | |
| A reaction: This raises some very nice questions, about the extent to which various aspects of self-concern are instinctive and natural, or culturally induced, and even totally misguided and false. I can worry about the distant death of my guinea pig, or my grandson. |
| 5518 | It doesn't matter whether I exist with half my components replaced (any more than an audio system) [Parfit] |
| Full Idea: It is quite uninteresting whether, with half its components replaced, I have the same audio system, and also whether I exist if half of my body were simultaneously replaced. | |
| From: Derek Parfit (The Unimportance of Identity [1995], p.302) | |
| A reaction: It is impossible to deny this, if the part replaced is not the brain. My doubt about Parfit's thesis is that while I may not care whether some modified thing is still me, my lawyers and the police might be very concerned. |
| 9762 | We should focus less on subjects of experience, and more on the experiences themselves [Parfit] |
| Full Idea: It becomes more plausible, when thinking morally, to focus less upon the person, the subject of experiences, and instead to focus more upon the experiences themselves. | |
| From: Derek Parfit (Reasons and Persons [1984], §116) | |
| A reaction: This pinpoints how Parfit moves from a view of persons in terms of continuity of consciousness to a utilitarian morality. It brings out nicely what is wrong with utilitarianism - the reductio of a great ball of nice experiences, with no one having them. |
| 15886 | Science rests on the principle that nature is a hierarchy of natural kinds [Harré] |
| Full Idea: The animating principle behind the material and discursive practices of science is the thesis that nature exemplifies multiple hierarchies of natural kinds. | |
| From: Rom Harré (Laws of Nature [1993], 5) | |
| A reaction: I agree. I take it to be a brute fact that there seem to be lots of stable natural kinds, which are worth investigating as long as they stay stable. If they are unstable, there needs to be something stable to measure that by - or we give up. |
| 15864 | Classification is just as important as laws in natural science [Harré] |
| Full Idea: Classification systems, or taxonomies, are as important a part of the natural sciences as are the laws of nature. | |
| From: Rom Harré (Laws of Nature [1993], 1) | |
| A reaction: This illustrates how our view of science is radically shifted if we give biology equal prominence with physics. |
| 15865 | Newton's First Law cannot be demonstrated experimentally, as that needs absence of external forces [Harré] |
| Full Idea: We can never devise an experimental situation in which there are no external forces to act on a body. It follows that Newton's First Law could never be demonstrated by means of experiment or observation. | |
| From: Rom Harré (Laws of Nature [1993], 1) | |
| A reaction: It can't be wholly demonstrated, but certain observations conform to it, such as the movement of low friction bodies, or the movements of planetary bodies. |
| 15862 | Laws can come from data, from theory, from imagination and concepts, or from procedures [Harré] |
| Full Idea: Boyle's Law generalises a mass of messy data culled from an apparatus; Snell's Law is an experimentally derived law deducible from theory; Newton's First Law derives from concepts and thought experiments; Mendel's Law used an experimental procedure. | |
| From: Rom Harré (Laws of Nature [1993], 1) | |
| A reaction: Nice examples, especially since Boyle's and Newton's laws are divided by a huge gulf, and arrived at about the same time. On p.35 Harré says these come down to two: abstraction from experiment, and derivation from deep assumptions. |
| 15870 | Are laws of nature about events, or types and universals, or dispositions, or all three? [Harré] |
| Full Idea: What is Newton's First Law about? Is it about events? Is it about types or universals? Is it about dispositions? Or is it, in some peculiar way, about all three? | |
| From: Rom Harré (Laws of Nature [1993], 2) | |
| A reaction: If laws merely chart regularities, then I suppose they are about events (which exhibit the regular patterns). If laws explain, which would be nice, then they are only about universals if you are a platonist. Hence laws are about dispositions. |
| 15871 | Are laws about what has or might happen, or do they also cover all the possibilities? [Harré] |
| Full Idea: Is Newton's First Law about what has actually happened or is it about what might, or could possibly happen? Is it about the actual events and states of the world, or possible events and states? | |
| From: Rom Harré (Laws of Nature [1993], 2) | |
| A reaction: I presume the first sentence distinguishes between what 'might (well)' happen, and what 'could (just) possibly happen'. I take it for granted that laws predict the actual future. The question is are they true of situations which will never occur? |
| 15876 | Maybe laws of nature are just relations between properties? [Harré] |
| Full Idea: The idea of the Dretske-Armstrong-Tooley view is very simple: the laws of nature relate properties to properties. | |
| From: Rom Harré (Laws of Nature [1993], 2) | |
| A reaction: Presumably the relations are necessary ones. I don't see why we need to mention these wretched 'universals' in order to expound this theory. It sounds much more plausible if you just say a property is defined by the way it relates to other properties. |
| 15860 | We take it that only necessary happenings could be laws [Harré] |
| Full Idea: We do not take laws to be recordings of what happens perchance or for the most part, but specifications of what happens necessarily | |
| From: Rom Harré (Laws of Nature [1993], 1) | |
| A reaction: This sounds like a plausible necessary condition for a law, but it may not be a sufficient one. Are trivial necessities laws? On this view if there are no necessities then there are no laws. |
| 15872 | Must laws of nature be universal, or could they be local? [Harré] |
| Full Idea: Is a law of nature about everything in the universe or just about a restricted group of things? | |
| From: Rom Harré (Laws of Nature [1993], 2) | |
| A reaction: I presume the answer is that while a law may only refer to a small group of things, the law would still have to apply if that group moved or spread or enlarged, so it would have to be universals. A laws confined to one time or place? Maybe. |
| 15867 | Laws describe abstract idealisations, not the actual mess of nature [Harré] |
| Full Idea: The laws of nature are not simple descriptions of what can be seen to happen. They are descriptions of abstractions and idealisations from a somewhat messy reality. | |
| From: Rom Harré (Laws of Nature [1993], 1) | |
| A reaction: This view seems to have increasingly gripped modern philosophers, so that the old view of God decreeing a few simple equations to run the world has faded away. |
| 15892 | Laws of nature state necessary connections of things, events and properties, based on models of mechanisms [Harré] |
| Full Idea: A law of nature tells us what kinds of things, events and properties (all else being equal) go along with what. The 'must' of natural necessity has its place here because it is bound up with a model or analogy representing generative mechanisms. | |
| From: Rom Harré (Laws of Nature [1993], 5) | |
| A reaction: This is Harré's final page summary of laws. I agree with it. I would say that the laws are therefore descriptive, of the patterns of behaviour that arise when generative mechanisms meet. Maybe laws concern 'transformations'. |
| 17968 | By digging deeper into the axioms we approach the essence of sciences, and unity of knowedge [Hilbert] |
| Full Idea: By pushing ahead to ever deeper layers of axioms ...we also win ever-deeper insights into the essence of scientific thought itself, and become ever more conscious of the unity of our knowledge. | |
| From: David Hilbert (Axiomatic Thought [1918], [56]) | |
| A reaction: This is the less fashionable idea that scientific essentialism can also be applicable in the mathematic sciences, centring on the project of axiomatisation for logic, arithmetic, sets etc. |
| 15875 | In counterfactuals we keep substances constant, and imagine new situations for them [Harré] |
| Full Idea: In drawing 'countefactual' conclusions we can be thought imaginatively to vary the conditions under which the substance, set-up etc. is manipulated or stimulated, while maintaining constant our conception of the nature of the being in question. | |
| From: Rom Harré (Laws of Nature [1993], 2) | |
| A reaction: Presumably you could vary the substance and keep the situation fixed, but then the counterfactual seems to be 'about' something different. Either that or the 'situation' is a actually a set of substances to be tested. |