42 ideas
| 13827 | Logical consequence isn't a black box (Tarski's approach); we should explain how arguments work [Prawitz] |
| Full Idea: Defining logical consequence in the way Tarski does is a rather meagre result, treating an argument as a black box, observing input and output, while disregarding inner structure. We should define logical consequence on the basis of valid arguments. | |
| From: Dag Prawitz (On the General Idea of Proof Theory [1974], §2) |
| 13826 | Model theory looks at valid sentences and consequence, but not how we know these things [Prawitz] |
| Full Idea: In model theory, which has dominated the last decades, one concentrates on logically valid sentences, and what follows logically from what, but one disregards questions concerning how we know these things. | |
| From: Dag Prawitz (On the General Idea of Proof Theory [1974], §1) |
| 16588 | I prefer a lack of form to mean non-existence, than to think of some quasi-existence [Augustine] |
| Full Idea: I sooner judged that what lacks all form does not exist, than thought of as something in between form and nothing, neither formed nor nothing, unformed and next to nothing. | |
| From: Augustine (Confessions [c.398], XII.6), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 03.1 | |
| A reaction: Scholastics were struck by the contrast between this remark, and the remark of Averroes (Idea 16587) that prime matter was halfway existence. Their two great authorities disagreed! This sort of thing stimulated the revival of metaphysics. |
| 6472 | Continuity is a sufficient criterion for the identity of a rock, but not for part of a smooth fluid [Russell] |
| Full Idea: Continuity is not a sufficient criterion of material identity; it is sufficient in many cases, such as rocks and tables, where the appearances change slowly, but in others, such as the parts of an approximately homogeneous fluid, it fails us utterly. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §XI) | |
| A reaction: It might be debatable to what extent the 'parts' of a homogeneous fluid have identity. How many 'parts' are there in a glass of water? This seems, now, a problem for internalists; externalists can define the identity by the unseen molecules. |
| 22979 | Three main questions seem to be whether a thing is, what it is, and what sort it is [Augustine] |
| Full Idea: I am told that I can ask three sorts of questions - whether a thing is, what it is, and what sort it is. | |
| From: Augustine (Confessions [c.398], X.10) | |
| A reaction: This seems to be a very Aristotelian approach. I am pleased to see that what it is and what sort it is are not conflated. The first one must be its individual essence, and the second its generic essence. |
| 6473 | Physical things are series of appearances whose matter obeys physical laws [Russell] |
| Full Idea: We may lay down the following definition: Physical things are those series of appearances whose matter obeys the laws of physics. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §XI) | |
| A reaction: We will then have to define the laws of physic without making any reference to 'physical things'. There is an obvious suspicion of circularity somewhere here. I find it very odd to define objects just in terms of their appearances. |
| 6465 | We need not deny substance, but there seems no reason to assert it [Russell] |
| Full Idea: It is not necessary to deny a substance or substratum underlying appearances; it is merely expedient (by the application of Occam's Razor) to abstain from asserting this unnecessary entity. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §V) | |
| A reaction: Russell then goes on to struggle heroically in attempts to give accounts of 'matter' and 'objects' entirely in terms of 'sense-data'. If he failed, as many think he did, should we go back to belief in Aristotelian substance? |
| 6471 | The assumption by physicists of permanent substance is not metaphysically legitimate [Russell] |
| Full Idea: The assumption of permanent substance, which technically underlies the procedure of physics, cannot of course be regarded as metaphysically legitimate. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §XI) | |
| A reaction: It is a moot point whether physicists still thought this way after the full arrival of quantum theory in 1926. Russell raises all sorts of nice questions about the relationship between physics and philosophy here. I'm on Russell's side. |
| 6466 | Where possible, logical constructions are to be substituted for inferred entities [Russell] |
| Full Idea: The supreme maxim in scientific philosophising is this: Wherever possible, logical constructions are to be substituted for inferred entities. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §VI) | |
| A reaction: This seems to represent Russell's first move (in 1914) into what looks like phenomenalism. One might ask what is the difference between 'logical constructions' and 'inferred entities'. The latter appear to have unity, so I prefer them. |
| 6467 | No sensibile is ever a datum to two people at once [Russell] |
| Full Idea: No sensibile is ever a datum to two people at once. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §VII) | |
| A reaction: So a loud bang has to broken down into an almost infinite number of sound sensibilia - each one presumably the size of the apperture of a small ear. This is beginning to sound a bit silly. |
| 6483 | Russell held that we are aware of states of our own brain [Russell, by Robinson,H] |
| Full Idea: Russell held that we are aware of states of our own brain. | |
| From: report of Bertrand Russell (The Relation of Sense-Data to Physics [1914]) by Howard Robinson - Perception 1.1 | |
| A reaction: I can't say that I had ever intepreted Russell in this way, but it is a wonderfully thought-provoking idea. All the time that I thought I was looking at a table, I was just looking at my own brain, and drawing an unspoken inference that a table caused it. |
| 8244 | Sense-data are qualities devoid of subjectivity, which are the basis of science [Russell, by Deleuze/Guattari] |
| Full Idea: Rather than oppose sensory knowledge and scientific knowledge, we should identify the sensibilia that are peculiar to science. This is what Russell did when he evoked sense-data, qualities devoid of all subjectivity. | |
| From: report of Bertrand Russell (The Relation of Sense-Data to Physics [1914]) by G Deleuze / F Guattari - What is Philosophy? 2.5 | |
| A reaction: An interesting observation. Russell is striking for his lack of interest in theories of arts and ethics, and his whole work focuses on understanding the scientific view. What is involved in sensibilia is a key modern issue (e.g. McDowell). |
| 6462 | Sense-data are not mental, but are part of the subject-matter of physics [Russell] |
| Full Idea: I regard sense-data as not mental, and as being, in fact, part of the actual subject-matter of physics. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §III) | |
| A reaction: Russell had clearly given himself an ontological problem with the introduction of sense-data, and this is his drastic solution. In 1912 his account seems ambiguous between sense-data being mental and being physical. |
| 6463 | Sense-data are objects, and do not contain the subject as part, the way beliefs do [Russell] |
| Full Idea: Logically a sense-datum is an object, a particular of which the subject is aware; it does not contain the subject as a part, as for example beliefs and volitions do. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §IV) | |
| A reaction: This very firmly rejects any notion that a sense-datum is mental. It is a left as a strange sort of object which gets as close as it is possible to get to the 'borders' of the mind, without actually becoming part of it. |
| 6464 | Sense-data are usually objects within the body, but are not part of the subject [Russell] |
| Full Idea: The sense-datum is an external object of which in sensation the subject is aware; it is true that the sense-datum is in many cases in the subject's body, but the subject's body is as distinct from the subject as tables and chairs are. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §IV) | |
| A reaction: This is probably Russell's clearest statement of the nature of sense-data, which are objects within the subjects body, but are not part of the mind. So once again we come up against the question of their ontology. Are they made of neurons? |
| 6459 | We do not know whether sense-data exist as objects when they are not data [Russell] |
| Full Idea: We do not know, except by means of more or less precarious inferences, whether the objects which are at one time sense-data continue to exist at times when they are not data. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §II) | |
| A reaction: Note that he actually refers to sense-data as 'objects'. It shows how thoroughly reified they are in his theory if they have the possibility of independent existence. This invites the question 'what are they made of?' |
| 6460 | 'Sensibilia' are identical to sense-data, without actually being data for any mind [Russell] |
| Full Idea: I shall give the name 'sensibilia' to those objects which have the same metaphysical and physical status as sense-data without necessarily being data to any mind. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §III) | |
| A reaction: This is his response to the problem of whether sense-data can exist independently of experience, which was unclear in 1912. Presumably sensibilia are objects which are possible sources of experience, but that seems to cover most objects. |
| 6461 | Ungiven sense-data can no more exist than unmarried husbands [Russell] |
| Full Idea: We cannot ask, 'Can sense-data exist without being given?' for that is like asking, 'Can husbands exist without being married?' | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §III) | |
| A reaction: This follows hard on Idea 6460, which introduces the idea of 'sensibilia' for things which are like sense-data, but are not 'given'. This is a new distinction in 1914, which he had not made in 1912. |
| 6458 | Individuating sense-data is difficult, because they divide when closely attended to [Russell] |
| Full Idea: There is some difficulty in deciding what is to be considered one sense-datum: often attention causes divisions to appear where, so far as can be discovered, there were no divisions before. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §II) | |
| A reaction: This was, I suspect, why Russell had dropped the idea of sense-data by 1921. He does, however, say that they are the last unit in analysis, rather than being the most basic unit of perception. In other words, they are purely theoretical. |
| 6469 | Sense-data may be subjective, if closing our eyes can change them [Russell] |
| Full Idea: One reason often alleged for the subjectivity of sense-data is that the appearance of a thing itself may change when we find it hard to suppose that the thing itself has changed - as when we shut our eyes, or screw them up to make things look double. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §VIII) | |
| A reaction: Russell firmly denies that they are subjective. These examples are also said to support to proposed existence of sense-data in the first place, since they show the gap between appearance and reality. |
| 22981 | Mind and memory are the same, as shown in 'bear it in mind' or 'it slipped from mind' [Augustine] |
| Full Idea: The mind and the memory are one and the same. We even call the memory the mind, for when we tell a person to remember something, we tell them to 'bear this in mind', and when we forget something 'it slipped out of my mind'. | |
| From: Augustine (Confessions [c.398], X.14) | |
| A reaction: This idea has become familiar in modern neuroscience, I think, presumably because we do not find distinct types of neurons for consciousness and for memory. |
| 22980 | Memory contains innumerable principles of maths, as well as past sense experiences [Augustine] |
| Full Idea: The memory contains the innumerable principles and laws of numbers and dimensions. None of these can have been conveyed to me by the bodily senses. | |
| From: Augustine (Confessions [c.398], X.12) | |
| A reaction: Even if you have a fairly empirical view of the sources of mathematics (a view with which I sympathise), it must by admitted that our endless extrapolations from the sources also reside in memory. So we remember thoughts as well as experiences. |
| 22983 | We would avoid remembering sorrow or fear if that triggered the emotions afresh [Augustine] |
| Full Idea: If we had to experience sorrow or fear every time that we mentioned these emotions, no one would be willing to speak of them. | |
| From: Augustine (Confessions [c.398], X.14) | |
| A reaction: Remembering the death of a loved one can trigger fresh grief, but remembering their dangerous illness from which they recovered no longer contains the feeling of fear. |
| 22977 | I can distinguish different smells even when I am not experiencing them [Augustine] |
| Full Idea: I can distinguish the scent of lilies from that of violets, even though there is no scent at all in my nostrils. | |
| From: Augustine (Confessions [c.398], X.08) | |
| A reaction: Augustine has a nice introspective account of how we experience memory, and identifies lots of puzzling features. I know I can identify the smell of vinegar, but I can't bring it to mind, the way I can the appearance of roses. |
| 22982 | Why does joy in my mind make me happy, but joy in my memory doesn't? [Augustine] |
| Full Idea: How can it be that my mind can be happy because of the joy that is in it, and yet my memory is not sad by reason of the sadness that is in it? | |
| From: Augustine (Confessions [c.398], X.14) | |
| A reaction: This seems to contradict his thought in Idea 22981, that memory and mind are the same. Recall seems to be a part of consciousness which is not fully wired up to the rest of the mind. |
| 22978 | Memory is so vast that I cannot recognise it as part of my mind [Augustine] |
| Full Idea: The memory is a vast immeasurable sanctuary. It is part of my nature, but I cannot understand all that I am. Hence the mind is too narrow to contain itself entirely. Is the other part outside of itself, and not within it? How then can it be a part? | |
| From: Augustine (Confessions [c.398], X.08) | |
| A reaction: He seems to understand the mind as entirely consisting of consciousness. Nevertheless, this seems to be the first inklings of the modern externalist view of the mind. |
| 22984 | Without memory I could not even speak of myself [Augustine] |
| Full Idea: I do not understand the power of memory that is in myself, although without it I could not even speak of myself. | |
| From: Augustine (Confessions [c.398], X.16) | |
| A reaction: Even if the self is not identical with memory, this idea seems to establish that memory is an essential aspect of the self. This point is neglected by those who see the self as an entity (the 'soul pearl') which persists through all experience. |
| 5982 | If the future does not exist, how can prophets see it? [Augustine] |
| Full Idea: How do prophets see the future, if there is not a future to be seen? | |
| From: Augustine (Confessions [c.398], XI.17) | |
| A reaction: The answer, I suspect, is that prophets can't see the future. The prospect that the future already exists would seem to saboutage human freedom and responsibility, and point to Calvinist predestination, and even fatalism. |
| 22976 | Memories are preserved separately, according to category [Augustine] |
| Full Idea: In memory everything is preserved separately, according to its category. | |
| From: Augustine (Confessions [c.398], X.08) | |
| A reaction: This strikes me as the first seeds of the idea that the mind functions by means of mental files. Our memories of cats are 'close to' or 'linked to' our memories of dogs. |
| 22985 | Everyone wants happiness [Augustine] |
| Full Idea: Surely happiness is what everyone wants, so much so that there can be none who do not want it? | |
| From: Augustine (Confessions [c.398], X.20) | |
| A reaction: His concept of happiness is, of course, religious. Occasionally you meet habitual grumblers about life who give the impression that they are only happy when they are discontented. So happiness is achieving desires, not feeling good? |
| 6470 | Matter is the limit of appearances as distance from the object diminishes [Russell] |
| Full Idea: We offer the following tentative definition: The matter of a given thing is the limit of its appearances as their distance from the thing diminishes. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §IX) | |
| A reaction: This strikes me as empiricism gone mad. Russell is famous for being a 'realist', but you would hardly know it at this point. Personally I put emphasis on 'best explanation', which fairly simply delivers most of our commonsense understandings of reality. |
| 6468 | There is 'private space', and there is also the 'space of perspectives' [Russell] |
| Full Idea: In addition to the private spaces, ..there is the 'space of perspectives', since each private world may be regarded as the appearance which the universe presents from a certain point of view. | |
| From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §VII) | |
| A reaction: This replaces his concept of 'public space', which he introduced in 1912. Russell gradually dropped this, but I like the idea that we somehow directly perceive space in two ways simultaneously (which led him to say that space is six-dimensional). |
| 5984 | Maybe time is an extension of the mind [Augustine] |
| Full Idea: I begin to wonder whether time is an extension of the mind itself. | |
| From: Augustine (Confessions [c.398], XI.26) | |
| A reaction: The observation that the mind creates a 'specious present' (spreading experience out over a short fraction of second) reinforces this. Personally I like David Marshall's proposal that consciousness is entirely memory, which would deny this idea. |
| 22888 | To be aware of time it can only exist in the mind, as memory or anticipation [Augustine, by Bardon] |
| Full Idea: Augustine answers that for us to be aware of time it must exist only in the mind, …and the difference between past and future is just the difference between memory and anticipation. | |
| From: report of Augustine (Confessions [c.398]) by Adrian Bardon - Brief History of the Philosophy of Time 1 'Augustine's' | |
| A reaction: This is an extreme idealist view. Are we to say that the past consists only of what can be remembered, and the future only of what is anticipated? Absurd anti-realism, in my view. Where do his concepts come from, asks Le Poidevin. |
| 5980 | How can ten days ahead be a short time, if it doesn't exist? [Augustine] |
| Full Idea: A short time ago or a short time ahead we might put at ten days, but how can anything which does not exist be either long or short? | |
| From: Augustine (Confessions [c.398], XI.15) | |
| A reaction: A nice question, which gets at the paradoxical nature of time very nicely. How can it be long, but non-existent? We could break the paradox by concluding '..and therefore time does exist', even though we can't see how. |
| 5979 | If the past is no longer, and the future is not yet, how can they exist? [Augustine] |
| Full Idea: Of the three divisions of time, how can two, the past and the future, be, when the past no longer is, and the future is not yet? | |
| From: Augustine (Confessions [c.398], XI.14) | |
| A reaction: This is the oldest bewilderment about time, which naturally leads us to the thought that time cannot actually 'exist'. The remark implies that at least 'now' is safe, but that also succumbs to paradox pretty quickly. |
| 5981 | The whole of the current year is not present, so how can it exist? [Augustine] |
| Full Idea: We cannot say that the whole of the current year is present, and if the whole of it is not present, the year is not present. | |
| From: Augustine (Confessions [c.398], XI.15) | |
| A reaction: Another nice way of presenting the paradox of time. We are in a particular year, so it has to be real. |
| 5978 | I know what time is, until someone asks me to explain it [Augustine] |
| Full Idea: I know well enough what time is, provided that nobody asks me; but if I am asked what it is and try to explain, I am baffled. | |
| From: Augustine (Confessions [c.398], XI.14) | |
| A reaction: A justly famous remark, even though it adds nothing to our knowledge of time. This sort of thought pushes us towards accepting many things as axiomatic, such as time, space, identity, persons, mind. |
| 5983 | I disagree with the idea that time is nothing but cosmic movement [Augustine] |
| Full Idea: I once heard a learned man say that time is nothing but the movement of the sun and the moon and the stars, but I do not agree. | |
| From: Augustine (Confessions [c.398], XI.22) | |
| A reaction: It is tempting to say that you either take time or movement as axiomatic, and describe one in terms of the other, but you are stuck unable to give the initial statement of the axiom without mentioning the second property you were saving for later. |
| 5977 | Heaven and earth must be created, because they are subject to change [Augustine] |
| Full Idea: The fact that heaven and earth are there proclaims that they were created, for they are subject to change and variation; ..the meaning of change and variation is that something is there which was not there before. | |
| From: Augustine (Confessions [c.398], XI.04) | |
| A reaction: It seems possible that the underlying matter is eternal (as in various conservation laws, such as that of energy), and that all change is in the form rather than the substance. |
| 22887 | If God existed before creation, why would a perfect being desire to change things? [Augustine, by Bardon] |
| Full Idea: If nothing existed by God before creation, then what could have happened to, or within, God that led God to decide to create the universe at that particular moment? Why would an eternal or perfect being want or need to change? | |
| From: report of Augustine (Confessions [c.398]) by Adrian Bardon - Brief History of the Philosophy of Time 1 'Augustine's' | |
| A reaction: I suppose you could reply that change is superior to stasis, but then why did God delay the creation? |
| 5976 | If God is outside time in eternity, can He hear prayers? [Augustine] |
| Full Idea: O Lord, since you are outside time in eternity, are you unaware of the things that I tell you? | |
| From: Augustine (Confessions [c.398], XI.01) | |
| A reaction: This strikes me as the single most difficult and most elusive question about the nature of a supreme divine being. If the being is trapped in time, as we are, it is greatly diminished, and if it is outside, it is hard to see how it could be a participant. |