42 ideas
| 19066 | Philosophy aims to understand the world, through ordinary experience and science [Dummett] |
| Full Idea: Philosophy is an attempt to understand the world, as it is revealed to us both in our ordinary experience and by the discoveries and theories of science. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.311) | |
| A reaction: I don't see a sharp division between 'ordinary' and 'scientific'. I really like this idea, first because it makes 'understanding' central, and second because it wants both revelations. In discussing matter and time, there is too much emphasis on science. |
| 19067 | A successful proof requires recognition of truth at every step [Dummett] |
| Full Idea: For a demonstration to be cogent it is necessary that the passage from step to step involve a recognition of truth at each line. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.313) | |
| A reaction: Dummett cited Quine (esp. 1970) as having an almost entirely syntactic view of logic. Rumfitt points out that logic can move validly from one falsehood to another. Even a 'proof' might detour into falsehood, but it would not be a 'canonical' proof! |
| 19060 | Truth-tables are dubious in some cases, and may be a bad way to explain connective meaning [Dummett] |
| Full Idea: It is arguable whether two-valued truth tables give correct meanings for certain sentential operators, and even whether they constitute legitimate explanations of any possible sentential operators. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.294) | |
| A reaction: See 'Many-valued logic' for examples of non-binary truth tables. Presumably logicians should aspire to make their semantics precise, as well as their syntax. |
| 11066 | Deduction is justified by the semantics of its metalanguage [Dummett, by Hanna] |
| Full Idea: For Dummett the semantics of the metalanguage is the external and objective source of the justification of deduction. | |
| From: report of Michael Dummett (The Justification of Deduction [1973]) by Robert Hanna - Rationality and Logic 3.4 | |
| A reaction: This is offered as an answer to the Lewis Carroll problem that justifying deduction seems to need deduction, thus leading to a regress. [There is a reply to Dummett by Susan Haack] |
| 19058 | Syntactic consequence is positive, for validity; semantic version is negative, with counterexamples [Dummett] |
| Full Idea: A plausible account is that the syntactic notion of consequence is for positive results, that some form of argument is valid; the semantic notion is required for negative results, that some argument is invalid, because a counterexample can be found. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.292) | |
| A reaction: This rings true for the two strategies of demonstration, the first by following the rules in steps, the second by using your imagination (or a tableau) to think up problems. |
| 19063 | Beth trees show semantics for intuitionistic logic, in terms of how truth has been established [Dummett] |
| Full Idea: Beth trees give a semantics for intuitionistic logic, by representing sentence meaning in terms of conditions under which it is recognised to have been established as true. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.305) |
| 19059 | In standard views you could replace 'true' and 'false' with mere 0 and 1 [Dummett] |
| Full Idea: Nothing is lost, on this view, if in the standard semantic treatment of classical sentential logic, we replace the standard truth-values 'true' and 'false' by the numbers 0 and 1. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.294) | |
| A reaction: [A long context will explain 'on this view'] He is discussing the relationship of syntactic and semantic consequence, and goes on to criticise simple binary truth-table accounts of connectives. Semantics on a computer would just be 0 and 1. |
| 19062 | Classical two-valued semantics implies that meaning is grasped through truth-conditions [Dummett] |
| Full Idea: The standard two-valued semantics for classical logic involves a conception under which to grasp the meaning of a sentence is to apprehend the conditions under which it is, or is not, true. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.305) | |
| A reaction: The idea is that you only have to grasp the truth tables for sentential logic, and that needs nothing more than knowing whether a sentence is true or false. I'm not sure where the 'conditions' creep in, though. |
| 19065 | Soundness and completeness proofs test the theory of meaning, rather than the logic theory [Dummett] |
| Full Idea: A proof of soundess or completeness is a test, not so much of the logical theory to which it applies, but of the theory of meaning which underlies the semantics. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.310) | |
| A reaction: These two types of proof concern how the syntax and the semantics match up, so this claim sounds plausible, though I tend to think of them as more like roadworthiness tests for logic, checking how well they function. |
| 14308 | We can bring dispositions into existence, as in creating an identifier [Dennett, by Mumford] |
| Full Idea: We can bring a real disposition into existence, as in Dennett's case of a piece of cardboard torn in half, so that two strangers can infallibly identify one another. | |
| From: report of Daniel C. Dennett (Consciousness Explained [1991], p.376) by Stephen Mumford - Dispositions 03.7 n37 | |
| A reaction: Presumably human artefacts in general qualify as sets of dispositions which we have created. |
| 7384 | Words are fixed by being attached to similarity clusters, without mention of 'essences' [Dennett] |
| Full Idea: We don't need 'essences' or 'criteria' to keep the meaning of our word from sliding all over the place; our words will stay put, quite firmly attached as if by gravity to the nearest similarity cluster. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 13.2) | |
| A reaction: Plausible, but essentialism (which may have been rejuventated by a modern theory of reference in language) is not about language. It is offering an explanation of why there are 'similarity clusters. Organisms are too complex to have pure essences. |
| 7374 | Light wavelengths entering the eye are only indirectly related to object colours [Dennett] |
| Full Idea: The wavelengths of the light entering the eye are only indirectly related to the colours we see objects to be. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 12.2) | |
| A reaction: This is obviously bad news for naïve realism, but I also take it as good support for the primary/secondary distinction. I just can't make sense of anyone claiming that colour exists anywhere else except in the brain. |
| 7369 | Brains are essentially anticipation machines [Dennett] |
| Full Idea: All brains are, in essence, anticipation machines. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 7.2) | |
| A reaction: This would necessarily, I take it, make them induction machines. So brains will only evolve in a world where induction is possible, which is one where there a lot of immediately apprehensible regularities. |
| 19061 | An explanation is often a deduction, but that may well beg the question [Dummett] |
| Full Idea: An explanation is often a deductive argument, with the fact needing explaining as its conclusion. ...But the conclusion is usually given in advance, and we may only believe the premisses because they plausibly explain the conclusion. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.296) | |
| A reaction: [compressed (Dummett's wordy prose cries out for it!)] I suppose this works better in mathematics, which is central to Dummett's interests. In the real world the puzzle is not usually logically implied by its explanation. |
| 7393 | We can't draw a clear line between conscious and unconscious [Dennett] |
| Full Idea: Even in our own case, we cannot draw the line separating our conscious mental states from our unconscious mental states. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 14.2) | |
| A reaction: This strikes me as being a simple and self-evident truth, which anyone working on the brain takes for granted, but an awful lot of philosophers (stuck somewhere in the seventeenth century) can't seem to grasp. |
| 7367 | Perhaps the brain doesn't 'fill in' gaps in consciousness if no one is looking. [Dennett] |
| Full Idea: Perhaps the brain doesn't actually have to go to the trouble of "filling in" anything with "construction" - for no one is looking. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 5.4) | |
| A reaction: This a very nice point, because claims that the mind fills in in various psychological visual tests always has the presupposition of a person (or homunculus?) which is overseeing the visual experiences. |
| 7394 | Conscious events can only be explained in terms of unconscious events [Dennett] |
| Full Idea: Only a theory that explained conscious events in terms of unconscious events could explain consciousness at all. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 14.4) | |
| A reaction: This sounds undeniable, so it seems to force a choice between reductive physicalism and mysterianism. Personally I think there must be an explanation in terms of non-conscious events, even if humans are too thick to understand it. |
| 7391 | We can know a lot of what it is like to be a bat, and nothing important is unknown [Dennett] |
| Full Idea: There is at least a lot that we can know about what it is like to be a bat, and Nagel has not given us a reason to believe there is anything interesting or theoretically important that is inaccessible to us. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 14.2) | |
| A reaction: I agree. If you really wanted to identify with the phenomenology of bathood, you could spend a lot of time in underground caves whistling with your torch turned off. I can't, of course, be a bat, but then I can't be my self of yesterday. |
| 7387 | "Qualia" can be replaced by complex dispositional brain states [Dennett] |
| Full Idea: "Qualia" can be replaced by complex dispositional states of the brain. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 14.1) | |
| A reaction: 'Dispositional' reveals Dennett's behaviourist roots (he was a pupil of Ryle). Fodor is right that physicalism cannot just hide behind the word "complexity". That said, the combination of complexity and speed might add up to physical 'qualia'. |
| 7376 | We can't assume that dispositions will remain normal when qualia have been inverted [Dennett] |
| Full Idea: The goal of the experiment was to describe a case in which it was obvious that the qualia would be inverted while the reactive dispositions would be normalized. But the assumption that one could just tell is question-begging. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 12.4) | |
| A reaction: It certainly seems simple and plausible that if we inverted our experience of traffic light colours, no difference in driver behaviour would be seen. However, my example, of a conversation in a gallery of abstract art, seems more problematic. |
| 7372 | In peripheral vision we see objects without their details, so blindsight is not that special [Dennett] |
| Full Idea: If a playing card is held in peripheral vision, we can see the card without being able to identify its colours or its shapes. That's normal sight, not blindsight, so we should be reluctant on those grounds to deny visual experience to blindsight subjects. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 11.4) | |
| A reaction: This is an important point in Dennett's war against the traditional all-or-nothing view of mental events. Nevertheless, blindsight subjects deny all mental experience, while picking up information, and peripheral vision never seems like that. |
| 7373 | Blindsight subjects glean very paltry information [Dennett] |
| Full Idea: Discussions of blindsight have tended to ignore just how paltry the information is that blindsight subjects glean from their blind fields. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 11.4) | |
| A reaction: This is a bit unfair, because blindsight has mainly pointed to interesting speculations (e.g. Idea 2953). Nevertheless, if blindsight with very high information content is actually totally impossible, the speculations ought to be curtailed. |
| 7385 | People accept blurred boundaries in many things, but insist self is All or Nothing [Dennett] |
| Full Idea: Many people are comfortable taking the pragmatic approach to night/day, living/nonliving and mammal/premammal, but get anxious about the same attitude to having a self and not having a self. It must be All or Nothing, and One to a Customer. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 13.2) | |
| A reaction: Personally I think I believe in the existence of the self, but I also agree with Dennett. I greatly admire his campaign against All or Nothing thinking, which is a relic from an earlier age. A partial self could result from infancy or brain damage. |
| 7383 | The psychological self is an abstraction, not a thing in the brain [Dennett] |
| Full Idea: Like the biological self, the psychological or narrative self is an abstraction, not a thing in the brain. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 13.1) | |
| A reaction: Does Dennett have empirical evidence for this claim? It seems to me perfectly possible that there is a real thing called the 'self', and it is the central controller of the brain (involving propriotreptic awareness, understanding, and will). |
| 7386 | Selves are not soul-pearls, but artefacts of social processes [Dennett] |
| Full Idea: Selves are not independently existing soul-pearls, but artefacts of the social processes that create us, and, like other such artefacts, subject to sudden shifts in status. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 13.2) | |
| A reaction: "Soul-pearls" is a nice phrase for the Cartesian view, but there can something between soul-pearls and social constructs. Personally I think the self is a development of the propriotreptic (body) awareness that even the smallest animals must possess. |
| 7381 | We tell stories about ourselves, to protect, control and define who we are [Dennett] |
| Full Idea: Our fundamental tactic of self-protection, self-control and self-definition is telling stories, and more particularly concocting and controlling the story we tell others - and ourselves - about who we are. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 13.1) | |
| A reaction: This seems to suggest that there is someone who wants to protect themselves, and who wants to tell the stories, and does tell the stories. No one can deny the existence of this autobiographical element in our own identity. |
| 7382 | We spin narratives about ourselves, and the audience posits a centre of gravity for them [Dennett] |
| Full Idea: The effect of our string of personal narratives is to encourage the audience to (try to) posit a unified agent whose words they are, about whom they are: in short, to posit a centre of narrative gravity. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 13.1) | |
| A reaction: What would be the evolutionary advantage of getting the audience to posit a non-existent self, instead of a complex brain? It might be simpler than that, since we say of a bird "it wants to do x". What is "it"? Some simple thing, like a will. |
| 7370 | The brain is controlled by shifting coalitions, guided by good purposeful habits [Dennett] |
| Full Idea: Who's in charge of the brain? First one coalition and then another, shifting in ways that are not chaotic thanks to good meta-habits that tend to entrain coherent, purposeful sequences rather than an interminable helter-skelter power grab. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 8.1) | |
| A reaction: This is probably the best anti-ego account available. Dennett offers our sense of self as a fictional autobiography, but the sense of a single real controller is very powerful. If I jump at a noise, I feel that 'I' have lost control of myself. |
| 7379 | If an epiphenomenon has no physical effects, it has to be undetectable [Dennett] |
| Full Idea: Psychologists mean a by-product by an 'epiphenomenon', ...but the philosophical meaning is too strong: it yields a concept of no utility whatsoever. Since x has no physical effects (according to the definition), no instrument can detect it. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 12.5) | |
| A reaction: Well said! This has always been my half-formulated intuition about the claim that the mind (or anything) might be totally epiphenomenal. All a thing such as the reflection on a lake can be is irrelevant to the functioning of that specified system. |
| 7365 | Dualism wallows in mystery, and to accept it is to give up [Dennett] |
| Full Idea: Given the way dualism wallows in mystery, accepting dualism is giving up. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 2.4) | |
| A reaction: Some things, of course, might be inherently mysterious to us, and we might as well give up. The big dualist mystery is the explanation of how such different substances can interact. How do two physical substances manage to interact? |
| 7371 | All functionalism is 'homuncular', of one grain size or another [Dennett] |
| Full Idea: All varieties of functionalism can be viewed as 'homuncular' functionalism of one grain size or another. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 9.2) | |
| A reaction: This seems right, as any huge and complex mechanism (like a moon rocket) will be made up of some main systems, then sub-systems, then sub-sub-sub.... This assumes that there are one or two overarching purposes, which there are in people. |
| 7380 | Visual experience is composed of neural activity, which we find pleasing [Dennett] |
| Full Idea: All visual experience is composed of activities of neural circuits whose very activity is innately pleasing to us. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 12.6) | |
| A reaction: This is the nearest I can find to Dennett saying something eliminativist. It seems to beg the question of who 'us' refers to, and what is being pleased, and how it is 'pleased' by these neural circuits. The Hard Question? |
| 7366 | It is arbitrary to say which moment of brain processing is conscious [Dennett] |
| Full Idea: If one wants to settle on some moment of processing in the brain as the moment of consciousness, this has to be arbitrary. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 5.3) | |
| A reaction: Seems eliminativist, as it implies that all that is really going on is 'processing'. But there are two senses of 'arbitrary' - that calling it consciousness is arbitrary (wrong), or thinking that mind doesn't move abruptly into consciousness (right). |
| 19064 | Holism is not a theory of meaning; it is the denial that a theory of meaning is possible [Dummett] |
| Full Idea: In the sense of giving a model for the content of a sentence, its representative power, holism is not a theory of meaning; it is the denial that a theory of meaning is possible. | |
| From: Michael Dummett (The Justification of Deduction [1973], p.309) | |
| A reaction: This will obviously be because sentences just don't have meaning in isolation, so their meaning can't be given in terms of the sentences. |
| 22717 | Self-interest can fairly divide a cake; first person cuts, second person chooses [Poundstone] |
| Full Idea: To fairly divide a cake between two children, the first divides it and the second chooses. …Even division is best, as it anticipates the second child will take the largest piece. Fairness is enforced by the children's self-interests. | |
| From: William Poundstone (Prisoner's Dilemma [1992], 03 'Cake') | |
| A reaction: [compressed] This is introduced as the basic principle of game theory. There is an online video of two cats sharing a dish of milk; each one drinks a bit, then pushes the dish to the other one. I'm sure two children could manage that. |
| 22718 | Formal game theory is about maximising or minimising numbers in tables [Poundstone] |
| Full Idea: At the most abstract level, game theory is about tables with numbers in them - numbers that entities are are efficiently acting to maximise or minimise. | |
| From: William Poundstone (Prisoner's Dilemma [1992], 03 'Curve') | |
| A reaction: A brilliant idea. The question is the extent to which real life conforms to the numberical tables. The assumption that everyone is entirely self-seeking is blatantly false. Numbers like money have diminishing marginal utility. |
| 22719 | The minimax theorem says a perfect game of opposed people always has a rational solution [Poundstone] |
| Full Idea: The minimax theorem says that there is always a rational solution to a precisely defined conflict between two people whose interests are completely opposite. | |
| From: William Poundstone (Prisoner's Dilemma [1992], 03 'Minimax') | |
| A reaction: This is Von Neumann's founding theorem of game theory. It concerns maximising minimums, and minimising maximums. Crucially, I would say that it virtually never occurs that two people have completely opposite interests. There is a common good. |
| 22720 | Two prisoners get the best result by being loyal, not by selfish betrayal [Poundstone] |
| Full Idea: Prisoners A and B can support or betray one another. If both support, they each get 1 year in prison. If one betrays, the betrayer gets 0 and the betrayed gets 3. If they both betray they get 2 each. The common good is to support each other. | |
| From: William Poundstone (Prisoner's Dilemma [1992], 06 'Tucker's') | |
| A reaction: [by Albert Tucker, highly compressed] The classic Prisoner's Dilemma. It is artificial, but demonstrates that selfish behaviour gets a bad result (total of four years imprisonment), but the common good gets only two years. Every child should study this! |
| 22721 | The tragedy in prisoner's dilemma is when two 'nice' players misread each other [Poundstone] |
| Full Idea: The tragedy is when two 'nice' players defect because they misread the other's intentions. The puzzle of the prisoner's dilemma is how such good intentions pave the road to hell. | |
| From: William Poundstone (Prisoner's Dilemma [1992], 11 'Howard's') | |
| A reaction: I really wish these simple ideas were better known. They more or less encapsulate the tragedy of the human race, with its inability to prioritise the common good. |
| 22722 | TIT FOR TAT says cooperate at first, then do what the other player does [Poundstone] |
| Full Idea: The successful TIT FOR TAT strategy (for the iterated prisoner's dilemma) says cooperate on the first round, then do whatever the other player did in the previous round. | |
| From: William Poundstone (Prisoner's Dilemma [1992], 12 'TIT') | |
| A reaction: There are also the tougher TWO TITS FOR A TAT, and the more forgiving TIT FOR TWO TATS. The one-for-one seems to be the main winner, and is commonly seen in animal life (apparently). I recommend this to school teachers. |
| 22723 | Do unto others as you would have them do unto you - or else! [Poundstone] |
| Full Idea: TIT FOR TAT threatens 'Do unto others as you would have them do unto you - or else!'. | |
| From: William Poundstone (Prisoner's Dilemma [1992], 12 'TIT') | |
| A reaction: Essentially human happiness arises if we are all nice, but also stand up firmly for ourselves. 'Doormats' (nice all the time) get exploited. TIT FOR TAT is weak, because it doesn't exploit people who don't respond at all. |
| 7368 | Originally there were no reasons, purposes or functions; since there were no interests, there were only causes [Dennett] |
| Full Idea: In the beginning there were no reasons; there were only causes. Nothing had a purpose, nothing had so much as a function; there was no teleology in the world at all. The explanation is simple: there was nothing that had interests. | |
| From: Daniel C. Dennett (Consciousness Explained [1991], 7.2) | |
| A reaction: It seems reasonable to talk of functions even if the fledgling 'interests' are unconscious, as in a leaf. Is a process leading to an end an 'interest'? What are the 'interests' of a person who is about to commit suicide? |