79 ideas
| 2797 | As coherence expands its interrelations become steadily tighter, culminating only in necessary truth [Dancy,J] |
| Full Idea: As our system grows in coherence, the interrelations between its parts becomes tighter and tighter;… at the limit contingent truth vanishes, leaving only necessary truth. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 14.7) |
| 2768 | The correspondence theory also has the problem that two sets of propositions might fit the facts equally well [Dancy,J] |
| Full Idea: The correspondence theory as well as the coherence theory has the problem of more than one set of truths. Why can't two sets of propositions "fit the facts" equally well? | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 8.2) |
| 2765 | Rescher says that if coherence requires mutual entailment, this leads to massive logical redundancy [Dancy,J] |
| Full Idea: Rescher complains that if coherence requires mutual entailment, then what is entailed is logically redundant, and the whole system is infected with mutual redundancy. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 8.1) |
| 2769 | If one theory is held to be true, all the other theories appear false, because they can't be added to the true one [Dancy,J] |
| Full Idea: From the point of view of someone with a theory every other theory is false, because it cannot be added to the true theory. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 8.2) |
| 2766 | Even with a tight account of coherence, there is always the possibility of more than one set of coherent propositions [Dancy,J] |
| Full Idea: No matter how tight our account of coherence we have to admit that there may be more than one set of coherent propositions (as Russell pointed out (1907)). | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 8.2) |
| 1564 | True and false statements can use exactly the same words [Anon (Diss)] |
| Full Idea: There is no difference between a true statement and a false statement, because they can use exactly the same words. | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §4) |
| 2781 | Realism says that most perceived objects exist, and have some of their perceived properties [Dancy,J] |
| Full Idea: Realism in the theory of perception is that objects we perceive usually do exist, and retain some at least of the properties we perceive them as having. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 10.2) |
| 2745 | A pupil who lacks confidence may clearly know something but not be certain of it [Dancy,J] |
| Full Idea: Why isn't certainty required for knowledge? Because we are often prepared to allow that someone does in fact have knowledge when the person is so uncertain they would not claim knowledge for themselves (the 'diffident schoolboy'). | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 2.1) |
| 2755 | If senses are fallible, then being open to correction is an epistemological virtue [Dancy,J] |
| Full Idea: In my view, once we admit that our beliefs about our sensory states are not infallible, incorrigibility would be a vice rather than a virtue. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 4.3) | |
| A reaction: This seems to be axiomatic among modern philosophers, and I certainly agree with it. |
| 5677 | Naïve direct realists hold that objects retain all of their properties when unperceived [Dancy,J] |
| Full Idea: The naïve direct realist holds that unperceived objects are able to retain properties of all the types we perceive them as having, which includes not only a shape and a size, but also a colour, a taste and a smell. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 10.3) | |
| A reaction: This I take to be a completely untenable view, if we are including the qualia of red, sweet or pungent among the properties. It seems uncontroversial that objects retain the capacity to cause redness etc. when they are unperceived. |
| 5678 | Scientific direct realism says we know some properties of objects directly [Dancy,J] |
| Full Idea: The scientific direct realist accepts the directness of our perception of the world, but restricts his realism to a special group of properties, ..not including those which are dependent for their existence upon the existence of a perceiver. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 10.3) | |
| A reaction: Dancy goes on to say that this distinction is a 'close relative' of Locke's primary/secondary distinction. Am I a direct realist or a representative realist about primary properties? Maybe the distinction dissolves as we unravel the true process. |
| 5681 | Maybe we are forced from direct into indirect realism by the need to explain perceptual error [Dancy,J] |
| Full Idea: Direct realism is unlikely to be able to provide an explanation of perceptual error without collapsing into indirect realism. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 10.3) | |
| A reaction: If there is an error, there must be two things which don't match: the perception, and the reality. This seems to me a powerful reason for preferring indirect or representative realism. I like the idea that we make mental 'models' (rather than inferences). |
| 5683 | Indirect realism depends on introspection, the time-lag, illusions, and neuroscience [Dancy,J, by PG] |
| Full Idea: The four standard reasons for preferring indirect to direct realism are introspection of our mental processes, the time-lag argument, the argument from illusion, and the findings of neuroscience. | |
| From: report of Jonathan Dancy (Intro to Contemporary Epistemology [1985], 10.4) by PG - Db (ideas) | |
| A reaction: Ultimately one's views about realism depend on one's views of the mind/brain, and it is the last of the four reasons that sways me. We know enough about the complexity of the brain to accept that it represents reality, with no additional ontology. |
| 5682 | Internal realism holds that we perceive physical objects via mental objects [Dancy,J] |
| Full Idea: Indirect realism holds that in perception we are indirectly aware of the physical objects around us in virtue of a direct awareness of internal, non-physical objects. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 10.4) | |
| A reaction: This may be a slightly prejudicial definition which invites insoluble questions about the ontological status of the internal 'objects'. It seems to me obvious that we create some sort of inner 'models' or constructions in the process of perception. |
| 2778 | Phenomenalism includes possible experiences, but idealism only refers to actual experiences [Dancy,J] |
| Full Idea: Phenomenalism talks about actual and possible experiences, whereas idealism confines itself to the actual experiences. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 9.5) |
| 5684 | Eliminative idealists say there are no objects; reductive idealists say objects exist as complex experiences [Dancy,J] |
| Full Idea: The eliminativist idealist holds that there is no such thing as a material object; there is nothing but experience (idea, sensation). The reductive idealist holds that there are material objects, but they are nothing other than complexes of experience. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 10.6) | |
| A reaction: Dancy says Berkeley was of the latter type. The distinction doesn't strike me as entirely clear. I can't make much sense of the words 'are' or 'exist' in the second theory. To say it is only experiences translates (to me) as 'doesn't exist'. |
| 2777 | Extreme solipsism only concerns current experience, but it might include past and future [Dancy,J] |
| Full Idea: Extreme solipsism only considers present experiences, but more relaxed solipsism may include past and possible future experiences. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 9.5) |
| 2794 | Knowing that a cow is not a horse seems to be a synthetic a priori truth [Dancy,J] |
| Full Idea: The fact that a cow is not a horse is a candidate for a priori synthetic truth. It doesn't seem to be analytic, because you can know what a cow is without knowing what a horse is. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 14.3) |
| 2780 | Perception is either direct realism, indirect realism, or phenomenalism [Dancy,J] |
| Full Idea: There are three main families of theories of perception: direct realism, indirect realism, and phenomenalism. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 10.2) |
| 5679 | We can't grasp the separation of quality types, or what a primary-quality world would be like [Dancy,J] |
| Full Idea: There is doubt about whether our experience of the world is such that we can conceive of the sort of separation of primary and secondary qualities which the scientific view calls for, and can understand what the world is like with no secondary qualities. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 10.3) | |
| A reaction: Dancy attributes these doubts to Berkeley (e.g. Idea 3837). I think what is claimed here is false. Obviously we spend our whole lives immersed in secondary qualities, but separating the different aspects is precisely what scientists (and philosophers) do. |
| 5680 | For direct realists the secondary and primary qualities seem equally direct [Dancy,J] |
| Full Idea: For a direct realist our awareness of colour and heat can hardly be of a different order from our awareness of shape and size. Both sorts of properties are presented with equal directness. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 10.3) | |
| A reaction: This is a good objection to 'direct scientific realism', which claims direct apprehension of primary qualities alongside a totally relative view of secondary qualities. The best response seems to be to move to a representative view of primary properties. |
| 2782 | We can be looking at distant stars which no longer actually exist [Dancy,J] |
| Full Idea: An object such as a distant star can have ceased to exist by the moment at which we are directly aware of it. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 10.2) |
| 2775 | It is not clear from the nature of sense data whether we should accept them as facts [Dancy,J] |
| Full Idea: The question whether something which appears as datum should remain as accepted fact is one which is not even partially determined by its origin as datum. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 8.5) |
| 2784 | Appearances don't guarantee reality, unless the appearance is actually caused by the reality [Dancy,J] |
| Full Idea: If I stare at a white wall with my brain wired to a virtual reality computer, and it generates a white wall, we wouldn't say I am seeing reality. It seems that the wall itself must in some way cause my perception of it. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 11.4) | |
| A reaction: But suppose the computer generated in my mind an image of the wall which was actually in front of me? And suppose the computer got its image from the identical wall next door, not from mine? And it was only judged identical because the architect said so |
| 2785 | Perceptual beliefs may be directly caused, but generalisations can't be [Dancy,J] |
| Full Idea: A perceptual belief that p can have as its main cause the fact that p. More general facts (all men are mortal; e=mc2) cannot be the main cause of my belief, even if they do function causally in some way. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 11.5) | |
| A reaction: Note that the perceptual belief can be the "main" cause; it seems to me that most beliefs are caused by judgements, though I may normally accept beliefs which are directly caused by perception, if I have no reason to challenge them. |
| 2790 | I can remember plans about the future, and images aren't essential (2+3=5) [Dancy,J] |
| Full Idea: Memory is not solely concerned with the past, let alone one's own past (I remember that I must be in London next week), and need not involve images (2+2=4). | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 12.3) | |
| A reaction: I can hardly remember the future, so I presume I am remembering my past commitment to go to London, even if I visualise the future with me in London. The non-necessity of images seems right. I can remember the Mona Lisa without a precise image. |
| 2788 | If perception and memory are indirect, then two things stand between mind and reality [Dancy,J] |
| Full Idea: If perception is indirect as well as memory, this means there are two direct objects of awareness between the remembering mind and the original object. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 12.2) |
| 2791 | Phenomenalism about memory denies the past, or reduces it to present experience [Dancy,J] |
| Full Idea: Eliminative phenomenalism about memory holds that there is no such thing as the past, just certain present experiences; reductive phenomenalism holds that there is a past, but it is no more than a complex of those present experiences. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 12.4) |
| 2787 | Memories aren't directly about the past, because time-lags and illusions suggest representation [Dancy,J] |
| Full Idea: Direct realism about memory believes the memory is the past. But the time-lag argument and various illusions are powerful here, suggesting indirect realism involving a memory image. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 12.2) |
| 2754 | Foundations are justified by non-beliefs, or circularly, or they need no justification [Dancy,J] |
| Full Idea: Foundationalism can get rid of the regress argument with one of three types of belief: those justified by something other than beliefs, those which justify themselves, or those which need no justification. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 4.3) | |
| A reaction: A nice clear trilemma, and none of them will do, which is why foundationalism is false. I vote for Davidson's view, that only a belief can justify another belief. |
| 2749 | For internalists we must actually know that the fact caused the belief [Dancy,J] |
| Full Idea: The internalist would claim that even if the belief is caused by the true fact to which it refers, it is also necessary that the believer believes that this is how their belief arose, and not some other way. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 3.5) | |
| A reaction: I'm converted to internalism. If the belief is externally supported in the right way, then it may well be a true belief, but knowledge needs critical faculties, and justifications which can be articulated. |
| 2770 | Internalists tend to favour coherent justification, but not the coherence theory of truth [Dancy,J] |
| Full Idea: Internalists such as Keith Lehrer tend to suggest that we adopt a coherence theory of justification but reject the coherence theory of truth. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 8.3) | |
| A reaction: I agree with Lehrer. Truth just isn't coherence, for all sorts of well known reasons (found in this database!). High coherence can be totally false. For justification, though, it is the best we have. |
| 2752 | Foundationalism requires inferential and non-inferential justification [Dancy,J] |
| Full Idea: The core of any form of foundationalism is the view that there are two forms of justification - inferential and non-inferential - and that non-inferential justification must be possible to avoid a sceptical regress. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 4.1) | |
| A reaction: The foundation may be non-inferential, but is it also non-evidential, or devoid of any support at all, apart from its own eloquent self? I can't buy that, I'm afraid. |
| 2771 | Foundationalists must accept not only the basic beliefs, but also rules of inference for further progress [Dancy,J] |
| Full Idea: Foundationalists suppose we need not only basic beliefs, but also principles of inference to move to the more sophisticated superstructure. We may understand what justifies the basic beliefs, but what about the inference principles? | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 8.3) | |
| A reaction: Very nice question. Of course, you can't justify everything, but each part of a system can be scrutinised in turn by the other parts (with scrutinising principles tested pragmatically). |
| 2756 | If basic beliefs can be false, falsehood in non-basic beliefs might by a symptom [Dancy,J] |
| Full Idea: Falsehood in a non-basic belief would be a reason to doubt the basic beliefs which support it, once we have admitted that basic beliefs can be false. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 4.3) | |
| A reaction: The yearning for foundations arises from the yearning for certainty. If one embraces the fallibilist view of knowledge, as I do, then there is little motivation for foundationalism. |
| 2753 | Beliefs can only be infallible by having almost no content [Dancy,J] |
| Full Idea: Infallible beliefs must have vanishingly small content. No belief with enough content to support the superstructure in which we are really interested is going to be infallible. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 4.2) | |
| A reaction: I see no reason why a foundationalist should not be a fallibilist, rather than insisting on the infallibility of their basic beliefs. I don't, though, see how basic beliefs can count as knowledge. |
| 2773 | Coherentism gives a possible justification of induction, and opposes scepticism [Dancy,J] |
| Full Idea: Coherentists feel that their approach provides a possible justification for induction, and offers a general stance from which the sceptic can be defused, if not rebutted. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 8.3) | |
| A reaction: These are two good reasons why I vote for coherentism (about justification, NOT about truth). Coherence is the main tool for leading us to the best explanation. |
| 2779 | Idealists must be coherentists, but coherentists needn't be idealists [Dancy,J] |
| Full Idea: An idealist should perhaps be a coherentist, but there seems to be no reason why the coherentist should be an idealist; the link between the two is all one-way. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 9.5) | |
| A reaction: I don't see why an idealist shouldn't be a rationalist foundationalist, with a private reality full of certainties founded on simple a priori truths. Personally I'm an empiricist coherentist, this week. |
| 2786 | For coherentists justification and truth are not radically different things [Dancy,J] |
| Full Idea: The coherentist idea is that justification and truth are not properties of radically different types. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 11.6) | |
| A reaction: Oh. And I thought I was a coherentist. It take it that keeping coherence for foundations separate from coherence as truth is absolutely basic. The latter is nonsense. |
| 2767 | If it is empirical propositions which have to be coherent, this eliminates coherent fiction [Dancy,J] |
| Full Idea: If coherence is grounded in, and is trying to make sense of, a set of empirical propositions, this will eliminate some of the more fanciful sets of coherent propositions, such as the complete Sherlock Holmes stories. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 8.2) | |
| A reaction: Interestingly, I suspect that embracing the coherence view of justification drives one back to empiricisim (pace Bonjour), because that is the most authoritative part of the pattern of beliefs. |
| 2776 | Externalism could even make belief unnecessary (e.g. in animals) [Dancy,J] |
| Full Idea: One reading of the externalist approach may lead to a rejection of the belief condition for knowledge (in animals, perhaps). | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 9.3) | |
| A reaction: At this point the concept of 'knowledge' seems to disperse into the mist. This pushes me to a 'setting the bar high' view of knowledge. Otherwise plants will have it, and we don't want that. |
| 2746 | How can a causal theory of justification show that all men die? [Dancy,J] |
| Full Idea: How can a causal analysis of justification show that I know that all men die? | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 2.3) | |
| A reaction: I presume he means that inductive generalisations can't be purely causal. The claim that men are immortal is absurd because it is 'unconnected' to what actually happens. |
| 2747 | Causal theories don't allow for errors in justification [Dancy,J] |
| Full Idea: Causal accounts of justification do not allow for the possibility that a false belief may still be justified. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 2.4) | |
| A reaction: Good. If you switch to what you only think is the cause of your belief, you have gone internalist and ruined the party. You can't deny that a falsehood can be justified, or justification is vacuous. |
| 2772 | Coherentism moves us towards a more social, shared view of knowledge [Dancy,J] |
| Full Idea: An advantage of coherentism is that it directs attention away from the individual's struggle to achieve knowledge (the classical conception), and points to knowledge as a social phenomenon, shared, and increased by means of sharing. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 8.3) | |
| A reaction: This is exactly the view which I now embrace. Internal coherence is the basis, but that spills out into the community, and into books, and into the relativity of social acceptance. |
| 2743 | What is the point of arguing against knowledge, if being right undermines your own argument? [Dancy,J] |
| Full Idea: What is the point of arguing that justified belief is impossible, for if you were right there could be no reasons for your conclusion? | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 1.3) |
| 1559 | Thracians think tattooing adds to a girl's beauty, but elsewhere it is a punishment [Anon (Diss)] |
| Full Idea: Thracians think that tattooing enhances a girl's beauty, whereas for everyone else tattooing is a punishment for a crime. | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §2) |
| 1561 | Anything can be acceptable in some circumstances and unacceptable in others [Anon (Diss)] |
| Full Idea: Anything can be acceptable under the right circumstances, and unacceptable under the wrong circumstances. | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §2) |
| 1560 | Lydians prostitute their daughters to raise a dowery, but no Greek would marry such a girl [Anon (Diss)] |
| Full Idea: The Lydians find it acceptable for their daughters to work as prostitutes to raise money for getting married, but no one in Greece would be prepared to marry such a girl. | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §2) |
| 2751 | Probabilities can only be assessed relative to some evidence [Dancy,J] |
| Full Idea: In Probability Calculus probability is only assessed relative to some evidence. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 4.1) |
| 2757 | The argument from analogy rests on one instance alone [Dancy,J] |
| Full Idea: As an inductive argument Mill's argument from analogy (other people have inputs and outputs like mine, so the intermediate explanation must be the same) is weak because it is based on a single instance. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 5.3) | |
| A reaction: The argument may be 'weak' as a piece of pure logic, but when faced with a strange situation, one's own case seems like crucial evidence, like a single eye-witness to a crime. |
| 2758 | You can't separate mind and behaviour, as the analogy argument attempts [Dancy,J] |
| Full Idea: The analogy argument makes the error (as Wittgenstein showed) of assuming that mind is quite separate from behaviour, and yet I can understand what it is for others to have mental states, which is contradictory. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 5.3) | |
| A reaction: It has always seemed to me that Wittgenstein is excessively behaviourist, and he always seems to be flirting with eliminative views of mind, so he was never bothered about other minds. Minds aren't separate from behaviour, but they are distinct. |
| 2744 | Verificationism (the 'verification principle') is an earlier form of anti-realism [Dancy,J] |
| Full Idea: Verificationism (the 'verification principle') is an earlier form of anti-realism. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 1.note) | |
| A reaction: If the one true God announced that there is a real world out there, I might take that as a verification of the fact. |
| 2760 | Logical positivism implies foundationalism, by dividing weak from strong verifications [Dancy,J] |
| Full Idea: The foundationalist claim that there are inferential and non-inferential justifications is mirrored by the claim of logical empiricism (the verification principle) that all significant statements are either strongly or weakly verifiable. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 6.2) | |
| A reaction: I take it to be characteristic of both to divide the support for something into two types, one of which is basic, and the other built up on the basics. The first step is to decide what is basic. |
| 2761 | If the meanings of sentences depend on other sentences, how did we learn language? [Dancy,J] |
| Full Idea: It is clearly possible to learn a language from scratch, because we have all done it, but if holism is true and the meaning of each sentence depends on the meanings of others, how did we do it? | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 7.2) | |
| A reaction: The question of 'how did it ever get started?' actually seems to block almost every explanation of everything that ever happens. How do I begin to move my hand? |
| 2763 | There is an indeterminacy in juggling apparent meanings against probable beliefs [Dancy,J] |
| Full Idea: Indeterminacy stems from an interplay between belief and meaning, as with a man who tells you he keeps two rhinoceri in the fridge and squeezes the juice of one for a drink each morning. | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 7.4) | |
| A reaction: I don't understand why an 'interplay' is called an 'indeterminacy'. Typical philosophers. Close examination will usually show whether the change is just in belief, or just in meaning, or in both. |
| 2762 | Charity makes native beliefs largely true, and Humanity makes them similar to ours [Dancy,J] |
| Full Idea: One criterion for successful translation is that it show native beliefs to be largely true (Principle of Charity), and another is that it imputes to natives beliefs we can make sense of them having (Principle of Humanity). | |
| From: Jonathan Dancy (Intro to Contemporary Epistemology [1985], 7.4) | |
| A reaction: The trouble with such guidelines is that they always have to be 'all things being equal'. Sometimes the natives are really idiotic, and sometimes their attitudes seem quite inhuman. |
| 1567 | How could someone who knows everything fail to act correctly? [Anon (Diss)] |
| Full Idea: If someone knows the nature of everything, how could he fail to be able also to act correctly in every case? | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §8) |
| 1563 | Every apparent crime can be right in certain circumstances [Anon (Diss), by PG] |
| Full Idea: It can be right, in certain circumstances, to steal, to break a solemn promise, to rob temples, and even (as Orestes did) to murder one's nearest and dearest. | |
| From: report of Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §3) by PG - Db (ideas) | |
| A reaction: Not sure about the last one! I suppose you can justify any hideousness if the fate of the universe depends on it. It must be better to die than the perform certain extreme deeds. |
| 1562 | It is right to lie to someone, to get them to take medicine they are reluctant to take [Anon (Diss)] |
| Full Idea: It is right to lie to your parents, in order to get them to take a good medicine they are reluctant to take. | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §3) | |
| A reaction: I dread to think what the medicines were which convinced the writer of this. A rule such as this strikes me as dangerous. Justifiable in extreme cases. House on fire etc. |
| 1566 | The first priority in elections is to vote for people who support democracy [Anon (Diss)] |
| Full Idea: A lottery is not democratic, because every state contains people who are not democratic, and if the lottery chooses them they will destroy the democracy. People should elect those who are observed to favour democracy. | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §7) |
| 1565 | We learn language, and we don't know who teaches us it [Anon (Diss)] |
| Full Idea: We learn language, and we don't know who teaches us it. | |
| From: Anon (Diss) (Dissoi Logoi - on Double Arguments [c.401 BCE], §6) |
| 20624 | Work degrades into heat, but not vice versa [Close] |
| Full Idea: William Thomson, Lord Kelvin, declared (in 1865) the second law of thermodynamics: mechanical work inevitably tends to degrade into heat, but not vice versa. | |
| From: Frank Close (Theories of Everything [2017], 3 'Perpetual') | |
| A reaction: The basis of entropy, which makes time an essential part of physics. Might this be the single most important fact about the physical world? |
| 20623 | First Law: energy can change form, but is conserved overall [Close] |
| Full Idea: The first law of thermodynamics : energy can be changed from one form to another, but is always conserved overall. | |
| From: Frank Close (Theories of Everything [2017], 3 'Perpetual') | |
| A reaction: So we have no idea what energy is, but we know it's conserved. (Daniel Bernoulli showed the greater the mean energy, the higher the temperature. James Joule showed the quantitative equivalence of heat and work p.26-7) |
| 20625 | Third Law: total order and minimum entropy only occurs at absolute zero [Close] |
| Full Idea: The third law of thermodynamics says that a hypothetical state of total order and minimum entropy can be attained only at the absolute zero temperature, minus 273 degrees Celsius. | |
| From: Frank Close (Theories of Everything [2017], 3 'Arrow') | |
| A reaction: If temperature is energetic movement of atoms (or whatever), then obviously zero movement is the coldest it can get. So is absolute zero an energy state, or an absence of energy? I have no idea what 'total order' means. |
| 20628 | The electric and magnetic are tightly linked, and viewed according to your own motion [Close] |
| Full Idea: Electric and magnetic phenomena are profoundly intertwined; what you interpret as electric or magnetic thus depends on your own motion. | |
| From: Frank Close (Theories of Everything [2017], 3 'Light!') | |
| A reaction: This sounds like an earlier version of special relativity. |
| 20622 | All motions are relative and ambiguous, but acceleration is the same in all inertial frames [Close] |
| Full Idea: There is no absolute state of rest; only relative motions are unambiguous. Contrast this with acceleration, however, which has the same magnitude in all inertial frames. | |
| From: Frank Close (Theories of Everything [2017], 3 'Newton's') | |
| A reaction: It seems important to remember this, before we start trumpeting about the whole of physics being relative. ....But see Idea 20634! |
| 20635 | The general relativity equations relate curvature in space-time to density of energy-momentum [Close] |
| Full Idea: The essence of general relativity relates 'curvature in space-time' on one side of the equation to the 'density of momentum and energy' on the other. ...In full, Einstein required ten equations of this type. | |
| From: Frank Close (Theories of Everything [2017], 5 'Gravity') | |
| A reaction: Momentum involves mass, and energy is equivalent to mass (e=mc^2). |
| 20627 | Electric fields have four basic laws (two by Gauss, one by Ampère, one by Faraday) [Close] |
| Full Idea: Four basic laws of electric and magnetic fields: Gauss's Law (about the flux produced by a field), Gauss's law of magnets (there can be no monopoles), Ampère's Law (fields on surfaces), and Farday's Law (accelerated magnets produce fields). | |
| From: Frank Close (Theories of Everything [2017], 3 'Light!') | |
| A reaction: [Highly compressed, for an overview. Close explains them] |
| 20630 | Light isn't just emitted in quanta called photons - light is photons [Close] |
| Full Idea: Planck had assumed that light is emitted in quanta called photons. Einstein went further - light is photons. | |
| From: Frank Close (Theories of Everything [2017], 3 'Light!') | |
| A reaction: The point is that light travels as entities which are photons, rather than the emissions being quantized packets of some other stuff. |
| 20637 | In general relativity the energy and momentum of photons subjects them to gravity [Close] |
| Full Idea: In Einstein's general theory, gravity acts also on energy and momentum, not simply on mass. For example, massless photons of light feel the gravitational attraction of the Sun and can be deflected. | |
| From: Frank Close (Theories of Everything [2017], 5 'Planck') | |
| A reaction: Ah, a puzzle solved. How come massless photons are bent by gravity? |
| 20629 | Electro-magnetic waves travel at light speed - so light is electromagnetism! [Close] |
| Full Idea: Faradays' measurements predicted the speed of electro-magnetic waves, which happened to be the speed of light, so Maxwell made an inspired leap: light is an electromagnetic wave! | |
| From: Frank Close (Theories of Everything [2017], 3 'Light!') | |
| A reaction: Put that way, it doesn't sound like an 'inspired' leap, because travelling at exactly the same speed seems a pretty good indication that they are the same sort of thing. (But I'm not denying that Maxwell was a special guy!) |
| 20632 | In QED, electro-magnetism exists in quantum states, emitting and absorbing electrons [Close] |
| Full Idea: Dirac created quantum electrodynamics (QED): the universal electro-magnetic field can exist in discreet states of energy (with photons appearing and disappearing by energy excitations. This combined classical ideas, quantum theory and special relativity. | |
| From: Frank Close (Theories of Everything [2017], 3 'Light!') | |
| A reaction: Close says this is the theory of everything in atomic structure, but not in nuclei (which needs QCD and QFD). So if there are lots of other 'fields' (e.g. gravitational, weak, strong, Higgs), how do they all fit together? Do they talk to one another? |
| 20642 | Photon exchange drives the electro-magnetic force [Close] |
| Full Idea: The exchange of photons drives the electro-magnetic force. | |
| From: Frank Close (Theories of Everything [2017], 6 'Superstrings') | |
| A reaction: So light, which we just think of as what is visible, is a mere side-effect of the engine room of nature - the core mechanism of the whole electro-magnetic field. |
| 20639 | Quantum fields contain continual rapid creation and disappearance [Close] |
| Full Idea: Quantum field theory implies that the vacuum of space is filled with particles and antiparticles which bubble in and out of existence on faster and faster timescales over shorter and shorter distances. | |
| From: Frank Close (Theories of Everything [2017], 6 'Intro') | |
| A reaction: Ponder this sentence until you head aches. Existence, but not as we know it, Jim. Close says calculations in QED about the electron confirm this. |
| 20631 | Dirac showed how electrons conform to special relativity [Close] |
| Full Idea: In 1928 Paul Dirac discovered the quantum equation that describes the electron and conforms to the requirements special relativity theory. | |
| From: Frank Close (Theories of Everything [2017], 3 'Light!') | |
| A reaction: This sounds like a major step in the unification of physics. Quantum theory and General relativity remain irreconcilable. |
| 20641 | Electrons get their mass by interaction with the Higgs field [Close] |
| Full Idea: The electron gets its mass by interaction with the ubiquitous Higgs field. | |
| From: Frank Close (Theories of Everything [2017], 6 'Hierarchy') | |
| A reaction: I thought I understood mass until I read this. Is it just wrong to say the mass of a table is the 'amount of stuff' in it? |
| 20626 | Modern theories of matter are grounded in heat, work and energy [Close] |
| Full Idea: The link between temperature, heat, work and energy is at the root of our historical ability to construct theories of matter, such as Newton's dynamics, while ignoring, and indeed being ignorant of - atomic dimensions. | |
| From: Frank Close (Theories of Everything [2017], 3 'Arrow') | |
| A reaction: That is, presumably, that even when you fill in the atoms, and the standard model of physics, these aspects of matter do the main explaiining (of the behaviour, rather than of the structure). |
| 20633 | The Higgs field is an electroweak plasma - but we don't know what stuff it consists of [Close] |
| Full Idea: In 2012 it was confirmed that we are immersed in an electroweak plasma - the Higgs field. We curently have no knowledge of what this stuff might consist of. | |
| From: Frank Close (Theories of Everything [2017], 4 'Higgs') | |
| A reaction: The second sentence has my full attention. So we don't understand a field properly until we understand the 'stuff' it is made of? So what are all the familiar fields made of? Tell me more! |
| 20640 | Space-time is indeterminate foam over short distances [Close] |
| Full Idea: At very short distances, space-time itself becomes some indeterminate foam. | |
| From: Frank Close (Theories of Everything [2017], 6 'Intro') | |
| A reaction: [see Close for a bit more detail of this weird idea] |