43 ideas
| 10121 | Contradiction is not a sign of falsity, nor lack of contradiction a sign of truth [Pascal] |
| Full Idea: Contradiction is not a sign of falsity, nor the lack of contradiction a sign of truth. | |
| From: Blaise Pascal (works [1660]), quoted by A.George / D.J.Velleman - Philosophies of Mathematics Ch.6 | |
| A reaction: [Quoted in Auden and Kronenberger's Book of Aphorisms] Presumably we would now say that contradiction is a purely formal, syntactic notion, and not a semantic one. If you hit a contradiction, something has certainly gone wrong. |
| 22744 | Parts are not parts if their whole is nothing more than the parts [Sext.Empiricus] |
| Full Idea: If the whole is nothing more than the sum of the parts, the parts will not be parts. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.343) | |
| A reaction: Nice. Bricks lying on the ground are not parts of a wall. For them to be parts of a wall there has to be a wall which is not just the bricks. Nihilists like Van Inwagen can deny the wall in ontology, but in thought we need walls. Conceptual dependence. |
| 6346 | The main epistemological theories are foundationalist, coherence, probabilistic and reliabilist [Pollock/Cruz] |
| Full Idea: The most familiar epistemological theories are foundation theories, coherence theories, probabilistic theories, and reliabilist theories. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], Pref) | |
| A reaction: A helpful list. Reliabilism is now the dominant externalist theory. Probability theories will centre on Bayes' Theorem (Idea 2798). The authors want an internalist theory that includes perceptions as well as beliefs. I currently favour coherence. |
| 6351 | Most people now agree that our reasoning proceeds defeasibly, rather than deductively [Pollock/Cruz] |
| Full Idea: One of the most important modern advances in epistemology was the recognition of defeasible reasons; it is now generally acknowledged that most of our reasoning proceeds defeasibly rather than deductively. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §1.2) | |
| A reaction: I agree totally. This is why fallibilism is clearly a correct position in epistemology (e.g. Ideas 2736 and 2755). Deduction is not the only grounds given for certainty - there are rationalist foundations (Descartes) and empiricist foundations (Moore). |
| 6374 | To believe maximum truths, believe everything; to have infallible beliefs, believe nothing [Pollock/Cruz] |
| Full Idea: If we want an agent to believe as many truths as possible, this could be achieved by simply believing everything; if we want an agent to have only true beliefs, this could be achieved by believing nothing. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §6.6) | |
| A reaction: I like this. It highlights the pragmatic need for a middle road, in which a core set of beliefs are going to be approved of as 'knowledge', so that we can get on with life. This has to be a social matter, and needs flexibility of Fallibilism. |
| 6355 | Direct realism says justification is partly a function of pure perceptual states, not of beliefs [Pollock/Cruz] |
| Full Idea: We defend a version of direct realism, saying that justification must be partly a function of perceptual states themselves, and not just a function of our beliefs about perceptual states. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §1.5.3) | |
| A reaction: Judgement suggests that perceptual states give good justification about primary qualities (like mass or shape), but not of secondary qualities (like smell or colour). Perceptions can be downright misleading. |
| 6359 | Phenomenalism offered conclusive perceptual knowledge, but conclusive reasons no longer seem essential [Pollock/Cruz] |
| Full Idea: Phenomenalism offered the prospect of explaining perceptual knowledge within a framework that recognised only conclusive reasons; once it is acknowledged that at least induction uses nonconclusive reasons, it is no longer needed. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §2.3.3.2) | |
| A reaction: I'm not sure that that is the only motivation for phenomenalism, which seemed to be attempting to get as close to 'reality' as intellectual honesty would allow. I certainly favour the modern relaxed attitude to knowledge, which needn't be 'conclusive'. |
| 6366 | Perception causes beliefs in us, without inference or justification [Pollock/Cruz] |
| Full Idea: Perception is a causal process that inputs beliefs into our doxastic system without their being inferred from or justified on the basis of other beliefs we already have. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §3.2.3) | |
| A reaction: This topic is much discussed (e.g. by MacDowell). I don't see how something is going to qualify as a 'belief' if it doesn't involve concepts and propositions. The point that we are caused to have many of our beliefs (rather than judging) seems right. |
| 6362 | Sense evidence is not beliefs, because they are about objective properties, not about appearances [Pollock/Cruz] |
| Full Idea: We think it is a mistake to suppose that the evidence of our senses comes to us in the form of beliefs; in perception, the beliefs we form are almost invariably about the objective properties of physical objects - not about how they appear to us. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §2.5.5) | |
| A reaction: The tricky word here is 'evidence'. At what point in the process of perception does something begin to count as evidence? It must at least involve concepts (and maybe even propositions) if it is going to be thought about in that way. |
| 22748 | Some say motion is perceived by sense, but others say it is by intellect [Sext.Empiricus] |
| Full Idea: Some assert that motion is perceived by sense, but others that it is not perceived at all by sense but by the intellect through sensation. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], II.062) | |
| A reaction: Descartes' wax argument defends the idea that change is perceived by intellect. The intellect has to distinguish the relative aspect of each motion, such as when someone is walking around on a moving ship. Even sense also need memory. |
| 6371 | Bayesian epistemology is Bayes' Theorem plus the 'simple rule' (believe P if it is probable) [Pollock/Cruz] |
| Full Idea: Bayesian epistemology is based upon the 'simple rule' (believe P if it is sufficiently probable) and Bayes' Theorem. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §4.3.1) | |
| A reaction: For Bayes' Theorem, see Idea 2798. There is the question of whether the proposition is subjectively or objectively probable (I believe in ghosts, so any shadow is probably a ghost). There is also the problem of objective evidence for the calculation. |
| 6373 | Internalism says if anything external varies, the justifiability of the belief does not vary [Pollock/Cruz] |
| Full Idea: Internalist theories make justifiability of a belief a function of the internal states of the believer, in the sense that if we vary anything but his internal states the justifiability of the belief does not vary. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §5.4.3) | |
| A reaction: This seems to be a nice clear definition of internalism (and, by implication, externalism). It favours externalism. I know my car is in the car park; someone takes it for a joyride, then replaces it; my good justification seems thereby weakened. |
| 6353 | People rarely have any basic beliefs, and never enough for good foundations [Pollock/Cruz] |
| Full Idea: We argue that all foundations theories are false, for the simple reason that people rarely have any epistemological basic beliefs, and never have enough to provide a foundation for the rest of our knowledge. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §1.5.3) | |
| A reaction: Once surprising things start to happen in a film, we rapidly jettison our normal basic beliefs, to be ready for surprises. However, it seems to me that quite a lot of beliefs are hard-wired into us, or inescapably arise from the use of our senses. |
| 6361 | Foundationalism requires self-justification, not incorrigibility [Pollock/Cruz] |
| Full Idea: What foundationalism requires is self-justification, which is weaker than incorrigibility. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §2.5.3) | |
| A reaction: The writers oppose foundationalism, but this remark obviously helps the theory. Bonjour votes for a fallible rationalist foundationalism, and an fallible empiricist version seems plausible (because we must check for hallucinations etc.). |
| 6357 | Reason cannot be an ultimate foundation, because rational justification requires prior beliefs [Pollock/Cruz] |
| Full Idea: Reasoning, it seems, can only justify us in holding a belief if we are already justified in holding the beliefs from which we reason, so reasoning cannot provide an ultimate source of justification. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §2.1) | |
| A reaction: This sounds slick and conclusive, but it isn't. If we accept that some truths might be 'self-evident' to reason, they could stand independently. And a large body of rational beliefs might be mutually self-supporting, as in the coherence theory of truth. |
| 6363 | Foundationalism is wrong, because either all beliefs are prima facie justified, or none are [Pollock/Cruz] |
| Full Idea: Either no belief is prima facie justified or all beliefs are prima facie justified; …we regard this as a decisive refutation of foundationalism. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §2.5.5) | |
| A reaction: The full text must he examined, but it is not at all clear to me how my belief that quantum theory is correct could be even remotely as prima facie justified as my belief that this is my hand. I don't think basic beliefs need be sharply divided off. |
| 6365 | Negative coherence theories do not require reasons, so have no regress problem [Pollock/Cruz] |
| Full Idea: The regress argument has no apparent strength against negative coherence theories, because they do not require reasons for beliefs. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §3.2.3) | |
| A reaction: A nice point. Such theories endorse Neurath's picture (Idea 6348). On the whole philosophers like positive support for their beliefs, so the rather passive picture of accepting everything unless it is undermined is not appealing. A fall-back position. |
| 6354 | Coherence theories fail, because they can't accommodate perception as the basis of knowledge [Pollock/Cruz] |
| Full Idea: All coherence theories fail, because they are unable to accommodate perception as the basic source of our knowledge of the world. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §1.5.3) | |
| A reaction: An interesting claim, which the authors attempt to justify. They say it is direct realism, because the perceptions justify, without any intervening beliefs. My immediate thought is that they might justify knowledge of primary qualities, but not secondary. |
| 6367 | Coherence theories isolate justification from the world [Pollock/Cruz] |
| Full Idea: The Isolation Argument objects that coherence theories cut justification off from the world. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §3.2.4) | |
| A reaction: I don't see this as a strong objection. Justification can be in the way beliefs cohere together, but the beliefs themselves consist of holding propositions to be true, and truth asserts a connection to the world (I say). |
| 6370 | Externalism comes as 'probabilism' (probability of truth) and 'reliabilism' (probability of good cognitive process) [Pollock/Cruz] |
| Full Idea: There are two major kinds of externalist theory in the literature - probabilism (which expresses justification in terms of probability of the belief being true), and reliabilism (which refers to the probability of the cognitive processes being right). | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §4.1) | |
| A reaction: A useful clarification. Reliabilism has an obvious problem, that a process can be reliable, but only luckily correct on this occasion (a clock which has, unusually, stopped). A ghost is more probably there if I believe in ghosts. |
| 6358 | One belief may cause another, without being the basis for the second belief [Pollock/Cruz] |
| Full Idea: If I fall flat on my back running to a class, my belief that I was late for class may cause me to have the belief that there are birds in the trees, but I do not believe the latter on the basis of the former. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §2.3.1) | |
| A reaction: A nice example, which fairly conclusively demolishes any causal theory of justification. My example is believing correctly that the phone ring is from mother, because she said she would call. Maybe causation is needed somewhere in the right theory. |
| 6364 | We can't start our beliefs from scratch, because we wouldn't know where to start [Pollock/Cruz] |
| Full Idea: We cannot forsake all of our beliefs and start over again, because then we could not know how to start. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §3.1) | |
| A reaction: A point with which it is hard to disagree, but even Descartes agreed with it (Idea 3604). Presumably all your beliefs can take it in turn to be doubted, while others are held true, or you can whittle the beliefs which can't be abandoned down to a minimum. |
| 6352 | Enumerative induction gives a universal judgement, while statistical induction gives a proportion [Pollock/Cruz] |
| Full Idea: Enumerative induction examines a sample of objects, observes they all have a property, and infers that they all have that property; statistical induction observes a proportion of the objects having the property, and infers that proportion in general. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §1.4.6) | |
| A reaction: There is also induction by elimination, where it is either p or q, and observation keeps saying it isn't p. A small sample is very unreliable, but a huge sample (e.g. cigarettes and cancer) is almost certain, so where is the small/huge boundary? |
| 6372 | Since every tautology has a probability of 1, should we believe all tautologies? [Pollock/Cruz] |
| Full Idea: It follows from the probability calculus that every tautology has probability 1; it then follows in Bayesian epistemology that we are justified in believing every tautology. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §4.3.1.5) | |
| A reaction: If I say 'a bachelor is a small ant' you wouldn't believe it, but if I said 'I define a bachelor as a small ant' you would have to believe it. 'Bachelors are unmarried' men is a description of English usage, so is not really a simple tautology. |
| 6360 | Scientific confirmation is best viewed as inference to the best explanation [Pollock/Cruz] |
| Full Idea: The confirmation of scientific theories is probably best viewed in terms of inference to the best explanation. | |
| From: J Pollock / J Cruz (Contemporary theories of Knowledge (2nd) [1999], §2.3.3.3) | |
| A reaction: A simple claim, but one with which I strongly agree. 'Inference', of course, implies that there is some fairly strict logical thinking going on, which may not be so. I suspect that dogs can move to the best explanation. It is, though, a rational process. |
| 22746 | If we try to conceive of a line with no breadth, it ceases to exist, and so has no length [Sext.Empiricus] |
| Full Idea: When we have gone so far as to deprive the length of its breadth altogether, we no longer conceive even the length, but along with the removal of the breadth the conception of the length is also removed. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.392) | |
| A reaction: The only explanation of our retaining an understanding of a line even after we have removed its breadth is that we have abandoned experience and conceptualised the line - by idealising it. |
| 22741 | The incorporeal is not in the nature of body, and so could not emerge from it [Sext.Empiricus] |
| Full Idea: The incorporeal will never come into existence from body because the nature of the incorporeal does not exist in body. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.225) | |
| A reaction: So nothing high could be made of pebbles because pebbles are not high? His argument depends on incorporeality having an intrinsically incorporeal nature. Pebbles have some height which can be extended. |
| 22747 | A man walking backwards on a forwards-moving ship is moving in a fixed place [Sext.Empiricus] |
| Full Idea: If a ship moves forward and a man carries a rod backwards on it, then it is possible for an object to move without quitting its place. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], II.056) | |
| A reaction: [summary of a verbose paragraph] The point is that you cannot define movement as change of place (contrary to Russell's proposal!). The concept of a place seems to be relative. Walking on a treadmill. |
| 22749 | Time doesn't end with the Universe, because tensed statements about destruction remain true [Sext.Empiricus] |
| Full Idea: It is absurd to say that when the Universe is destroyed time does not exist; for the statement that it was destroyed once and that it is being destroyed are indicative of times. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], II.188) | |
| A reaction: Intriguing. He takes it that a proposition can be true even though nothing exists. This is not merely an affirmation of the tensed A-series view of time, but he even offers tenses as evidence that the A-series is correct. That time could cease was a view. |
| 22750 | Time is divisible, into past, present and future [Sext.Empiricus] |
| Full Idea: Time cannot be indivisible, since it is divided into past, present and future. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], II.193) | |
| A reaction: Does the fact that you can name the parts of something prove that it is divisible? Do electrons have left and right-hand sides? |
| 22742 | Socrates either dies when he exists (before his death) or when he doesn't (after his death) [Sext.Empiricus] |
| Full Idea: Socrates either dies when existing, or when not existing. …He does not die when he exists, for he is alive, and he does not die when he has died, for then he will be dying twice, which is absurd. So then, Socrates does not die. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.269) | |
| A reaction: A nice dramatisation of a major dilemma. The present moment is just the boundary between the past and the future, and so has no magnitude, and hence nothing can occur during the present. Perhaps my favourite philosophical dilemma. |
| 22751 | If the present is just the limit of the past or the future, it can't exist because they don't exist [Sext.Empiricus] |
| Full Idea: If the present is the limit of the past, and the limit of the past has passed away together with that of which it is the limit, the present no longer exists. And if the present begins the future, which doesn't exist, the present does not yet exist. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], II.201) | |
| A reaction: If I mark a line on the ground where the wall will begin, the limit seems prior to the object. The gun starts the race, but is not part of it. That said, I cannot think of any more mysterious entity than the present moment. It isn't a line or a bang. |
| 22730 | All men agree that God is blessed, imperishable, happy and good [Sext.Empiricus] |
| Full Idea: All men have one common preconception about God, according to which he is a blessed creature and imperishable and perfect in happiness and receptive of nothing evil. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.033) | |
| A reaction: He observes this after he has pointed the enormous variety of religious beliefs. He offers this unanimity as a reason to believe that it is true. |
| 22739 | God must suffer to understand suffering [Sext.Empiricus] |
| Full Idea: God cannot have a notion of suffering if he has not experience it. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.163) | |
| A reaction: Christians like to portray God as suffering because of his son's horrible death. We can imagine experiences we have never had, and presumably God is better at that than we are. |
| 22738 | The Divine must lack the virtues of continence and fortitude, because they are not needed [Sext.Empiricus] |
| Full Idea: If the Divine is all-virtuous, it possesses all the virtues. But it does not possess the virtues of continence and fortitude unless there are certain things which are hard for God to abstain from and hard to endure. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.151) | |
| A reaction: Courage would also be unnecessary, we assume. Good people are not tempted to steal, and hence do not need to resist it. It is a mistake to attribute human virtues to the Divine. Humans lack the virtues of a good frog. |
| 22734 | God is defended by agreement, order, absurdity of denying God, and refutations [Sext.Empiricus] |
| Full Idea: Arguments for God have four modes: from universal agreement, from the orderly arrangement of the universe, from the absurd consequences of denying God, and from undermining the opposing arguments. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.060) | |
| A reaction: [compressed] The loss of status of the argument from universal agreement has had a huge influence. We now realise that a very wide consensus is no guarantee of truth in anything. |
| 22736 | God's sensations imply change, and hence perishing, which is absurd, so there is no such God [Sext.Empiricus] |
| Full Idea: If God has sensation he is altered, …so he is receptive of change, including change for the worse. If so, he is also perishable, but that is absurd; therefore it is absurd also to claim that God exists. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.146) | |
| A reaction: [compressed] It is certainly paradoxical to think that God is eternal and unchanging, but also capable of perception and thought, which necessitate change. Some theological ingenuity is needed to explain this. |
| 22740 | God without virtue is absurd, but God's virtues will be better than God [Sext.Empiricus] |
| Full Idea: If the Divine exists it either has or has not virtue. If it has not it is base and unhappy, which is absurd. But if it has it, there will exist something which is better than God, just as a virtue of a horse is better than the horse itself. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.176) | |
| A reaction: It is obviously better to think of a virtue as some mode of a thing, rather than as a separate attachment. This is an ontological argument, because it is inferred from the concept of God. |
| 22735 | The original substance lacked motion or shape, and was given these by a cause [Sext.Empiricus] |
| Full Idea: They say that the substance of existing things being of itself motionless and shapeless must be put in motion and shape by some cause. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.075) | |
| A reaction: Interestingly, Sextus doesn't seem to think that the existence of the original substance also needs a cause. This substance sounds like a relative of Aristotle's Prime Matter. The source of motion isn't really a 'design' argument. |
| 22732 | The perfections of God were extrapolations from mankind [Sext.Empiricus] |
| Full Idea: It is said that …the idea that God is eternal and imperishable and perfect in happiness was introduced by way of transference from mankind. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.045) | |
| A reaction: This view is found in Hume, and in Feuerbach. I presume 'transference' means extrapolation and idealisation. If God exists, we may have no option but to think of God anthropomorphically. |
| 22728 | Gods were invented as watchers of people's secret actions [Sext.Empiricus] |
| Full Idea: It is asserted that those who first led mankind …invented gods as watchers of all the sinful and righteous acts of men, so that none should dare to do wrong even in secret. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.016) | |
| A reaction: Sextus is a sceptic about everything, so this scepticism about the gods is nothing special. I'm not sure if this is why the gods were invented, but it seems to be the main role assigned to God by the Christian church, as the basis of religious morality. |
| 22737 | An incorporeal God could do nothing, and a bodily god would perish, so there is no God [Sext.Empiricus] |
| Full Idea: The Divine is not incorporeal, since that is inanimate and insensitive and incapable of any action; nor is it a body, since that is subject to change and perishable; so the Divine does not exist. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.151) | |
| A reaction: I find this quite persuasive. An incorporeal God has to be ascribed magical powers in order to interact with what is corporeal. A corporeal God is subject to entropy and all the depredations of the physical world. |
| 22731 | It is mad to think that what is useful to us, like lakes and rivers, are gods [Sext.Empiricus] |
| Full Idea: To suppose that lakes and rivers, and whatsoever else is of a nature to be useful to us, are gods surpasses the height of lunacy. | |
| From: Sextus Empiricus (Against the Physicists (two books) [c.180], I.040) | |
| A reaction: He also points out the what is useful to us decays and changes. Sextus lived in a time when monotheism was becoming dominant. |