44 ideas
| 4739 | In "if and only if" (iff), "if" expresses the sufficient condition, and "only if" the necessary condition [Engel] |
| Full Idea: Necessary and sufficient conditions are usually expressed by "if and only if" (abbr. "iff"), where "if" is the sufficient condition, and "only if" is the necessary condition. | |
| From: Pascal Engel (Truth [2002], §1.1) | |
| A reaction: 'I take my umbrella if and only if it is raining' (oh, and if I'm still alive). There may be other necessary conditions than the one specified. Oh, and I take it if my wife slips it into my car… |
| 1502 | Parmenides was much more cautious about accepting ideas than his predecessors [Simplicius on Parmenides] |
| Full Idea: Parmenides would not agree with anything unless it seemed necessary, whereas his predecessors used to come up with unsubstantiated assertions. | |
| From: comment on Parmenides (fragments/reports [c.474 BCE], A28) by Simplicius - On Aristotle's 'Physics' 9.116.2- | |
| A reaction: from Eudemus |
| 4737 | Are truth-bearers propositions, or ideas/beliefs, or sentences/utterances? [Engel] |
| Full Idea: The tradition of the Stoics and Frege says that truth-bearers are propositions, Descartes and the classical empiricist say they are ideas or beliefs, and Ockham and Quine say they are sentences or utterances. | |
| From: Pascal Engel (Truth [2002], §1.1) | |
| A reaction: I'm with propositions, which are unambiguous, can be expressed in a variety of ways, embody the 'logical form' of sentences, and could be physically embodied in brains (the language of thought?). |
| 4750 | The redundancy theory gets rid of facts, for 'it is a fact that p' just means 'p' [Engel] |
| Full Idea: The redundancy theory gets rid of facts, for 'it is a fact that p' just means 'p'. | |
| From: Pascal Engel (Truth [2002], §2.2) | |
| A reaction: But then when you ask what p means, you have to give the truth-conditions for its assertion, and you find you have to mention the facts after all. |
| 4744 | We can't explain the corresponding structure of the world except by referring to our thoughts [Engel] |
| Full Idea: The correspondence theory implies displaying an identity or similarity of structure between the contents of thoughts and the way the world is structured, but we seem only to be able to say that the world's structure corresponds to our thoughts. | |
| From: Pascal Engel (Truth [2002], §1.2) | |
| A reaction: I don't accept this. The structure of the world gives rise to our thoughts. There is an epistemological problem here (big time!), but that doesn't alter the metaphysical situation of what truth is supposed to be, which is correspondence. |
| 4738 | The coherence theory says truth is an internal relationship between groups of truth-bearers [Engel] |
| Full Idea: The coherence theory of truth says that it is a relationship between truth-bearers themselves, that is between propositions or beliefs or sentences. | |
| From: Pascal Engel (Truth [2002], §1.1) | |
| A reaction: We immediately begin to wonder how many truth-bearers are required. Two lies can be coherent. It is hard to make thousands of lies coherent, but not impossible. What fixes the critical number. 'All possible propositions' is not much help. |
| 4745 | Any coherent set of beliefs can be made more coherent by adding some false beliefs [Engel] |
| Full Idea: Any coherent set of beliefs can be made more coherent by adding to it one or more false beliefs. | |
| From: Pascal Engel (Truth [2002], §1.3) | |
| A reaction: A simple but rather devastating point. It is the policeman manufacturing a bogus piece of evidence to clinch the conviction, the scientist faking a single observation to fill in the last corner of a promising theory. |
| 4753 | Deflationism seems to block philosophers' main occupation, asking metatheoretical questions [Engel] |
| Full Idea: Deflationism about truth seems to deprive us of any hope of asking genuinely metatheoretical questions, which are the questions that occupy philosophers most of the time. | |
| From: Pascal Engel (Truth [2002], §2.5) | |
| A reaction: This seems like the best reason for moving from deflationism to at least minimalism. Clearly one can talk meaningfully about the success of assertions and theories. You can say a sentence is true, but not assert it. |
| 4755 | Deflationism cannot explain why we hold beliefs for reasons [Engel] |
| Full Idea: The deflationist view is silent about the fact that our assertions and beliefs are generally made or held for certain reasons. | |
| From: Pascal Engel (Truth [2002], §2.5) | |
| A reaction: The point here must be that I attribute strength to my beliefs, depending on how much support I have for them - how much support for their real truth. I scream "That's really TRUE!" when I have very good reasons. |
| 4751 | Maybe there is no more to be said about 'true' than there is about the function of 'and' in logic [Engel] |
| Full Idea: We could compare the status of 'true' with the status of the logical operator 'and' in logic. Once we have explained how it functions to conjoin two propositions, there is not much more to be said about it. | |
| From: Pascal Engel (Truth [2002], §2.4) | |
| A reaction: A good statement of the minimalist view. I don't believe it, because I don't believe that truth is confined to language. An uneasy feeling I can't put into words can turn out to be true. Truth is a relational feature of mental states. |
| 4752 | Deflationism must reduce bivalence ('p is true or false') to excluded middle ('p or not-p') [Engel] |
| Full Idea: It is said that deflationism cannot even formulate the principle of bivalence, for 'either p is true or p is false' will amount to the principle of excluded middle, 'either p or not-p'. | |
| From: Pascal Engel (Truth [2002], §2.4) | |
| A reaction: Presumably deflationists don't lost any sleep over this - in fact, it looks like a good concise way to state the deflationist thesis. However, excluded middle refers to a proposition (not-p) that was never mentioned by bivalence. Cf Idea 6163. |
| 448 | No necessity could produce Being either later or earlier, so it must exist absolutely or not at all [Parmenides] |
| Full Idea: What necessity impelled Being, if it did spring from nothing, to be produced later or earlier? Thus it must be absolutely, or not at all. | |
| From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1- |
| 447 | Being must be eternal and uncreated, and hence it is timeless [Parmenides] |
| Full Idea: Being has no coming-to-be and no destruction, for it is whole of limb, without motion, and without end. And it never was, nor will be, because it is now, a whole all together, one, continuous; for what creation of it will you look for? | |
| From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1- |
| 449 | Being is not divisible, since it is all alike [Parmenides] |
| Full Idea: Being is not divisible, since it is all alike. | |
| From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1- |
| 1503 | There is no such thing as nothing [Parmenides] |
| Full Idea: There is no such thing as nothing. | |
| From: Parmenides (fragments/reports [c.474 BCE], B06), quoted by Simplicius - On Aristotle's 'Physics' 9.86.27- |
| 445 | The realm of necessary non-existence cannot be explored, because it is unknowable [Parmenides] |
| Full Idea: The other way of enquiry, that IT IS NOT, and IT is bound NOT TO BE, cannot be explored, for you could neither recognise nor express that which IS NOT. | |
| From: Parmenides (fragments/reports [c.474 BCE], B02), quoted by Simplicius - On Aristotle's 'Physics' 9.116.28- |
| 21820 | Parmenides at least saw Being as the same as Nous, and separate from the sensed realm [Parmenides, by Plotinus] |
| Full Idea: Parmenides made some approach to the doctrine of Plato in identifying Being with Intellectual-Principle [Nous] while separating Real Being from the realm of sense. | |
| From: report of Parmenides (fragments/reports [c.474 BCE]) by Plotinus - The Enneads 5.1.08 | |
| A reaction: The point is that for Parmenides the One is the essence of Being, but for platonists there is something prior to and higher than Being. For Plato it is the Good; for Plotinus it is a revised (non-Being) concept of the One. |
| 452 | All our concepts of change and permanence are just names, not the truth [Parmenides] |
| Full Idea: All things that mortals have established, believing in their truth, are just a name: Becoming and Perishing, Being and Not-Being, and change of position, and alteration of bright colour. | |
| From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1- |
| 1504 | Something must be unchanging to make recognition and knowledge possible [Aristotle on Parmenides] |
| Full Idea: Parmenides and Melissus were the first to appreciate that there must be unchanging entities, if recognition and knowledge are to exist. | |
| From: comment on Parmenides (fragments/reports [c.474 BCE], A25) by Aristotle - On the Heavens 298b14 |
| 444 | The first way of enquiry involves necessary existence [Parmenides] |
| Full Idea: The first way of enquiry is the one that IT IS, and it is not possible for IT NOT TO BE, which is the way of credibility, for it follows truth. | |
| From: Parmenides (fragments/reports [c.474 BCE], B02), quoted by Simplicius - On Aristotle's 'Physics' 9.116.28- | |
| A reaction: also Proclus 'Timeus' |
| 450 | Necessity sets limits on being, in order to give it identity [Parmenides] |
| Full Idea: Powerful necessity holds Being in the bonds of a limit, which constrains it round about, because divine law decrees that Being shall not be without boundary. For it is not lacking, but if it were spatially infinite, it would lack everything. | |
| From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1- |
| 4762 | The Humean theory of motivation is that beliefs may be motivators as well as desires [Engel] |
| Full Idea: A problem for the Humean theory of motivation is that it is disputed that beliefs are only representational states, which cannot, unlike desires, move us to act. | |
| From: Pascal Engel (Truth [2002], §4.2) | |
| A reaction: This is a crucial issue for Humeans and empiricists. Rationalists claim that people act for reasons, so that reasons are intrinsically motivational (like the Form of the Good), and reasons may even be considered direct causes of actions. |
| 4754 | Our beliefs are meant to fit the world (i.e. be true), where we want the world to fit our desires [Engel] |
| Full Idea: Belief is said to 'aim at truth', in the sense that beliefs are the kind of mental states that have to be true for the mind to 'fit' the world (where our desires have the opposite 'direction of fit'; the world is supposed to fit our desires). | |
| From: Pascal Engel (Truth [2002], §2.5) | |
| A reaction: I don't think it is possible to give a plausible definition of belief without mentioning truth. Hume's account of them as thoughts with a funny feeling attached is ridiculous. Thinking is an activity, not a passive state. |
| 4763 | 'Evidentialists' say, and 'voluntarists' deny, that we only believe on the basis of evidence [Engel] |
| Full Idea: The 'evidentialists' (such as Locke and Hume) deny, and the 'voluntarists' (such as William James) affirm, that we ought to, or at least may, believe for other reasons than evidential epistemic reasons (e.g. for pragmatic reasons). | |
| From: Pascal Engel (Truth [2002], §5.2) | |
| A reaction: No need to be black-or-white here. Blatant evidence compels belief, but we may also come to believe by spotting a coherence, without additional evidence. We can also be in a state of trying to believe something. But see 4764. |
| 451 | Thinking implies existence, because thinking depends on it [Parmenides] |
| Full Idea: To think is the same as the thought that IT IS, for you will not find thinking without Being, on which it depends for its expression. | |
| From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1- |
| 1506 | Parmenides treats perception and intellectual activity as the same [Theophrastus on Parmenides] |
| Full Idea: Parmenides treats perception and intellectual activity as the same. | |
| From: comment on Parmenides (fragments/reports [c.474 BCE], A46) by Theophrastus - On the Senses 3.1 | |
| A reaction: cf Theaetetus pt 1 |
| 3058 | Only reason can prove the truth of facts [Parmenides] |
| Full Idea: Reason alone will prove the truth of facts. | |
| From: Parmenides (fragments/reports [c.474 BCE]), quoted by Diogenes Laertius - Lives of Eminent Philosophers 09.3.3 |
| 4746 | Pragmatism is better understood as a theory of belief than as a theory of truth [Engel] |
| Full Idea: Pragmatism in general is better construed as a certain conception of belief, rather than as a distinctive conception of truth. | |
| From: Pascal Engel (Truth [2002], §1.5) | |
| A reaction: Which is why aspiring relativists drift towards the pragmatic theory - because they want to dispense with truth (and hence knowledge), and put mere belief in its place. |
| 4764 | We cannot directly control our beliefs, but we can control the causes of our involuntary beliefs [Engel] |
| Full Idea: Direct psychological voluntarism about beliefs seems to be false, but we can have an indirect voluntary control on many of our beliefs, by manipulating the states in us that are involuntary and which lead to certain beliefs. | |
| From: Pascal Engel (Truth [2002], §5.2) | |
| A reaction: Very nice! This points two ways - to scientific experiments, which can have compelling outcomes (see Fodor), and to brain-washing, and especially auto-brainwashing (only reading articles which support your favourites theories). What magazines do you take? |
| 4759 | Mental states as functions are second-order properties, realised by first-order physical properties [Engel] |
| Full Idea: For functionalism mental states as roles are second-order properties that have to be realised in various ways in first-order physical properties. | |
| From: Pascal Engel (Truth [2002], §3.3) | |
| A reaction: I take that to be properties-of-properties, as in 'bright red' or 'poignantly beautiful'. I am inclined to think (with Edelman) that mind is a process, not a property. |
| 1590 | The just man does not harm his enemies, but benefits everyone [Plato] |
| Full Idea: First, Socrates, you told me justice is harming your enemies and helping your friends. But later it seemed that the just man, since everything he does is for someone's benefit, never harms anyone. | |
| From: Plato (Clitophon [c.372 BCE], 410b) | |
| A reaction: Socrates certainly didn't subscribe to the first view, which is the traditional consensus in Greek culture. In general Socrates agreed with the views later promoted by Jesus. |
| 555 | People who say that the cosmos is one forget that they must explain movement [Aristotle on Parmenides] |
| Full Idea: Those who assert that the universe is one and a single nature, when they try to give the causes of generation and destruction, miss out the cause of movement. | |
| From: comment on Parmenides (fragments/reports [c.474 BCE]) by Aristotle - Metaphysics 988b |
| 5081 | There could be movement within one thing, as there is within water [Aristotle on Parmenides] |
| Full Idea: Why does it follow from there being only one thing that it is unmoving, since, for example, water moves internally while remaining one? | |
| From: comment on Parmenides (fragments/reports [c.474 BCE]) by Aristotle - Physics 186a16 | |
| A reaction: One suspects that Parmenides wasn't used to critical questions like this, and would have sharpened up his theory if it had been subjected to criticism. How big was the One? Maybe Aristotle is the real father of philosophy. |
| 1509 | The one can't be divisible, because if it was it could be infinitely divided down to nothing [Parmenides, by Simplicius] |
| Full Idea: Since the one is everywhere alike, then if it is divisible, it will be equally divisible everywhere….so let it be divided everywhere. It is obvious that nothing will remain and the whole will vanish, and so (if it is compound) it is composed of nothing. | |
| From: report of Parmenides (fragments/reports [c.474 BCE]) by Simplicius - On Aristotle's 'Physics' 9.139.5- | |
| A reaction: he is quoting Porphyry |
| 20900 | Defenders of the One say motion needs the void - but that is not part of Being [Parmenides, by Aristotle] |
| Full Idea: Defenders of the One say that there could not be motion without a void, and that void is what does not exist, and that nothing that is not belongs to being. | |
| From: report of Parmenides (fragments/reports [c.474 BCE]) by Aristotle - Coming-to-be and Passing-away (Gen/Corr) 325a26 | |
| A reaction: This is why motion is an illusion, a view also supported by the paradoxes of Zeno of Elea. Aristotle goes on to give Democritus's response to this idea. Parmenides was contemplating 'void', before Democritus got to it. |
| 226 | The one is without any kind of motion [Parmenides] |
| Full Idea: The one is without any kind of motion. | |
| From: Parmenides (fragments/reports [c.474 BCE]), quoted by Plato - Parmenides 139a |
| 1505 | Reason sees reality as one, the senses see it as many [Aristotle on Parmenides] |
| Full Idea: Since he is forced to be guided by appearances, he assumes that the one exists from the viewpoint of reason, but that a plurality exists from the viewpoint of the sense, and so he posits two principles and causes - hot and cold. | |
| From: comment on Parmenides (fragments/reports [c.474 BCE], A24) by Aristotle - Metaphysics 986b27- | |
| A reaction: A profound thought. Empiricists emphasies experience, and end up with fragmented reality. Reason explains experience, and in the process sees the world as unities (like objects), though a single unity is going too far. |
| 453 | Reality is symmetrical and balanced, like a sphere, with no reason to be greater one way rather than another [Parmenides] |
| Full Idea: Since there is a spatial limit, it is complete on every side, like the mass of a well-rounded sphere, equally balanced from its centre in every direction; for it is not bound to be at all either greater or less in this direction or that. | |
| From: Parmenides (fragments/reports [c.474 BCE], B08 ll.?), quoted by Simplicius - On Aristotle's 'Physics' 9.145.1- |
| 1792 | He taught that there are two elements, fire the maker, and earth the matter [Parmenides, by Diog. Laertius] |
| Full Idea: He taught that there were two elements, fire and earth; and that one of them occupies the place of the maker, the other that of the matter. | |
| From: report of Parmenides (fragments/reports [c.474 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 09.Pa.2 |
| 5115 | It is feeble-minded to look for explanations of everything being at rest [Aristotle on Parmenides] |
| Full Idea: For people to ignore the evidence of their senses and look for an explanation for everything being at rest is feeble-minded. | |
| From: comment on Parmenides (fragments/reports [c.474 BCE]) by Aristotle - Physics 253a32 | |
| A reaction: Not exactly an argument, but an interestingly robust assertion of commonsense against dodgy arguments. Aristotle is not exactly an empiricist, but he is on that side of the fence. |
| 13217 | The void can't exist, and without the void there can't be movement or separation [Parmenides, by Aristotle] |
| Full Idea: Some philosophers thought what is must be one and immovable. The void, they say, is not: but unless there is a void what is cannot be moved, nor can it be many, since there is nothing to keep things apart. | |
| From: report of Parmenides (fragments/reports [c.474 BCE]) by Aristotle - Coming-to-be and Passing-away (Gen/Corr) 325a06 | |
| A reaction: Somehow this doesn't seem very persuasive any more! I suppose we would distinguish various degrees of void, and assert the existence of sufficient void to allow movement and separation. We must surely agree that total nothingness doesn't exist. |
| 22918 | What could have triggered the beginning [of time and being]? [Parmenides] |
| Full Idea: What need would have aroused it later or sooner, starting from nothing to come into being? | |
| From: Parmenides (fragments/reports [c.474 BCE]), quoted by Robin Le Poidevin - Travels in Four Dimensions 02 'Everything' | |
| A reaction: [Barnes 1982:178] This remains an excellent question. The last I heard was a 'quantum fluctuation', but that seems to be an event, which therefore needs time. |
| 1794 | He was the first to discover the identity of the Morning and Evening Stars [Parmenides, by Diog. Laertius] |
| Full Idea: He appears to have been the first to discover that Hesperus and Lucifer were the same star. | |
| From: report of Parmenides (fragments/reports [c.474 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 09.Pa.3 | |
| A reaction: This is the famous example used by Frege to discuss reference and meaning. |
| 1791 | He was the first person to say the earth is spherical [Parmenides, by Diog. Laertius] |
| Full Idea: He was the first person who asserted that the earth was of a spherical form. | |
| From: report of Parmenides (fragments/reports [c.474 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 09.Pa.2 |