| 22149 | Scholastics assess possibility by what has actually happened in reality [Suárez, by Boulter] |
| Full Idea: The scholastic view is that Actuality is our only guide to possibility in the real order. One knows that it is possible to separate A and B if one knows that A and B have actually been separated or are separate. | |
| From: report of Francisco Suárez (Disputationes metaphysicae [1597], Bk VII) by Stephen Boulter - Why Medieval Philosophy Matters 4 | |
| A reaction: It may be possible to separate A and B even though it has never happened, but it is hard to see how we could know that. (But if I put my pen down where it has never been before, I know I can pick it up again, even though this has not previously happened). |
| 4818 | People who are ignorant of true causes imagine anything can change into anything else [Spinoza] |
| Full Idea: Those who are ignorant of true causes make complete confusion - thinking that trees might talk just as well as men, that men might be formed from stones as well as seed, and imagine that any form might be changed into any other. | |
| From: Baruch de Spinoza (The Ethics [1675], I Pr 08 n2) | |
| A reaction: Spinoza himself can be guilty of this, but it strikes me as a key idea. Humean scepticism about causation seems to me the product of eighteenth century ignorance about the mechanisms of cause and effect which have since been uncovered by science. |
| 20310 | Error does not result from imagining, but from lacking the evidence of impossibility [Spinoza] |
| Full Idea: The mind does not err from the fact that it imagines, but only insofar as it is considered to lack an idea which excludes the existence of those things which it imagines to be present to it. | |
| From: Baruch de Spinoza (The Ethics [1675], II Pr 17 s) | |
| A reaction: These may be the wisest words I have yet found on conceivability and possibility. My example is imagining a bonfire on the moon, which seems possible until you fully grasp what fire is. |
| 23487 | What is thinkable is possible [Wittgenstein] |
| Full Idea: What is thinkable is possible too. | |
| From: Ludwig Wittgenstein (Tractatus Logico-Philosophicus [1921], 3.02) | |
| A reaction: [Plucked from a context!] The modern tide has turned against this idea. The more clearly you understand the facts, the more restricted the possibilities become. If you think the impossible is possible, it is because you are bad at thinking. |
| 5819 | Conceivability is no proof of possibility [Putnam] |
| Full Idea: Conceivability is no proof of possibility. | |
| From: Hilary Putnam (Meaning and Reference [1973], p.159) | |
| A reaction: This strikes me as a really basic truth which all novice philosophers should digest. It led many philosophers, especially rationalists, into all sorts of ill-founded claims about what is possible or necessary. Zombies, for instance… |
| 5478 | Imagination tests what is possible for all we know, not true possibility [Ellis] |
| Full Idea: The imaginability test of possibility confuses what is really or metaphysically possible with what is only epistemically possible. ..The latter is just what is possible for all we know. | |
| From: Brian Ellis (The Philosophy of Nature: new essentialism [2002], Ch.6) |
| 15098 | Empirical evidence shows that imagining a phenomenon can show it is possible [Shoemaker] |
| Full Idea: We have abundant empirical evidence that when we can imagine some phenomenal situation, e.g., imagine things appearing certain ways, such a situation could actually exist. | |
| From: Sydney Shoemaker (Causal and Metaphysical Necessity [1998], VI) | |
| A reaction: There seem to be good reasons for holding the opposite view too. We can imagine gold appearing to be all sorts of colours, but that doesn't make it possible. What does empirical evidence really tell us here? |
| 15100 | Imagination reveals conceptual possibility, where descriptions avoid contradiction or incoherence [Shoemaker] |
| Full Idea: Imaginability can give us access to conceptual possibility, when we come to believe situations to be conceptually possible by reflecting on their descriptions and seeing no contradiction or incoherence. | |
| From: Sydney Shoemaker (Causal and Metaphysical Necessity [1998], VI) | |
| A reaction: If take the absence of contradiction to indicate 'logical' possibility, but the absence of incoherence is more interesting, even if it is a bit vague. He is talking of 'situations', which I take to be features of reality. A priori synthetic? |
| 15764 | 'Conceivable' is either not-provably-false, or compatible with what we know? [Shoemaker] |
| Full Idea: We could use 'conceivable' to say it is not provable that it is not the case, or we could use it to say that it is compatible with what we know. | |
| From: Sydney Shoemaker (Causality and Properties [1980], §10) | |
| A reaction: Rather significant, since the first one would seem to allow in a great deal that the second one would rule out. Any disproof of some natural possibility founders on the remark that 'you never know'. |
| 13967 | Kripke's essentialist necessary a posteriori opened the gap between conceivable and really possible [Soames on Kripke] |
| Full Idea: With Kripke's essentialist route to the necessary a posteriori came a sharp distinction between conceivability and genuine possibility - ways things could conceivably be versus ways things could really be (or have been). | |
| From: comment on Saul A. Kripke (Naming and Necessity lectures [1970]) by Scott Soames - Significance of the Kripkean Nec A Posteriori p.167 | |
| A reaction: A key idea, for me. I love 'could there be a bonfire on the moon?' Imagining it is easy-peasy. 'Could wood combine with oxygen when there is no oxygen present?' We imagined it all right, but did we 'conceive' it? |
| 13970 | Kripke gets to the necessary a posteriori by only allowing conceivability when combined with actuality [Kripke, by Soames] |
| Full Idea: Kripke's first (superior) route to necessary a posteriori has a sharp distinction between how the universe could conceivably and really be. ..On this picture conceivability is a fallible but useful guide, when combined with knowledge of actuality. | |
| From: report of Saul A. Kripke (Naming and Necessity lectures [1970]) by Scott Soames - Significance of the Kripkean Nec A Posteriori p.168 | |
| A reaction: [compressed from p.168 and 170] To dismiss conceivability is ridiculous (see Williamson on that), and this formula of Soames sound right. To understand possibility, you have to study actuality (across time and space). Study history! |
| 14659 | We can imagine being beetles or alligators, so it is possible we might have such bodies [Plantinga] |
| Full Idea: We easily understand Kafka's story about the man who wakes up to discover that he now has the body of a beetle; and in fact the state of affairs depicted is entirely possible. I can imagine being an alligator, so Socrates could have had an alligator body. | |
| From: Alvin Plantinga (World and Essence [1970], III) | |
| A reaction: This really is going the whole hog with accepting whatever is conceivable as being possible. I take this to be shocking nonsense, and it greatly reduces Plantinga in my esteem, despite his displays of intelligence and erudition. |
| 16522 | It is hard or impossible to think of Caesar as not human [Wiggins] |
| Full Idea: It is hard or impossible to conceive of Caesar's not being a man (human). | |
| From: David Wiggins (Sameness and Substance [1980], 4.5) | |
| A reaction: So is it 'hard' or is it 'impossible'? Older generations of philosophers simply didn't read enough science fiction. Any short story could feature Caesar's failure to be a man. His assassination was a disaster for the Martian invasion of 44 BCE. |
| 16473 | Modal Rationalism: conceivability gives a priori access to modal truths [Chalmers, by Stalnaker] |
| Full Idea: Chalmers' 'modal rationalist' is one who identifies what is possible with what is conceivable; the central claim of the doctrine is that we have a priori access to modal truth. | |
| From: report of David J.Chalmers (Does Conceivability Entail Possibility? [2002]) by Robert C. Stalnaker - Mere Possibilities 5 | |
| A reaction: A helpful clarification, as I can now see how hopelessly and utterly wrong Chalmers is (about almost everything), and I find my confidence in any sort of genuine a priori knowledge (except of conceptual relations) dwindling by the minute. |
| 19258 | Evaluate primary possibility from some world, and secondary possibility from this world [Chalmers, by Vaidya] |
| Full Idea: For Chalmers, that water is XYZ is 'primary possible' (a priori, or conceptually), because it is true in some world considered as actual. It is 'secondary impossible', when it is evaluated from the Earth as actual. | |
| From: report of David J.Chalmers (Does Conceivability Entail Possibility? [2002]) by Anand Vaidya - Understanding and Essence Intro | |
| A reaction: [compressed] This is Chalmers' account of how we can know possibility from conceivability, via his two-dimensional semantics (see alphabetical themes). |
| 13963 | Maybe logical possibility does imply conceivability - by an ideal mind [Chalmers] |
| Full Idea: If we understand conceivability as conceivability-in-principle (by a superbeing?) then it is plausible that logical possibility of a world implies conceivability of the world, so logical possibility of a statement implies its conceivability. | |
| From: David J.Chalmers (The Conscious Mind [1996], 1.2.4) | |
| A reaction: I see nothing incoherent in the possibility that there might be aspects of existence which are utterly inconceivable to any conscious mind. Infinity might be a start, if an 'infinite' mind were impossible. |
| 16536 | Williamson can't base metaphysical necessity on the psychology of causal counterfactuals [Lowe on Williamson] |
| Full Idea: The psychological mechanism that Williamson proposes as the supposedly reliable source of our knowledge of necessities only seems applicable to counterfactuals that are distinctively causal, not metaphysical, in character. | |
| From: comment on Timothy Williamson (The Philosophy of Philosophy [2007]) by E.J. Lowe - What is the Source of Knowledge of Modal Truths? 5 | |
| A reaction: My rough impression of Williamson's account is that it is correct but unilluminating. We have to assess necessities by counterfactual thinking, because nothing else is available (apart from evaluating the coherence of the findings). |
| 9596 | We scorn imagination as a test of possibility, forgetting its role in counterfactuals [Williamson] |
| Full Idea: The epistemology of modality often focuses on (and pours scorn on) imagination or conceivability as a test of possibility, while ignoring the role of the imagination in the assessment of mundane counterfactuals. | |
| From: Timothy Williamson (The Philosophy of Philosophy [2007], 5.4) | |
| A reaction: Good point. I've been guilty of this easy scorn myself. Williamson gives our modal capacities an evolutionary context. What is needed is well-informed imagination, rather than wild fantasy. |
| 18853 | A proposition is 'correctly' conceivable if an ominiscient being could conceive it [Rosen] |
| Full Idea: To a first approximation, P is correctly conceivable iff it would be conceivable for a logically ominiscient being who was fully informed about the nature of things. | |
| From: Gideon Rosen (The Limits of Contingency [2006], 05) | |
| A reaction: Isn't the last bit covered by 'ominiscient'? Ah, I think the 'logically' only means they have a perfect grasp of what is consistent. This is to meet the standard problem, of ill-informed people 'conceiving' of things which are actually impossible. |
| 15167 | Empiricism explores necessities and concept-limits by imagining negations of truths [Sidelle] |
| Full Idea: In the traditional empiricist picture, we go about modal enquiry by trying to see whether we can imagine a situation in which it would be correct to assert the negation of a proposed necessary truth. Thus we can find out the limits of our concepts. | |
| From: Alan Sidelle (Necessity, Essence and Individuation [1989], Ch.1) |
| 15177 | Contradictoriness limits what is possible and what is imaginable [Sidelle] |
| Full Idea: Contradictoriness is the boundary both of what is possible and also of what is imaginable. | |
| From: Alan Sidelle (Necessity, Essence and Individuation [1989], Ch.4) | |
| A reaction: Of course we may see contradictions where there are none, and fail to grasp real hidden contradictions, so the two do not coincide in the practice. I think I would say it is 'a' boundary, not 'the' boundary. |
| 9505 | Empiricist saw imaginability and possibility as close, but now they seem remote [Bird] |
| Full Idea: Whereas the link between imaginability and possibility was once held, under the influence of empiricism, to be close, it is now widely held to be very remote. | |
| From: Alexander Bird (Nature's Metaphysics [2007], 8) | |
| A reaction: Tim Williamson nicely argues the opposite - that assessment of possibility is an adjunct of our ability to think counterfactually, which is precisely an operation of the imagination. Big error is possible, but how else could we do it? |
| 14606 | Only ideal conceivability could indicate what is possible [Schaffer,J] |
| Full Idea: The only plausible link from conceivability to possibility is via ideal conceivability. | |
| From: Jonathan Schaffer (Causation and Laws of Nature [2008], n22) | |
| A reaction: [He cites Chalmers 2002] I'm not sure what 'via' could mean here. Since I don't know any other way than attempted conceivability for assessing a possibility, I am a bit baffled by this idea. |
| 16978 | If conceivability is a priori coherence, that implies possibility [Tahko] |
| Full Idea: Maybe conceivability could be understood as a priori coherence, which implies possibility. | |
| From: Tuomas E. Tahko (The Epistemology of Essence (draft) [2013], 3.2) | |
| A reaction: I'm not quite sure why 'a priori' has to be there. Assessing conceivability just is assessing coherence. That couches it as a rational activity, rather than as a purely imaginary one. Trying to conceive a square circle isn't just daydreaming. |
| 19440 | How do you know you have conceived a thing deeply enough to assess its possibility? [Vaidya] |
| Full Idea: The main issue with learning possibility from conceivability concerns how we can be confident that we have conceived things to the relevant level of depth required for the scenario to actually be a presentation or manifestation of a genuine possibility. | |
| From: Anand Vaidya (The Epistemology of Modality [2015], 1.2.2) | |
| A reaction: [He cites Van Inwagen 1998 for this idea] The point is that ignorant imagination can conceive of all sorts of absurd things which are seen to be impossible when enough information is available. We can hardly demand a criterion for this. |
| 19267 | Define conceivable; how reliable is it; does inconceivability help; and what type of possibility results? [Vaidya] |
| Full Idea: Conceivability as evidence for possibility needs four interpretations. How is 'conceivable' defined or explained? How strongly is the idea endorsed? How does inconceivability fit in? And what kind of possibility (logical, physical etc) is implied? | |
| From: Anand Vaidya (Understanding and Essence [2010], 'Application') | |
| A reaction: [some compression] Williamson's counterfactual account helps with the first one. The strength largely depends on whether your conceptions are well informed. Inconceivability may be your own failure. All types of possibility can be implied. |