| 15779 | Possibility is when the necessity of the contrary is false [Aristotle] |
| Full Idea: The potential occurs when it is not necessary that its contrary be false. For example, it is potential that a man should be seated, since it is not false of necessity that he is not seated. | |
| From: Aristotle (Metaphysics [c.324 BCE], 1019b26) | |
| A reaction: This is the standard point in modal logic that possibly is equivalent to not-necessarily-not (◊p → ¬□¬p). |
| 15769 | Anything which is possible either exists or will come into existence [Aristotle] |
| Full Idea: If what we have stated either is the possible or something connected to it, there can of course be no question of its being true to say that x is capable of being but will not be. ...What is not but is capable of being either is or comes into being. | |
| From: Aristotle (Metaphysics [c.324 BCE], 1047b05) | |
| A reaction: I'm a bit startled to find the great Aristotle spouting this nonsense. It's possible that every bird in England could simultaneously land in my home town, but it ain't never going to happen. Modern women could bear 50 children, but won't. |
| 22518 | The actual must be possible, because it occurred [Aristotle] |
| Full Idea: Actual events are evidently possible, otherwise they would not have occurred. | |
| From: Aristotle (The Poetics [c.347 BCE], 1451b18) | |
| A reaction: [quoted online by Peter Adamson] Seems like common sense, but it's important to have Aristotle assert it. |
| 20832 | The Master Argument seems to prove that only what will happen is possible [Diod.Cronus, by Epictetus] |
| Full Idea: The Master Argument: these conflict 1) what is past and true is necessary, 2) the impossible does not follow from the possible, 3) something possible neither is nor will be true. Hence only that which is or will be true is possible. | |
| From: report of Diodorus Cronus (fragments/reports [c.300 BCE]) by Epictetus - The Discourses 2.19.1 | |
| A reaction: [Epictetus goes on to discuss views about which of the three should be given up] It is possible there will be a sea fight tomorrow; tomorrow comes, and no sea fight; so there was necessarily no sea fight; so the impossible followed from the possible. |
| 20790 | A proposition is possible if it is true when nothing stops it being true [Stoic school, by Diog. Laertius] |
| Full Idea: That proposition is possible which admits of being true, if external factors do not prevent it from being true, for example, 'Diocles is alive'. | |
| From: report of Stoic school (fragments/reports [c.200 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 07.75 | |
| A reaction: Well that's different. So every unprevented possibility will occur tomorrow. Any possibility that does not occur tomorrow must have been prevented in some way. Whatever does occur prevents innumerable other things from occurring. Your turn… |
| 22142 | In future, only logical limits can be placed on divine omnipotence [Anon (Par), by Boulter] |
| Full Idea: The Condemnation stipulated that all portions of the ancient intellectual heritage that placed non-logical limits on divine omnipotence were no longer to be tolerated. ...Philosophers now had to entertain the wildest ideas with all seriousness. | |
| From: report of Anon (Par) (The Condemnation of 1277 [1277]) by Stephen Boulter - Why Medieval Philosophy Matters 3 | |
| A reaction: Boulter identifies this as 'the ultimate source of Hume's philosophical delirium'. Presumably the angels-on-a-pinhead stuff originated with this. It is crazy to think that the only limit on possible existence is logic. Can God make a planet of uranium? |
| 12779 | There is a reason why not every possible thing exists [Leibniz] |
| Full Idea: There is a reason why not every possible thing exists. | |
| From: Gottfried Leibniz (Letters to Des Bosses [1715], 1716.05.29) | |
| A reaction: This is the kind of wonderful speculative metaphysical remark that we are not allowed to make any more. Needless to say, he doesn't tell us what the reason is. Overcrowding, perhaps. |
| 13084 | How can things be incompatible, if all positive terms seem to be compatible? [Leibniz] |
| Full Idea: It is yet unknown to me what is the reason of the incompossibility of things, or how it is that different essences can be opposed to each other, seeing that all purely positive terms seem to be compatible. | |
| From: Gottfried Leibniz (works [1690], G VII:194), quoted by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 3.4.4 | |
| A reaction: Since 'heavy' seems straightforwardly opposed to 'light', we would have to ask what he means by 'positive'. The suspicion is that all things are compossible by definition, so it is not surprising that impossibilities are a bit puzzling. |
| 5566 | Is the possible greater than the actual, and the actual greater than the necessary? [Kant] |
| Full Idea: Whether the field of possibility is greater than the field that contains everything actual, and whether the latter is in turn greater than the set of that which is necessary, are proper questions. | |
| From: Immanuel Kant (Critique of Pure Reason [1781], B282/A230) | |
| A reaction: A good overview. Is the actual necessary (i.e. is only the actual possible?)? Why is the non-actual possible? What would a theory look like which explains why the necessary is necessary, the actual actual, and the possible possible? A religion? |
| 18795 | A concept is logically possible if non-contradictory (but may not be actually possible) [Kant] |
| Full Idea: The concept is always possible if it does not contradict itself (the logical mark of possibility). Yet it can be an empty concept. ...We cannot infer from the possibility of the concept (logical possibility) to the possibility of the thing (real). | |
| From: Immanuel Kant (Critique of Pure Reason [1781], B624/A596 n) |
| 5613 | The analytic mark of possibility is that it does not generate a contradiction [Kant] |
| Full Idea: The analytic mark of possibility is the fact that mere positings (realities) do not generate a contradiction. | |
| From: Immanuel Kant (Critique of Pure Reason [1781], B630/A602) | |
| A reaction: I think this is wrong. I would offer self-evident absurdity (but with no actual contradiction) as another analytic mark of possibility. Natural possibility may coincide with metaphysical possibility. Human thought does not determine possibilities. |
| 21410 | That a concept is not self-contradictory does not make what it represents possible [Kant] |
| Full Idea: That the concept of a thing is possible (not self-contradictory) is not yet sufficient for assuming the possibility of the thing itself (the objective reality of the concept). | |
| From: Immanuel Kant (Metaphysics of Morals II:Doctrine of Virtue [1797], 382 Intro I) | |
| A reaction: I take this to be an inkling of Kripke's a posteriori scientific necessities, which place far greater restrictions on the possibilies of what we seem to have conceived, in addition to the mere need for consistency. |
| 14786 | Some logical possibility concerns single propositions, but there is also compatibility between propositions [Peirce] |
| Full Idea: Many say everything is logically possible which involves no contradiction. In this sense two contradictory propositions may be severally possible. In the substantive sense, the contradictory of a possible proposition is impossible (if we were omniscient). | |
| From: Charles Sanders Peirce (The Nature of Mathematics [1898], III) |
| 22308 | Only the actual exists, so possibilities always reduce to actuality after full analysis [Russell] |
| Full Idea: Possibility always marks insufficient analysis: when analysis is completed, only the actual can be relevant, for the simple reason that there is only the actual, and that the mere possibility is nothing. | |
| From: Bertrand Russell (Papers of 1913 [1913], VII.26), quoted by Michael Potter - The Rise of Analytic Philosophy 1879-1930 42 'Logic' | |
| A reaction: Quine agreed with Russell on this. You won't get far in life if you deny possibilities. The answer is to recognise that the actual is dynamic, and not passive. |
| 8361 | What is true used to be possible, but it may no longer be so [Wright,GHv] |
| Full Idea: It is not very natural to say of that which is true that it is also possible. ...What is true was possible - but whether it still is a potency of the world is not certain. | |
| From: G.H. von Wright (Logic and Epistemology of Causal Relations [1973], §5) | |
| A reaction: A simple and rather important distinction. Before encountering this, I would certainly have been happy to affirm that the actual is possible, but actually it may not be. The power to create differs from the power to sustain. Could God re-create the world? |
| 15782 | Quine wants identity and individuation-conditions for possibilia [Quine, by Lycan] |
| Full Idea: Quine notoriously demands identity and individuation-conditions for mere possibilia. | |
| From: report of Willard Quine (works [1961]) by William Lycan - The Trouble with Possible Worlds 01 | |
| A reaction: Demanding individuation before speaking of anything strikes me as dubious. 'Whoever did this should own up'. 'There must be something we can do'. Obviously you need some idea of what you are talking about - but not much. |
| 15542 | All possibilities are recombinations of properties in the actual world [Armstrong, by Lewis] |
| Full Idea: Armstrong's thesis is that recombination gives all the possibilities there are. There is no 'outer sphere' of possibilities wherein are found new and different universals alien to the actual world. No extra fundamental properties of fundamental particles. | |
| From: report of David M. Armstrong (A Combinatorial Theory of Possibility [1989]) by David Lewis - Armstrong on combinatorial possibility 'Combinatorialism' | |
| A reaction: I can't grasp what Armstrong's basis would be for such a claim. I surmise that current fundamental particles can only have the properties they currently have, but I can't see the impossibility of new stuff with new properties. |
| 10269 | Mathematics eliminates possibility, as being simultaneous actuality in sets [Putnam] |
| Full Idea: Mathematics has got rid of possibility by simply assuming that, up to isomorphism anyway, all possibilities are simultaneous actual - actual, that is, in the universe of 'sets'. | |
| From: Hilary Putnam (What is Mathematical Truth? [1975], p.70), quoted by Stewart Shapiro - Philosophy of Mathematics 7.5 |
| 5479 | Scientific essentialists say science should define the limits of the possible [Ellis] |
| Full Idea: Scientific essentialists hold that one of the primary aims of science is to define the limits of the possible. | |
| From: Brian Ellis (The Philosophy of Nature: new essentialism [2002], Ch.6) | |
| A reaction: I'm not sure working scientists will go along with that, but I like the claim that philosophy is very much part of the same enterprise as practical science (and NOT subservient to it!). I think of metaphysics as very high level physics. |
| 8554 | Possible difference across worlds depends on difference across time in the actual world [Shoemaker] |
| Full Idea: The ways in which a given thing can be different in different possible worlds depend on the ways in which such a thing can be different at different times in the actual world. | |
| From: Sydney Shoemaker (Causality and Properties [1980], §05) | |
| A reaction: Where change in a thing is possible across time in the actual world seems to require a combination of experiment and imagination. Unimaginability does not entail necessity, but it may be the best guide we have got. |
| 17059 | Unicorns are vague, so no actual or possible creature could count as a unicorn [Kripke] |
| Full Idea: If the unicorn myth is supposed to be a particular species, with insufficient internal structure to determine it uniquely, then there is no actual or possible species of which we can say that it would have been the species of unicorns. | |
| From: Saul A. Kripke (Naming and Necessity notes and addenda [1972], Add (a)) | |
| A reaction: Dummett and Rumfitt discuss this proposal elsewhere. |
| 3697 | The concept of possibility is prior to that of necessity [Bonjour] |
| Full Idea: While necessity and possibility are interdefinable concepts, it is the idea of a possible world or situation which is intuitively primary. | |
| From: Laurence Bonjour (In Defence of Pure Reason [1998], §1.3) |
| 12653 | There's statistical, logical, nomological, conceptual and metaphysical possibility [Fodor] |
| Full Idea: Statistically, logically, nomologically, conceptually, and metaphysically possible. That's all the kinds of possibility there are this week, but feel free to add others. | |
| From: Jerry A. Fodor (LOT 2 [2008], Ch.4.3) | |
| A reaction: There's also epistemic possibility (possibility 'for all I know'), but I suppose that isn't the real thing. How about 'imaginative possibility' (possibility 'as far as I can imagine')? |
| 11963 | What is the truthmaker for a non-existent possible? [Molnar] |
| Full Idea: What is the nature of the truthmaker for 'It is possible that p' in cases where p itself is false? | |
| From: George Molnar (Powers [1998], 12.2.2) | |
| A reaction: Molnar mentions three views: there is a different type of being for possibilia (Meinong), or possibilia exist, or possibilia are merely represented. The third view is obviously correct, though I presume possibilia to be based on actual powers. |
| 9212 | Possible states of affairs are not propositions; a proposition can't be a state of affairs! [Fine,K] |
| Full Idea: Possible states of affairs have often been taken to be propositions, but this cannot be correct, since any possible state of affairs is possibly a state of affairs, but no proposition is possibly a state of affairs. | |
| From: Kit Fine (The Problem of Possibilia [2003], 2) | |
| A reaction: The point is, presumably, that the state of affairs cannot be the proposition itself, but (at least) what the proposition refers to. I can't see any objection to that. |
| 15568 | When we consider possibilities, there must be something we are considering [Polt] |
| Full Idea: We would hardly want to say that a possibility is nothing, since surely we are considering something when we consider possibilities. | |
| From: Richard Polt (Heidegger: an introduction [1999], 1) | |
| A reaction: A nice contribution to the issue of whether modality is a feature of actuality. I would prefer to say that we can self-evidently utter truths and falsehoods about what is or is not possible, in nature, in logic, and maybe in metaphysics. |
| 16131 | The metaphysically possible is what acceptable principles and categories will permit [Lowe] |
| Full Idea: What is 'metaphysically' possible hinges …on the question of whether acceptable metaphysical principles and categories permit the existence of some state of affairs. | |
| From: E.J. Lowe (The Possibility of Metaphysics [1998], 1.3) | |
| A reaction: Lowe breezes along with confident assertions like this. I once heard Kit Fine tease him for over-confidence. All you do is work out 'acceptable' principles and categories, and you've cracked it! |
| 4195 | It is impossible to reach a valid false conclusion from true premises, so reason itself depends on possibility [Lowe] |
| Full Idea: Reasoning itself depends upon a grasp of possibilities, because a valid argument is one in which it is not possible for the conclusion to be false if the premises are true. | |
| From: E.J. Lowe (A Survey of Metaphysics [2002], p.11) | |
| A reaction: A very valuable corrective to my pessimistic view of philosophers' attempts to understand metaphysical necessity. But if we can only grasp natural necessity, then all reason is naturalistic. |
| 7801 | Possibilities can be logical, theoretical, physical, economic or human [Girle] |
| Full Idea: Qualified modalities seem to form a hierarchy, if we say that 'the possibility that there might be no hunger' is possible logically, theoretically, physically, economically, and humanly. | |
| From: Rod Girle (Modal Logics and Philosophy [2000], 7.3) | |
| A reaction: Girle also mentions conceptual possibility. I take 'physically' to be the same as 'naturally'. I would take 'metaphysically' possible to equate to 'theoretically' rather than 'logically'. Almost anything might be logically possible, with bizarre logic. |
| 5739 | Sometimes we want to specify in what ways a thing is possible [Melia] |
| Full Idea: Sometimes we want to count the ways in which something is possible, or say that there are many ways in which a certain thing is possible. | |
| From: Joseph Melia (Modality [2003], Ch.2) | |
| A reaction: This is a basic fact about talk of 'possibility'. It is not an all-or-nothing property of a situation. There can be 'faint' possibilities of things. The proximity of some possible worlds, especially those sharing our natural laws, is one answer. |
| 8941 | We can't explain 'possibility' in terms of 'possible' worlds [Fisher] |
| Full Idea: Explaining 'it is possible that p' by saying p is true in at least one possible world doesn't get me very far. If I don't understand what possibility is, then appealing to possible worlds is not going to do me much good. | |
| From: Jennifer Fisher (On the Philosophy of Logic [2008], 06.III) | |
| A reaction: This seems so blatant that I assume friends of possible worlds will have addressed the problem. Note that you will also need to understand 'possible' to define necessity as 'true in all possible worlds'. Necessarily-p is not-possibly-not-p. |
| 14376 | States of affairs are only possible if some substance could initiate a causal chain to get there [Jacobs] |
| Full Idea: A non-actual state of affairs in possible if there actually was a substance capable of initiating a causal chain, perhaps non-deterministic, that could lead to the state of affairs that we claim is possible. | |
| From: Jonathan D. Jacobs (A Powers Theory of Modality [2010], §4.2) | |
| A reaction: [He is quoting A.R. Pruss 2002] That seems exactly right. Of course the initial substance(s) might create a further substance, such as a transuranic element, which then produces the state of affairs. I favour this strongly actualist view. |
| 14578 | Possibility might be non-contradiction, or recombinations of the actual, or truth in possible worlds [Mumford/Anjum] |
| Full Idea: Possibility could be just logical possibility (as involving no formal contradictions), or recombinations of all the existing elements (Armstrong), or truth in other concrete worlds (Lewis). | |
| From: S.Mumford/R.Lill Anjum (Getting Causes from Powers [2011], 8.4) | |
| A reaction: All wrong, I would say. Well, avoiding contradiction is obviously a sense of 'possible'. Armstrong is wrong. It rules out new 'elements' being possible, and implies impossible combinations of the current ones. As for Lewis... |
| 18824 | Since possibilities are properties of the world, calling 'red' the determination of a determinable seems right [Rumfitt] |
| Full Idea: Some philosophers describe the colour scarlet as a determination of the determinable red; since the ways the world might be are naturally taken to be properties of the world, it helps to bear this analogy in mind. | |
| From: Ian Rumfitt (The Boundary Stones of Thought [2015], 6.4) | |
| A reaction: This fits nicely with the disposition accounts of modality which I favour. Hence being 'coloured' is a real property of objects, even in the absence of the name of its specific colour. |
| 18828 | If two possibilities can't share a determiner, they are incompatible [Rumfitt] |
| Full Idea: Two possibilities are incompatible when no possibility determines both. | |
| From: Ian Rumfitt (The Boundary Stones of Thought [2015], 7.1) | |
| A reaction: This strikes me as just the right sort of language for building up a decent metaphysical picture of the world, which needs to incorporate possibilities as well as actualities. |
| 17955 | Possible worlds allow us to talk about degrees of possibility [Vetter] |
| Full Idea: The apparatus of possible worlds affords greater expressive power than mere talk of possibility and necessity. In particular, possible worlds talk allows us to introduce degrees of possibility. | |
| From: Barbara Vetter (Essence and Potentiality [2010], §3) | |
| A reaction: A nice feature, but I'm not sure that either the proportion of possible worlds or the closeness of possible worlds captures what we actually mean by a certain degree of possibility. There is 'accidental closeness', or absence of contingency. See Vetter. |
| 17957 | Maybe possibility is constituted by potentiality [Vetter] |
| Full Idea: We should look at the claim that possibility is constituted by potentiality. | |
| From: Barbara Vetter (Essence and Potentiality [2010], §4) | |
| A reaction: A problem that comes to mind is possibilities arising from coincidence. The whole of reality must be described, to capture all the possibilities for a particular thing. So potentialities of what? Nice thought, though. |
| 19378 | Early modern possibility is what occurs sometime; for Leibniz, it is what is not contradictory [Arthur,R] |
| Full Idea: For Descartes, Hobbes and Spinoza, if a state of things is possible, it must occur at some time, whether past, present or future. For Leibniz possibility makes no reference to time; an individual is possible if its concept contains no contradiction. | |
| From: Richard T.W. Arthur (Leibniz [2014], 4 'Contingent') | |
| A reaction: It has always struck me as fallacious to say that anything that is possible must at some time occur. If '6' is possible on the die, what will constrain it to eventually come up when thrown? Mere non-contradiction doesn't imply possibility either. |
| 19010 | All possibility is anchored in the potentiality of individual objects [Vetter] |
| Full Idea: Potentiality is, metaphorically speaking, possibility anchored in individual objects; I claim that all possibility is thus anchored in some individual object(s) or other. | |
| From: Barbara Vetter (Potentiality [2015], 1.1) | |
| A reaction: This will be fine for specific physical possibilities, but may become tricky for possibilities that are increasingly abstract, or universal, or idealised. I agree with the general approach. Anchor modality in reality (which is physical!). |
| 19013 | Possibility is a generalised abstraction from the potentiality of its bearer [Vetter] |
| Full Idea: We should think of possibility as potentiality in abstraction from its bearer. So 'it is possible that p' is defined as 'something has an iterated potentiality for it to be the case that p'. | |
| From: Barbara Vetter (Potentiality [2015], 1.4) | |
| A reaction: If possibilities are abstractions from potentialities, I am inclined the treat potentialities as abstractions from dispositions, and dispositions (and properties) as abstractions from powers. Powers are not abstractions - they are the reality. |
| 19028 | Possibilities are potentialities of actual things, but abstracted from their location [Vetter] |
| Full Idea: When we speak of possibility, we speak of potentiality in abstraction from its possessor; a possibility is a potentiality somewhere or other in the world, no matter where. | |
| From: Barbara Vetter (Potentiality [2015], 6.1) | |
| A reaction: I note that, as so often, this is psychological abstraction, which is usually sneered at by modern philosophers (e.g. Geach), and yet is employed all the time. This is Vetter's key thesis, which I like. |