15 ideas
| 16951 | It was realised that possible worlds covered all modal logics, if they had a structure [Dummett] |
| Full Idea: The new discovery was that with a suitable structure imposed on the space of possible worlds, the Leibnizian idea would work for all modal logics. | |
| From: Michael Dummett (Could There Be Unicorns? [1983], 1) |
| 16953 | Relative possibility one way may be impossible coming back, so it isn't symmetrical [Dummett] |
| Full Idea: If T is only possible if S obtains, T and S hold in the actual world, and S does not obtain in world v possible relative to the actual world, then the actual is not possible relative to v, since T holds in the actual. Accessibility can't be symmetrical. | |
| From: Michael Dummett (Could There Be Unicorns? [1983], 1) |
| 16952 | If something is only possible relative to another possibility, the possibility relation is not transitive [Dummett] |
| Full Idea: If T is only possible if S obtains, and S is possible but doesn't obtain, then T is only possible in the world where S obtains, but T is not possible in the actual world. It follows that the relation of relative possibility is not transitive. | |
| From: Michael Dummett (Could There Be Unicorns? [1983], 1) | |
| A reaction: [compressed] |
| 16960 | If possibilitiy is relative, that might make accessibility non-transitive, and T the correct system [Dummett] |
| Full Idea: If some world is 'a way the world might be considered to be if things were different in a certain respect', that might show that the accessibility relation should not be taken to be transitive, and we should have to adopt modal logic T. | |
| From: Michael Dummett (Could There Be Unicorns? [1983], 8) | |
| A reaction: He has already rejected symmetry from the relation, for reasons concerning relative identity. He is torn between T and S4, but rejects S5, and opts not to discuss it. |
| 16958 | In S4 the actual world has a special place [Dummett] |
| Full Idea: In S4 logic the actual world is, in itself, special, not just from our point of view. | |
| From: Michael Dummett (Could There Be Unicorns? [1983], 8) | |
| A reaction: S4 lacks symmetricality, so 'you can get there, but you can't get back', which makes the starting point special. So if you think the actual world has a special place in modal metaphysics, you must reject S5? |
| 8132 | We now have a much more sophisticated understanding of logical form in language [Burge] |
| Full Idea: The second half of the twentieth century has seen the development of a vastly more sophisticated sense of logical form, as applied to natural languages. | |
| From: Tyler Burge (Philosophy of Mind: 1950-2000 [2005], p.462) | |
| A reaction: Burge cites this as one of the three big modern developments (along with the critique of logical positivism, and direct reference/anti-individualism). Vagueness may be the last frontier for this development. |
| 16957 | Possible worlds aren't how the world might be, but how a world might be, given some possibility [Dummett] |
| Full Idea: The equation of a possible world with the way that the (actual) world might be is wrong: the way a distant world might be is not a way the world might be, but a way we might allow it to be given how some intervening world might be. | |
| From: Michael Dummett (Could There Be Unicorns? [1983], 8) | |
| A reaction: The point here is that a system of possible worlds must include relative possibilities as well as actual possibilities. Dummett argues against S5 modal logic, which makes them all equal. Things impossible here might become possible. Nice. |
| 16959 | If possible worlds have no structure (S5) they are equal, and it is hard to deny them reality [Dummett] |
| Full Idea: If our space of possible worlds has no structure, as in the semantics for S5, then, from the standpoint of the semantics, all possible worlds are on the same footing; it then becomes difficult to resist the claim that all are equally real. | |
| From: Michael Dummett (Could There Be Unicorns? [1983], 8) | |
| A reaction: This is a rather startling and interesting claim, given that modern philosophy seems full of thinkers who both espouse S5 for metaphysics, and also deny Lewisian realism about possible worlds. I'll ponder that one. Must read the new Williamson…. |
| 8126 | Anti-individualism says the environment is involved in the individuation of some mental states [Burge] |
| Full Idea: Anti-individualism is the view that not all of an individual's mental states and events can be type-individuated independently of the nature of the entities in the individual's physical or social environment environment. | |
| From: Tyler Burge (Philosophy of Mind: 1950-2000 [2005], p.453) | |
| A reaction: While the Twin Earth experiment emphasises the physical environment, Burge has been responsible for emphasising the social environment. The suspicion is that the whole concept of 'individual' minds will collapse on this view. |
| 8127 | Broad concepts suggest an extension of the mind into the environment (less computer-like) [Burge] |
| Full Idea: Certain thought experiments made trouble for standard functionalism, which limits input/output to the surface of an individual; proposals to extend this into the environment reduces the reliance on a computer paradigm, but increases complexity. | |
| From: Tyler Burge (Philosophy of Mind: 1950-2000 [2005], p.454) | |
| A reaction: [He has the Twin Earth experiment in mind] The jury is out on this, but it looks a bit of a slippery slope. Accounts of action and responsibility need a fairly sharp concept of an individual. Externalism begins to look like just a new scepticism. |
| 8129 | Anti-individualism may be incompatible with some sorts of self-knowledge [Burge] |
| Full Idea: The idea of anti-individualism raised problems about self-knowledge. The question is whether anti-individualism is compatible with some sort of authoritative or privileged warrant for certain types of self-knowledge. | |
| From: Tyler Burge (Philosophy of Mind: 1950-2000 [2005], p.457) | |
| A reaction: [See under 'Nature of Minds' for 'Anti-individualism'] The thought is that if your mind is not entirely in your head, you can no longer be an expert on it. It might go the other way: obviously we can be self-experts, so anti-individualism is wrong. |
| 8131 | Some qualities of experience, like blurred vision, have no function at all [Burge] |
| Full Idea: There appear to be qualitative aspects of experience that have no function in the life of the organism. They constitute dysfunction or noise. Blurriness in a visual experience is an example. | |
| From: Tyler Burge (Philosophy of Mind: 1950-2000 [2005], p.460) | |
| A reaction: The best account of blurred vision would seem to be adverbial - I see 'in a blurred way' (nay, blurredly). Hence maybe blurred vision is functional, but it just isn't functioning very well. |
| 16764 | The soul conserves the body, as we see by its dissolution when the soul leaves [Toletus] |
| Full Idea: Every accident of a living thing, as well as all its organs and temperaments and its dispositions are conserved by the soul. We see this from experience, since when that soul recedes, all these dissolve and become corrupted. | |
| From: Franciscus Toletus (Commentary on 'De Anima' [1572], II.1.1), quoted by Robert Pasnau - Metaphysical Themes 1274-1671 24.5 | |
| A reaction: A nice example of observing a phenemonon, but not being able to observe the dependence relation the right way round. Compare Descartes in Idea 16763. |
| 16956 | To explain generosity in a person, you must understand a generous action [Dummett] |
| Full Idea: It cannot be explained what it is for a person to be generous without first explaining what it is for an action to be generous. | |
| From: Michael Dummett (Could There Be Unicorns? [1983], 4) | |
| A reaction: I presume a slot machine can't be 'generous', even if it favours the punter, so you can't specify a generous action without making reference to the person. A benign circle, as Aristotle says. |
| 16954 | Generalised talk of 'natural kinds' is unfortunate, as they vary too much [Dummett] |
| Full Idea: In my view, Kripke's promotion of 'natural kinds', coverning chemical substances and animal and plant species, is unfortunate, since these are rather different types of things, and words used for them behave differently. | |
| From: Michael Dummett (Could There Be Unicorns? [1983], 2) | |
| A reaction: My view is that the only significant difference among natural kinds is their degree of stability in character. Presumably particles, elements and particular molecules are fairly invariant, but living things evolve. |