21 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) |
| 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] |
| 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) |
| 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? |
| 3509 | Externalism may be the key idea in philosophical naturalism [Papineau] |
| Full Idea: Some people view an externalist approach to epistemology as the essence of philosophical naturalism. | |
| From: David Papineau (Philosophical Naturalism [1993], Intro) | |
| A reaction: I suspect philosophers avoid psychology and mental events, simply because they are elusive. Externalism is a theory about justification, and independent of naturalism as a metaphysic. |
| 15642 | If kinds depend only on what can be observed, many underlying essences might produce the same kind [Eagle] |
| Full Idea: If the kinds there are depend not on the essences of the objects but on their observed distinguishing particulars, ...then for any kind that we think there is, it is possible that there are many underlying essences which are observably indistinguishable. | |
| From: Antony Eagle (Locke on Essences and Kinds [2005], IV) | |
| A reaction: Eagle is commenting on Locke's reliance on nominal essences. This seems to be the genuine problem with jadeite and nephrite (both taken to be 'jade'), or with 'fool's gold'. This isn't an objection to Locke; it just explains the role of science. |
| 15645 | Nominal essence are the observable properties of things [Eagle] |
| Full Idea: It is clear the nominal essences really are the properties of the things which have them: they are (a subset of) the observable properties of the things. | |
| From: Antony Eagle (Locke on Essences and Kinds [2005], IV) | |
| A reaction: I think this is wrong. The surface characteristics are all that is available to us, so our classifications must be based on those, but it is on the ideas of them, not their intrinsic natures. That is empiricsm! What makes the properties 'essential'? |
| 15643 | Nominal essence mistakenly gives equal weight to all underlying properties that produce appearances [Eagle] |
| Full Idea: Nominal essence does not allow for gradations in significance for the underlying properties. Those are all essential for the object behaving as it observably does, and they must all be given equal weight when deciding what the object does. | |
| From: Antony Eagle (Locke on Essences and Kinds [2005], IV) | |
| A reaction: This is where 'scientific' essentialism comes in. If we take one object, or one kind of object, in isolation, Eagle is right. When we start to compare, and to set up controlled conditions tests, we can dig into the 'gradations' he cares about. |
| 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…. |
| 3513 | How does a dualist mind represent, exist outside space, and be transparent to itself? [Papineau] |
| Full Idea: Even dualists must explain how the mind represents things, but then their mind-stuff has so many special powers already (being outside space but in time, being transparent to itself etc.) that one more scarcely seems worth worrying about. | |
| From: David Papineau (Philosophical Naturalism [1993], 3.1 n1) | |
| A reaction: I share the exasperation. It is hard to see how a dualist could even begin to formulate a theory about HOW the mind does so many different things. Could Descartes get a research grant for it? Would we understand God if he tried to explain it to us? |
| 3514 | Functionalism needs causation and intentionality to explain actions [Papineau] |
| Full Idea: The functionalist approach to the mind needs to invoke assumptions about what desires are for and beliefs are about, in order to infer what agents will do. | |
| From: David Papineau (Philosophical Naturalism [1993], 3.2) | |
| A reaction: Isn't the idea that you discover what desires are for and what beliefs are about by examining their function, and what the agent does? Which end should we start? |
| 3510 | Epiphenomenalism is supervenience without physicalism [Papineau] |
| Full Idea: Supervenience is a necessary condition for physicalism, but it is not sufficient. Epiphenomenalism rules out mental variation without physical variation, but says mental properties are quite distinct from physical properties. | |
| From: David Papineau (Philosophical Naturalism [1993], 1.2) | |
| A reaction: I take full epiphenomenalism about mind to be incoherent, and not worth even mentioning (see Idea 7379). Papineau seems to be thinking of so-called property dualism (which may also be incoherent!). |
| 3511 | Supervenience requires all mental events to have physical effects [Papineau] |
| Full Idea: The argument for supervenience rests on the principle that any mental difference must be capable of showing itself in differential physical consequences. | |
| From: David Papineau (Philosophical Naturalism [1993], 1.8) | |
| A reaction: With our current knowledge of the brain, to assume anything less than this sort of correlation would be crazy. |
| 3515 | Knowing what it is like to be something only involves being (physically) that thing [Papineau] |
| Full Idea: Physicalism does not deny that there are conscious experiences, nor that 'it is like something to have them'. The claim is only that this is nothing different from what it is to be a physical system of the relevant kind. | |
| From: David Papineau (Philosophical Naturalism [1993], 4.2) | |
| A reaction: The implication is that no physicalist is an extreme eliminativist about consciousness, which seems to be correct. We all concede that weather exists, but have a reductive view of it. The key question is whether mind is reducible to physics. |
| 3512 | If a mental state is multiply realisable, why does it lead to similar behaviour? [Papineau] |
| Full Idea: If functionalism implies that there is nothing physically in common among the realisations of a given mental state, then there is no possibility of any uniform explanation of why they all give rise to a common physical result. | |
| From: David Papineau (Philosophical Naturalism [1993], 2.2) | |
| A reaction: This is the well known interaction problem for dualism. The standard reply is to accept interaction as a given (with no apparent explanation). A miracle, if you like. |
| 3516 | The Private Language argument only means people may misjudge their experiences [Papineau] |
| Full Idea: I take the moral of the Private Language argument to be that there must be room for error in people's judgements about their experiences, not that those judgements must necessarily be expressed in a language used by a community. | |
| From: David Papineau (Philosophical Naturalism [1993], 4.4 n10) | |
| A reaction: These two readings don't seem to be in conflict, and the argument must have something to say about the communal nature of thought expressed in language. Language imposes introspection on us? |
| 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. |
| 15641 | Kinds are fixed by the essential properties of things - the properties that make it that kind of thing [Eagle] |
| Full Idea: The natural thought is to think that real kinds are given only by classification on the basis of essential properties: properties that make an object the kind of thing that it is. | |
| From: Antony Eagle (Locke on Essences and Kinds [2005], II) | |
| A reaction: Circularity alert! Circularity alert! Essence gives a thing its kind - and hence we can see what the kind is? Test for a trivial property! Eagle is not unaware of these issues. Does he mean 'necessary' rather than 'essential'? |
| 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. |