16 ideas
| 14970 | Normal system K has five axioms and rules [Cresswell] |
| Full Idea: Normal propositional modal logics derive from the minimal system K: wffs of PC are axioms; □(p⊃q)⊃(□p⊃□q); uniform substitution; modus ponens; necessitation (α→□α). | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1) |
| 14971 | D is valid on every serial frame, but not where there are dead ends [Cresswell] |
| Full Idea: If a frame contains any dead end or blind world, then D is not valid on that frame, ...but D is valid on every serial frame. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1.1) |
| 14972 | S4 has 14 modalities, and always reduces to a maximum of three modal operators [Cresswell] |
| Full Idea: In S4 there are exactly 14 distinct modalities, and any modality may be reduced to one containing no more than three modal operators in sequence. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1.2) | |
| A reaction: The significance of this may be unclear, but it illustrates one of the rewards of using formal systems to think about modal problems. There is at least an appearance of precision, even if it is only conditional precision. |
| 14973 | In S5 all the long complex modalities reduce to just three, and their negations [Cresswell] |
| Full Idea: S5 contains the four main reduction laws, so the first of any pair of operators may be deleted. Hence all but the last modal operator may be deleted. This leaves six modalities: p, ◊p, □p, and their negations. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1.2) |
| 14976 | Reject the Barcan if quantifiers are confined to worlds, and different things exist in other worlds [Cresswell] |
| Full Idea: If one wants the quantifiers in each world to range only over the things that exist in that world, and one doesn't believe that the same things exist in every world, one would probably not want the Barcan formula. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.2.2) | |
| A reaction: I haven't quite got this, but it sounds to me like I should reject the Barcan formula (but Idea 9449!). I like a metaphysics to rest on the actual world (with modal properties). I assume different things could have existed, but don't. |
| 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. |
| 14974 | A relation is 'Euclidean' if aRb and aRc imply bRc [Cresswell] |
| Full Idea: A relation is 'Euclidean' if aRb and aRc imply bRc. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.1.2) | |
| A reaction: If a thing has a relation to two separate things, then those two things will also have that relation between them. If I am in the same family as Jim and as Jill, then Jim and Jill are in the same family. |
| 14975 | A de dicto necessity is true in all worlds, but not necessarily of the same thing in each world [Cresswell] |
| Full Idea: A de dicto necessary truth says that something is φ, that this proposition is a necessary truth, i.e. that in every accessible world something (but not necessarily the same thing in each world) is φ. | |
| From: Max J. Cresswell (Modal Logic [2001], 7.2.1) | |
| A reaction: At last, a really clear and illuminating account of this term! The question is then invited of what is the truthmaker for a de dicto truth, assuming that the objects themselves are truthmakers for de re truths. |
| 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? |
| 7903 | The six perfections are giving, morality, patience, vigour, meditation, and wisdom [Nagarjuna] |
| Full Idea: The six perfections are of giving, morality, patience, vigour, meditation, and wisdom. | |
| From: Nagarjuna (Mahaprajnaparamitashastra [c.120], 88) | |
| A reaction: What is 'morality', if giving is not part of it? I like patience and vigour being two of the virtues, which immediately implies an Aristotelian mean (which is always what is 'appropriate'). |