Hmm, I think it's pretty standard to treat 'actual...

2006-10-15T07:53:08.616-04:00

Hmm, I think it's pretty standard to treat 'actually' as a rigidifying operator. We can talk about Twin Earth, and how it lacks any of "the actual watery stuff". Our use of "the actual president" will pick out Bush, even when we apply it to Kerry-worlds, etc.

But the standard use might be as a rigidified indexical ("this world"). Then folk in Twin Earth would speak truly when they say "the actual watery stuff - i.e. water - is XYZ". But that's just because their term "actual" (like "water") has a different semantic value from ours. I might need to be clearer about that. But the key logical point is clarified in one of my missing footnotes: for any possible world w, [our sentence] ‘actually P’ is true in w iff P is true in @. See, e.g., Davies and Humberstone (1981) ‘Two notions of necessity’.

See also this old post for a related (but slightly messy) discussion.

Arr. I have a usage question about one of the exam...

2006-10-15T03:44:28.520-04:00

Arr. I have a usage question about one of the examples you use in 1.1 --

"To clarify this point, consider the statement:
(A) “S is as long as S actually is”
While (A) is presumably a priori, it may yet be false in other possible worlds, so long as the “actually” operator is understood as fixedly referring to our world. There are worlds where S is a different length from what it actually is, after all. So statements like (A) are contingent despite being a priori.

To make this more precise, let us understand the modal operator ‘actually’ as signifying ‘in @’, where ‘@’ names the actual world. Consider some contingent proposition P that is actually true. Because P is contingent, there will be some possible world w at which it is false. At such a world, P is false, despite it being the case that P is true at @, i.e. ‘actually P’ is true. Because ‘P’ and ‘actually P’ differ in truth-value at world w, we find that ‘P iff actually P’ is false at w, and thus not metaphysically necessary."

Is it common to have 'actual' rigidly designate the actual world? I realise you're jumping from Kripke here, but -- at least in On the Plurality of Worlds -- David Lewis appears to want it a bit more flexible than that, where 'the actual world' is non-rigid and is used to denote the 'own world' of whichever counterfactual citizen was under discussion.

I've never seen it used to rigidly designate our world. That said, it doesn't seem to interfere with the logic of the example, and it may be that what you're doing is legitimate. [I haven't read much of this stuff.] Is it common to use 'actual' in the way that you have?

Comments on Philosophy, et cetera: Chapter One [draft]

Hmm, I think it's pretty standard to treat 'actual...

Arr. I have a usage question about one of the exam...