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Single Idea 16959

[filed under theme 10. Modality / E. Possible worlds / 1. Possible Worlds / c. Possible worlds realism ]

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.

Gist of Idea

If possible worlds have no structure (S5) they are equal, and it is hard to deny them reality

Source

Michael Dummett (Could There Be Unicorns? [1983], 8)

Book Ref

Dummett,Michael: 'The Seas of Language' [OUP 1993], p.348


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….


The 13 ideas with the same theme [proposal that possible worlds really exist]:

It is pointless to say possible worlds are truthmakers, and then deny that possible worlds exist [Martin,CB]
Possible worlds realism is only needed to give truth conditions for modals and conditionals [Ellis]
If possible worlds have no structure (S5) they are equal, and it is hard to deny them reality [Dummett]
For Lewis there is no real possibility, since all possibilities are actual [Oderberg on Lewis]
Lewis posits possible worlds just as Quine says that physics needs numbers and sets [Lewis, by Sider]
If possible worlds really exist, then they are part of actuality [Sider on Lewis]
A world is a maximal mereological sum of spatiotemporally interrelated things [Lewis]
For me, all worlds are equal, with each being actual relative to itself [Lewis]
Unlike places and times, we cannot separate possible worlds from what is true at them [Forbes,G]
The problem with possible worlds realism is epistemological; we can't know properties of possible objects [Forbes,G]
You can't embrace the formal apparatus of possible worlds, but reject the ontology [Heil]
How can modal Platonists know the truth of a modal proposition? [Read]
Concrete worlds, unlike fictions, at least offer evidence of how the actual world could be [Jacobs]