“As the realm of sets is for mathematicians, so logical space is a paradise for philosophers. We have only to believe in the vast realm of possibilia, and there we find what we need to advance our endeavours” – David Lewis, On the Plurality of Worlds, p. 4
I don’t know anyone else who can make modal realism – the idea that all possible worlds are equally real – sound so enticing as David Lewis. All our problems dissolve and we live in paradise if we just swallow this one premise! What seemed utterly absurd a second ago becomes tempting upon reading Lewis.
Beside attesting to Lewis’ qualities as a used-car salesman, the quote reveals features of Lewis’ conception of philosophy. It is a philosophy which invites the comparison with mathematics, in which formal logic and metaphysical debates about the reality of possible worlds go hand in hand. Paradise lies in construncting the simplest and most powerful theory describing all we ever want to describe.