Parallel Universes and The Plurality of Possible Worlds of David Lewis

[via "Matthew Yglesias":http://www.matthewyglesias.com/archives/000407.html#000407 via "Brian Weatherson":http://philosophyweblog.blogspot.com/]

The “Scientific American”:http://www.sciam.com/ has “an article about parallel universes”:http://www.sciam.com/print_version.cfm?articleID=000F1EDD-B48A-1E90-8EA5809EC5880000, which mentions David Lewis’ “modal realism”. Are all those possible worlds we quantify over in possible worlds semantics really real?