At the "April" 2010 American Physical Society meeting I argued in favor of alternate realities (Bull. Am. Phys. Soc., vol. 55, #1, 2010) (See my web site http://www.robert-w-jones.com/ , click on philosopher and then alternate realities.) I find that Kevin Kelly has a similar argument on pages 381 and 382 of his book The Logic of Reliable Inquiry, Oxford Univ. Press, 1996.