Many thanks Dr Manhattan. A scholarly version plus a bibliography ( PDF: http://www.biointelligence-explosion.com/biointelligence-explosion.pdf ) will appear in Springer's forthcoming Singularity volume (cf. http://singularityhypothesis.blogspot.com/p/central-questions.html ) published later this year. Here's a question for lesswrong members. I've been asked to co-author the Introduction. One thing I worry about is that causal readers of the contributors' essays won't appreciate just how radically the Kurzweilian and SIAI conceptions of the Singularity are at odds. Is there anywhere in print or elsewhere where Ray Kurzweil and Eliezer Yudkowski, say, directly engage each other's arguments in debate ? Also, are there any critical but non-obvious points beyond the historical background you think should be included the introductory overview?