Ray Kurzweil gives his views on the current state of play, particularly a debate between Eric Drexler and Richard Smalley about the feasibility of nanotechnology.

Smalley's argument is of the form that "we don't have 'X' today, therefore 'X' is impossible." I encounter this class of argument repeatedly in the area of artificial intelligence. Critics will cite the limitations of today's systems as proof that such limitations are inherent and can never be overcome. These critics ignore the extensive list of contemporary examples of AI (for example, airplanes and weapons that fly and guide themselves, automated diagnosis of electrocardiograms and blood cell images, automated detection of credit card fraud, automated investment programs that routinely outperform human analysts, telephone-based natural language response systems, and hundreds of others) that represent working systems that are commercially available today that were only research programs a decade ago.

And ultimately, of course, this stuff will all be settled in the lab. I know which way I'm betting.