Click here to watch David's talk on possibilianism at PopTech. Executive director Andrew Zolli wrote: "This is one of the best talks ever at PopTech. Everyone should watch this."
SUM was chosen as the best book of 2009 by Chicago Tribune's Pulitzer-winning literary critic Julia Keller.
In September, 2009, Sum became the number 2 book in the United Kingdom on Amazon's bestseller list, only behind Dan Brown's Lost Symbol.