Unlike large corporations, startup meetings are not about achieving consensus for every objection raised. They are about forward motion, momentum and feedback loops (i.e. Customer Development.)
The heuristic I suggest is: hear the corner case objections, make the objector calculate the odds, if the potential damage estimate is low (probability of the event occurring multiplied by its ability to put you out of business) keep the meeting focused and move on. If you do this consistently your team will catch on.
(Link: Killing innovation with corner cases | VentureBeat)


November 24, 2009
