Great advice from 37 Signals blog.
Give me spark - (37signals):
"Some of the best decisions and designs at 37signals have emerged from intensely contested debates. Not just between Jason and me, but from anyone in the company. When sparks fly, some truly great ideas come to light.
The catch is that the heat must arise around the decision itself. Debates go off track when personal biases or old grudges come into play. So long as each party sticks to the merits, adding some fire will only unearth new angles and concerns."