David Eagleman, author of Incognito: The Secret Lives of the Brain, reckons that our brains are made up of a team of rivals.
Starting with the rivals of the left and right side of our brains to a multitude of small rival subroutines that contribute to our complicated decision making.

A team of rivals can be an individual struggling within or a couple throwing ideas off each other.

If rivalry and diversity of thinking parts within our own mind is crucial for decision making, then maybe that same rivalry is just as important in the teams that we form in business and in personal relationships.