If you start with questions instead of conclusions.

A blogger I read, talking about drug legalization policy, makes this comment:

Really, this stuff isn’t that hard, if you start with questions instead of conclusions.

Holds true for much of economics too.  This stuff isn't physics, its not like all the easy questions have been answered already, but it is a sad commentary on the world that so many people get so much stuff wrong because they start with conclusions they're looking to justify, rather than questions they'd like to answer.