There may be other differences within a progressive coalition --

There may be other differences within a progressive coalition -- on trade, fiscal policy, or gun rights -- but those disagreements need not be crippling. If we begin to think about the world as environmentalists do, as a complex and nonlinear system in which small interventions can have huge impact for good or for ill, perhaps we can begin to see the method by which progressives of many stripes can begin to act politically, act together, and reverse the current vicious cycle of politics and policy.