The value of a progressive/left reading of history

I suppose I should start this off by saying again I'm fine with replacing Old Hickory's face on the $20 bill with that of Underground Railroad leader Harriet Tubman. I'm sure Tubman said something sometime that Ben Carson wouldn't approve. Or something else that would seem retrograde in the context of 2015 progressive politics in the US. But I'm down with using her image on the $20.

What I'm also insistent on is a progressive reading of history that recognizes complexity of progress, which often occurs simultaneously with retrogression in other areas.

Paul Krugman has a good blog post on this topic, Fighting for History 05/13/2015:

... progressives are much too willing to cede history to the other side. Legends about the past matter. Really bad economics flourishes in part because Republicans constantly extol the Reagan record, while Democrats rarely mention how shabby that record was compared with the growth in jobs and incomes under Clinton. The combination of lies, incompetence, and corruption that made the Iraq venture the moral and policy disaster it was should not be allowed to slip into the mists.

And it’s not just an American issue. Europe’s problems are made significantly worse by the selectivity of German historical memory, in which the 1923 inflation looms large but the Brüning deflation of 1930-32, which actually led directly to the fall of Weimar and the rise of you-know-who, has been sent down the memory hole.

There’s a reason conservatives constantly publish books and articles glorifying Harding and Coolidge while sliming FDR; there’s a reason they’re still running against Jimmy Carter; and there’s a reason they’re doing their best to rehabilitate W. And progressives need to fight back. [my emphasis]

I should note that the idea of a progressive/left reading of history quickly runs into objections from postmodernism, which is highly resistant to anything that might suggest a "meaning" in history, much less a scary Hegelian "teleology."