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Grass-roots activism can be very good for a political party, or it can cause problems.

A story in this weekend’s Times focused on the latter — the tensions that the recent surge of left-wing activism has created for the Democratic Party. The activists, Alexander Burns of The Times wrote, “are increasingly rattling primary elections around the country, and they promise to grow as a disruptive force in national elections.”

It’s clear how these tensions could hurt Democrats: Divisive primaries might alienate some voters whose preferred candidate — either on the left or in the center — doesn't win. If those voters then stay home in the general election, the party could lose winnable races. As James Comey wrote in a much-noticed tweet on Sunday: “Democrats, please, please don’t lose your minds and rush to the socialist left.”

But let’s take a deep breath. I think it’s worth noting that, so far, progressive activism has been much more of a positive for Democrats than a negative .