The Paradox of tolerance and current events

[TaraJo]

So, I'm sure everyone here who's had conversations lately about current events in America, especially in regards to politics, has seen some variation of this.  Leftists, who usually get the reputation as being all about tolerance, are reacting with violence and aggression against right wing protesters or their causes.  The line is simple: "So much for the tolerant left."  

For me, it brings to mind Karl Popper and the paradox of tolerance.  His claim was that a universally tolerant society will ultimately lead to the destruction of tolerance in that tolerating intollerance will lead to the intollerant eliminating toleration.  Therefore, he argued, a free, open society should not tolerate intollerance.

And I can't help but think he was right.  Germany, back in the 20's and early 30's tolerated national socialism and let that idea into the free marketplace of ideas.  The end result is that this group gained power and had no interest in tolerating Jews, gays, intellectuals or differing political ideologies.  

Now we have people showing up for political protests, flying nazi flags and proudly wearing kkk robes and I'm left here wondering, when do we need to apply this idea?  When do we get to stand up and tell the intollerant "No more"?