Pakistan, April 15 -- Even at the best of times, democracy is a tough balancing act. It is easy to forget the shared purpose and destiny that bind a nation together as grievances and belligerence drive people poles apart. It's a hard challenge to protect democratic values and principles. A vibrant democracy needs constant public action, engagement, and vigilance.

There are powerful lessons from the violent events in Washington. The dilution of democracy can happen slowly, over years, in small gradual pieces: mean-spirited politics, extreme political polarization, warring partisan factions and rancorous citizen engagement.

These days there are few things that we can probably agree on across the political spectrum. One is that open debate...