In November 2010, I took a bus from my home in Philadelphia to the National Mall in Washington. The night before the trip, I stood in my kitchen and wrote in large letters on cardboard: “The People’s Work Starts Now!”

When the bus reached the mall and we stepped out into the bitter wind, I looked at the monuments and realized that I was not there as a tourist this time, but as an activist — an idea I would have been allergic to just a year before.

But I, like millions of others, was becoming the new American radical, defined by my belief in a limited government that allows people, not bureaucracy, to flourish.

Before all of this, my main contributions to American politics were voting, voraciously reading American history and Austrian economic theory and irritating liberals at dinner parties.