On a damp, gray afternoon in April, I took my daughter with me to vote in the New York Democratic primary. After a long Tuesday, she was keen to get home to Cheddar Bunnies and apple juice; instead, she was watching me fumble with a series of locked doors outside a local high school in Brooklyn. As it started to rain, I realized that my problem was acute: I had to explain to the hungry four-year-old on my shoulders why I had taken a precious chunk of her afternoon in order to cast an empty ballot.

She realized it,…