The Democratic Party convention arrives in Boston next week, and Holland Cotter says that the pols could do worse than to leave the convention hall for a few hours of good old-fashioned Bostonian-American culture. “Utopian thought is a visionary version of yes-saying; principled dissent among the most constructive ways of saying no. The two are flip sides of the same coin; together they can bring out the best, and curb the worst, in human behavior. Boston knows all about them.”