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After I wrote a column a couple of months ago about the promise and disappointment of Kamala Harris’s presidential campaign, one Times reader from Boston left a comment that I thought was particularly smart. “Prosecutors rarely translate well when it comes to governing at the executive level,” the reader wrote. “Their default mode is neither policy nor the long view.”

Harris came up through California politics as a prosecutor. And she never seemed to develop a clear theory of how to use government to improve people’s lives. Barack Obama, who worked as a state legislator, did develop such a theory. So did Bill Clinton, who started as a prosecutor but then spent years as a governor. So has Elizabeth Warren, who came from academia.

An especially interesting contrast this year is Pete Buttigieg, whose résumé is less impressive than Harris’s and who, in my view, isn’t as charismatic as she is. But when I listen to Buttigieg describe his vision, I understand it. His time as a mayor of a small city shaped that vision, much as it did for Bernie Sanders decades earlier. With Harris, I was never quite sure what her vision was. Her vaguely titled memoir (“The Truths We Hold”) and oddly flat campaign slogans (like “Justice Is on the Ballot”) captured the problem.