People have been talking about this all week, noting the author, quoting the first paragraph and then footnote 2. But Rudd begins a quote from Dashiell Hammett

Nobody thinks clearly, no matter what they pretend. . . . That’s why people hang on so tight to their beliefs and opinions; because, compared to the haphazard way they’re arrived at, even the goofiest opinion seems wonderfully clear, sane, and self-evident.

Now Leiter's found it, via an article in the Times.

In his life my father was known mostly for politics, but he'll remembered beyond family and friendships for one essay on Hammett. His father was a Pinkerton, a hired killer, who died of TB a year after my father was born.