Roughly seventy years ago, FBI Director J. Edgar Hoover famously declared, “There is no organized crime in America.” Hoover’s stubborn denial of the existence of the mafia continued despite ample evidence to the contrary, from arrests to congressional testimony. Many have speculated on why Hoover maintained his stubborn denial. Perhaps, they say, he was trying to avoid the political embarrassment of long ignoring the single largest criminal network in the country. Many today seem to be adopting a Hoover-esque wilful blindness about another violent group: Antifa. Politicians and pundits are denying that the left-wing anarchist group exists, mocking President Trump’s...