Clifford D. May is president of the Foundation for Defense of Democracies, a policy institute focusing on national security.

Perhaps because St. Patrick’s Day is coming up, I’ve found myself re-reading Edmund Burke and Conor Cruise O’Brien — and drinking Irish whiskey. I first became acquainted with these three sources of stimulation back in 1978. That was also my first brush with terrorism.

I was a young foreign correspondent sent to Northern Ireland to cover the “Troubles,” the conflict between Catholics and Protestants, Republicans (Irish nationalists) and Loyalists (those favoring solidarity with the United Kingdom) that broke out in the 1960s and dissipated just before the turn of the century.

I spent many hours in pubs, listening to those on both sides of the divide tell me what they believed, whom they despised, and what acts of violence they would countenance — and in some cases carry out — to achieve their objectives.

In Ireland I also developed a habit I’ve since kept of reading the important writers of every country I visit — as well as partaking of local libations. Burke, of course, was a great 18th-century Irish author, statesman, and political philosopher. An enthusiastic supporter of the American Revolution, he saw early on that the revolution in France was heading into darkness, including la Terreur — mass executions of “enemies of the revolution.”...