John Mitchel propagandised for slavery as an institution and encouraged the use of torture to keep enslaved people in line. Last week, Trinity College Dublin decided to take the name of the great 18th-century philosopher George Berkeley off its main library. This raises the more awkward question of all the GAA clubs named after another advocate for chattel slavery, John Mitchel. It is probably true that most Irish people don’t know or care much about Berkeley — which makes “denaming” a university library relatively painless. Confronting the truth about Mitchel, a hero of the Irish national struggle, is a lot...