IN 2011, the British historian Stephen Ellis published a paper concluding that Nelson Mandela had been a member of the South African Communist Party — indeed, a member of its governing Central Committee. Although Mandela’s African National Congress and the Communist Party were openly allied against apartheid, Mandela and the A.N.C. have always denied that the hero of South Africa’s liberation was himself a party member. But Ellis, drawing on testimony of former party members and newly available archives, made a convincing case that Mandela joined the party around 1960, several years before he was sentenced to life in prison for conspiring to overthrow the government.

Does it matter?

The news excited some critics and historical revisionists, who claimed it exposed the A.N.C. as a Stalinist front. (“ ‘Saint’ Mandela? Not So Fast!” exulted one right-wing blog.) It probably stirred a sense of vindication among Americans who endorsed their government’s Cold War support of the fiercely anti-Communist apartheid regime. Professor Ellis is no apologist for white rule — he occupies a university chair in Amsterdam named for another hero of the South African resistance, Archbishop Desmond Tutu — but he contends that the affiliation with the Communists shaped the A.N.C.’s ideology in ways that endure, ominously, to this day.

“Today, the A.N.C. officially claims still to be at the first stage ... of a two-phase revolution,” Ellis told me in an email exchange. “This is a theory obtained directly from Soviet thinking.”

Indeed, the remnants of Communist protocol and jargon — “comrades” and “counterrevolutionaries” — live on in the platform and demeanor of South Africa’s ruling party. My own perspective on this question, shaped by covering the Soviet Union from 1986 to 1991 and South Africa from 1992 to 1995, is respectful of scholarship, but also wary of its limits. Both in Gorbachev’s Russia and in transitional South Africa, I realized that what people profess at party plenums and codify in party records is not always a reliable guide to what they will do, or even what they actually believe.