The legitimacy of the ages-old conflict is renewed on a regular basis.
If not at a ceremony of commemoration, then some official report or other dealing with decades-old atrocities reminds people who are troubled by these things they have a legitimate cause and their enemies did great wrong.
Thursday night’s BBC Panorama programme, in which the highly respected former Northern Ireland police ombudsman Nuala O’Loan claimed that “hundreds and hundreds” of deaths would not have happened in Northern Ireland without security force collusion, is another contribution to that process.
It is of essential that wrongdoing, especially official wrongdoing, is uncovered without fear or favour.
The challenge comes in how we respond to these revelations, which in this instance, have been disputed by the PSNI chief constable George Hamilton. Most of us will accept and regret that collusion did take place — after all the Provos had spies in Garda stations too — but a minority will use disclosures like this to fuel their hatred and anti-democratic campaigns.
It would be a tragedy if those planning 1916 centenary celebrations fell into that trap.