Unionists are quite right to boycott the Taoiseach’s all-Ireland Brexit forum. Or at least they are being entirely rational, contrary to the impression from the SDLP.

In a statement on Monday, issued in the name of party leader Colum Eastwood, the SDLP sought to assure unionists that “in the confines of that forum there is no trapdoor to Irish unity. Nor is it a papist conspiracy. Those attending will not be sprayed with holy water at the door”.

The implication is that unionist objections to all-Ireland co-operation are of a piece with deranged religious bigotry. Lest anyone accuse this in turn of being a gratuitous sectarian insult, the SDLP carefully directed its statement at “political unionism”. This is a phrase used to separate unionist people from their politics, so it is of a piece with the dismissal of unionism as a false consciousness.

However, most nationalists are genuinely unaware of doing this. It is a subconscious accusation of false consciousness.

If there is an irrational unionist reaction against the idea of an all-Ireland forum, it stems from the 1984 New Ireland Forum, which the SDLP was instrumental in creating.

A united Ireland

To demonstrate how open-minded they were, they included some interim options – what might now be termed “soft unity” – but these were struck out at the last minute by Charlie Haughey, leaving only hard unity.

The SDLP could have assured political unionism that the new all-Ireland forum will be nothing like the old New Ireland Forum but sadly it neglected to do so.

Of course, a great deal has changed since 1984. For example, the SDLP is now led by a 33-year-old man from Derry instead of by a 47-year-old man from Derry.

The passage of time has given unionists two rational reasons to decline the Taoiseach’s invitation. First, there are the institutions for cross-Border discussion already set up under the Belfast Agreement. These are separated into “strands”, north-south and east-west, each served by statutory bodies with standing secretariats, and each tasked with hosting regular negotiations up to heads-of-government level. They are the North/South Ministerial Council, the British-Irish Council and the British-Irish Intergovernmental Conference.

Delicate balancing act

The UUP only accepted the North/South Ministerial Council in exchange for its east-west counterpart, while the DUP remained officially anti-agreement until 2006. So unilaterally dropping another North-South body onto the scales is highly irresponsible. It is a particularly blatant bypass of the agreed mechanisms because the North/South Ministerial Council is empowered by law and treaty to establish an all-Ireland civic forum, whose proposed make-up appears indistinguishable from the Taoiseach’s all-Ireland forum. If anyone else messed with the agreement in this manner there would be dark mutterings of a threat to the peace process.

Unionists do not generally issue such threats because they are ambivalent about the process or see themselves as harmless. Even so, the DUP has been admirably diplomatic, insisting it will gladly join all-Ireland Brexit talks via the proper channels.

The second good reason for a unionist no-show is that the real Brexit negotiations will be east-west, between London and Dublin. Sovereign states present their terms to Brussels, which bends its “fundamental principles” accordingly – that is how the EU actually works.

If Irish nationalists want an additional voice for Northern Ireland, the correct forum for that is the British-Irish Intergovernmental Conference, which brings the Stormont Executive together with London and Dublin and whose remit specifically includes EU membership and the common travel area.

If Scottish nationalists want to join the conversation they can raise it at the British-Irish Council, which has a seat for every state, devolved region and dependency in the British and Irish isles.

Perhaps the Taoiseach is ignoring all this because his forum is just a gimmick or a distraction for political rivals – in which case, everyone should boycott it.

Or perhaps it is a serious venture, subverting the Belfast Agreement only because urgent haste makes that necessary. Perhaps this really is where Ireland’s collective response to Brexit will be forged.

In that case, however, the place for unionists is forging the UK’s response. Their stance need not be hostile but they are on the British side by definition.

Expecting unionists to speak for Ireland as well is another subconscious accusation of false consciousness. Unionists will negotiate with Ireland, through the agreed institutions for doing so – and no good is served by being rude about it.