The hardline stance of the Democratic Unionist Party (DUP) in opposition to British prime minister Theresa May's deal with the European Union is a classic example of how in politics emotion can prevail over rational self-interest. By any yardstick the deal gives Northern Ireland the best of both worlds. It recognises the integrity of the United Kingdom while giving the North the flexibility to continue to trade seamlessly with the Republic and hence the rest of the EU regardless of the Brexit outcome.
This reality is understood by the organisations representing business and farming in the North, which have welcomed the deal. Unfortunately this appears to mean nothing to the DUP, which has insisted on seeing betrayal and treachery behind every attempt to protect the interests of people who live in the North. Some unwise words in the past year from Taoiseach Leo Varadkar and Tánaiste Simon Coveney about their long-term hopes for a united Ireland may have fuelled DUP suspicions but the reality is that the party would have adopted the same head-in-the-sand attitude no matter what politicians in the Republic said.
There is now an obvious danger that the DUP determination to vote down the May deal will contribute to its defeat in the House of Commons, making a hard Brexit at the end of March more likely. Such an event would probably have more damaging consequences for Northern Ireland than for any other part of the UK but that does not appear to matter to the DUP.
On a more practical political level, a decision to undermine the Conservative prime minister will damage the standing of the DUP with the Tory mainstream and could lead to an end of the confidence and supply arrangement which had such potential benefits for the North. By putting its confidence in a political charlatan like Boris Johnson the DUP has shown just how poor its judgment is.
The reality is that every potential outcome of the current crisis, apart from the unlikely one of remaining in the EU – which the DUP strongly opposes – will be worse for Northern Ireland than the deal signed by May at the weekend.