Of all the vacuous platitudes regularly trotted out by Brexiteers, one of the most irritating is the mantra that “no deal is better than a bad deal”. What, exactly, would such a bad deal look like? We are never informed, making the claim “not even wrong”.

In contrast, it is pretty easy to define what a bad deal would look like, from an Irish perspective. First, and most obviously, and most importantly, it would be a deal that restored a visible border in Ireland, whether involving border guards of one sort or another, or physical border infrastructure, or both. This would undermine one of the fundamental premises of the Good Friday Agreement: that given the freedom to choose your citizenship, and without a meaningful border, it should no longer matter, very much, on which side of that border you live. The restoration of a border would therefore threaten the security of this island. A deal that allowed this would be a pretty dreadful one, by any reasonable standard.

Second, a bad deal would expose Irish agribusiness to competition from cheap overseas suppliers in the UK market. Such Anglospheric competition would severely reduce Irish exports to Britain, irrespective of whether Irish exporters faced WTO tariffs or not.

It’s pretty easy, therefore, to define what a bad deal for Ireland would look like in principle. Unfortunately, if the UK follows through on its threat to leave the EU’s Single Market, and refuses to become a member of a new EU27-UK customs union replicating the current EU28 customs union, then any deal that the EU will strike with the UK will necessarily be a bad one, thus defined. Most importantly, there will have to be a border on this island. And, since the UK will then do a variety of trade deals with the US and other countries, on the basis of an exceptionally weak bargaining position, it is highly likely that Ireland agribusiness will lose valuable markets there, even if they don’t face WTO tariffs.

So, in the Irish case, we have a meaningful definition of a bad deal, and we can therefore meaningfully pose the question of whether a bad deal would be better than no deal.

No deal would also mean a border in Ireland, and the loss of export markets consequent on the imposition of WTO tariffs. And it would involve additional economic costs, over and beyond those implied by a bad deal, of which more later. But I don’t think that you can automatically conclude that no deal would be worse for Ireland than a bad deal, mostly for political reasons.

As things stand, we have convinced our EU partners that a border in Ireland is unacceptable. The language from Barnier, Verhofstadt, Macron, and many others on the issue is exactly what we have been looking for. By signing on to a bad deal, we would be conceding the principle that a border is, in fact, acceptable. We would be saying to the EU26: “yes, we have been trying hard to convince you that a border is simply unthinkable and must never be allowed to happen, but actually, we didn’t really mean it. If push comes to shove, we’ll accept a border if that is the price that has to be paid for a deal with the UK.” If we were to take such an attitude, we could hardly expect our European partners to take the opposite one!

Once the point of principle regarding the border has been conceded, it becomes likely that the border will prove to be a permanent fixture on the island. The Brexiteers will be happy: they will be able to import as much chlorinated chicken as they want from wherever they want, and the Irish border issue will no longer be on the table to complicate matters for them. There will be no reason for the UK to ever get rid of the border, and we will have lost all leverage on the issue.

By contrast, if there is no deal, because of insufficient progress on the border issue, the point of principle will not have been conceded. Yes, there will still be a border, but there will be a border anyway under a bad deal. And the UK will know that, if it ever wants a trade deal with the largest market in the world, and its nearest neighbour, it will have to erase that border.

And I think that it is almost inevitable that the UK will, eventually, decide that it needs to have such a trade deal.** In which case the border will only have been reintroduced temporarily.

No deal will involve more economic costs for Ireland than a bad deal, and as I said in a previous post, I would like to see those additional costs quantified, taking into account the negative impact upon Ireland of the trade deals that Liam Fox is likely to sign. And it is therefore intellectually respectable to claim that a bad deal is better than no deal. But it is also intellectually respectable to argue that for Ireland, no deal is in fact better than a bad deal.

To an extent, it comes down to what our preferences are. If they are lexicographic, with the absence of a border dominating other Irish interests, then no deal is surely better than a bad deal. If, on the other hand, we are willing to accept a higher risk of the resumption of violence, in order to mitigate economic costs elsewhere on the island, then a bad deal might well be better than no deal. I think that these are issues that we need to debate, honestly, as a society.

My own view is that when things can go badly wrong, they often do, and that we should never take peace and stability for granted. I also think that the primary duty of a state is to provide security. And like everyone my age, I remember the Troubles. And so I tend to the view that we should not concede on the fundamental point of principle that has been forcefully articulated by our government and diplomatic service: a border in Ireland is simply unacceptable.

And what that means in practice, I think, is that in the months ahead — through December and if necessary beyond — we should hold our nerve, stick to our principles, and continue to insist that we need a solution to the Irish border question before the UK withdrawal talks proceed to the second stage.

** It may take time.