This post originally appeared on the UCL European Institute blog.

One of the more consistent elements of religious systems around the world is the notion of treating others as you would have them treat you. For social animals such as humans, it’s pretty essential for building extended groups and stable relationships.

It’s also pretty helpful for thinking about how to make negotiations work better. The more you can treat your interlocutors constructively and fairly, the more chance you have of getting similar behaviour in return: by grounding yourself in external benchmarks and standards, you’re also giving both sides the opportunity to feel more confident about the equity of any agreement you might reach.

For that reason, even in apparently lop-sided negotiations, you often find negotiators making reference to commonly-held principles and practices, despite apparently limiting their own ability to impose their preferences on the other side. You might have the upper hand this time, but if everyone has bought into the basic underpinnings of a deal, then they’re more likely to comply in a lasting fashion with it and they’re more likely to reciprocate should the tables be turned down the line.

In short, the more equity and justice we can bring to negotiations, the better the chances that equity and justice will be present in whatever follows those negotiations, to everyone’s benefit.

But of course, theory doesn’t always play out this way in practice.

Here is not the place to go into the details of the UK government’s decision to introduce the Internal Market Bill, with its provisions to disapply parts of the Withdrawal Agreement, signed and ratified by that same government earlier this year, but it does raise a question of the structural understanding of Brexit that the UK has.

In particular, suggests there are two, interlinked issues that have plagued decision-making in London.

The first is simply that Brexit lacks a purpose.

Yes, there was the decision of the referendum in 2016, but that was not a purpose in and of itself. Both campaigns made multiple arguments about why voting for them would result in wonderful things happening, but there was no commitment to actually enact any of those, nor any post-vote mechanism to try and build a plan.

Instead, we had the tussles between and within political parties to try and ‘own’ the result: Theresa May came as close as anyone, only to have the rug pulled out from under her with the 2017 general election. The drift towards an ever-harder Brexit since the referendum reflects the continued in-fighting in Westminster rather than public opinion, which has remained as divided as it was in June 2016.

Despite two general elections, one European election and endless discussion, we still have nothing that even vaguely resembles a broadly-agreed plan of what kind of society the UK wants to be and of how it fits into the international system. In its place, we find only the slogan of ‘get Brexit done’, which is more about the weariness of it all than anything else.

One hardly needs to work on negotiation theory to realise that it’s very hard indeed to strike a deal with someone else if you don’t know what you want. At best, it leads to finding something that is ‘good enough’ for the moment, but which risks creating new problems down the line.

In such cases, trying to negotiate dispassionately and with objective benchmarks makes more sense: it’s a way of working from what is settled into the areas of uncertainty, plus it creates more confidence about extending the talks into future elements more constructively.

But here we run into the second issue that has hampered the British approach to Brexit: the pre-dominance of the domestic arena.

International negotiation represents a two-level exercise: national governments have to find a deal with their counterparts abroad, but also have to be able to have it agreed back home. One without the other doesn’t work.

In the case of the UK, the intense political attention paid to Brexit this past half-decade has drawn Number 10 (regardless of resident) into managing domestic challenges. Parliament, courts, opposition and – especially – their own party have all presented objections and challenges that have been impossible to ignore or override.

But in focusing on those problems, May and Johnson have both found themselves failing to consider sufficiently whether the local solution to their problems might be acceptable to the EU.

The Internal Market Bill is a case in point. Even with the acceptance of the Neill amendments, the Bill still seems almost certainly to break the terms of the Withdrawal Agreement – not to mention the customary principle of pacta sunt servanda – which in turn compromises the ability to be considered as a good faith partner in the Future Relationship talks.

And beyond the UK-EU relationship, the entire episode has damaged the UK’s global reputation as an upholder of international law and commitments, which will prove to be a drag on any new trade deals with other parts of the world. Given that these deals represent almost the entire substance of the ‘Global Britain’ narrative of some Brexiters, this is very much a case of cutting off one’s nose.

All of which brings us back to the golden rule.

Politics is never simple or straight-forward, but if we don’t try to project the values that we want from those around us, then we risk making the international system even less friendly than it needs to be.