This week, with impeccable timing, The House magazine published an interview with Conservative Environment Minister Zac Goldsmith. In it the arch Brexiteer and committed environmental campaigner - a once rare but now increasingly commonplace combination - offers a candid and engaging defence of the government's track record.
He acknowledges bolder action on climate change and biodiversity is urgently required - "next year has to be a super year for the environment, or frankly we're stuffed" - but insists the government and the Prime Minister are aware of what is at stake and are up to the task. He accepts the government of which he is a part supports the Heathrow expansion he is fiercely opposed to, but predicts the third runway will never get built. And, crucially, he admits the Brexit deal does open the door to environmental deregulation in the future, but insists it is a door the current government has no interest in barging its way through.
When pushed on the point, Goldsmith asks and answers his own question. "Will future governments be tempted to water things down?" he says. "Possibly, but then it is for parliament and for people to apply pressure, but that won't be necessary with this government."
And there it is. The beating heart of the Brexit crisis, the source of the division that has split the country asunder, the basis for both the Leave camp's argument that we have nothing to fear from leaving the over-bearing superstate structures of the EU and the Remain camp's argument that Brexiters are clinging to an outmoded, 19th century model of nation statehood. All of it wrapped up in one short sentence. A sentence that can be condensed to an even shorter word: sovereignty.
When you boil the rolling Brexit drama right down to first principles, when you simmer off all the spin, mendacity, and illegality, the contestable economic impact assessments and fantasy trade deals, the competing tribal ideologies, the culture wars, the social media sewers, the constitutional chicanery, and the nasty, even violent, degradation of the public sphere, what you are left with is a question about what sovereignty means and where it should reside.
And it is here that the Brexit debate gets both challenging and strangely reassuring. Because amidst the torched wreckage of our political dialogue, it is on the question of sovereignty where well-intentioned people disagree, where competing visions of the future play out, and where no one is advocating to leave the EU because a Polish plumber talked funny on a train.
It is also the issue that presents the biggest challenge to those green-minded remainers and soft Brexiters - myself included - who are currently arguing for much stronger environmental protections to be included in the government's Brexit deal and accompanying legislation. Because Goldsmith asks a good question, doesn't he? Why shouldn't the UK's sovereign parliament decide to deregulate if a majority of our elected representatives choose to do so? Why should they be constrained? Isn't it up to the British public and the politicians it elects to ensure pressure is applied so that this and future governments live up to their promises on the environment? Why do we need Brussels to save us from ourselves?
These are entirely legitimate questions and they are particularly difficult for both committed remainers and those in favour of a much softer Brexit to engage with, because the answers lie in the knotty philosophical debate about the pros and cons of the nation state and the modern nature of sovereignty. Faced with such esoteric complexity you can see why people find it easier to fixate on Parliamentary maths or Dominic Cummings' game theories.
However, Goldsmith's challenge demands a response. Why shouldn't future British governments be permitted to torch environmental protections if they choose to do so?
There are four inter-locking counter-arguments, each of which is more difficult to land with the public than the last.
The first is the somewhat circular argument that attempting to place legal obligations on future Parliaments does not negate their ability to repeal those obligations. No Parliament can bind the hands of the next. Sovereignty always resides in the crown in parliament.
The biggest misunderstanding throughout the whole Brexit process was that Parliament was always sovereign. It could always choose to leave the EU, as it has done. It is just that in opting to reclaim the sovereignty that had been pooled in Brussels it had to accept the consequences. Consequences that include either a hard border between Ireland and Northern Ireland or the effective annexation of the province, not to mention the installation of massive trade barriers and resulting economic damage, or continued access to the single market without a say over its rules. The story of the past three years has been that of a concerted attempt to avoid the inevitable consequences that no one properly explained to the public.
Precisely the same is now true of the calls for more robust legal environmental protections. A future government with a majority in favour of deregulation could find a way to repeal or overrule such protections. It would just have to accept the likely consequences for any future trade deal with the EU, not to mention the state of the UK's environment and green economy.
Why then bother with such legal protections? Why make the case for non-regression provisions and regulatory alignment with the EU if such decisions can be reversed in the future?
Well, because in putting such protections into law the government sends a resounding signal to investors and businesses about its priorities and intentions. It takes Goldsmith's rhetorical insistence that there is no risk of this government diluting green policies and gives it some legal iron-cladding, over and above the still rather flawed Environment Bill. The government's repeated argument that there is no reason to include such protections in the Withdrawal Agreement Bill is torpedoed by a simple question: if you are so committed to higher standards why object to a binding non-regression clause? What are you trying to hide?
The second counter-argument is that the ability of Parliament and the public to apply pressure to ensure standards are maintained and strengthened is badly undermined by the continuing flaws in our democratic system.
Polls show the American public is overwhelmingly in favour of bolder environmental action, but it has not done them much good with repeated Republican administrations. The UK's electoral system may not be as grievously gerrymandered as its US cousin (yet), but it is entirely possible that a majority government could be formed with less than 40 per cent of the vote. Such a government could then claim a mandate for both a no deal Brexit at the end of the transition period next year followed by an unprecedented deregulatory agenda, all based on a couple of sentences in a manifesto that no one reads - indeed, this is precisely what some of Goldsmith's colleagues are banking on.
Third, a commitment to non-regression and, better yet, the maintenance of a level playing field with the EU, is not simply a case of giving up sovereignty - it is a trade-off for which the UK gets something in return. Why should the government be restricted from watering down environmental protections? Because such dilution of standards would not only harm the environment, but also result in yet more barriers between the UK and its largest trading partner. Legal non-regression commitments serve to firm up the policy framework that patient green capital relies upon, while also removing export hurdles for clean technologies.
Moreover, if the government really is committed to higher standards post-Brexit then some form of level playing field provisions cut both ways. The UK can seek assurances that it will not be undercut by the EU, just as the EU will seek the same assurances for its businesses. There is a quid pro quo to pooled sovereignty.
All of which leads to the really crunchy philosophical issue right at the heart of the Brexit project. It is possible to argue, as Goldsmith and others have done, that the most effective response to the climate crisis will be driven by nation states with high levels of sovereignty and the resulting freedom to tailor their policy frameworks to meet their specific needs and the agility to select their own innovation priorities. Under such a model, the most competitive economies would build net zero hubs and other nations would then quickly emulate those leaders who have provided the template for a clean, green 21st century economy. This is a legitimate and compelling argument.
But what if such an approach leads not to trail-blazing leadership followed by widespread adoption amongst a network of international allies, but instead nationalism and protectionism? What if pooling sovereignty with the world's largest market and arguably most effective peace project can be done in a way that both enables the development of net zero hubs and speeds their spread around the world? What if the challenges the UK now faces - from national security and data protection to climate change and biodiversity loss - are so international in their nature, that hoarding as much sovereignty as possible quickly becomes counter-productive? What if one of the reasons why future UK governments should face legal measures designed to dissuade them from torching domestic environmental rules is that slashed protections here would pollute the lungs and prospects of our international neighbours, both on the other side of The Channel and the other side of the world? What if pooling sovereignty in the face of a century that will be defined by epochal, civilisation-shaping challenges and opportunities is in our national interests.
These are fundamental questions on which reasonable people disagree. They point to the type of country we want to be and how we can best build a cleaner and healthier economy. The tragedy is that as Brexit enters its latest crucial - but in no way conclusive phase - we are still no closer to answering them. The fear is that with the government steadfastly refusing to include any non-regression commitments in its Brexit legislation and the Prime Minister repeatedly telling the Commons this afternoon that the Withdrawal Bill contains robust Workers Rights protections that are in reality so weak as to be virtually non-existent, it looks as if the pollutocrats and deregulators are winning.