If you voted for Brexit, did you think it was a state of pure and perfect national independence, or did you think that given how connected the UK is to the EU – economically, diplomatically, in respect of security – it might be a bit of a fudge and compromise?
Is Brexit an absolute state of putative grace – or a place on a spectrum, somewhere between Switzerland and Norway, which are semi-independent, and North Korea, which is wholly independent?
Because your answer will help you determine whether or not you think Boris Johnson is being reasonable in rejecting the EU stipulation that the UK should not weaken its environmental, labour and state aid standards (inter alia) in return for not paying any tariffs or being subject to any quantitative restrictions when trading with the world's biggest market.
The EU in essence wants its firms to be able to sue in British courts if the UK weakens its adherence to those standards in a way that gives UK firms an unfair competitive advantage. Boris Johnson says that is outrageous.
And, mark you, he is outraged even though the EU is not doing what many Brexiters feared, and which it started off by doing, which was insist on a role for the European Court of Justice in adjudicating on such disputes.
Johnson's view is that even if he has no intention of weakening environment and labour standards in the UK, or unfairly subsidising exporters, no 'independent sovereign' country can have its ability to pass laws or rules circumscribed by an external power – even if that external power is only asking the UK to do what it would choose to do of its own free will.
One senior Tory sees him as the equivalent of Life of Brian's Stan, a member of the People's Front of Judea, who insisted that the sect should pass a motion acknowledging his right to have babies, although there were conspicuous practical reasons why he wouldn't be having one (he was a man). Whereas members of the ultra Brexiter European Research Group see Johnson – for now at least – as the keeper and protector of the true Brexit flame.
To be clear, whatever Brexit deal Boris Johnson were able to agree with the EU would sail through the Commons, because Labour will definitely not vote against it. Unlike the ERG and apparently Johnson himself, Labour is terrified of the economic, social and geopolitical consequences of quitting the EU in acrimony with no deal.
But Johnson has apparently decided no post-Brexit free trade deal is worth the name if it is not backed by the majority of Tory MP members of the European Research Group – perhaps because without their unseating of Theresa May and backing for him, he would not be in his job today.
What I don't know is whether he understands the weighty significance of sticking to that position. Because if he continues to press the EU for a deal that would win the universal acclaim of the MPs of the European Research Group, the UK will be leaving the transition at one second after midnight on 31 December without a deal.