I am borderline innumerate. Angus enjoys reminding our children of this, perhaps because his own identity is so bound up with numbers. Raised on a sheep property in the bleak Monaro high country – where for years on end things could get very tough – he cannot look at a paddock without calculating the cost of what to do with it. A mob of sheep presents another calculation: sell or hold, wool or fat lambs, sow down to feed pasture, assess feed costs against expected prices? I see a paddock. Angus sees the economy occurring inside it.

He understands economic reality as the hard ground beneath almost everything else. A family farm cannot be preserved, if the enterprise supporting it does not work. For Angus, economics makes preservation – and prosperity – possible.

Were I a politician, I’d never seek a portfolio involving fiscal projections or forward estimates. I know my limitations. That brings me back yet again to my favourite One Nation politician: Barnaby Joyce.

Barnaby is not innumerate. He is a qualified accountant, even if it may have been some time since he sharpened the proverbial pencil. He has been deputy prime minister and a cabinet minister. He knows what costings are for. His refusal to produce them is now a clear political choice, whose name is hubris.

At the Sydney Institute in July, Angus estimated that One Nation’s four largest financial commitments alone could cost the budget in the order of a trillion dollars over a decade. In answer, Joyce declined to guarantee that One Nation’s policies would be submitted to the Parliamentary Budget Office. His explanation was that the party lacked the resources available to the major parties.

It was always a poor excuse. The Parliamentary Budget Office exists to give parliamentarians confidential and independent costing and budget analysis. Barnaby just needed to ask.

When the excuse collapsed, the costings did not materialise. Instead we were given a new excuse. Asked by Sarah Ferguson on 7.30 on the ABC whether One Nation had modelled the effects of its superannuation proposals on retirement incomes and inflation, Joyce replied, ‘I’m not Jesus Christ’.Nobody had asked Barnaby to perform a miracle. He was asked whether the policy had received basic economic scrutiny.

Now the number Angus mentioned is bigger, but the defence has hardened. Challenged over the economic consequences of One Nation’s announced migration plan, Joyce said Australians were ‘tired of economists’ and the Parliamentary Budget Office. Forward estimates were rarely right anyway. He had ‘no concern’ about following ‘the will of the Australian people’. Hanson has since confirmed that she will just ‘implement the will of the people’.

There is a pattern here. First, One Nation lacked the resources to do the numbers. Then, only Jesus Christ could do this. Now, even bothering to try is just an establishment obstruction to democracy which is framed only by the ‘will of the people’. God help us: now they’re not even pretending.

No farmer would proceed this way. The rain may not come and the prices may fall. Uncertainty does not relieve him of the need to prepare a budget. In fact, it makes the exercise more important.

Nor can a small business survive by declaring that forecasts are frequently wrong and budgets therefore unnecessary. ‘The will of the customers’ is no answer when the bills come in. One Nation now openly proposes to run a nation with less discipline than most would routinely apply to a farm or shop.

‘Responsible government’ actually means something. It is not just a constitutional phrase. Over centuries it came to describe a system in which those exercising executive power must answer to parliament for their decisions, expenditure and consequences. Together with the rule of law and parliamentary control of public money, it helped create the most stable and prosperous civilisation the world has known. Right now, we’re busy tearing it down. One Nation represents an understandable pushback to the swamp’s rule by unaccountable experts, but it now copies the left’s playbook: just say it and it will be so.

The system has never been infallible. Unforeseen events, dear boy, arise. But like running a farm, business or even a household, budgeting is a discipline that forces a party to confront trade-offs.

Hanson and Joyce are now openly doing the opposite. One Nation is putting together a mix of wild economic nationalism, proposals borrowed from Canada, farmers’ groups, and a bevy of new economic policies principally copied and pasted from the Coalition, but without any economic analysis or costings. One Nation takes from anyone and anywhere that offers a quick headline and an immediate political return. There is clearly no process for reconciling one promise with another. The only coherence is an intransigent refusal to do the numbers.

Hanson is the reason Joyce is in this quagmire. Having attached himself to a leader who will never retreat, Joyce cannot honestly cost the promises without exposing their contradictions, and he cannot resolve the contradictions without asking Hanson to retreat. As Treasury spokesman, he is now compelled to attack the obligation to do any numbers at all.

Naturally, in ancient Rome we can find a warning. Marcus Aurelius represented discipline and government understood as an obligation. His son Commodus preferred the cheering crowd. Commodus supplied endless spectacle and mistook applause for successful rule. Rome called it bread and circuses: satisfy the immediate appetites and hang the reckoning – which came.

One Nation hopes its outsider momentum will carry it through an election before it is judged as a government. Until now, the fourth estate has largely indulged the performance.

The larger responsibility belongs to those who would form government. As the economy worsens Labor will struggle to prosecute the economic case having lost – yet again – all economic credibility. The Coalition must explain why economic discipline and smarts, for which the Coalition has long been known and upon which it has always delivered, must prevail – for the preservation of our society.

Responsible government does not require governments to be infallible, just serious. Barnaby Joyce’s answers over time show a party moving from unseriousness towards a fully blown, unapologetic repudiation of responsibility. Hanson seems to believe her electoral momentum places her beyond the laws of political gravity, and that the ‘will of the people’ can suspend basic economics as well.

Political gravity can take quite a long time to play out. And even I know that economic gravity is remorseless. Good luck with the bread and circuses. Our children will pay dearly.