Conventional wisdom holds that an elected government’s first budget should be its bravest. Albeit with a micro-majority, Malcolm Turnbull is an elected prime minister, rather than merely a coup leader. So next week’s budget should be an opportunity to place his economic stamp on the country.

It’s becoming clearer what the budget is likely to contain: there’ll be ‘good’ borrowing to fund more infrastructure, especially railways; there’ll be some superannuation concessions for seniors who downsize the family home; there’ll be some savings that will annoy the hell out of the impacted sectors but won’t make much of a dent in the...