There have been some breathtakingly inconsistent responses as three bright young senators tripped and face-planted over section 44 (i) of the constitution, the provision that renders political candidates ineligible to stand for office if they hold dual citizenship.

When Greens deputy leaders Scott Ludlam and Larissa Waters realised their mistakes (he was born in New Zealand, settled in Australia as a child and assumed his New Zealand citizenship had been relinquished when he was naturalised in his teens; she was born to Australian parents who were living in Canada at the time), they took responsibility and resigned.

Despite their obviously profound shock and deep distress, gloating tabloids labelled them “fake senators” and “fraudulent”. Columnists clamoured for them to be forced to repay the salaries they’d drawn over the years. Some openly doubted the senators’ insistence that they had had no idea of their dual citizenship status, implausibly suggesting they’d known all along but kept their career-ending status secret.

Andrew Bolt saw it all as a wonderful portent of a broader Green demise. “The Greens are dying at last,” he enthused. “But not fast enough and not before causing terrible damage around the world.”

The prime minister himself was incredulous.

“It is pretty amazing, isn’t it, that you have had two out of nine Greens senators didn’t realise they were citizens of another country. It shows incredible sloppiness on their part,” Malcolm Turnbull said.

The attorney general, George Brandis, advised Australians not to “shed too many tears over the consequences of Mr Ludlam’s own negligence”.

“He knew he was born in New Zealand obviously when he stood for parliament. He must be taken to have been aware of the constitution and yet he never took the trouble to ensure that he had relinquished his New Zealand citizenship,” was Brandis’s too bad, not sad assessment.

But then, as if by some act of constitutional karma, the Nationals senator Matt Canavan stumbled over the very same clause and just days after that stony lack of sympathy for Ludlam, Brandis was standing alongside Canavan as he stood down from the cabinet for the same reason.

And oh, how the tone changed. It was now all very matter of fact and resting sombre face at the turn events had taken. They’d discussed it, but Canavan had no idea his mother had applied for Italian citizenship on his behalf, and he’d never signed any papers. The government would be testing his eligibility in the high court. On social media, it was now the left’s turn for rejoicing.

Constitutional experts are divided about Canavan’s chances, and given all the confusion it’s probably not a bad thing to seek clarification, although Waters and Ludlam also had very reasonable explanations for why they genuinely had no idea of the dual citizenship deemed to signify an allegiance to another land.

But the lack of empathy in some of our human responses to this constitutional tragi-comedy has been telling. Have we lost the ability to disagree, even hate, the ideas someone advocates, without hating the person or rejoicing in a lightning-bolt end to a promising career?

My deep disagreement with many of Canavan’s ideas is on record – his open advocacy for new coalmines that will push the world even faster towards dangerous global warming, for example, or his arguments for hobbling what I regard as necessary environmental advocacy. His Facebook post this week explaining how it had been “such an honour to represent the Australian mining sector over the past year” sums up the essence of our differences. It was easy to feel a flutter of schadenfreude when news filtered through of his problem.

But Waters, who had every reason to feel that way, responded differently.

Senator @mattjcan & I disagree on almost everything, especially #Adani, but my heart goes out to him, family & staff with dual citizen news — Larissa Waters (@larissawaters) July 25, 2017

And if Canavan is ruled ineligible, he’ll be replaced in this Senate by someone who thinks much like him. As with Ludlam and Waters, in terms of actual outcomes, the contest of ideas, the balance of power, there’s nothing to be gained from his demise for those of us who don’t like some of the policies he’s been advocating. (Of course if an MP, rather than a senator, was found to be ineligible, that would be a different story).

We know Donald Trump has honed utter lack of empathy into a political weapon. We know we often now exist in our own filter bubbles, segregated personal and online communities where we mostly hear only ideas that we already share. We know political debate has become polarised, binary and couched so often in angry metaphors of war.

Those are all much broader questions than how we react to the sudden end of some promising political careers, but they’re connected.

If politicians can’t look at a colleague’s demise and think “There but for the grace of God go I”, if commentators and headline writers see politics less as a contest of ideas and more as a blood sport, if we all reserve empathy only for those with whom we agree – how can we possibly nurture the things that we share?