You will all need that indispensable instrument, your moral compass, because your columnist is about to ask you a probing, soul-examining question.

The question is, could you ever vote for, even actively and evangelically barrack for a politician you knew was personally and privately a morally disgusting swine? Could you do this because you felt this politician would be an effective force for a cause that is hugely important for you? Could you do something so pragmatic, so morally bereft?

It emerges that this pragmatic readiness to champion politicians for what we hope they will do, irrespective of who and what they are, is a much-discussed phenomenon of our times. For those of us (are we fossils?) who have always had to believe someone is good (or at least blameless) before we can vote for them, this is a soul-boggling trend.

Bear with me as I approach the matter from left field.

Just as one had resigned oneself to never fathoming any of the Five Great Mysteries of Life (Is there a God? What is consciousness? Is the Universe infinite? Why are the USA's evangelical Christians such passionate supporters of sinful Trump? How did the unicorns become extinct?) suddenly one of those mysteries has after all been plausibly explained!

Peter Wehner, veteran assistant of three Republican presidencies, a long-time Republican and lifelong conservative Christian has just been explaining, on ABC Radio National's Sunday Extra, how it comes to pass that his troubled nation's conservative Christians are so fanatically supportive of Donald Trump.

"They [his conservative Christian brothers and sisters] won't speak truth to power [and so won't criticise Trump's immorality]," Wehner grieves.

"But the watching world sees this and they say 'Wait a second. I remember when you guys used to say morality was central to presidential leadership. When Clinton was president [you were righteously enraged about his affair with Monica Lewinsky].'

"'But here you have a guy who has had multiple affairs, who in 2016 we know made an illegal hush payment to a porn star while he was cheating on his mistress, while his third wife was at home with a newborn son, and you don't have anything to say about that?'"

The watching world is understandably aghast at this hypocrisy, Wehner sighs.

"But the white Christian evangelicals I talk to," he reports, "say 'We are in an existential moral moment and that if a Democrat won the presidency, if Democrats put liberal justices on the Supreme Court, if Democrats control Congress, then America will morally collapse. Christianity will be under assault.'"

"Conservative Christians, they look at Trump and say 'He's our guard dog','' Wehner explains, despairingly.

A similar phenomenon has been at work in Britain, some diagnose. Those of us who thought that the fact that slimy liars like Boris Johnson and Nigel Farage were leading the pro-Brexit campaign was reason in itself to feel in one's bones that the Brexit cause was malignant and to vote Remain, missed the point. Passionately pro-Brexit people didn't care that Johnson and Farage are awful human beings but felt that these unattractive little people were just what the giant, beautiful cause of Brexit needed.

Will this phenomenon reach our shores? One day, will it not concern us if an Australian prime minister or prime ministerial aspirant is a known debauchee? Will we, not bothered with what he or she gets up to with consenting porn stars in private, instead make pragmatic judgments about who we want empowered and why we want them.

Yes, she's had multiple affairs, but what if she's the best person to guard our sovereign borders against armadas of boat people? Yes he pays hush money to porn stars, but what if he's the man most likely to protect my franking credits from the Socialists?

Some of us, still with our principles, could never shake Donald Trump's hand without the watching media capturing our open shudder of revulsion. Scott Morrison (a conservative Christian who must find Trump's debauched, porn-stained personality repugnant) stoically hid his sincere pentecostal shudders when with Trump in recent days.

Perhaps it is that for any Australian prime minister any president of the great and powerful USA is Australia's "guard dog" in a dangerous world and so (as with all dogs we want to love us) must be romped with, however feigned our prime minister's affections are for something so hairy, slobbery and barking mad.