This lustrous pearl of wisdom is inspired in me by the hair-raising news reports of the Tax Office fraud scandal.

Yes, being law-abiding costs nothing. And it imparts a peace of mind that the unfortunately and unhappily criminal and trouble-attracting can never know. The law-abiding rest easy knowing that the police car prowling their street is not stalking them. The law-abiding feel no fear of the airport sniffer dog finding anything stickytaped to their thighs, hidden in their luggage. There is nothing as clean and clear as a squeaky-clear conscience.

Alleged frauds like the ATO horror and famous mega-crimes like the Great Train Robbery fill the law-abiding mind and bosom with wonder. "Did they really think they'd get away it?" we gasp.

There was a Great Stupidity about the 17 Great Train Robbers' idea that they could become happily rich, for ever after, by stealing £2.6 million from a Royal Mail train. There was so much that could go wrong and it duly did, with the ringleaders inevitably caught and sent to prison for 30 years.

Coincidentally, just as the alleged ATO scam has us again asking what on earth goes through criminal minds, University of California neuroscience whizz Kate Fehlhaber has addressed this very matter. Her piece What know-it-alls don't know, or the illusion of competence shimmers in the latest edition of the digital magazine Aeon.

"One day in 1995," Fehlhaber begins, "a middle-aged man robbed two Pittsburgh banks in broad daylight. He didn't wear a mask or any sort of disguise. And he smiled at surveillance cameras before walking out of each bank."

"Later that night, police arrested a surprised McArthur Wheeler. When they showed him the surveillance tapes, Wheeler stared in disbelief. 'But I wore the juice,' he mumbled. Apparently, Wheeler thought that rubbing lemon juice on his skin would render him invisible to videotape cameras. After all, lemon juice is used as invisible ink so he should have been completely invisible.

"The saga caught the eye of the psychologist David Dunning at Cornell University, who enlisted his graduate student, Justin Kruger, to see what was going on. They reasoned that some people mistakenly assess their abilities as being much higher than they actually are. This 'illusion of confidence' is now called the 'Dunning-Kruger effect', and describes the cognitive bias to inflate self-assessment."

To investigate this phenomenon Dunning and Kruger designed some clever experiments. You can read all about them in Aeon. The findings were always of an "illusion of competence" with the subjects (the more stupid) with the lowest scores in tests always overestimating, by a lot, how well they did.

"And the Dunning-Kruger effect," Fehlhaber fancies, "can also be observed in people's self-assessment of a myriad of other personal abilities.

"If you watch any talent show on television today, you will see the shock on the faces of contestants who are rejected by the judges … these people are genuinely unaware of how much they have been misled by their illusory superiority.

"The problem is that when people are incompetent, not only do they reach wrong conclusions and make unfortunate choices but, also, they are robbed of the ability to realise their mistakes … As Charles Darwin wrote in The Descent of Man (1871): 'Ignorance more frequently begets confidence than does knowledge.'

"The difference is that competent people can and do adjust their self-assessment given appropriate feedback, while incompetent individuals cannot.

"And therein lies the key to not ending up like the witless bank robber. The trick is to not be fooled by illusions of superiority and to learn to accurately re-evaluate our competence. After all, as Confucius reportedly said, real knowledge is knowing the extent of one's ignorance."

Yes, approached by "conspirators" to join in committing a big crime the "competent" law-abiding will run a mile. We can imagine a zillion things that can go wrong, flinging us into clink.

I feel no moral superiority to brigands. There but for the grace of God I too might have gone, sometimes teetering on the brink of brigandom. But I do feel different from them.

Last Saturday's Canberra Times reported how "one of the alleged conspirators in the $165 million fraud on the ATO, racked up $100,000 on his corporate American Express card on strippers and [prostitutes] in four months". The Times called this the big spender's "spree".

Law-abiding readers! How different our sprees as "competents" would be if $100,000 cascaded into our law-abiding laps. In my case, probably splurging little or nothing on strippers and strumpets (although I respect their noble professions) I might instead treat myself to a visit to the Venice Biennale and to other cultural treats that, unless I rob a bank, I will never be able to afford now that I am an incorruptible self-funded retiree.

*The Best Things In Life Are Free, by Ray Henderson, Buddy De Sylva and Lew Brown.