“Trust is a social good to be protected just as much as the air we breathe or the water we drink. When it is damaged, the community as a whole suffers; and when it is destroyed, societies falter and collapse.”

— Sissela Bok, Lying: Moral Choice in Public and Private Life.

Rob Ford is a liar. Admitted. Bald-faced. Serial.

Since many of his lies have to do with his use of illegal drugs, bizarre behaviour and dubious company, and as he remains despite this the titular mayor of a major city, Ford’s falsehoods have made him — and Toronto — a global laughingstock.

Like most world-class liars, Ford is cunning and slippery. On the first instalment this past week of Ford’s YouTube series conducted with his brother Doug, the mayor sought to recast his grosser character flaws as a simple human failing shared by all.

“Why did I lie? I think everybody in the world has lied. Because I was embarrassed . . . Everybody’s lied. So maybe people can tell me, why do you lie?”

In that comment is packed a clever dodge, a fair assessment, and a good question.

Ford is right about one thing. In various ways and to various degrees, research finds, everybody does lie. Deceit is both a social lubricant and an evolutionary strategy. It occurs every day, everywhere and in ever inventive ways.

Nature itself is full of shape-shifters, colour-changers and fraudsters of blossom or feather. Just as all around the world, every day of the week, one partner is telling another that he or she has to work late, someone is saying ‘it’s not you, it’s me,’ someone is warning that a house for sale, or maybe a car or painting, has other keenly interested buyers.

Cheating scandals and epidemics of lies have occurred in recent years in the White House, on Wall Street, in major league sports and show business — from Bill Clinton to John Edwards to Anthony Weiner, Barry Bonds to Lance Armstrong to Alex Rodriguez. As is often the case with deceit, money, sex or substances to either improve performance or alter reality are somewhere in the story.

“Perjury is committed all too often at the highest levels of business, media, politics, sports, culture — even the legal profession itself — by people celebrated for their achievements, followed avidly by the media, and held up as role models,” said James B. Stewart in his 2011 book Tangled Webs: How False Statements Are Undermining America, from Martha Stewart to Bernie Madoff.

So, as Rob Ford asks, why do we lie?

In short, we usually lie to get something we want, or to protect something we have. We lie to make ourselves seem a little better than we are (be it in a job interview or the dating world), or to profit (whether in the markets or on the campaign trail), or to avoid punishment (whether for stealing a cookie or consorting with a big-haired intern while holding high office).

In various ways and to different extremes, everybody does lie, writes psychologist Robert Feldman in The Liar in Your Life: The Way to Truthful Relationships.

Deception, he says, “is deeply engrained in our everyday interactions and in our broader culture.” Political spin, hockey dekes, poker bluffs, bigger penises, easy weight loss, Nigerian princes bearing bequests, world exclusives, “you-look-great-in-that-dress.” The world is, literally and figuratively, full of it.

By his lies, Rob Ford — whether consciously or not — is exploiting advantages found in human psychology.

Studies repeatedly show that people have a great deal of faith in their ability to catch a lie when, in fact, we really aren’t very good at it. Research shows people are able to distinguish lies from truth less than half the time.

“Even those who are trained to detect lying and deception are not particularly good at it,” say psychologists Paul Babiak and Robert D. Hare in Snakes in Suits: When Psychopaths Go To Work.

“Criminal justice personnel are often asked to determine whether someone is lying or not, but recent research shows that their results are no better than that of the average untrained person.”

Feldman says liars also prosper from a psychological phenomenon known as ‘truth bias.’ Assuming we aren’t being lied to is our default position. It enables us to live without the paralyzing and exhausting task of testing every routine daily transaction and encounter for honesty.

“Someone needs to give us a compelling reason to think they’re lying” Feldman says, before we bring that sort of scrutiny to bear.

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Furthermore, what he calls “the willing accomplice principle” inclines us not to disbelieve someone in whose character or standing we have a stake — our children, a person we hired, someone we elected or campaigned for. Willing accomplices are not neutral observers. They want to believe them. “My children don’t lie!”

But children, alas, do lie. And how could it be otherwise when raised by parents, or villages, or media, well versed in the art of casual deceit? A parent phoning in sick when healthy. A father too tired to play but not to golf. A mother assuring her friend a ghastly hairstyle is lovely. Kids get the message.

Feldman’s research has found that verbal lies start in most children around age 3 — accompanying the discovery that parents have rules and there are penalties for breaking them.

It suggests something of the emotional development of some elected officials to hear Feldman say that “the earliest are almost reflexive attempts to avoid these punishments . . . The first lies children tell are often of the ‘I-didn’t-do-it’ variety.”

The lies become more nuanced at 4 or 5, Feldman says, moving from “I didn’t to it” to “the dog did.” By kindergarten, he says, most children understand the social utility of such things as false flattery and the benefits bestowed on a teacher’s pet.

“The message is clear: Lying works as a social tactic.”

Even so, however, we intuitively know the importance of honesty and the cost of lying. In fact, an instinct for truth seems to be wired into us. “The brain may be a fluent perjurer,” writes Jeremy Campbell in The Liar’s Tale: A History of Falsehood. “But the body gives the brain away.”

Polygraph technology is based on the fact that lying is stressful for humans, that intentional deceit causes anxiety that is measurable in unconscious bodily reactions of pulse, respiration, perspiration.

In the liar, so long as he or she is not a psychopath and retains a twinge of conscience, lying produces discomfort, what is called “cognitive dissonance,” the irreconcilable tension that arises when a man, say, confesses to lying while professing to be a straight-shooter.

For Sissela Bok, whose 1978 book Lying is a classic in the field, “few lies are solitary ones.” It’s easy to tell a lie, but hard to tell only one. After the first lies, others come more easily.

“Psychological barriers wear down; lies seem more necessary, less reprehensible; the ability to make moral distinctions can coarsen; the liar’s perception of his chances of being caught may warp.”

Moreover, she says, liars underestimate the harm they do to themselves and the harm done the general level of trust and responsibility. Once public servants especially “lose their bearings in this way,” she wrote just a few years after Watergate, all manner of “shabby deceits” become possible.

As Bok says, “Trust and integrity are precious resources, easily squandered, hard to regain. They can thrive only on a foundation of respect for veracity.”

And has the great Joan Didion has observed, there is, in the end, no getting away from ourselves and our actions.

“It had counted, after all, every evasion and every procrastination, every mistake, every word, all of it.”