It is no secret that politicians often lie, but consider this – they can do so simply by telling the truth. Confused?
That statement becomes clearer when you realise that we've probably all done it. A classic example might be if your mum asks if you've finished your homework and you respond: "I've written an essay on Tennessee Williams for my English class." This may be true, but it doesn't actually answer the question about whether your homework was done. That essay could have been written long ago and you have misled your poor mother with a truthful statement. You might not have even started your homework yet.
Misleading by "telling the truth" is so pervasive in daily life that a new term has recently been employed by psychologists to describe it: paltering. That it is so widespread in society now gives us more insight into the grey area between truth and lies, and perhaps even why we lie at all.
We lie all the time, despite the fact that it costs us considerably more mental effort to lie than to tell the truth. US president Abraham Lincoln once said that "no man has a good enough memory to be a successful liar".
I told her that she looked good when I thought that she looked like a blimp
In 1996 one researcher, Bella DePaulo even put a figure on it. She found that each of us lies about once or twice a day. She discovered this by asking participants for one week to note down each time they lied, even if they did so with a good intention. Out of the 147 participants in her original study, only seven said they didn’t lie at all - and we can only guess if they were telling the truth.
Many of the lies were fairly innocent, or even kind, such as: "I told her that she looked good when I thought that she looked like a blimp." Some were to hide embarrassment, such as pretending a spouse had not been fired. DePaulo, a psychologist at the University of California Santa Barbara, says that the participants in her study were not aware of how many lies they told, partly because most were so "ordinary and so expected that we just don't notice them".
It is when individuals use lies to manipulate others or to purposely mislead that it is more worrying. And this happens more often than you might think.
When Todd Rogers and his colleagues were looking at how often politicians dodge questions during debates they realised something else was going on. By stating another truthful fact, they could get out of answering a question. They could even imply something was truthful when it was not. Politicians do this all the time, says Rogers, a behavioural scientist at Harvard Kennedy School. He and colleagues therefore set out to understand more about it.
He found that paltering was an extremely common tactic of negotiation. Over half the 184 business executives in his study admitted to using the tactic. The research also found that the person doing the paltering believed it was more ethical than lying outright.
The individuals who had been deceived, however, did not distinguish between lying and paltering. "It probably leads to too much paltering as communicators think that when disclosed, it will be somewhat ethical, whereas listeners see it as a lie," says Rogers.
It is also difficult to spot a misleading "fact" when we hear something that on the face of it, sounds true. For instance, the UK's Labour Party campaign video to lower the voting age said: "You're 16. Now you can get married, join the Army, work full-time." The BBC's reality check team discovered that these facts do not tell the whole truth.
"You can only join the Army aged 16 or 17 with your parents' permission,” the Reality Check team wrote. “At that age you also need your parents' permission to get married unless you do so in Scotland. Since 2013, 16 and 17-year-olds cannot work full-time in England, but can in the other three home nations with some restrictions."
We want to achieve our narrow objective – [selling a house or car] – but we also want people to see us as ethical and honest
In another example, the then-presidential-nominee Donald Trump paltered during the presidential debates. He was questioned about a housing discrimination lawsuit early on in his career and stated that his company had given "no admission of guilt". While they may not have admitted it, an investigation by the New York Times found that his company did discriminate based on race.
And even if we do spot misleading truths, social norms can prevent us from challenging whether or not they are deceptive. Take a now infamous interview in the UK, where journalist Jeremy Paxman interviewed the politician Michael Howard (pictured below). He repeatedly asks Howard whether he "threatened to overrule" the then prisons governor. Howard in turn, continues to evade the question with other facts in a bizarre exchange that becomes increasingly awkward to watch. Not many of us are comfortable challenging someone in that way.
While it's common in politics, so too is it in everyday life. Consider the estate agent who tells a potential buyer that an unpopular property has had "lots of enquiries" when asked how many actual bids there have been. Or the used car salesman who says a car started up extremely well on a frosty morning, without disclosing that it broke down the week before. Both statements are true but mask the reality of the unpopular property and the dodgy car.
Paltering is perhaps so commonplace because it is seen as a useful tool. It happens because we constantly have so many competing goals, suggests Rogers. "We want to achieve our narrow objective – [selling a house or car] – but we also want people to see us as ethical and honest." He says these two goals are in tension and by paltering, people believe they are being more ethical than outright lying. "We show evidence they are making a mistake," says Rogers.
We can see the problems this sort of thinking can cause reflected in society today. The public are clearly sick of being lied to and trust in politicians is plummeting. One 2016 poll found that the British public trust politicians less than estate agents, bankers and journalists.
It's unethical and it makes our democracy worse. But it's how human cognition works
And despite the fact that we now frequently expect lies from those in power, it remains challenging to spot them in real time, especially so if they lie by paltering. Psychologist Robert Feldman, author of The Liar in Your Life, sees this as worrying both on a personal and on a macro level. "When we're lied to by people in power, it ruins our confidence in political institutions – it makes the population very cynical about [their] real motivations."
Lying can and does clearly serve a devious social purpose. It can help someone paint a better picture than the truth, or help a politician dodge an uncomfortable question. "It's unethical and it makes our democracy worse. But it's how human cognition works," says Rogers.
Unfortunately, the prevalence of lies might stem from the way we are brought up. Lies play a role in our social interactions from a very young age. We tell young children about tooth fairies and Santa, or encourage a child to be grateful for an unwanted present. "We give our kids very mixed messages," says Feldman. "What they ultimately learn is that even though honesty is the best policy, it's also at times fine and preferable to lie about things."
So next time you hear a fact that sounds odd, or someone to be deflecting a question, be aware that what you think is the truth may very well be deceptive.
Melissa Hogenboom is BBC Future's feature writer, she is @melissasuzanneh on twitter.
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