When it comes to lying in politics, Donald Trump is in a class of his own. According to the Washington Post , he made 30,573 false or misleading claims in his four years as president, increasing year-on-year from six per day in his first year to 39 per day in his fourth.
Although other presidents have lied to the public, none have lied like this. Some of Trump's lies are trivial, and many are self-aggrandising ("Nobody builds better walls than me"). Then there are his more egregious lies, like the one about the 2020 presidential election being "stolen" - demonstrably and dangerously contrary to the facts, with serious consequences for the nation and public trust.
And these lies can cut through. Research by political scientists Kevin Arceneaux and Roy Truex found that this "big lie" about the stolen election was very "sticky". Around 50% of Republican voters believed it, regardless of any emerging contrary evidence. The researchers also found that belief in this lie boosted Republican supporters' self-esteem - as they weren't "losers" after all.
Politicians who lie can gain a strategic advantage. If you can successfully embellish the truth or construct a new reality, this often tends to be more interesting and engaging than the complicated truth. The truth may be a bit dull and uninspiring; the lie can be whatever you want it to be. You know what your audience wants to hear.
Politicians know that lying is part of our everyday lives. Research in psychology using lie diaries tells us that people lie on average twice a day. Many are harmless "white" lies told for the benefit of others, but some are not so harmless and told for the benefit of the liar themselves.
Some people get significant pleasure from telling such self-centred lies. Psychologists call this "duping delight" . It confuses the recipient of the lie, who expects to detect signs of guilt or anxiety. Instead, all they see is a faint smile of satisfaction. The liar gets away with it - that smile could mean anything.
Who likes lying?
Certain types of personality are drawn to telling these sorts of lies, including those with little empathy, such as narcissists and psychopaths. They don't care about the consequences for the recipient; it's all about them.
People typically start lying early in life - between two and three years of age. Charles Darwin observed this in his own son.
And the ability to lie improves as our cognitive abilities develop. Like any skill, we get better at it with practice. While many adults still feel guilt when they don't tell the truth, some politicians don't appear to feel any guilt, shame or sadness at telling a lie.
Telling a big lie
Politics was once thought of as an art. It was political philosopher Nicolo Machiavelli who, in 1532, wrote: "Those princes who have done great things … have known how to circumvent the intellect of men by craft." Part of that craft was lying. Machiavelli argued that rulers should do whatever it takes to retain power, and this could include "being a great dissembler".
Politicians can lie by omission and by exaggeration - but sometimes, like Trump, they tell outright "big lies". This term was introduced by Adolf Hitler in Mein Kampf , and the concept of the big lie was used by the Nazis to justify persecution of the Jews .
A big lie is often defined as "a deliberate gross distortion of the truth used especially as a propaganda tactic". These have, it is argued, the power to disrupt society .
Political historian Timothy Snyder accused Trump of using the big lie technique in his denial of the 2020 election result.
To work, according to Hitler, big lies must also be able "to awaken the imagination of the public through an appeal to their feelings". They are not aimed at our rational selves, but our unconscious and emotional selves.
Trump saying that immigrants are eating the dogs and cats in Springfield, Ohio, is not appealing to our rational system. It's providing us with a vivid image, and trying to affect our emotional and unconscious system.
As the sociobiologist Robert Trivers has pointed out, lying can give you a clear evolutionary advantage. Status, wealth and achievements are important in that great evolutionary battle, the survival of the genes - that's why people (including Trump) lie about them. But Trivers says self-deceit can also be evolutionarily advantageous, because if you can convince yourself then it makes you more convincing to others, and therefore more effective.
Perhaps Trump managed to convince himself that they really were eating the dogs and cats in Springfield. Or perhaps he thought to himself: "Plant the emotional image, that's all you need for the faithful."
Attractive fictions might well engage us and sweep us along but, as Shakespeare suggested in the Merchant of Venice, many people hope the "truth will out" eventually. The last few months of the US election campaign suggest this may not always be true.