In Plato’s Cratylus, on the philosophy of language, Socrates says that the Greek word for truth, aletheia, is a compression of the phrase “a wandering that is divine”.

Since Plato, many thinkers have spoken of truth and God in the same breath, and truth has also been linked with concepts such as justice, power, and freedom. According to John the Apostle, Jesus said to the Jews: “And ye shall know the truth, and the truth shall make you free.”

Today, the belief in God may be dying, but what about truth? Rudy Giuliani, Donald Trump’s personal lawyer, claimed that “truth isn’t truth”, while Kellyanne Conway, Trump’s counsellor, presented the public with what she called “alternative facts”.

Over in the U.K. in the run-up to the Brexit referendum, Michael Gove, then Minister of Justice and Lord Chancellor, opined that people “have had enough of experts”. Accused by the father of a sick child of visiting a hospital for a press opportunity, Prime Minister Boris Johnson replied, “There’s no press here”—while being filmed by a BBC camera crew.

The anatomy of a lie

What constitutes a lie? A lie is not simply an untruth. For centuries, people taught their children that the earth was at the centre of the universe. This was not a lie, insofar as they believed it to be true.

For something to be a lie, the person putting it out has to believe that it is false, even if, by chance, it happens to be true. If I tell you, “I’m not actually my father’s biological son”, believing that I am, and it so happens that I am not, I am still telling a lie.

Of course, it could be that I am being sarcastic, or joking—and, if I have made this sufficiently clear, I could not be counted as lying. For my statement to be a lie, it is not enough that I believe it to be false. I must also intend you to believe that it is true, that is, I must also intend to deceive you. If my intention in deceiving you is a good one, I am telling a white lie; if it is a bad one, I am telling a black lie; and if it is a bit of both, a blue lie.

When Olympias told her son Alexander the Great that his father was not Philip of Macedon but Zeus himself, she would only have been lying if (1) she believed this to be false, and (2) she intended to deceive Alexander. Olympias—who, according to Plutarch, slept with snakes in her bed—probably did believe it to be true, which highlights an important problem with lying, namely, that people can believe the most fantastical things.

A special case is when someone tells the naked truth, intending others to interpret it as a lie or joke. In Game of Thrones, after killing the Freys, Arya Stark runs into some Lannister soldiers, who share with her their meal of roast rabbit and blackberry wine. When one of the soldiers (not the one played by Ed Sheeran) asks, “So why is a nice girl on her own going to King’s Landing?” Arya replies, point blank, “I’m going to kill the queen.” After an awkward silence, everyone including Arya bursts out laughing.

If I am late to a dinner party, I can tell a small lie about some heavy traffic, or I can tell a bolder lie about being pushed into a muddy ditch by a chihuahua and having to go home to get changed. The more unusual and imaginative (and embarrassing) the lie, the more it is likely to be believed.

Or I could try instead to hide the lie. For example, I might lie by omission or “mental reservation”: “Sorry, I had a flat tyre” (last month). Or I might lie by equivocation (playing on words), as Bill Clinton famously did when he stated, “I did not have sexual relations with that woman, Monica Lewinsky.”

A special kind of lie is the bluff, which involves pretending to have an asset or intention or position that one does not actually have. An infamous example of a bluff is former prime minister Theresa May’s Brexit mantra that “no deal is better than a bad deal”.

Lies versus bullsh*t

Is there any difference between telling lies and talking bullsh*t? According to the philosopher Harry Frankfurt, lies differ from bullsh*t in that liars must track the truth in order to conceal it, whereas bullsh*tters have no regard or sensitivity for the truth or even for what their intended audience believes, so long as this audience is convinced or carried by their rhetoric.

Bullsh*tters will say whatever it takes, from moment to moment, to limp on to the next moment.

For Frankfurt:

“Someone who lies and someone who tells the truth are playing on opposite sides, so to speak, in the same game. Each responds to the facts as he understands them, although the response of the one is guided by the authority of the truth, while the response of the other defies that authority and refuses to meet its demands. The bullsh*tter ignores these demands altogether. He does not reject the authority of the truth, as the liar does, and oppose himself to it. He pays no attention to it at all. By virtue of this, bullsh*t is a greater enemy of the truth than lies are.”

Pathological lying

Pathological lying—also sometimes called compulsive lying or mythomania—is a controversial construct, and not tightly defined. It refers to habitual lying, typically for no discernible external gain. It is often although not always a feature of the four Cluster B personality disorders, namely, borderline personality disorder, histrionic personality disorder, narcissistic personality disorder, and antisocial personality disorder, and is in Factor One of the Psychopathy Checklist.

As with pathological lying, most lying is actually carried out for internal, or emotional, gain, to attract attention or sympathy, or to alleviate feelings of abandonment, rejection, or worthlessness.

We often lie to ourselves and to others from a position of vulnerability: we lie not out of strength or smartness, but out of need and necessity.

The philosophy of lying

St Augustine’s treatise on lying begins with, “There is a great question about lying…” [Magna quæstio est de mendacio…].

It may be permissible to lie when the positive consequences clearly outweigh any negative consequences. Thus, it may be reasonable to lie in a life and death situation, for instance, to save someone from being discovered by a murderer. And it may be reasonable to lie if the person being lied to has forfeited their right to the truth, for example, by threatening violence.

But such situations are few and far between. Much more common are the small white lies that lubricate our social interactions, such as greeting acquaintances with “good to see you” and starting a letter to a stranger or antagonist with “Dear”.

Outside vis majorand social convention, it is usually a bad idea to lie. In the fifth century BCE, Herodotus wrote that from their fifth year to their twentieth, the Persians of the Pontus were instructed in three things: “to ride a horse, to draw a bow, and to speak the Truth.”

“The most disgraceful thing in the world [the Persians] think is to tell a lie; the next worst, to owe a debt: because, among other reasons, the debtor is obliged to tell lies.”

The first person to suffer from a lie is none other than the liar. Lying feels bad and damages pride and self-esteem. It is a slippery slope that leads to further and greater lies and other ethical violations. Having told a lie, it can take a lot of thought and exertion and sacrifice to avoid being found out. If found out (or even merely suspected), the liar loses authority and credibility, undermines their reputation and relationships, and may suffer further sanctions, including being lied to in return. Last but not least, by keeping them under the radar, lying prevents critical issues from being addressed and dealt with.

And then there is the harm to others. To lie is to treat people as means-to-an-end rather than as ends-in-themselves, which is why being lied to is experienced as disrespectful and demeaning. It also leads people to act on false information, which can have untold and unforeseen consequences.

When faced with a choice between a life of limitless pleasure as a detached brain in a vat, and a genuine, human life along with all its struggle and suffering, most people opt for the latter. This suggests that we value truth for its own sake, as well as for its utility. To deny us a part of reality is therefore to impoverish our life.

There is a line of reasoning that, since the natural end of speech is to communicate the thoughts of the speaker, lying is a perversion of language. Curiously, language runs into serious metaphysical difficulties as soon as a lie is introduced. Consider the sentence: “This statement is false.” If the statement is false, it is true; but if it is true, it is not false.

The strongest argument against lying is perhaps that it could not be made into a universal principle. If everyone started lying here and there and everywhere, everything would quickly come apart. For just this reason, Plato bans even poetry from his ideal state, reasoning that poetry is “thrice removed from the truth”.

It’s worrying that we as a society are increasingly tolerant of lies. When people take to lying, they have to tell more and more lies to shore up their earlier lies. This tangled web we weave undermines trust, to the point that we no longer believe anything, least of all the truth.

In the fifth century BCE, the Persian King of Kings Darius the Great had the following advice engraved for his successor Xerxes:

“Thou who shalt be king hereafter, protect yourself vigorously from the Lie; the man who shall be a lie-follower, him do thou punish well, if thus thou shall think. May my country be secure!”

If Darius knew it then, why do we not know it now?