Sources · Is lying always wrong?
This house believes lying is always wrong.
Fact bank v1 · 12 cards
This is a philosophy motion, so the judge never rules either side's view true or false. These cards say what philosophers generally accept, and cover facts such as who argued what.
- LIE-01
“Kant said lying is always wrong, even lying to a murderer who asks where your friend is hiding.”
What philosophers generally accept
Confirmed: the German philosopher Immanuel Kant said lying is always wrong. He said this even about lying to a would-be murderer who is looking for his victim.
Kant argued this in a 1797 essay called 'On a Supposed Right to Lie from Philanthropy'. Saint Augustine and Thomas Aquinas also said you must not lie, even to a would-be murderer. But in his lectures on ethics, Kant gave a different example. If a thief grabs you by the throat and asks where you keep your money, saying 'I have no money' is not a lie, he said, because the thief has no right to the truth.
“Kant maintains lying is always wrong (Kant 1785, 1797).”
Stanford Encyclopedia of Philosophy·William David RossPeer-reviewed research · 2 Mar 2022 ↗Further sources for this card
- LIE-02
“Thomas Aquinas taught that every lie is wrong, even a lie told to save someone's life.”
What philosophers generally accept
Confirmed: Aquinas held that every lie is wrong to some degree. But he did not think all lies are equally bad. Lying to save an innocent person's life was still wrong, but only a small ('venial') sin. Lying to get an innocent person killed was a very serious ('mortal') sin.
For Aquinas, the wrong is in saying something you believe is false, not in keeping quiet. He thought it is often fine, and sometimes a duty, to hide what you know. In a war fought for a just cause, a soldier could pretend to run away to lead an unjust enemy into a trap, but should not lie to that enemy.
“Aquinas’ thesis is that lying, properly defined, is always to be excluded as to some extent wrong.”
Stanford Encyclopedia of Philosophy·Aquinas' Moral, Political, and Legal PhilosophyPeer-reviewed research · 16 Mar 2021 ↗Further sources for this card
- LIE-03
“All the great philosophers agree that lying is always wrong.”
What philosophers generally accept
Not true. Augustine, Aquinas and Kant said you must never lie, even to a would-be murderer. But many others, including John Stuart Mill, Henry Sidgwick, Benjamin Constant and Sissela Bok, said lying to a would-be murderer can be allowed, or can even be your duty.
The philosopher W. D. Ross thought lying is normally wrong, but that this can be outweighed. His example was lying to stop a would-be murderer from finding and killing your friend. Philosophers still disagree about this today.
“or permissible (i.e., either optional or obligatory), as consequentialists and moderate deontologists maintain”
Stanford Encyclopedia of Philosophy·The Definition of Lying and DeceptionPeer-reviewed research · 25 Dec 2015 ↗Further sources for this card
- LIE-04
“Some philosophers say that telling a would-be killer something false, to save an innocent life, is not really lying at all.”
What philosophers generally accept
Confirmed: the 17th-century Dutch thinker Hugo Grotius said a lie, in the strict sense, wrongs a person's right to judge things for themselves. That right can be lost when an innocent person's life is at stake, or when it is the only way to stop a dishonest act.
So for Grotius, saying something false in those cases is not a lie at all. He also said you cannot lie, in this strict sense, to children, or to someone who has agreed to be told untrue things. The modern philosopher Alan Donagan said much the same about a would-be murderer who threatens your life. Critics, such as Sissela Bok, say this makes the word 'lying' cover too little.
“can also be taken away in cases “When the life of an innocent Person, or something equal to it,” is at stake”
Stanford Encyclopedia of Philosophy·The Definition of Lying and DeceptionPeer-reviewed research · 25 Dec 2015 ↗ - LIE-05
“Plato argued that the rulers of his ideal city should tell the people a 'noble lie'.”
What philosophers generally accept
Confirmed: in Plato's Republic, the rulers of the ideal city tell a 'noble lie'. It is a made-up story meant to make citizens accept their unequal places in society and feel closely tied to their city.
The Republic also says the city's guardians should value truth but be willing to lie when it is good for the city. The Stanford Encyclopedia of Philosophy calls this propaganda, and a sign that the rulers control too much. Early in the same book, Socrates also questions the idea that being just simply means telling the truth and paying back what you owe. You should not, he says, give weapons back to a friend who has gone mad.
“they advance a “noble lie” to convince citizens of their unequal standing and deep tie to the city”
Stanford Encyclopedia of Philosophy·Plato's Ethics and Politics in The RepublicPeer-reviewed research · 12 Sept 2017 ↗Further sources for this card
- LIE-06
“On average, people tell one or two lies a day.”
What philosophers generally accept
Confirmed: in two diary studies, 77 college students reported telling 2 lies a day on average, and 70 members of the public told 1 a day.
People said they did not see their lies as serious, did not plan them much and did not worry much about being caught. Even so, conversations with a lie in them were less pleasant and less close than conversations without one. People told more lies to benefit themselves than to help others, except in conversations between two women, where both kinds were equally common. An average can hide big differences between people (see LIE-07).
“In 2 diary studies of lying, 77 college students reported telling 2 lies a day, and 70 community members told 1.”
Journal of Personality and Social Psychology (via NCBI PubMed, NIH)·Lying in everyday life (Journal of Personality and Social Psychology, PubMed abstract)Government / parliament · 1 May 1996 ↗ - LIE-07
“Everybody lies all the time.”
What philosophers generally accept
Not really. When 1,000 US adults were asked about the last 24 hours, 60% said they had told no lies at all. Almost half of all the lies reported were told by just 5% of people.
So a small group of frequent liars tells most of the lies. The researchers found the same pattern when they looked again at older data, and in a group of students. These numbers come from people reporting on themselves, so some lies may be missed.
“Sixty percent of subjects report telling no lies at all, and almost half of all lies are told by only 5% of subjects”
Human Communication Research (Oxford Academic)·The Prevalence of Lying in America: Three Studies of Self-Reported LiesPeer-reviewed research · 1 Jan 2010 ↗ - LIE-08
“Most people can tell when someone is lying to them.”
What philosophers generally accept
Not true. A review of 206 research reports, with 24,483 people judging, found they sorted lies from truths correctly only 54% of the time. That is only a little better than the 50% you would get by guessing. They caught just 47% of the lies.
In these studies, people judged on the spot, with no training or special tools. People did better with lies they could hear than with lies they could only see. People also tend to assume that the person they are talking to is being honest.
“people achieve an average of 54% correct lie-truth judgments, correctly classifying 47% of lies as deceptive and 61% of truths as nondeceptive”
Personality and Social Psychology Review (via NCBI PubMed, NIH)·Accuracy of deception judgments (Personality and Social Psychology Review, PubMed abstract)Government / parliament · 1 Aug 2006 ↗ - LIE-09
“Telling small lies makes it easier to tell bigger ones.”
What philosophers generally accept
Mostly true, but the evidence comes from a lab game. In a 2016 study, people's lies grew bigger the more times they told them, when the lies helped themselves. At the same time, the response to lying in the amygdala, a part of the brain linked to emotions, got weaker.
The bigger the drop in that brain response, the bigger the next lie tended to be. In the main experiment, 55 people in London guessed the money in jars of pennies, and 25 of them had brain scans. Lies that only helped the other player did not grow. Because it was a lab game, it shows how a 'slippery slope' could work, not that it always happens in real life.
“what begins as small acts of dishonesty can escalate into larger transgressions”
Nature Neuroscience·The brain adapts to dishonestyPeer-reviewed research · 24 Oct 2016 ↗Further sources for this card
- LIE-10
“Even doctors sometimes tell their patients things that aren't true.”
What philosophers generally accept
Confirmed: in a 2009 survey of 1,891 US doctors, just over one in ten said they had told a patient something untrue in the past year.
Almost one in five did not fully agree that doctors should never tell a patient something untrue. Most doctors fully agreed that patients should be told about the risks and benefits of treatments. The researchers warned that some patients may not be getting complete and accurate information.
“Just over one-tenth said they had told patients something untrue in the previous year.”
Health Affairs (via NCBI PubMed, NIH)·Survey shows that at least some physicians are not always open or honest with patients (Health Affairs, PubMed abstract)Government / parliament · 1 Feb 2012 ↗ - LIE-11
“Most seriously ill patients would rather not be told bad news.”
What philosophers generally accept
Mostly not true, at least for cancer patients. In a large UK study of 2,331 cancer patients, 87% wanted all possible information, good and bad, and 98% wanted to know whether or not their illness was cancer.
Only a small group, 58 out of 440 (13.2%), said they would generally rather leave it to the doctor what to tell them. They tended to be over 70, and even they still wanted to know some details. The researchers said that holding back information, on the idea that many patients prefer not to know, cannot be justified. The study was published in 2001 and only looked at cancer patients in the UK, so it may not hold for every illness or country.
“87% (2027) wanted all possible information, both good and bad news and 98% (2203) preferred to know whether or not their illness was cancer”
British Journal of Cancer (via PubMed Central, NIH)·Information needs of patients with cancer: results from a large study in UK cancer centresGovernment / parliament · 5 Jan 2001 ↗ - LIE-12
“A placebo (dummy pill) only works if the doctor lies to the patient about it.”
What philosophers generally accept
Mostly not true. In 'open-label' trials, patients are told honestly that they are getting a dummy pill. A 2025 review of 60 such trials found these honest placebos still had a small helpful effect, mainly on how people said they felt.
The effect on things measured by tests, rather than by asking people how they felt, was very small. In a well-known 2010 trial of 80 people with irritable bowel syndrome, those given honest placebo pills improved more than those given no pills. An earlier 2021 review called this research still 'in its infancy'.
“OLPs yielded a small positive effect across various health-related outcomes”
Scientific Reports (Nature Portfolio)·Effects of open-label placebos across populations and outcomes: an updated systematic review and meta-analysis of randomized controlled trialsPeer-reviewed research · 15 Aug 2025 ↗
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