The Boundary of Truth

Is It Always Wrong to Lie?

Lying has a bad reputation in every society. It is not difficult to understand why. A society cannot endure if words lose their credibility. When a promise means nothing, when testimony cannot be trusted, and when another person may always be concealing a different intention behind what is said, something fundamental breaks down. We can live with disagreement. We can also live with mistakes and misunderstandings. But we can scarcely live together if we can no longer trust that others are at least trying to say what they believe to be true.

This is why children are taught from an early age not to lie. The prohibition appears in religions, laws, and moral traditions throughout the world. A lie does not harm only the person who is deceived. It attacks the relationship between human beings. It turns the other person into a means to the liar’s ends. I make you act on the basis of a reality that I know does not exist.

Yet this does not settle the matter. What are we to do when truth itself can be used as a weapon?

Imagine that someone is being persecuted and seeks refuge in your house. Soon afterwards, the pursuer knocks at your door and asks whether that person is there. Should you answer truthfully? If you do, someone may be killed. If you lie, you violate the duty of truthfulness—but perhaps save a life.

A seemingly simple moral principle then becomes a question of practical philosophy: Is truth always good, regardless of how it is used?

Kant’s Uncompromising Answer

This is not merely a thought experiment. Immanuel Kant addressed precisely this example in a much-debated dispute with the French philosopher Benjamin Constant in 1797. Constant had argued that an unconditional duty to tell the truth would make any society impossible. Kant responded with one of his strictest positions: we have no right to lie, not even to save someone from a murderer knocking at the door.

For Kant, truthfulness is not a rule that we may set aside when the consequences become unpleasant. If I make an exception of myself, I weaken the very law that I expect others to obey. Nor can I ever have complete control over the consequences. The person I am hiding may have escaped through the back door. Through some unforeseen turn of events, my lie might then contribute to the very outcome I intended to prevent.

There is something important in Kant’s severity. It reminds us how readily we grant ourselves permission to lie when we believe that we have good reasons. Many lies are told in the name of care, politics, religion, or the common good. The liar rarely presents the lie as evil. We say that we are protecting someone, sparing them, or serving a higher cause.

Yet Kant’s answer also seems too strict. A person who tells the murderer where the victim is hiding can hardly wash their hands of the matter and say: I merely did my duty to the truth. Truthfulness also derives its moral meaning from a human situation. When a truthful answer delivers an innocent person into the hands of violence, it is no longer enough to ask whether the words were correct. We must also ask whom the truth served.

Nietzsche’s Suspicion

Nietzsche makes the question more unsettling—not by simply saying that a lie is truth, or that all claims are equally true, but by challenging the very idea that human beings have direct access to a pure, uninterpreted reality. Already in his early essay *On Truth and Lies in a Nonmoral Sense*, he argues that we think and speak through concepts, images, and metaphors. Language does not simply mirror the world; it orders, simplifies, and interprets it.

What we call truth is therefore not merely something we discover. Truth is also shaped through human perspectives, habits, and relations of power. Some truths are acknowledged because they fit the order a society has already established. Other experiences are overlooked because they lack language, authority, or witnesses.

Nietzsche does not thereby abolish the distinction between speaking truthfully and deceiving. Rather, he makes us aware that those who claim to possess the truth may also be concealing something—perhaps above all from themselves. A literally correct statement can present a profoundly untrue picture of a human being. A story may contain invented characters and events, yet still reveal something true about grief, love, or fear.

Here we approach a crucial distinction: the opposite of a lie is not always the whole truth, and the opposite of truth is not always fiction.

A Lie Requires an Intention

A lie is more than a statement that turns out to be false. I can be mistaken without lying. I may remember incorrectly, misunderstand a question, or rely on incomplete knowledge. A lie begins when I say something I believe to be false with the intention that another person should believe it to be true.

Intention therefore matters. But a good intention is not enough. Parents may lie to children because they want to spare them. Doctors have in the past withheld diagnoses in order to protect patients. Governments may conceal information in the name of public safety. In all these cases, care can slide into paternalism. The person who lies assumes the right to decide what reality another person will be allowed to inhabit. And often, if we are honest, the liar also escapes the discomfort of facing the truth.

We must therefore ask more than whether the lie was well-intentioned:

- Am I protecting the other person, or am I protecting myself?

- Does the lie prevent serious harm or injustice—or merely an uncomfortable conversation?

- Am I depriving the other person of the possibility of making a free choice?

- Is this a temporary act of necessity, or the beginning of a pattern?

- Am I willing to accept responsibility if the lie is later exposed?

The lie told to hide someone who is being persecuted differs from the lie that conceals infidelity, abuse of power, or personal gain. In the first case, I am trying to prevent another person from committing a grave injustice. In the second, I am often trying to avoid the consequences of my own actions. Both are lies, but they are not morally equivalent.

Does Everyone Have a Right to the Truth?

The question may also be put differently: Does every person have a right to every truthful answer?

No. Truthfulness does not mean that we owe everyone complete openness. A human being has a right to a private sphere. Silence is not necessarily a lie. We may decline to answer a question, say that we do not wish to respond, or protect something another person has told us in confidence. The person who asks does not automatically acquire ownership of the truth.

This becomes particularly clear when a question is asked under coercion. The murderer at the door does not seek the truth in order to understand, but in order to harm. He has turned truth into an instrument of violence. Denying him that truth is not a betrayal of the human community. It may instead be a way of defending it.

Yet even here we do not find a rule that resolves everything. If we say that lying is permissible whenever we ourselves believe that the purpose is good, we have opened a dangerous door. Practical philosophy cannot close this door with a simple formula. It can only require us to pause before it and examine who is being protected, who is being harmed, and who is being given power over reality.

A Promise I Broke

Let me leave the thought experiment for a moment. I have stood at such a threshold myself. There was no unknown murderer to turn away, only a relationship of trust for which I was responsible.

In my work, I was responsible for helping a pregnant woman who was using drugs during her pregnancy. To protect the child, I had to persuade her to give birth in hospital. She demanded a promise from me as a condition: that she would be allowed to keep the child with her after the birth. I gave her that promise. And I lied, because I knew that it would not be kept.

The child was born with withdrawal symptoms and had to be flown by helicopter to Oslo in order to be saved.

This differs from Kant’s murderer at the door in one crucial respect. I did not merely refuse a stranger’s demand for a truthful answer. I made a promise that I knew from the outset I would break, to a person who was dependent on me and who trusted me precisely because I represented an institution with power over her life. It was the slide into paternalism that I described earlier. But this time it was not some distant doctor or public authority. It was I, there in the room, who assumed that right.

Was it necessary? The child’s condition revealed how serious the danger had been. Whether the lie was the only possible path, I cannot know. At the time, I saw no other way. Did that make it good? No.

The theologian Dietrich Bonhoeffer himself lived with concealment and deception through his resistance to Nazism and during his interrogation by the Gestapo. In his 1943 essay *What Does It Mean to Tell the Truth?*, written while he was living under this pressure, he argued that truth is never merely a matter of correspondence between a statement and a fact. Truth is something that happens *between* human beings, shaped by the relationship in which we stand and by the responsibility we bear.

Bonhoeffer did not write from a safe distance. For him, literal truth could become an instrument of a criminal regime. But that did not make deception innocent. He could not take refuge in a simple rule, even when deception was used to protect human beings. I recognise something of this. The unease following my own action has never left me, even though I have never doubted the seriousness of the situation.

When I put the five questions to myself, the answers are not simple either. I was protecting the child above all, not myself. I was trying to prevent serious harm and perhaps to save a life. I deprived the woman of a choice, and that too must be said. But the choice stood between her wishes and the child’s life and health. It was an act of necessity, not a pattern. And I have had to bear responsibility for it ever since. Carrying it has never become easy.

Truth as a Relationship

Truth is not merely a matter of correspondence between a statement and a fact. Between human beings, truth is also a relationship. To speak truthfully is to allow the other person to encounter the world without my having secretly falsified it. This is why a lie can be experienced as a profound betrayal, even when the matter itself appears small. What hurts is not only that something was false. It is the discovery that the relationship was not what one believed it to be.

At the same time, the truth can be spoken without truthfulness. We may choose the most hurtful moment, omit the context, and utter a correct statement in order to humiliate another person. “I am only telling the truth” is sometimes the defence of the cruel. But a truth used to wound does not become false. It becomes a truth without care or responsibility.

The boundary between truth and lies therefore does not run only between correct and incorrect statements. It also passes through intention, situation, and our relationship to the other person. Yet we must hold fast to the fact that the boundary exists. If everything is merely a matter of perspective, those in power may also call their propaganda their truth. Nietzsche’s suspicion must therefore be directed both ways: towards those who claim to possess the final truth, but also towards those who use perspective as an excuse for deception.

A Necessary Unease

Is it permissible to lie in order to save a human being? I believe that it is. There are situations in which the protection of life and human dignity, and the need to prevent grave injustice, outweigh the duty to give a truthful answer. But this does not make the lie good. It may be necessary—and still leave behind an unease.

Perhaps this unease is itself morally important. It reminds us that we have violated something valuable, even if we did so in order to protect something more valuable still. The dangerous liar is not always the person who lies, but the person who lies without unease, without responsibility, and without asking what the lie does to another human being.

Truth cannot be reduced to a rule applied without judgement. But neither can it be reduced to a perspective that we are free to shape according to our needs. We live between these extremes: between the demand for truthfulness and our responsibility for the other person.

The question for practical philosophy may therefore be not only, “Am I permitted to lie?” It is also, “What am I trying to protect—and am I willing to bear responsibility for what I say?”

For truth does not belong to words alone. It also reveals itself in the way we protect another person’s life, freedom, and trust—whether that person is a stranger knocking at a door, or a person asking you for a promise you know you must break.