Why does AI "lie"? ── Easy-to-understand explanation of the halcination problem

![Why does AI "lie"?] ](images/2025-08-01-ai-hallucination/main.jpg)

"That's what AI is making up."

"ChatGPT sometimes says '' plausibly."
Have you ever heard of such a story?

In fact, this is a phenomenon called "hallucination" in AI.
Literally translated, it means "hallucinations" - that is, "telling things that are not true as if they were facts".

But why does this happen?
In this article, we will explain the true nature of halcination without using technical terms as much as possible.

What is Hallucination?

Halcination is when AI "returns information that does not actually exist in a plausible atmosphere".

For example...

Introduce papers that do not exist
Explain laws that do not exist
Talking about fictional companies and people as "real"

These can be said to be "full of confidence even though I don't know" rather than AI lying.

Why does halcination occur?

There are two main causes.

(1) AI thinks in terms of probability, not "meaning"

AI (especially language models like ChatGPT) predicts the "next word" with "probability".
In other words, it is just imitating the pattern of language, "If you say this, it looks like that, right?"

📌 *Example: If you are asked, it is natural to continue, "What is ○○?" *

However, the AI itself does not determine whether the content is true or not. **

(2) Limitations and Mixing of Training Data

AI has learned a lot of text from the past, and some of it...

Outdated information
Inaccurate information
Fiction (novels, films), etc.

In other words, for AI, "information that appears a lot on the Internet" may be prioritized.
The fact that majority rule is not true is the problem here.

When is it easy to wake up?

Halcination is especially likely to occur in the following times:

Professional content (medical, legal, research, etc.)
Minor topics (topics that AI doesn't know)
Vague questions (lack of context)

If you feel, "Is this true?", it's a possible hallucination.

How to tell the difference? What are the countermeasures?

While halcination cannot be completely prevented, the following measures can help:

✅ Check Sources

Check if the information the AI has cited has a source.
In particular, it is important to search for the title of the paper or the name of the law.

✅ Be confident but have a "skeptical attitude"

Even if the AI answers confidently, it may just be "saying it like that".
Human intuition is still important.

✅ Be Specific to Your Questions

"Is that an announcement from the Ministry of Health, Labor and Welfare in 2024?", etc., specifying a specific time and source may improve accuracy.

Conclusion|"Just the right distance" with AI

If you understand that the AI's answers are not perfect,
We can use AI as a "consulting partner" well.

AI is just a "smart suggester".
When combined with human judgment, its power is multiplied. **

That's why it's important to be suspicious and not to believe too much in order to deal with AI.
**And the final judgment is still "yourself". **