Why does AI get things wrong: understanding hallucinations
A hallucination is a false answer delivered with confidence. It stems from how language models work — they generate what is plausible, not what is verified. No current model is immune. The remedy is methodological: ask for sources, cross-check, verify every critical fact.
A hallucination is a false response produced by generative AI, delivered with the same confidence as an accurate answer. It is not an occasional bug: it is a direct consequence of how language models work — they generate what is plausible without verifying. No current model is entirely free of it. The good news is that the phenomenon can be managed through method: knowing when to be wary, demanding sources, verifying critical facts.
Where hallucinations come from
The model predicts the most likely continuation. When it does not have the exact information, it does not stop to say it does not know: it produces a coherent continuation, which may be false. It can invent a reference, a quote, a statistic, a law article, a court ruling, a book title, with perfect confidence.
The phenomenon worsens on precise topics that are poorly represented in the data, on very recent facts, and on requests that call for an exact reference.
How to spot them
Be wary of overly precise answers on verifiable points: an exact number, a date, an attributed quote. These are precisely where invention creeps in. Be wary of references that do not exist anywhere else. Be wary when the answer comes without the slightest hesitation on a topic where a human expert would hedge.
How to protect yourself
Adapt your vigilance to the stakes. For a draft, a reformulation, an idea, an error is inconsequential. For a health, legal or financial decision, it can be costly.
Ask for sources and verify them yourself in the primary source. A source cited by AI must exist and say what it claims.
Cross-check with a reliable independent source. For law, Légifrance and EUR-Lex. For administration, service-public.fr. For health, a professional.
Rephrase the question from another angle. If the answers diverge, be wary.
Frequently Asked Questions
Will hallucinations disappear?
They decrease with technical progress and the addition of real-time search, but no method eliminates them entirely to date.
Does an AI connected to the internet hallucinate less?
Often yes on recent facts, because it can cite sources. But it can misinterpret what it reads. Verification remains necessary.
Is it serious?
It depends entirely on the use. The rule is simple: never base an important decision on an unverified response.
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