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Notes on AIE033Act 3 — Steering & Trust

What Hallucinations Are

E033 · by — AI Strategist, Practitioner & Educator · Founder, AI Center of Excellence

Define hallucinations accurately without mystique.

Full Explanation

A hallucination is what happens when an AI model produces plausible-sounding text that isn't actually true. The word suggests something unusual — a drift, a malfunction. But the model isn't doing anything unusual. It generates the most plausible continuation of its input, exactly as it was trained to. When that output happens to match reality, we call it correct. When it doesn't, we call it a hallucination. The model was doing the same thing both times.

There is no built-in step in the core generation process where the model checks its output against reality. Modern systems can reduce hallucinations by adding external checks — retrieving documents, verifying against sources, applying constraints — but these work around the model, not inside it. The underlying behavior doesn't change: the model produces fluent text with no mechanism for knowing whether that text is true. That gap between fluency and truth is the thing to understand.

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Transcript

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A hallucination isn't a malfunction of a YAG model, it is a normal output. We use the word "hallucination" as if something unusual is happening, as if the model drifted into a strange state and started dreaming or began to invent. This is not exactly what is happening. Here is what the model actually does. Given any input, it generates the most plausible sounding continuation. It was trained on enormous amount of text, so it learned what fluid or structured language looks like. And it produces exactly that. There is no built-in step where the model checks the answer against reality.

It has no mechanism for that. Large language models by design generate text that sounds right, because that is what it was trained to do. When the output happens to match reality, we call it a correct answer. When it doesn't, we call it a hallucination. But the model was doing the same thing both times. So if we define it simply, a hallucination is a plausible sounding answer that isn't actually true. Confidence is not something it adds on top when it is sure. It is the default register of the output, because the training data was written by humans that sounded confident.

Now an important clarification. This doesn't mean that nothing can be improved. Modern systems are already designed to reduce hallucinations. They can check answers against external sources, retrieve documents, apply constraints, or verify parts of the output. And these systems are getting better. But notice something important. All of that happens around the model, not inside the core generation step. The model itself is still producing the most plausible continuation. So hallucinations can be reduced even significantly, but the underlying behavior, producing fluent text without a built-in truth check, does not change.

A hallucination is not the model breaking down. It is the model working exactly as it was designed. Producing fluent text with no way to know whether the text is true or not. Even as systems around it improve, the distinction remains. The gap between fluency and truth is the thing to understand. This was a note on AI. today, thank you for watching and see you in the next one.

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Alexey Makarov

Alexey Makarov

AI Strategist, Practitioner & Educator. Founder & Global Lead of the AI Center of Excellence at SEFE. Creator of the Unreasonable AI YouTube channel. Based in Berlin.

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