Why can ChatGPT provide different answers to the same question?

Why can ChatGPT provide different answers to the same question?

ChatGPT can provide different answers because text generation allows multiple plausible continuations, and an apparently identical question may be processed with different surrounding context.

Different wording does not necessarily mean a different factual conclusion. Two accurate explanations can use different examples or organize the same ideas differently.

More than one continuation can fit

A language model assigns scores to possible next tokens. Depending on the decoding method, the system may sample from a distribution instead of always choosing the highest-scoring token.

Once one token differs, later generation follows a different context. A small variation can therefore change the structure of an entire paragraph.

OpenAI's generation documentation notes that outputs are nondeterministic and that different model versions can behave differently.

The visible question is not the entire input

Earlier messages, application instructions, supplied files, and tool results can influence a response. A request to "explain recursion" may produce a different answer after a discussion of JavaScript than after a discussion of mathematics.

Model updates and changes in retrieved information can also matter. Searching a changing website may produce different evidence even if the question stays the same.

Compare substance, not just phrasing

For a creative task, variation may be helpful. For a factual or structured task, decide which aspects must remain stable and evaluate those directly.

You might require a summary to preserve three specified facts while allowing different wording. If repeated answers disagree about those facts, investigate the evidence rather than assuming the most common answer is correct.

Clear instructions and a stable evaluation setup improve consistency, but they do not turn every generated response into a guaranteed repeatable fact.