Why do AI models hallucinate?

AI hallucinations occur when models generate false information with high confidence, such as citing non-existent research papers or fabricating statistics. These errors stem from the predictive nature of AI, which attempts to determine the next likely word or idea based on vast internet datasets; when faced with obscure or niche topics, the system prioritizes being helpful over admitting ignorance. To mitigate this, developers at Anthropic train models like Claude to value honesty and utilize rigorous testing with thousands of "trick" questions to measure accuracy and appropriate hedging. Users can reduce the impact of these errors by explicitly telling the AI it is acceptable to not know an answer, asking the model to verify its own sources in a new chat session, and cross-referencing critical data like dates and names with trusted external sources.