What type of question is most effective for uncovering underlying assumptions in a person's reasoning?

The most effective type of question for uncovering underlying assumptions in a person's reasoning is a probing question. Probing questions are designed to delve deeper into a person's thinking, challenging them to articulate the reasons behind their statements and to examine the validity of their beliefs. These questions often start with phrases like 'Why do you believe that?', 'What makes you say that?', 'Can you explain your reasoning behind this conclusion?', or 'What evidence supports that claim?' Unlike leading questions, which subtly suggest a desired answer, or closed-ended questions, which elicit only brief responses, probing questions encourage the speaker to explore their thought process, making any hidden assumptions more apparent. For example, if someone states 'This project will definitely fail,' a probing question would be 'What specific factors lead you to believe that the project will fail?' This question prompts them to reveal the underlying assumptions or concerns that are driving their pessimistic prediction.