Ask “why” one more time than feels polite. That’s usually where the real answer is hiding.

First answers are the ones people keep ready. They are true enough and designed to close the subject, and most conversations stop there out of politeness. One more question past that point gets you the reason behind the reason, which is usually more specific, more honest and occasionally something the person has not said out loud before.

Try it with warmth rather than as an interrogation, and only when you actually want to know. Ask it of a rule at school or work that seems pointless, or of somebody explaining their decision. Ask it of your own opinions too, until you hit something you cannot explain further.