The 5 Whys is a root-cause analysis technique developed by Sakichi Toyoda and refined within the Toyota Production System. By repeatedly asking "Why?" — typically five times — you move from surface-level symptoms to the underlying cause of a problem. Simple, fast, and remarkably effective for operational and interpersonal problems, it is the most widely-used structured problem-solving technique in manufacturing, software, and management worldwide.
Rubber Duck Debugging is the practice of explaining a problem in detail to an inanimate listener — traditionally a rubber duck — to solve it. The act of articulating a problem precisely and sequentially, out loud or in writing, triggers the self-explanatory process that reveals where reasoning has gone wrong or where assumptions are unjustified. Widely used in software engineering, it extends to any problem-solving context where verbalisation clarifies thinking.