The architect of the Toyota Production System, Taiichi Ohno, described the 5 Whys method as "the basis of Toyota's scientific approach by repeating why five times the nature of the problem as well as its solution becomes clear."
丰田生产系统的设计师大野耐一曾经将五问法描述为“……丰田科学方法的基础……重复五次，问题的本质及其解决办法随即显而易见”。