The four characters create a vivid metaphor: “To chase the root and investigate to the bottom.” This paints a picture of someone digging deep, following every lead (the roots) until they reach the absolute foundation (the bottom) of an issue. It's not a superficial glance; it's a complete and determined inquiry.
The concept of 追根究底 is highly valued in Chinese culture, particularly in contexts of scholarship, justice, and engineering. It reflects a mindset that prioritizes thoroughness and understanding the fundamental principles of a matter rather than accepting surface-level explanations. A close Western equivalent is “to leave no stone unturned.” However, 追根究底 has a slightly different flavor. While “leaving no stone unturned” implies a wide, comprehensive search of an area, 追根究底 suggests a deep, vertical dive to find a single, fundamental origin or cause. It's less about breadth and more about depth. This can be linked to the high value placed on intellectual rigor and the pursuit of knowledge in traditional Chinese thought. A scholar's duty was not just to know facts, but to understand the underlying principles (理, lǐ) of the world, which required a 追根究底 approach.
This idiom is common in both formal and informal contexts. Its connotation can be positive, neutral, or slightly negative depending on the situation.