This methodology goes back to the time of Plato and has been the major methodology used by philosophers since then.
The basic idea is that questions like 'What is knowledge?', 'What is justice?', or 'What is truth?' can be answered solely on the basis of one's grasp of the relevant concepts.
The primary reason for using conceptual analysis is to understand the meaning of an idea or concept. The secondary reason is to determine how that idea or concept relates to other philosophical problems. A good example of this is in Plato’s Republic, where he analyzes the concept of justice in context to the ideal state.
Although conceptual analysis is primarily used by philosophers with regard to abstract ideas, this type of analysis is of great importance for all other academic disciplines. The notion that a precise definition is first and foremost necessary in the analysis of any idea or concept, before any investigation into its meaning and relationship to other ideas and concepts, is what generates understanding and the expansion of knowledge for any subject area. Understanding philosophical concepts is paramount to understanding religion, the arts, and the natural and social sciences.