In persuasive writing, clear logic is vital for the writer’s claim to be accepted by the reader. This importance of logic is widely recognized by English teachers at the secondary school level, where teaching of logic is considered an essential part of the teaching of persuasive writing. In teaching logic, it is general practice to judge the logicality of a piece of writing based on whether it follows a specific discourse structure. However, such a formal approach has its own limitation because the essence of logic resides not in the superficial structure of a passage but rather in the contents of the discussion. Since the contents of discussion are topic-specific, the writer cannot build an effective logic based only on a general superficial structure. To overcome this limitation, the author focused on the specific content of each piece of writing which his students wrote, and taught them to build their logic through an inductive process before finally reaching a deductive logic, which is standard in persuasive writing. This approach contributed to improving the students’ logic by enabling them to explore specific contents before reaching more abstract reasoning.