Everyone seems to agree that a nation's willingness to fight is vital for its defense and resilience in the event of an attack. In Swedish history, interpretations of this concept have varied, but no lasting scientific definition has emerged. Previousresearch in the field has taken a quantitative approach, focusing on identifying variables that seem to influence the willingness to fight. Few researchers have attempted to explain the significance of the concept itself. This study aims to bridge the gap that arises when researchers measure willingness to fight without truly understanding what the concept entails.Using Gerring’s conceptual theory, this study analyzes the understanding and application of the concept willingness to fight within the context of the Swedish total defense. The result reveals a broad interpretation, emphasizing the necessity of finding a common definition of the concept to mitigate potential misunderstandings and enhance its scientific and practical utility.