This study examines how individuals reason about, justify, and morally evaluate counterproductive knowledge behavior (CKB) in the workplace, including knowledge hiding, hoarding, and sabotage. While prior research largely frames these behaviors as harmful, this study questions whether such framing aligns with how employees understand and justify these actions in everyday work contexts. Using a qualitative vignette-based approach, 150 working adults in the United States were recruited via Prolific and asked to respond to scenarios depicting different forms of CKB. Participants provided open-ended explanations of their reasoning, justification, and evaluations. The data were analyzed using abductive thematic analysis to identify recurring patterns in how individuals interpret, justify, and morally evaluate these behaviors. Findings reveal that participants often view CKB as contextually acceptable or even necessary, depending on the situation. Individuals justify these behaviors through a range of motives, including self-interest, relational concerns, workplace norms, restorative justice, and perceived unfairness or retaliation. Moreover, moral evaluations of CKB vary, with participants describing these behaviors as ethical, unethical, or ambiguous depending on the context. The study contributes to a more nuanced understanding of workplace behavior by highlighting the role of moral reasoning in shaping how CKB is interpreted and evaluated. It suggests that counterproductive behaviors cannot be fully understood without considering the subjective and context-dependent nature of moral judgment. These insights have implications for how organizations address knowledge-related behaviors and manage ethical decision-making in complex work environments.