Use when assessing the real cost of an action and tempted to focus only on the literal target. Use when a justification depends on dehumanizing the victim ('no real person was hurt'). Use when you want to see through self-deception by asking what the deed did to the doer.

This is the novel's deepest contradiction and its moral core. Raskolnikov insists the old woman was 'a louse,' yet he also knows 'I am perhaps viler and more loathsome than the louse I killed.' The theory was supposed to elevate him above ordinary morality; instead it crushed his own soul before any court could. It is a permanent corrective to the 'no real harm done' defense.