 One important dimension of the disagreement between those liberals who defend a right to pornography and those who think that liberals should be open to the legitimacy of censorship is empirical: They disagree about the crucial empirical issue of whether there is reliable evidence to show that the production and consumption of pornography by consenting adults in fact causes harm to others, particularly women. But frequently they also disagree about some important conceptual matters as well. In particular, they may disagree (albeit sometimes implicitly) about how three central elements of the harm principle should be understood: (i) exactly what counts as “harm” to others in the relevant sense; (ii) when can we say that something is a “cause,” or a sufficiently “direct cause,” of a harm; and (iii) how much harm to others is “sufficiently great” to justify coercive sanctions against the speech or conduct that produces it. In other words, they disagree about how the harm principle should be interpreted and applied.