 Liberal defenders of pornography readily admit that, if there were reliable evidence to show that consumption of pornography significantly increases the incidence of violent sexual crime, there would be a very strong liberal case for prohibiting it. However, liberal defenders of pornography remain unconvinced that there is reliable evidence to show that pornography is a cause of rape or other sexual crime. Ronald Dworkin, for example, writes “…in spite of MacKinnon’s fervent declarations, no reputable study has concluded that pornography is a significant cause of sexual crime: many of them conclude, on the contrary, that the causes of violent personality lie mainly in childhood, before exposure to pornography can have had any effect, and that desire for pornography is a symptom rather than a cause of deviance” (1993, 38).