There are two broadly philosophical literatures on pornography. By far the largest is concerned with moral issues raised by pornography. This literature falls into two phases. The first phase comprises the debate between moral conservatives, who objected to pornography on the grounds of its explicit sexual nature, and liberals, who defended pornography on grounds of something like freedom of speech or expression. Though this debate is not stone cold, the liberals seem to have won it. However, it has been largely replaced by a different one between feminists who object to pornography on the basis that it contributes to the oppression of women and those who reject these feminist arguments. There is also a much smaller literature concerned with aesthetic or artistic issues concerning pornography. For the most part, this literature has been concerned with examining the distinction commonly made between pornography and art (particularly 'erotic art').