The "xing e shuo (性悪説)" is Xunzi (荀子)'s most important work reguarding humanity. But many researchers assert that "xing e shuo (性悪説)" is wrought with pradox without thinking about the basis and the aim of "xing e shuo (性悪説)".
Xunzi (荀子) held that "xing (性)" isn't a substantial concept of it own. Xing, he thought, is a movement of desire, and this desire has a tendency to cause disorders. But, on the other side, this desire is able to tell righ from wrong. It means that "xing (性)" is ont only right but also wrong. In this respect, it has two meanings. From this perspective, Xunzi (荀子) asserted the "xing e shuo (性悪説)".
He asserted that humanity must repress and control their desire by themselves, and have to reform their "xing (性)" in order to become a shengren (聖人=a confucian sage)