In what sense is Mencius' theory of good nature reasonable? Under what circumstances will there be negative effects?
When the society is harmonious and the etiquette and law are stable, the theory of good nature is beneficial to educate and guide people to encourage good deeds, improve their self-cultivation and maintain a good social order.
However, in the era of the collapse of rites and the horror of turmoil, the theory of good nature will be pedantic and useless. After all, only a person who meets material needs can become a person with real spiritual pursuit, not an animal.