Within the public sphere, inequality produces harm and injustice for the members of marginalised groups. Drawing on the contemporary debate among liberal political theorists, this chapter analyses the formation of public opinion, highlighting its political implications. It explains the concepts of epistemic and structural injustice. The chapter describes the concept of dialogic injustice to depict the specific form of epistemic injustice which harms members of marginalised and oppressed groups when they experience credibility deficits or apparently insurmountable difficulties in acceding to the public sphere as free and equal members. There are two main assumptions for the existence of a public sphere. First, within a certain society there is a sufficient degree of liberty to allow the proliferation of ideas, opinions, beliefs, and tastes. Second, all these different ideas, opinions, beliefs, and tastes can be publicly spelled out and any citizen has equal right to express her/his own thought or to profess her/his faith.