Why did John Stuart Mill fear that public opinion could restrict individual freedom?

John Stuart Mill feared that public opinion could restrict individual freedom because he believed that, in a democracy, the collective voice of the majority could become a form of oppression. While he accepted democracy as inevitable, he was concerned that complete democracy might not emancipate opinion but instead make it more restrictive, leading to a "tyranny of the majority" where minority views and individual creativity are stifled.12

Mill argued that civilization relies on the free play of speculative intelligence and the contributions of a minority of creative minds. He believed that without the freedom to express diverse and even dissenting opinions, society would become a "stagnant pool" and progress would cease. Consequently, he insisted that the "collision of adverse opinions" is essential for the search for truth. For Mill, the worth of a state is ultimately determined by the worth of the individuals composing it; therefore, he viewed the pressure of conventional public opinion as a significant threat to the intellectual and cultural development of society.13