Final answer:
John Stuart Mill objected to the kind of infallibility that resists questioning and imposes on individual liberties, emphasizing open debate and the harm principle in matters of personal freedom.
Step-by-step explanation:
John Stuart Mill objected to the type of infallibility that is dogmatic and resistant to questioning or criticism. His work in On Liberty stresses the importance of personal freedom and sets out the harm principle, which posits that individuals should be free to act as they wish, so long as they do not harm others. This principle is also a critique against the idea that societal norms, leaders, or governments are infallible in their judgments, and hence should not have unchecked authority over individual liberties. Mill's approach was not only a defense of individual liberty, but it was also a call for open debate and discussion, which he considered vital to the protection of a free society against the imposition of supposed infallible beliefs or actions, whether they originate from the state, society, or otherwise.