In his book On Liberty, John Stuart Mill lays the foundation for liberal thought and his ideas have penetrated many aspects of democratic rights and freedoms. His concern emanated from the fact that considerably more people (due to manifold revolutions in Europe and the United States) were involved in the legislative process and political decision-making than previously when it has been restricted to the monarchs and nobility. Like Constant, Tocqueville, and many contemporaries of his day, Mill feared the tyranny of the majority would infringe or suppress the vital interests of an individual who dared to disagree with the mob.
Heavily influenced by the Enlightenment, Mill gave three arguments in defence of the individual’s right to express himself through ideas and opinions that were novel or contrary to the norms of the day. First, he posited that the idea that had previously been thought false or misguided might actually be true and ample proof would be provided in time. Second, if the idea showed itself to be false, then the criticism and argument that went towards disproving it would inevitably strengthen the truth of its counterpart. Thirdly, the idea might not consist of the whole truth, but may in fact be merely a part of it, in which case we ought to consider it all the same. Healthy debate of new ideas is conducive to the progress of society and contributes to the self-development of an individual who conceives such hypotheses and embarks on such investigations.