It is important to realize that Mill does not believe freedom to be an inherent right belonging to all men simply because they are human. Mill specifically rejects trying to justify liberty claims in this manner (by things like natural law or divine will). Rather, Mill wants to show that liberty is beneficial to the individual and to society; his book is an attempt to show the utility of individuality. As a result, he sets limits on how far liberty should extend. It would seem natural that Mill's support of liberty extends to support self- government, and in general it does. However, he believes that children and "barbarians" lack the necessary tools to enjoy liberty. For these people, it is the state's job to try to provide them with the civilized ability to enjoy freedom. For children, this results in measures like mandating public education. For barbarians, Mill leaves open the possibility of imperial rule, by which people are ruled with the hope that they can one day rule themselves. Thus, Mill accepts imperialism because he has a hierarchical conception of societies, where only some are advanced enough to benefit from the protection of individuality. Mill sees barbarians as inferior peoples, in some sense childlike. As a result, the most beneficial way of treating them is as children. Mill thus would accept a kind of benevolent imperialism whose goal was to civilize people to a state where they could benefit from self-government. For those people who were capable of self-government, however, liberty protections would still hold.

One of the most important assumptions about human nature that Mill makes is about how people best learn about their own opinions and activities. He argues that even if a person is correct, she will only truly understand her views if she is challenged by dissenting opinions and has to defend herself. A similar claim holds in the case of nonconformist activities. Mill's belief, however, is disputable; it is questionable whether people will best understand their opinions and values because of facing dissent. For example, one could argue that a person might simply become unnecessarily hurt and upset because of facing challenging views. Thus, since Mill's view is based on the social utility of individuality, if his belief is incorrect some of the strength of the theory is lost. Mill must be able to show that his theory brings about the most desirable outcome from the point of view of overall well-being. If people do not learn from dissenting opinions and nonconformity, then it is much harder to make the case that liberty increases utility. The argument would also lose a lot of rhetorical power if Mill's view of human nature were wrong. Mill is probably correct that most opinions and activities are not completely right. However, most people tend to believe that their own views are correct. Thus, if Mill is wrong that people are best off being challenged when they are right, then his other discussions would likely not have resonance with his readers, because they would not necessarily see themselves as being potentially wrong about deeply held beliefs.

Mill's theory can be seen as both bolstering and inhibiting social reformers. In some ways, his theory leaves a lot of room for social reform. Mill believes that the only way for society to progress is to allow the expression of individuality in speech and action. Thus, he leaves room for untraditional views of society to be expressed. For example, Mill would not support inhibiting the free speech of reformers, or forcing them to conform to social norms with which they disagreed. In these ways, reformers would be given a lot of freedom to pursue their vision of an ideal society. However, social reformers would also likely be frustrated by Mill's conception of liberty. While Mill believes that social reformers should not be legally or socially restricted, he would also argue that they should not legally or socially restrict other people's activities. Thus, Mill would not support movements like the 19th century temperance movement, or movements against prostitution. He accepts that reformers can try to convince people to change their view of society. He even accepts the idea that there are better and worse ways to structure society, and these reformers may be right about how society should be altered. However, regardless of the correctness of their views, Mill believes that reformers should not try to force people to adapt those views. He holds the value of individuality too highly. As a result, many of the traditional methods used by reformers would not be acceptable under Mill's system.