Mill's mission in writing On Liberty can perhaps be best understood by
looking at how he discussed his work in his Autobiography. Mill wrote
that he believed On Liberty to be about "the importance, to man and
society, of a large variety in types of character, and of giving full freedom to
human nature to expand itself in innumerable and conflicting directions." This
celebration of individuality and disdain for conformity runs throughout On
Liberty. Mill rejects attempts, either through legal coercion or social
pressure, to coerce people's opinions and behavior. He argues that the only
time coercion is acceptable is when a person's behavior harms other
people--otherwise, society should treat diversity with respect.
Mill justifies the value of liberty through a Utilitarian approach. His
essay tries to show the positive effects of liberty on all people and on society
as a whole. In particular, Mill links liberty to the ability to progress and to
avoid social stagnation. Liberty of opinion is valuable for two main reasons.
First, the unpopular opinion may be right. Second, if the opinion is wrong,
refuting it will allow people to better understand their own opinions. Liberty
of action is desirable for parallel reasons. The nonconformist may be correct,
or she may have a way of life that best suits her needs, if not anybody else's.
Additionally, these nonconformists challenge social complacency, and keep
society from stagnating.
Mill's argument proceeds in five chapters. In his first chapter, Mill provides
a brief overview of the meaning of liberty. He also introduces his basic
argument in favor of respecting liberty, to the degree it does not harm anybody
else. His next two chapters detail why liberty of opinion and liberty of action
are so valuable. His fourth chapter discusses the appropriate level of
authority that society should have over the individual. His fifth chapter looks
at particular examples and applications of the theory, to clarify the meaning of
his claims.
Mill's essay has been criticized for being overly vague about the limits of
liberty, for placing too much of an emphasis on the individual, and for not
making a useful distinction between actions that only harm oneself, and actions
that harm others. That said, the essay does provide an impassioned defense of
nonconformity as a positive good for society, and an equally impassioned
reminder that no one can be completely sure that his or her way of life is the
best or the only way to live.