The subject of this essay is "Social Liberty: the nature and limits of the power which can be legitimately exercised by society over the individual." "The struggle between Liberty and Authority is the most conspicuous feature ... of history". In previous societies, this struggle was between the ruler and the ruled. A powerful sovereign was a dangerous necessity, to prevent harm from outsiders.
Limits to the sovereign's powers were attempted in 2 ways:
- Recognition by a ruler of their duty to protect certain political rights of their subjects, failure of which justified revolution, and to which most rulers were forced to accept.
- The establishment of constitutional checks on executive power.
Over time, those being ruled realised that it was preferential to have temporary rulers who shared the interests of the ruled, rather than permanent rulers who's interest were at odds with theirs. When representational democracy was realised, the demands to constrain the authority of government lessened.
It is a mistake to think that popular government needs no limits. "The “people” who exercise the power, are not always the same people with those over whom it is exercised, and the “self-government” spoken of, is not the government of each by himself, but of each by all the rest." The majority can still impose its will on society.
But the tyranny of the majority can come from society as well as public officials. " Protection, therefore, against the tyranny of the magistrate is not enough; there needs protection also against the tyranny of the prevailing opinion and feeling; against the tendency of society to impose, by other means than civil penalties, its own ideas and practices as rules of conduct on those who dissent from them; to fetter the development, and, if possible, prevent the formation, of any individuality not in harmony with its ways, and compel all characters to fashion themselves upon the model of its own."