John Stuart Mill's On Liberty (1859) launches a diatribe against conformity. He claims that collectivity threatens to annihilate the very core of English individuality:
The greatness of England is now all collective; individually small, we only appear capable of anything great by our habit of combining; and with this our moral and religious philanthropists are perfectly contended. But it was men of another stamp than this that made England what it has been; and men of another stamp will be needed to prevent its decline. The despotism of custom is everywhere the standing hindrance to human advancement. 
Whereas custom and habit were the eighteenth-century tools that Hume used to ply his skepticism, Mill sees the "despotism of custom" as an all-pervasive herd mentality, which diminishes the individual. Human achievement is performed by the collective work of philanthropy, says Mill. The England of individual greatness and achievement is long gone. The true individual has become a hindrance that the masses threaten to snuff out at every turn.
Mill sees mass psychology developing in two directions at once. On the one hand, state power becomes a vehicle of the masses:
A more powerful agency . . . is the complete establishment, in this and other free countries, of the ascendancy of public opinion in the State. As various social eminences which enabled persons entrenched on them to disregard the opinion of the multitude gradually become leveled; as the very idea of resisting the will of the public, when it is positively known that they have a will, disappears more and more from the minds of practical politicians; there ceases to be any support for nonconformity – any substantive power in society which, itself opposed to the ascendancy of numbers, is interested in taking under its protection opinions and tendencies at variance with those of the public. 
Democracy takes on a newfound strength in the form of public opinion. The will of the people speaks with one voice, and as a result, the nonconformist becomes a nonentity in the world of politics. The State has devolved the sources of its power to the masses with the result that laws and policies come to institutionalize and codify the Public Will as a monolithic entity.
If State power is one pole of collective uniformity that operates from the pinnacles of society downwards, the crowd is the basis of popular sentiment that extends upwards:
[Public opinion is] always a mass, that is to say, collective mediocrity. And what is still greater novelty, the mass do not take their opinions from dignitaries in Church or State, from ostensible leaders, or from books. Their thinking is done for them by men much like themselves, addressing them or speaking in their name, on the spur of the moment, through the newspapers. 
In the form of public opinion mass sentiment detached itself from the dictates of State authority. The State is no longer led by dignitaries or emissaries but by print mouthpieces to the public sphere. The tropes of anonymity in print debate (think of letters signed "Publius" or "A Citizen") become a faćade for the herd mentality, which claims to speak for everyone.
The behavior of both State institutions and mass mediate threaten to destroy the nonconformist individual who would dare to say and think otherwise.
1. A century after Adam Smith's Theory of Moral Sentiments (1759) sought to regulate feeling through the function of sympathy, Mill's
2. How does taste operate as a conformist tendency?
3. How does Mill's cry against the mediocrity of mass thought align with Arnold's call for a culture of sweetness and light?
4. What role does sentiment play on Mill's Utilitarianism?
Mill, John Stuart.
Last modified 3 December 2006