...communitarian individualism could not survive the intellectual, economic, and political developments of nineteenth century America. A new and more distinctively American form of individualism emerged and began to develop independently of the older religious and civic forms that were European in origin. The humanistic Unitarianism that eventually came to displace the Calvinistic Protestantism of New England emphasized the capacity of the individual soul for growth and perfectibility, and all social and political forms came to be seen as subservient and secondary to the perfection of the soul. This new individualist credo was expressed in the religious teaching of W.H. Channing, which many identified as the basis of the new religion for the new democracy, but it found its purest expression in the writings of Ralph Waldo Emerson. For Emerson, self-reliance and self-determination forms the true basis for democracy: "The root and seed of democracy is the doctrine, Judge for yourself" ... Emerson and later theorists such as Josiah Warren, whose doctrine of the "sovereignty of the individual" greatly influenced John Stuart Mill ..., rejected any form of social organization that would constrain the autonomy of the individual...

The Disappearance of the Social
in American Social Psychology
p. 149, emphasis mine