The sole end for which mankind are warranted, individually or collectively,
in interfering in the liberty of action of any of their number, is self-protection.
That the only purpose for which power can be rightfully exercised over any
member of a civilized community, against his will, is to prevent harm to others.
His own good, either physical or moral, is not a sufficient warrant. He cannot
rightfully be compelled to do or forbear because it will be better for him to do
so, because it will make him happier, because in the opinions of others, to do
so would be wise, or even right.
John Stuart Mill, On LIberty (London, 1859)