d
institutions to new conditions. To advance knowledge and to correct
errors, unrestricted freedom of discussion is required.

[240] History shows that knowledge grew when speculation was perfectly
free in Greece, and that in modern times, since restrictions on inquiry
have been entirely removed, it has advanced with a velocity which would
seem diabolical to the slaves of the mediaeval Church. Then, it is
obvious that in order to readjust social customs, institutions, and
methods to new needs and circumstances, there must be unlimited freedom
of canvassing and criticizing them, of expressing the most unpopular
opinions, no matter how offensive to prevailing sentiment they may be.
If the history of civilization has any lesson to teach it is this: there
is one supreme condition of mental and moral progress which it is
completely within the power of man himself to secure, and that is
perfect liberty of thought and discussion. The establishment of this
liberty may be considered the most valuable achievement of modern
civilization, and as a condition of social progress it should be deemed
fundamental. The considerations of permanent utility on which it rests
must outweigh any calculations of present advantage which from time to
time might be thought to demand its violation.

It is evident that this whole argument depends on the assumption that
the progress of the race, its intellectual and moral development,

[241] is a reality and is valuable. The argument will not appeal to any
one who holds with Cardinal Newman that "our race's progress and
perfectibility is a dream, because revelation contradicts it"; and he
may consistently subscribe to the same writer's conviction that "it
would be a gain to this country were it vastly more superstitious, more
bigoted, more gloomy, more fierce in its religion, than at present it
shows itself to be."

While Mill was writing his brilliant Essay, which every one should read,
the English Government of the day (1858) instituted prosecutions for the
circulation of the doctrine that it is lawful to put tyrants to death,
on the ground that the doctrine is immoral. Fortunately the prosecutions
were not persisted in. Mill refers to the matter, and maintains that
such a doctrine as tyrannicide (and, let us add, anarchy) does not form
any exception to the rule that "there ought to exist the fullest liberty
of professing and discussing, as a matter of ethical conviction, any
doctrine, however i