...there ought to exist the fullest liberty of professing and discussing, as a matter of ethical conviction, any doctrine, however immoral it may be considered.
John Stuart MillThis is what writers mean when they say that the notion of cause involves the idea of necessity. If there be any meaning which confessedly belongs to the term necessity, it is unconditionalness. That which is necessary, that which must be, means that which will be, whatever supposition we may make in regard to all other things.
John Stuart Mill... All ideas need to be heard, because each idea contains one aspect of the truth. By examining that aspect, we add to our own idea of the truth. Even ideas that have no truth in them whatsoever are useful because by disproving them, we add support to our own ideas.
John Stuart MillAll political revolutions, not affected by foreign conquest, originate in moral revolutions. The subversion of established institutions is merely one consequence of the previous subversion of established opinions.
John Stuart Mill