Mill might have adduced a catena of authorities beginning with the seventeenth century writers who,having themselves suffered persecution,were slowly perceiving that persecution even of error was objectionable.It is a proof of his ability that he could give fresh interest to so old a topic.In the previous generation indeed it had still been a practical question.The early Utilitarians had to attack the disqualifications imposed upon dissenters,and had remonstrated against the persecution of Carlisle.That incident had started Mill's literary career.

Moreover,as he points out,the prosecutions of Pooley,Truelove,and Mr Holyoake showed that the old spirit was not extinct in 1857.(8)Still,these were but 'rags and remnants of persecution.'In denouncing them Mill was going with the tide.

The ground upon which he plants his argument is more significant.

The older writers had chiefly insisted upon the question of right.It cannot be just to punish a man for acting rightly,and it must surely be right for me to speak what I conscientiously believe to be true.One of James Mill's articles in the Westminster took this ground.Samuel Bailey had argued that a man cannot be responsible to men for his beliefs,inasmuch as they are beyond his own control.He may be foolish,but he cannot be immoral --a thesis which James Mill defended against certain theological opponents.(9)J.S.Mill,taking the ground of 'utility,'is led to wider considerations.He argues in substance that the suppression of opinions or of their free utterance is always opposed to the most vital interests of society.Hence the question as to liberty of thought connects itself with the whole question as to liberty of conduct.It comes under his general principle as to the rightful provinces of collective and individual action.His general conclusion upon freedom of dismission is summed up in four propositions.(10)The opinions suppressed may,in the first place,be true.To deny that possibility is to assume infallibility.Secondly,if not wholly,they may be partly,true;and to suppress them is to prevent necessary corrections of the accepted beliefs.Thirdly,even a true opinion which refuses to be tested by controversy will be imperfectly understood.And fourthly,an opinion so held will become a dead formula,and only 'cumber the ground,'preventing the growth of real and heartfelt convictions.