Mr. Mill's memorable plea for social liberty was little more than an enlargement, though a very important enlargement, of the principles of the still more famous Speech for Liberty of Unlicensed Printing with which Milton ennobled English literature two centuries before. Milton contended for free publication of opinion mainly on these grounds: First, that the opposite system implied the 'grace of infallibility and incorruptibleness' in the licensers. Second, that the prohibition of bold books led to mental indolence and stagnant formalism both in teachers and congregations, producing the 'laziness of a licensing church.' Third, that it 'hinders and retards the importation of our richest merchandise, truth;' for the commission of the licenser enjoins him to let nothing pass which is not vulgarly received already, and 'if it come to prohibiting, there is not aught more likely to be prohibited than truth itself, whose first appearance to our eyes, bleared and dimmed with prejudice and custom, is more unsightly and unplausible than many errors, even as the person is of many a great man slight and contemptible to see to.' Fourth, that freedom is in itself an ingredient of true virtue, and 'they are not skilful considerers of human things who imagine to remove sin by removing the matter of sin; that virtue therefore, which is but a youngling in the contemplation of evil, and knows not the utmost that vice promises to her followers, and rejects it, is but a blank virtue, not a pure; her virtue is but an excremental virtue, which was the reason why our sage and serious poet Spenser, whom I dare be known to think a better teacher than Scotus or Aquinas, describing true temperance under the form of Guion, brings him in with his palmer through the cave of Mammon and the tower of earthly bliss, that he might see and know and yet abstain.'
The four grounds on which Mr. Mill contends for the necessity of freedom in the expression of opinion to the mental wellbeing of mankind, are virtually contained in these. His four grounds are, (1) that the silenced opinion may be true; (2) it may contain a portion of truth, essential to supplement the prevailing opinion; (3) vigorous contesting of opinions that are even wholly true, is the only way of preventing them from sinking to the level of uncomprehended prejudices; (4) without such contesting, the doctrine will lose its vital effect on character and conduct.
But Milton drew the line of liberty at what he calls 'neighbouring differences, or rather indifferences.' The Arminian controversy had loosened the bonds with which the newly liberated churches of the Reformation, had made haste to bind themselves again, and weakened that authority of confessions, which had replaced the older but not more intolerant authority of the universal church. Other controversies which raged during the first half of the seventeenth century,—those between catholics and protestants, between prelatists and presbyterians, between socinians and trinitarians, between latitudinarians, puritans, and sacramentalists,—all tended to weaken theological exclusiveness. This slackening, however, was no more than partial. Roger Williams, indeed, the Welsh founder of Rhode Island, preached, as early as 1631, the principles of an unlimited toleration, extending to catholics, Jews, and even infidels. Milton stopped a long way short of this. He did not mean 'tolerated popery and open superstition, which, as it extirpates all religious and civil supremacies, so itself should be extirpate, provided first that all charitable and compassionate means be used to win and regain the weak and the misled: that also which is impious or evil absolutely either against faith or manners no law can possibly permit that intends not to unlaw itself.'
Locke, writing five-and-forty years later, somewhat widened these limitations. His question was not merely whether there should be free expression of opinion, but whether there should furthermore be freedom of worship and of religious union. He answered both questions affirmatively,—not on the semi-sceptical ground of Jeremy Taylor, which is also one of the grounds taken by Mr. Mill, that we cannot be sure that our own opinion is the true one,—but on the strength of his definition of the province of the civil magistrate. Locke held that the magistrate's whole jurisdiction reached only to civil concernments, and that 'all civil power, right, and dominion is bounded to that only care of promoting these things; and that it neither can nor ought in any manner to be extended to the saving of souls. This chiefly because the power of the civil magistrate consists only in outward force, while true and saving religion consists in the inward persuasion of the mind, without which nothing can be acceptable to God, and such is the nature of the understanding that it cannot he compelled to the belief of anything by outward force.... It is only light and evidence that can work a change in men's opinions; and that light can in no manner proceed from corporal sufferings, or any other outward penalties.' 'I may grow rich by an art that I take not delight in; I may be cured of some disease by remedies that I have not faith in; but I cannot be saved by a religion that at I distrust and a ritual that I abhor.' (First Letter concerning Toleration.) And much more in the same excellent vein. But Locke fixed limits to toleration. 1. No opinions contrary to human society, or to those moral rules which are necessary to the preservation of civil society, are to be tolerated by the magistrate. Thus, to take examples from our own day, a conservative minister would think himself right on this principle in suppressing the Land and Labour League; a catholic minister in dissolving the Education League; and any minister in making mere membership of the Mormon sect a penal offence. 2. No tolerance ought to be extended to 'those who attribute unto the faithful, religious, and orthodox, that is in plain terms unto themselves, any peculiar privilege or power above other mortals, in civil concernments; or who, upon pretence of religion, do challenge any manner of authority over such as are not associated with them in their ecclesiastical communion.' As I have seldom heard of any sect, except the Friends, who did not challenge as much authority as it could possibly get over persons not associated with it, this would amount to a universal proscription of religion; but Locke's principle might at any rate be invoked against Ultra-montanism in some circumstances. 3. Those are not at all to be tolerated who deny the being of God. The taking away of God, though but even in thought, dissolves all society; and promises, covenants, and oaths, which are the bonds of human society, have no hold on such. Thus the police ought to close Mr. Bradlaugh's Hall of Science, and perhaps on some occasions the Positivist School.
Locke's principles depended on a distinction between civil concernments, which he tries to define, and all other concernments. Warburton's arguments on the alliance between church and state turned on the same point, as did the once-famous Bangorian controversy. This distinction would fit into Mr. Mill's cardinal position, which consists in a distinction between the things that only affect the doer or thinker of them, and the things that affect other persons as well. Locke's attempt to divide civil affairs from affairs of salvation, was satisfactory enough for the comparatively narrow object with which he opened his discussion. Mr. Mill's account of civil affairs is both wider and more definite; naturally so, as he had to maintain the cause of tolerance in a much more complex set of social conditions, and amid a far greater diversity of speculative energy, than any one dreamed of in Locke's time. Mr. Mill limits the province of the civil magistrate to the repression of acts that directly and immediately injure others than the doer of them. So long as acts, including the expression of opinions, are purely self-regarding, it seems to him expedient in the long run that they should not be interfered with by the magistrate. He goes much further than this. Self-regarding acts should not be interfered with by the magistrate. Not only self-regarding acts, but all opinions whatever, should, moreover, be as little interfered with as possible by public opinion, except in the way of vigorous argumentation and earnest persuasion in a contrary direction; the silent but most impressive solicitation of virtuous example; the wise and careful upbringing of the young, so that when they enter life they may be most nobly fitted to choose the right opinions and obey the right motives.
The consideration by which he supports this rigorous confinement of external interference on the part of government, or the unorganised members of the community whose opinion is called public opinion, to cases of self-protection, are these, some of which have been already stated:—
1. By interfering to suppress opinions or experiments in living, you may resist truths and improvements in a greater or less degree.
2. Constant discussion is the only certain means of preserving the freshness of truth in men's minds, and the vitality of its influence upon their conduct and motives.
3. Individuality is one of the most valuable elements of wellbeing, and you can only be sure of making the most of individuality, if you have an atmosphere of freedom, encouraging free development and expansion.
4. Habitual resort to repressive means of influencing conduct tends more than anything else to discredit and frustrate the better means, such as education, good example, and the like. (Liberty, 148.)