Secondly, the injustice of punishing men for their opinions and arguments will be still more visible if we reflect on the nature of punishment. Punishment is one of the classes of coercion, and, as such, may perhaps be allowed to have an occasional propriety, where the force introduced is the direct correlative of corporal violence previously exerted. But the case of false opinions and perverse arguments is of a very different nature. Does any man assert falsehood? Nothing further can appear requisite than that it should be confronted with truth. Does he bewilder us with sophistry? Introduce the light of reason, and his deceptions will vanish. Where argument, erroneous statements, and misrepresentation alone are employed, argument alone should be called forth to encounter them.
To enable us to estimate properly the value of laws for the punishment of heresy, let us suppose a country to be sufficiently provided with such laws, and observe the result. The object is to prevent men from entertaining certain opinions, or, in other words, from thinking in a certain way. What can be more absurd than to undertake to put fetters upon the subtlety of thought? How frequently does the individual who desires to restrain it in himself fail in the attempt? Add to this that prohibition and menace in this respect, will frequently give new restlessness to the curiosity of the mind. I must not so much as think of the propositions that there is no God; that the stupendous miracles of Moses and Christ were never really performed; that the dogmas of the Athanasian creed are erroneous.
I must shut my eyes, and run blindly into all the opinions, religious and political, that my ancestors regarded as sacred. Will this, in all instances, be possible?
There is another consideration, trite indeed, but the triteness of which is an additional argument of its truth. Swift says 'Men ought to be permitted to think as they please, but not to propagate their pernicious opinions.'