We take for granted that the freedom of the press is essential for a freedom from a corrupt and tyrannical government, but we have a harder time seeing the value of freedom of thought. Even in the most ideal situation, according to Mill, when the government is perfectly executing the will of the people, if the will of the people is to restrict the freedom of though of a minority, not only is it a great injustice to the minority, but it is harming the rest of the population even more. If the minority is right, then society has missed an opportunity for the truth. If the minority is wrong, then society has missed an opportunity to sharpen the truth.
We all know that we are fallible, but few of us take the necessary precautions that this awareness requires. At best we assume that the things that the people around us agree upon are correct, but no age in history has had everything correct. We have no reason to believe we are any different.
Reasoned discourse, safe, open-minded public debate, is the best tool humans have for arriving at the truth. We learn from experience, but even to learn from experience the interpretation of the experience must be open for debate. Mill says 99% of the people have no capacity for reasoned discourse, and the other 1% only by comparison.
Some say that there are some beliefs that are essential for maintaining the peace and stability of society, and the truth of the beliefs is not of primary concern, but Mill argues that the Greatest Moral Thinkers in history have never been concerned with the stability of society, but rather on the truth of their beliefs.
Some argue that there is no harm in creating laws against the truth because the truth cannot be stamped out, while laws against heresies only help the truth. The problem with this line of thinking, though, is that it is not true, and it is unfriendly to new ideas. We can see in history that even if truth is not stamped out entirely, it can be pushed back hundred of years.
And it should be pointed out that laws usually support social stigma. It is social stigma that actually prevents freedom of though. Thinkers are constrained to partial truths, and to what is practical. The help given to the heretic by social stigma does not outweigh the harm caused to the rest of society that is afraid to think.
If we want a world with great thinkers, “no one can be a great thinker who does not realize that as a thinker it is his or her first duty to follow his intellect to whatever conclusion it may lead.” We get closer to the truth when thinking people make mistakes than when true opinions are held by those who don’t think for themselves. The moments in history in which this has happened have been brief and rare, but all major improvements in society have come from these times.