People are entitled to make mistakes, provided they are not overly detrimental to others. What is offensive is not having a mistaken opinion (particularly when this is a freshly formed mistaken impression rather than an entrenched bias), but attempting to spread it far and wide.
Existing safeguards against this include our concept of expertise. More people will listen to someone who has advanced understanding of an area of knowledge, versus a novice. Usually an expert in a subject really can provide better guidance to form valid opinions.
The trouble arises when you have an expert in an area that is not rationally mappable to reality, e.g. the Bible or religious experience. A preacher can claim expertise on the issue of origins because of biblical knowledge and claims of personal religious experience, without needing to prove that he knows enough biology or basic science to criticize the theory of evolution.
So perhaps we need a norm that criticizes use of authority in one area to make claims in an unrelated area. A preacher's opinion carries little weight in biology, just as biologists do not typically do much to define religious rhetoric.
So perhaps we need a norm that criticizes use of authority in one area to make claims in an unrelated area. A preacher's opinion carries little weight in biology, just as biologists do not typically do much to define religious rhetoric.
But that would also mean that nobody but an authority in the religion could criticize the religion.
These rules always have to be symmetrical.
A currently existing social norm basically says that everyone has the right to an opinion on anything, no matter how little they happen to know about the subject.
But what if we had a social norm saying that by default, people do not have the right to an opinion on anything? To earn such a right, they ought to have familiarized themselves on the topic. The familiarization wouldn't necessarily have to be anything very deep, but on the topic of e.g. controversial political issues, they'd have to have read at least a few books' worth of material discussing the question (preferrably material from both sides of the political fence). In scientific questions where one needed more advanced knowledge, you ought to at least have studied the field somewhat. Extensive personal experience on a subject would also be a way to become qualified, even if you hadn't studied the issue academically.
The purpose of this would be to enforce epistemic hygiene. Conversations on things such as public policy are frequently overwhelmed by loud declarations of opinion from people who, quite honestly, don't know anything on the subject they have a strong opinion on. If we had in place a social norm demanding an adequate amount of background knowledge on the topic before anyone voiced an opinion they expected to be taken seriously, the signal/noise ratio might be somewhat improved. This kind of a social norm does seem to already be somewhat in place in many scientific communities, but it'd do good to spread it to the general public.
At the same time, there are several caveats. As I am myself a strong advocate on freedom of speech, I find it important to note that this must remain a *social* norm, not a government-advocated one or anything that is in any way codified into law. Also, the standards must not be set *too* high - even amateurs should be able to engage in the conversation, provided that they know at least the basics. Likewise, one must be careful that the principle isn't abused, with "you don't have a right to have an opinion on this" being a generic argument used to dismiss any opposing claims.