Under what circumstances does one have a right to an opinion? Can one have an opinion about any subject? Are there some subjects on which no one has the right to an opinion? Are there others on which some have the right to an opinion, and some do not?
Let’s start with a simple example. We all know that 2+5=7. We can imagine a situation in which a person may say that this is not so, but in that case ey is simply wrong. When discussing questions that have clear yes-or-no answers, such as whether 2+5=7, it’s not very sensible to let a person decide for emself whether or not to believe this. It’s safe to say that when it comes to questions such as these that a person cannot sensibly have an opinion.
So, we can’t have an opinion about any subject. But which ones do not lend themselves well to opinions? As discussed above, we don’t get to have opinions about mathematical facts. But what about mathematical conjectures? My advisor recently asked me whether I believe that imaginary quadratic fields can have exponentially small K_3 regulators. (I said no, but I didn’t do the calculations needed to figure out exactly what the ramifications would be; perhaps my answer would be different with a better understanding of that.) So, at least he thinks that one could have an opinion about open problems. I agree, up to a point.
Let’s now leave the realm of mathematics and discuss scientific questions. When it comes to questions of known truths, we still don’t get to have opinions. We can’t have opinions about whether a ball will fall when dropped, or about how fast it will fall. This is a well-understood phenomenon, so we don’t get to argue about it.
When it comes to the science of current events, though, things are a bit less clear. We are being dishonest to claim that we know what the world will look like in 2050 if we are to continue our current trends. We have models for it, and the evidence may be fairly convincing, but it’s a falsehood to claim that we are certain. We’ve now left the realm of scientific truths and moved into the world of scientific conjectures.
Still, I don’t believe that I have the right to an opinion on whether global warming exists, and if it is, then whether or not it is caused by humans. This is because I am not sufficiently knowledgeable about the subject to be able to make a meaningful contribution to the discussion. There are scientists who have spent many years tirelessly working to understand what is most likely to happen to the climate in the future. I’m not one of them. I’m just some person with a casual interest in the subject, someone who occasionally reads articles about it so as to stay informed to a degree consistent with my interest.
So, a scientist who has spent years researching climate change has the right to an opinion. It could be that eir opinion is wrong, but ey still has permission to have one, provided that it is based on eir study of scientific research. By not having done the work myself, or even having read much of the extensive literature produced by those who have, I forfeit the right to an opinion. Even if I wanted to for some perverse reason, how could I, in good conscience, disagree with the overwhelming consensus of those who have done the work that I haven’t?
Other people who don’t have the right to an opinion are those who base their judgment not on science but on their own financial or political agendas. The CEO of an oil company, for instance, whose financial well-being depends on encouraging others to consume as much oil as possible, is unlikely to look at the science alone and come to a conclusion consistent with the research done. If ey is intellectually honest enough to do a thorough review of the literature and use that body of literature, and that alone, to make a judgment, then ey has the right to an opinion. If ey cannot do that, ey has no more right to an opinion than I do.
Similarly, politicians whose well-being depends on persuading voters, either way, about the nature of climate change are unlikely to possess enough intellectual honesty to be able to make decisions based on the science alone. They also don’t have the right to an opinion. Similarly, I would be mildly annoyed if someone with much less mathematical background than I have were to disagree with me on some point of mathematics, since I have earned more of a right to an opinion than others have. (One can tell me I’m wrong if I am, of course; that’s perfectly reasonable! I make plenty of arithmetic errors.) From time to time, this has come up in my teaching: students request more points on problems because they feel their solutions are more valid than I think they are. In such situations, my opinions matter and are (almost certainly) right; their opinions don’t matter.
Moving further from science and toward "the humanities," we have the right to an opinion increasingly often. A person who reads a novel can have an opinion about the symbolism present in the book, for instance. Our opinions are based on other things we know about the world, or about other literature, but regardless of how well-read we are, we all have the right to opinions about various aspects of literature. To a somewhat lesser degree, this is also true of history: with some analysis of historical documents, we are already capable of saying meaningful things about historical events, even if we haven’t read all of them about some particular subject.
Those who know nothing or very little will frequently admit to not being qualified to have an opinion about history. That is laudable. But when it comes to politically charged questions of a scientific nature, so many people feel they have the right to an opinion, without doing much work at all to deserve this right.
Let’s return to mathematical conjectures. I was already uneasy about deciding whether the size of K_3 regulators can be exponentially small, even though I have read quite a lot of papers on this and related topics. I think my knowledge of the subject just barely gives me the right to an opinion. The bar is high indeed for questions that have such definitive yes/no answers. If one were to ask me another open question in mathematics, especially outside of number theory, about something I had studied less, I would not have the right to an opinion on that, in spite of years of training as a mathematician.
It would be wonderful if, as a society, we were able to give up the idea that everyone has the right to an opinion on any topic, regardless of how ill-informed one is, and that everyone’s opinion is, if not equally valid, at least close. I won’t hold my breath for that though.