Dr. Stokes, a philosopher at Deakin University, summarizes just about everything I have ever wanted to say on the endless “opinions” that everyone appears to have, particularly on social media.
If “Everyone’s entitled to their opinion” just means no-one has the right to stop people thinking and saying whatever they want, then the statement is true, but fairly trivial. No one can stop you saying that vaccines cause autism, no matter how many times that claim has been disproven.
But if ‘entitled to an opinion’ means ‘entitled to have your views treated as serious candidates for the truth’ then it’s pretty clearly false. And this too is a distinction that tends to get blurred.
This is especially important in distinguishing between good and bad science. In good science, you will find hypotheses, which are the results of observations and application of knowledge. In bad science, you will always hear opinions, albeit cleverly disguised as “hypotheses.”