“That’s just your opinion.” It is a pernicious claim, devoid of clear meaning, and it should be consigned to the flames – or so I shall argue here.
This entire article is based on the opinion of this writer, and he supports his claim that this phrase shouldn't be used. The article itself sets up and uses the exact thing that he s trying to encourage others to do. To not only say your opinion but to support it in a compelling way.
“That’s just your opinion” has a clear use: It is a conversation-stopper. It’s a way of diminishing a claim, reducing it to a mere matter of taste which lies beyond dispute.
This is totally true, both for the sake of this article and in real life. People use this phrase to try and dismantle or even belittle the argument that someone else is making, no matter how serious or petty the topic at hand.
the fact/opinion distinction is ambiguous
For what is being explained here, this is super important because, well, it is. What is opinion to one person is fact to another, and there's little grey space between.
Some have tried to explain the distinction to me by arguing that facts are true. This answer is not at all helpful, since opinions are typically put forth as true, and some factual claims turn out to be false. For example, most people would say that it’s true that genocide is wrong, and there may or may not be beer in my refrigerator. The fact/opinion distinction varies independently of the true/false distinction.
To me what this is saying, is that the line between fact and opinion becomes blurred because people often present their opinions as if they were hard facts, and some see facts simple opinions that people have.