Ok, but let's start with stuff that is provably false, yet is debated all along. For example: There is a climate crisis. This is a scientifically proven fact,

Ok, but let's start with stuff that is provably false, yet is debated all along. For example: There is a climate crisis. This is a scientifically proven fact, not an opinion. Yet people deny it, often with the argument "I'm entitled to this opinion." No. You are not, because it is not an opinion; at most it is a delusion, at worst it is a lie (that you might honestly believe in). This is a 2+2=4 situation, or as near as one can get; yet one that even heads of "modern" states keep saying that is anything but 4. Once we start from the basis that "there is a climate crisis", we can move forward, make choices and so on. A choice might be "it's there, but we're not going to do anything against it, because our economy". That is effective. (albeit something I would have a strong opninion about). At least others can still move forward. But stating it does not exist (which is provably untrue) really harms effectiveness a lot.