I go through phases where I think that I have all the evidence, all the arguments and rebuttals, to convince anyone of a truth that is obviously true. Anyone who’s willing to have a conversation with me about the subject should find themselves convinced, or at least humbled.
It is inexpressibly difficult to come to terms with the fact that in our world, that will just never be how it works.
Now, when there are people who are clearly aware of their own ignorance, and questing for an answer to an important question, then all the arguments and evidence and rebuttals will probably make a difference for the person.
But a great deal of the time, even people who present themselves in this way will have an answer chosen beforehand that they want to see triumph, and woe to you if you don’t get the right one. The person who is disposed to be a genuine sponge of learning is rare indeed.
It is also possible, if a person doesn’t care about a question or its answer at all, but has great respect for you, that the arguments and evidence can have an effect.
In basically all other discussions, we should resign ourselves either to not trying at all to convince the other person, or at least to not having any expectation of success. Practically speaking, for me what I’ve been trying to do lately is just allow myself to feel sad for the other person’s wrongness, while fighting my impulse to try and fix it. This is a lesson I’ve been learning for a lot of years, and it is still one I’m struggling to absorb fully.
If a person is convinced of a wrong answer, you are almost certain to fail in convincing them of a different one. Depressing, but true. That’s not to say the attempt couldn’t have some good outcomes — it’s possible — but at the very least they won’t be the ones you probably expect them to be.