Semantics is important because if two people don't agree on the meaning of a word and don't even realize it, they'll be talking past each other. And if they realize that a seemingly larger disagreement depends on differences in understanding a word (or corresponding situation), then they have gotten somewhere.

No one is obligated to agree with anyone else. Too often in a discussion there's this sense that Thou Shalt See It This Way Or Else. It's never said, really, but it's often implied by tone or dogged repetition.

The only legitimate way to command agreement, in my view, is to be transparent about logic + evidence. What are the logic and evidence that led you to believe what you believe? If those pieces hold up, they more or less speak for themselves. If no one can find the problem with those pieces, or provide an equally compelling logic + evidence argument, then this is the reigning answer, not because anyone is bullying anyone, or demanding anything, but because we live in a material universe that operates according to logic. That is how you establish truth if you find it important to do so. There is no better or more reliable way, and there is no reliable shortcut.

You definitely don't have to think so - no one does, our thoughts are free - but if you don't think so, I would bet you large amounts of money (if I have it) that this will show in the inaccuracy of your beliefs and your thinking. And if I make that bet, I will be walking away richer.

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This is the game of debate. And it is a game. 

And realizing it is a game makes you better at it, because this allows you to step back and see with a bit of detachment, and therefore from more angles. Clinging to one of them isn't conducive to finding the right answer, or proving you've found it if you have.

Ironically the most productive debate is one in which you can humor a position you find incorrect, and others can do the same. It's the attitude of play that brings flexibility to thought where emotions may run high. Expressing a stronger emotion than someone else doesn't establish that you're right. Often what it does is get you caught up in an inflexibility that impairs the process.

Global poverty is serious. But if you can't talk about it as if it weren't serious, you are doing your objectivity - and your debates - a disfavor. This is counterintuitive, and that's why so many debates go badly. Debate is a game. It works better that way. It's more productive that way. If you love someone, set them free. If you want shared truth, open your hands, let go of certainty, and play around with ideas that may seem untrue.

The appearance that you will refuse to even go there - refuse to even consider a possibility - may look strong and persuasive to some people, but to a slightly more sophisticated reasoner, it looks as if you're on crutches and don't know what's going on.

Everyone can benefit from watching and rewatching the movie 12 Angry Men, I suspect, including me. The protagonist is a hero because he's a better debater, and he's a better debater because his stance is flexible. Even though his motives and his questioning are principled and insistent, his stance is flexible. Everyone else is on crutches. He can dance. And that gives him more clarity, not less. Compared to them, he is playing. He knows debate is a game, even when it's deadly serious.