We all have different opinions on the same matter, I love to connect with people and hear their opinions, but yes you can't agree with them always, in the same manner just because they are losing out on some logical leap doesn't mean you have to fight. Here below I have listed few tips to take notes on the next time you have a discussion.

Start with things you agree on. This is the best way you could start a discussion. Getting on common grounds would make things easy. This helps to keep a lot of things intact.

The next step you should follow is to listen to the other person and understand their point of view. Don't just wait until they stop talking, try to figure out what they are likely to say.

Never put vague points just to prove that your points are valid, it's extremely annoying when someone makes up a totally invalid situation. Be sure about what you speak and don't just blabber. 

Make sure you are an active listener, don't just listen but make sure you heard it right. Often, it's quite possible that the other person is saying something different and you understood something wrong. 

Go get yourself some perspective, yeah it sounds cliche but put yourself in others' shoes and look from their point of view. A bit of perspective can really make things level out. Figure out where they are coming from.

Don't come to conclusions on the basis of emotions, It's quite possible that things get messy and then you people emotionally blackmail each other, that's not a fair thing to do. Always try to look past the arguments and don't throw the person out on basis of emotions

Never value winning the argument over the relation, you should make sure the will to win should not overpower your relation with that person. Friendships and relationships are too important over any argument or anything else for that matter

Now if you go too far and things are messed up make sure you apologize fast. There's nothing wrong in saying sorry when you crossed the line. Things get heated up but make sure you apologize for that matter. Your points may be right but the way you showed them up could be a disagreement. Stay classy and own it

 Give your friend a hug and remind yourselves it's just an argument , but the bond you have is real.