We all live in our bubbles - our family, friends, co-workers, and Friday visitors from a local pub. Some of them you like more, some of them less, but most of these, you've chosen to listen or not. We have even decided to consider or not their opinions.
It's safe and comfy. Even at work, where you fight with many small and stupid things, it's safe. It's easy to think 'this failed because you missed my mail.' 'This is not possible as things work differently.' Or 'we've tried this bambolleon times, and it never worked.' That's wrong.
Instead of thinking about the ideas and opinions that may let you grow, you were searching for an opportunity to avoid the thought. Very similarly as you can deny any feedback (check this hilarious TEDx talk).
Within any discussion, seek for the motivation of your counterpart. Believe it or not, it's almost always positive. Why is this person contacting you? Maybe you are the right one with critical information. Or influence, or perhaps he was just sharply denied by everyone else.
I'm not saying to blindly accept all comments, ideas, and solutions without critical thinking or any revision. Just start the discussion: "I can see your point, and here are my 5 cents." Work hardest as you can to understand the motivation of the speaker and to find at least one mutual point. Many want something else :).
Once you have this, you have won. Not against the other - tougher match: against yourself.
Two notes below the line:
1) This whole approach is not always possible. Rarely, you may find yourself in a specific mood, which blocks you from any rational thinking. Grab a coffee, eat a whole cake, get a pint, or ask your colleague to wait till tomorrow (and do follow up).
2) No need to limit this just to your workplace. Politics, sport, tough family decisions... it's just harder. In the office, most people are more motivated to find mutual agreements.