Classifying people as allies or enemies

I just read an insightful little quote:

"Humans classify people based on whether they are likely to be an ally or enemy."

It was in a Newsweek article about people's voting habits, but it seems to apply to so much more in life. More times than I can count I've experienced situations where showing a little sympathy and letting people know that you're on their side made a world of difference in their attitudes towards me.

By contrast, I recently responded to a technical proposal I read at work by emailing the person making the proposal some pointed questions about things I saw missing or poorly explained. My goal was to help them come up with a better and more reasonable proposal, but they clearly inferred from my comments that I was more likely to be an adversary than an ally for them and their ideas. That's one relationship that really got off on the wrong foot. Fortunately some other allies of mine were able to step in and smooth things over, and we're building a better working relationship now. A little older, a little wiser I guess. I'll now make it a point to present myself as a potential ally to people I meet whenever possible.