People frequently present unrepresentative parts of themselves. They interact at the margins, instead of interacting with the main part of their personality/values/interests.
People more often pursue problems at the edges of their knowledge, not in the middle. They get interested in some ideas they know less about, or found out about more recently, to try it out and see how it is. They want to push boundaries and expand themselves.
For example, I like Objectivism. A lot. And I have some disagreements. Liking Objectivism is the main thing. But when I go to an Objectivist forum, sometimes I'll bring up induction and Karl Popper – an area where I have a disagreement. Then we talk about that, and people get the impression I don't like Objectivism that much. I agree with 90% of Objectivism, but discussion can be 90% about the parts I disagree with.
Disagreement is interesting. Points of controversy and conflict are important. But people should also keep things in perspective. In many cases, people agree a lot and the disagreement is at a margin.
Sometimes it's worth mentioning points of agreement, and reminding people of them, and relating the issues back to those.
In marriages, spouses sometimes get into a pattern of fighting. They keep interacting about their problems. And most of their conversations focus on that too. It'd help to remember all the other stuff they do like and keep doing some of it too. If you only have problems with your spouse on 10% of topics, don't let those topics be 90% of your interactions!
Two chess players might spend 80% of their time together playing chess, even though chess is only 10% of each of their lives. This can give them a false impression of what the other person is like, overall.
You often interact with someone's conclusions – the ideas at the end (edge, margin) of a chain.
The currently active ideas someone is thinking about are usually not representative of their overall ideas. It's new stuff they are trying, areas with some doubts to shore up, new stuff to add on to their life. What gets attention is often problems and experiments, rather than the most normal things in their life. Normal can become routine and easy and take up less attention. (Which is mostly good, you want to be able to do the main stuff in your life easily and seamlessly without it needing tons of direct attention.)
Remember that you may be seeing a marginal part of someone's worldview. You shouldn't necessarily be put off without getting a more accurate, broader perspective on what they are like.
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Acknowledgments: some ideas presented are modified from, or inspired by, ideas from Karl Popper, Ayn Rand, David Deutsch and William Godwin. Thank you!