You might not know anything about risk-taking behavior of firefighters but you may already have some vague belief like "firefighters are heroes" that obliquely colors your impression of their behavior.

Or alternatively you might hold onto the info that Germany is colder because your underlying belief is more like, you don't like cold and you don't like Germany, so you'd like to also believe that Germany is colder than other places.

This entails two things. One, your apparent position on firefighter behavior or the weather in Germany can change depending on what in the context of the conversation is being construed as good or bad. Second, trying to inform you with specific facts on these issues is unlikely to change your mind because the drivers of your positions are your more general beliefs about firefighters and Germany.

In politics, I think partisanship often degenerates in this way. Arguing the issues is often just a facade for arguing for your party's position or arguing against an opposing party's position, regardless of merit. Facts won't work here to change minds.