Our attitudes are shaped much more by our social groups than they are by facts on the ground. We are not great reasoners. Most people don't like to think at all, or like to think as little as possible. And by most, I mean roughly 70 percent of the population. Even the rest seem to devote a lot of their resources to justifying beliefs that they want to hold, as opposed to forming credible beliefs based only on fact.
Think about if you were to utter a fact that contradicted the opinions of the majority of those in your social group. You pay a price for that.
I live in a very limited universe, and so I have to depend on the beliefs and knowledge of other people. I know what I’ve read; I know what I’ve heard from experts. In that sense, the decisions we make, the attitudes we form, the judgments we make, depend very much on what other people are thinking.
Steven Sloman quoted in Vox