Being a good guy is inconvenient. Our brains are hardwired to save time by filling in the missing detail before we have grasped a concept or seen something fully. We needed it for evolution. We see what could possibly be fragments of a lion between the rustling grass, and we think we see the lion. And we baleka. And we live. The guys who didn't want to assume anything until they saw the whole lion probably got eaten. And ended that evolutionary line.
And we do it every day, in every tiny action. I'm no linguist, but I'd guess it's a necessary part of language, actually - to use experience to fill in the missing detail, and categorise everything. Instead of spending all morning trying to grasp the intricacies of the contraption in your friend's kitchen, experience tells you it's almost certainly a fridge - even if you haven't seen that particular model before. Happy with the judgement call, you move on to more interesting discussions, like when the brownies will be ready. But when it comes to concepts and other people, that in-built pattern-recogniser is exactly the problem: As soon as we have found a category for someone or some idea, we disengage. We no longer spend energy trying to understand them or it. We think we have, already.
The labels we give one another certainly save time. But they stop us from really seeing the other person. Once someone is "woman" or a "Marxist" or an "accountant" or a "boyfriend", a whole bunch of expectations, beliefs and prejudices kick in in our dealings with them. We become guided, to a large extent, by our
experience with that category of person, rather than with the individual. And the same is true of ideas. Once we recognise enough in what someone is saying to classify it, we stop listening. We can write it off as "religion" or "capitalism" or "environmentalism" and we'll miss the interesting new points that are being made.
It is the greatest disservice to another person to think you understand them just because you know similar people. You owe it to them not to fill in the missing detail for yourself, but to spend the time finding it out. Google outcompeted the other search engines precisely because it did not navigate the web by categories, but by the actual details of every specific piece of content. That is what turns out the greatest value. In people and ideas, too.
