I want to compile a list of things that when you talk about them people feel compelled to tell you all about them, like they’re experts.

I’ll also note that most such people talk about things they read that couldn’t possibly cover the topic thoroughly.

More importantly, they rarely experiment and find out on their own. I don’t know how many people have told me not eating meat is bad for my health without trying. They just read something somewhere and regurgitate. Or how many people tell me running is bad for human knees, who somehow disregard that tens of thousands of people who run a marathon in just one day in New York City, or how many people run all around the world and have for tens of thousands of years. Then they start telling me that hard pavement makes all the difference, without ever having compared running long distance on both surfaces themselves. Maybe there are more variables involved than they comprehend but they talk about the only one they know about.

I’ll add to the table over time. Please share know-it-all behavior you know. If you do any of these things — we all do at some time, or something like them — be aware.

Topic	What people tell you	What they don’t recognize or do
Eating	How bad for you some food (vegetarian, meat, fat, carbohydrates, etc) is; How bad your diet is; how great their diet is; the latest in food research	How many different types of diets exist; how complex the body is
Running	How bad it is for your knees	How many people in the world run every day; run a lot
Getting more fit	How hard it is for them; how their genes are different	How hard it is for everyone; how our genes today are the same as our ancestors, but two-thirds of their population wasn’t obese
How to do what you’re doing	How to do it their way, which they say is better	That your way might work better; that you might want to do it your way anyway

• ← An essay on money, part 2
• Everyone has insecurities. Why don’t some people seem insecure? →