Often complex bodies of knowledge and issues where the answer is “it depends” are boiled down to simple rules.

• Look both ways before crossing.
• Wear a helmet when cycling.
• Don’t eat too much sugar (or is it fat we’re not supposed to eat now? Or processed foods? Are vegetables bad for you now?)
• Correlation is not causation.
• Don’t compare floating point numbers for equality.

You can probably think of many others.

These rules are useful. They provide you with handy heuristic shortcuts that you can remember and follow without having to load the whole complex set of circumstances back into your head. They’re things to bear in mind and follow when the cost of thinking about it is greater than the cost of just following the rule.

But that’s all they are. They are useful heuristics. They are there to help you in your daily activities, not to be preached as gospel.

And what this means is that if you think you see someone who is not following the heuristic you do, that’s OK. You should at most say “hey so here’s a heuristic I use in these circumstances. Maybe you would find this useful?”.

If you instead say “You must always follow this heuristic and you are a bad person and should feel bad for not doing so” then you have forgotten the purpose of your heuristic and you are a bad person and you should feel bad.

There may be circumstances in which you are in a position of consensually teaching someone about something and you knowingly say “Here is a heuristic that is not always true, but it is useful and teaching you the full complex set of actual rules would take way more time than it’s worth to you right now”. That’s OK. That is not the circumstance you find yourself in with strangers.

I would like “assume competency until proven otherwise” to be a basic rule of courtesy. I know many people aren’t competent, but treating someone like they’re incompetent is a fast track to an extremely unpleasant interaction, and saying “Have you considered that maybe you should unerringly follow this simple reductive rule instead of the complex picture of the situation you thought you had?” is one of the easiest ways to achieve that. Don’t do it.

PS. Attempting to boil this post down to simple reductive rules in order to annoy me is extremely predictable and not actually funny. Don’t do that either.