Categories are an excellent idea if the system is small enough and everybody using it is familiar with the convention. It's just that you have to accept they ar

Categories are an excellent idea if the system is small enough and everybody using it is familiar with the convention. It's just that you have to accept they are flawed, unaccurate, partial and biased. That doesn't mean they are not useful. Think about supermarket scales: each vegetable or fruit is in a single category. The category is flawed, but nobody wants to have to type a precise list of tags to filter what they need. You want to go to vegetable and chose tomatoes, not to have a inner debate about the tomatoes taxonomy. Isn't a fruit? Wait, is fruit a biology thing or a commercial concept? I don't care, give me my damn tomatoes! It's the same for my notes. Some stuff are in weird directories. But I know how I sort them out, so I can find them quickly. I don't want to have to be precise or accurate, only find what I need. Category don't replace tags, buts tags are mainly useful for advanced searches and filtering. Anyway, the best systems out there consider a category as a tag, just the main tag.