That said, I think the “second brain” metaphor has three problems: It implies delegating cognition. The promised outcome is a prosthetic mind. That is, the system will relieve you of thinking and (especially!) long-term recall. (Westenberg: “I believed I was solving a problem of forgetting.”) It sets expectations PKMs can’t meet. This isn’t a promise current PKMs — even with AI — can deliver. The system won’t “extract the gold,” at least not for a long time and after a lot of work on your part. These are bad expectations to begin with. Even if PKMs could do this, you shouldn’t want this. If you want to think better, your goal shouldn’t be to delegate your thinking: It should be enabling your first brain to work better.
Arango has 3 issues with second brain metaphor: 1) implies delegation of thinking to it, 2) oversells pkm as delivering 'gold' (vgl Luhmann's 'septic tank' in contrast) 3) even if PKM could do it, they're not desirable traits. Iow PKM is primarily a tool to support your own brain, not outsourcing.