PKM methods compared: PARA, Zettelkasten, GTD and AI

Four different answers to the same problem: how do you organize what you know so you can find it again in six months. Every method below is a real, workable answer. Every one of them also assumes you will keep doing the organizing yourself, forever. That assumption is the part AI changes.

People searching for a PKM method are usually not choosing between apps. They are choosing between disciplines: what to write down, where it goes, and how it gets found again. Obsidian, Notion, and a dozen other tools can run any of the methods below. The method is the thinking; the app is just where you do it. If you want the app-level comparison instead, that lives on the note-taking app comparison page.

The four methods, side by side

Notice the pattern in that last column. Every method has a maintenance step that only works if you do it on schedule: PARA needs re-sorting, BASB needs distilling, Zettelkasten needs linking, GTD needs the weekly review. None of that is a flaw in the thinking. It is the cost of a system that a human has to run by hand, and it is the exact reason these systems tend to work beautifully for six weeks and then quietly stop. I go through why in more depth on why second brain systems fail, and the one fix.

PARA: organize by actionability

Tiago Forte's PARA sorts everything into Projects, Areas, Resources, and Archives, based on how actionable it is rather than what subject it's about. It is the most widely adopted PKM structure in the productivity world, and for good reason: it maps naturally onto how work actually moves, from active to dormant to done. The catch is that the sorting is a decision you have to keep making. See PARA with AI for what changes when something else makes that call as a side effect of you just talking about your week.

Building a Second Brain: PARA plus a capture habit

Forte's book built a full method on top of PARA, adding a capture-and-distill habit (his "CODE" framework: capture, organize, distill, express) so the archive is actually useful later, not just a pile of saved links. It is the best-known book in this space, and it deserves a fair, specific answer to "what does AI change here." That answer is on Building a Second Brain with AI: what changes.

Zettelkasten and GTD: connection and commitment

Zettelkasten, the "slip box" method popularized by Sönke Ahrens, organizes by connection: one idea per note, linked to related notes, so patterns emerge that you didn't plan for. GTD, David Allen's system, organizes by commitment: everything you've agreed to do gets captured, clarified into a next action, and reviewed weekly so nothing falls through. Both are covered in depth on Zettelkasten with AI and GTD with AI.

What AI changes, and what it doesn't

AI is good at the mechanical half of every method above: filing a note into the right PARA bucket, drafting a Zettelkasten-style link between two ideas, turning a meeting transcript into GTD next actions. It is not good at deciding what matters to you, and it shouldn't be making that call unsupervised. The workable version is AI doing the upkeep of a method you already trust, triggered by the conversations and work you were already having, not a new inbox you have to remember to check. That pattern, applied across capture, review, and follow-through, is what the AI second brain workflows section covers method by method.

Whichever method you start from, the failure mode is the same one: a system that depends on a Saturday you don't always have. Pick the method that fits how you think, then automate its upkeep rather than hoping you'll keep up with it by hand.