Beyond Second Brain: My NEW Cognitive Exoskeleton Vision

After 6 years and 6,000 students, I stopped teaching Building a Second Brain. It wasn't a clean strategic pivot. Something about that moment felt existential to me, not just professionally, but personally. It forced me to return to the bedrock of who I am and what I stand for. It's now been 1,200 days and I've spent that time trying to answer one question. What does it actually mean to extend your mind with technology now that AI can perform most knowledge work? And what I kept finding there are two very different visions of what AI is supposed to do for us. The first one is everywhere right now. It's the vision of AI as a replacement. Autonomous agents doing your work for you, taking over tasks, running in the background while you step aside. AI as a substitute for human effort and judgment. The second vision is one I first wrote about way back in 2015 before large language models, before chat GPT, before any of this. I described it as a cognitive exoskeleton, both protecting us from the ravages of forgetfulness and amplifying our blows as we take on creative challenges. An exoskeleton doesn't replace the person wearing it. It makes them more powerful, more capable, more themselves. That's the vision I've been building toward for a decade now, and I think we're finally there.