In the 19th century, there was a philosophical movement called [[Phenomenology may be the most under-rated philosophical idea|Phenomenology]]. This was a reaction against too much Cartesian abstraction. It was an attempt to bring the subjective human experience back into relevance. It focused on what it actually felt like to be human.
We live in an increasingly complex civilization. While there have been lots of theories of complexity that approach it from an abstract theoretical level, there is an increasing need for a phenomenology of complexity. We need a description of what it feels like to be a human being swimming in a complex world.
GTD and Zettelkasten are two approaches that take this phenomenology into account. They describe a mind overwhelmed with tasks and projects, with information overload, with the need for sense-making. Then they propose solutions that involve taking this inchoate mess in the mind, and putting it all down into a trusted external system, so as to achieve "mind like water", a zen state of calm.
Paradoxically, it is necessary for humans to become cyborgs, to externalize their mental load, in order for us to achieve a tribal simplicity again. As Alexander Bard has pointed out, humans are meant to be neither individualistic nor collectivist. We function best in the middle tier of being tribal. (He argues that we can easily cope with the Dunbar number of 150, which he defines as a clan. Add some storytelling and other co-ordinating mechanisms, and we can easily increase this to 2000, which he defines as a tribe.)
Meditation is another essential phenomenological weapon. We will need others to cope with economic complexity, political complexity, technological and scientific complexity. The litmus test of whether a solution for complexity is the right one is that it opens a door for simplicity to slip back in. The benchmark for simplicity is "mind like water".