Why you need a second brain

The concept was popularised by David Allen’s classic productivity book Getting Things Done, and is best contextualised by a quote from Allen: “Your brain is for having ideas, not holding them”.

If we try to hold information in our heads, bad things happen:

  • We forget important things;
  • We worry that we’re going to forget important things;
  • This lead to ‘open loops’ – nagging tasks that cause us stress until we can get them done, or close them off.

Our brains aren’t good at holding tasks and to-dos because of the limits of working memory. We can only hold about 4 items in working memory, and not for long. If we want to encode them into long-term memory, and we need to make a conscious effort to do so, with a lot of repetition – and we can’t do that for all our to-dos!

So, we need an external second brain. A place to capture and process all of our tasks and to-dos. Once something is safely captured, and we’re 100% confident we won’t forget about it, then we can close the open loop.

The end result, if we can maintain a state of no open loops, is what David Allen calls a ‘mind like water’. We can see more clearly, and our cognitive energy can be focused on creativity and problem solving, rather than just trying (and usually failing) to keep track of all our commitments.