What is Lifelogging and why do it?

It is a life where all the information needed for living is stored outside the head, in a readily accessible format. (See Don Norman, The Design of Everyday Things and David Allen, Getting Things Done.)

I want to go a step further than Allen’s brilliant reduction of the entire GTD ethos, “What’s the next action,” and cover these additional areas:

where have I been
what did I do
when did I do it
who was there
what did I get
where did I put it

We spend too much of our time trying to remember stuff. The brain of Homo Sapiens was not designed to hold the information the 21st century demands we store. Until we evolve to the next level, we need to store this information somewhere outside of our heads; we need to offload it.

Everything we need to remember must be offloaded into what Allen calls a trusted source. And it should only be in one location, though obviously it should be copied (backed up), unless we have the time and patience to transfer the information or the systems sync with each other automatically.

Legal malpractice insurers generally require attorneys to keep at least two calendaring systems. This rule is probably well meant, but in practice results in missed dates and sanctions.
Most trial lawyers enter court dates into paper calendars while trying to listen to what the judge is saying and juggling papers. Then they have to transfer the information to the second system, usually a computer-based application, when they get back to the office. That’s when the trouble begins. Either the lawyers or the assistants to whom they entrust the task invariably forget or transpose a date.

Why? Because the task of remembering to transfer the information is left in the brain. It’s entrusted to your memory. That violates Allen’s first law: nothing must be entrusted to memory.
Can we set up a system that reminds us of everything? Yes.