Why I started a decision log

I started keeping a decision log because I kept making the same mistakes.

Not big mistakes. Small ones. The kind that don't show up in postmortems because they didn't break anything obvious. I'd revisit a decision six weeks later and realize I'd already had this exact debate with myself two months before, and I'd come down on the opposite side, and I couldn't remember why.

Six weeks of work could come down to: I don't remember what past-me was thinking.

The decision log fixes that. Each entry has the same shape: what was the question, what did I choose, what did I rule out, what was I optimistic about, what was I worried about. Some are five lines. Some are a paragraph. The discipline is in the writing, not the length.

What I expected when I started it: it would help me track decisions.

What it actually did: it made me a better decider.

Writing the call down forces you to articulate it. Articulating it forces you to confront the parts you were going to fudge. By the time you've written I'm going with X because Y, even though Z worries me, you've made the decision twice. Once in your head and once on the page. The version on the page is sharper because it had to be defendable to its own author.

The second thing it does: it removes the relitigation tax. Six weeks later when the topic comes back, you don't have to think it through again. You read the entry, decide if the inputs have changed, and move on. If the inputs have changed, you make a new entry and explain why you're reversing. Reversing on the record is much harder than reversing in your head, which is the whole point.

The third thing: it accumulates. Year three of doing this is a different kind of asset. Pattern recognition starts to happen on its own. You see that you keep making a certain class of mistake. You design a standing rule to head it off. The decisions get cleaner because the log made the patterns visible.

This is the only operating practice I'd insist on. Most people don't keep one because writing the decision down is uncomfortable. The discomfort is the whole point. The discomfort is the part where you stop fooling yourself.

The cheapest moat. The most uncomfortable practice. The thing nobody else can copy because nobody else made your decisions.

Start one tomorrow.