Why write your decisions down
The outcome of a decision always survives somewhere — in revenue, in a signed contract, in the shape of the company.
The reasoning behind it survives nowhere.
Three days after leaving the room, the outline of what you weighed has already faded. Six months later it has compressed into a single line: there was no other choice at the time. The reasoning disappears long before the result does.
Cairn was built to keep the part that disappears.
Go buy a notebook
In the English-speaking world there is a practice called the decision journal.
There is a well-known exchange behind it. The investor Michael Mauboussin asked the behavioural economist Daniel Kahneman how best to improve his decision making. The answer came without hesitation: go to the drug store and buy a notebook.
Whenever you make a decision that matters, write down what you expect to happen and why you expect it. That is the whole method.
The reason is that memory cannot be trusted. Once an outcome is known, we quietly rewrite our own reasoning. A decision that worked out becomes something we were sure of all along; a decision that failed collects doubts we never actually had. Hindsight bias, as it is called, makes it very hard to learn from experience.
There is only one reliable way to know what you were thinking: write it down before you know how it turns out.
Bringing that practice to Japan was the first thing that set this in motion.
Only the conclusions were kept
The second came from consulting work.
When you sit beside executives while they decide, you notice how carefully the conclusions are recorded. Minutes, approval documents, decision logs. Organisations have built whole systems for this.
But what is written down is only what was concluded. What was weighed against what. Why one option was set aside. Which single consideration finally settled it. None of that is kept anywhere.
So a few months later, when a similar question comes around, you start from the same place again. You recognise the road, but not how you walked it. The same hesitation returns, wearing a new face every time.
There is no established practice for keeping the reasoning itself. If there were, it would pay off eventually — that was the thought.
Another version of you
And there is one more idea beyond that.
A single recorded decision is just a note. But once decisions accumulate in the same shape, something else appears: the questions you always ask, the risks you consistently underweight, the conditions under which you stall. What we call judgment starts to take on an outline, made visible by the records themselves.
That, arguably, is another version of you.
An outside advisor has to be briefed first — the background, the history, the internal politics. Every conversation spends time there before reaching the real question. Your past self needs no briefing. It already knows all of it.
Most decisions that linger for days are not short of information. They are short of a well-formed question. If your past self already holds that form, the lingering can be shortened. Compressing the time spent deciding is where this is headed.
Which is why Cairn does not decide
That is why this exists.
Cairn does not judge. It does not score or rank. All it does is keep what you decided and why, in the same shape, and place it beside the decision in front of you when it matters.
The one who decides is always you. You are simply no longer alone in it.