Designing rules you will not break
A rule you break weekly is not a discipline problem. It is a design problem, and the fix is to redesign the rule rather than to try harder — the first chapter said this, and this one is about how.
Rules fail for three reasons, and they need different repairs. Some are unenforceable: they depend on a judgement you have to make in the moment you are least able to make it. "I will not trade when I am emotional" cannot work, because the state it names is the state that decides whether it applies. Replace it with something countable — a trade cap, a time window, a loss limit.
Some are too strict for how you actually trade. A rule that forbids something you genuinely need forces a choice between breaking it and trading badly, and the rule loses. If you keep overriding a rule for good reasons, the rule is wrong.
And some have no consequence. A rule that nothing enforces is a preference. This is why a limit in the platform beats a limit in a notebook, and why any constraint you can waive by clicking past a warning provides roughly nothing.
A workable rule has three properties: it is countable, so you can tell afterwards whether you kept it; it is decided in advance, so the stressed version of you never gets a vote; and it fails closed, meaning that when you ignore it something actually stops. Test a new rule against those three before you adopt it, and check after a month how often you kept it. A rule you kept 95% of the time is working. One you kept 60% of the time is telling you something.
What to take away
- Unenforceable rules depend on judgement in the moment judgement fails — replace with countable ones.
- A rule you override for good reasons is the wrong rule.
- A rule nothing enforces is a preference.
- Countable, decided in advance, fails closed. Then measure how often you actually kept it.
This chapter, measured against your own trades
In the app the same chapter ends in your figures rather than an example: how often you did the thing it describes, over your last ninety days. You pick one change to make, and Evidence checks afterwards whether it actually changed — from your journal, arithmetic, no opinion involved. Questions you get wrong come back a week later and again a month after that.
Open the free plan →Check that it stuck
Answers shown — in the app these are asked before you see them, and the ones you get wrong come back after a week.