Margen
Make an important decision and wait a few months: the outcome will seem obvious in hindsight. If it went well, you "saw it coming"; if it went badly, you "always suspected it". It's not bad faith — it's hindsight bias, and it rewrites your memory so smoothly you never notice the edit.
The antidote is a decision journal, and it fits in a paragraph. Every time you decide something that matters — taking a job, moving, investing, ending a relationship — write down three things: what you decided, exactly why, and what you expect to happen (with dates, if you can). Close it and don't touch it.
Six or twelve months later, go back. The point is not to check whether you were right: it's to compare your reasoning back then with what actually happened. Sometimes you were right for the wrong reasons — pure luck dressed up as talent. Sometimes you were wrong having thought well: bad luck, not bad judgment. Without the page, the two are impossible to tell apart, and you learn the wrong lessons.
Outcomes depend on chance; your process is the only thing you can train. A decision journal is the one way to look your process in the eye, without the makeup your memory puts on it.