Make your judgment compound.

Anika had been on the matter fourteen months. When it closed, she blocked a Saturday to write the handoff note her successor would need. The Saturday came and went. So did two more.

The chronology was in the record. The advice was in the record. The draft structures, the calls, the changes in position — all of it was somewhere. What her successor needed was not another route into the file. He needed the thing that had made the file intelligible while the matter was alive.

What carried the matter was a live state: a compact, current mental model of what the matter was really about, which assumptions were still safe, where the real pressure was building. The memo was asking her to flatten a live state into a static record.

The Kalman filter is an algorithm for combining imperfect, heterogenous information. It takes readings from multiple sensors — each with its own characteristic pattern of error — and produces a single estimate of the truth that is better than any individual sensor could provide.

The key word is characteristic. The filter doesn’t just average its inputs. It maintains an explicit model of how each sensor is wrong. The IMU drifts over time and the filter trusts it less as time passes. The optical sextant is intermittent but precise and the filter weights it heavily when it arrives.

What makes this work is that all these errors are not systematically correlated. Uncorrelated errors produce disagreement that a well-governed system can interpret. Correlated errors produce agreement that no system can see past.

Senior professional judgment — the kind that takes decades to develop and cannot be transmitted to a new colleague through briefings or documents — has a particular shape.

What the senior person carries is not information about the situation. It is an accumulated read of how things move, what breaks, where the real pressure sits, which signals matter and which do not. The output — their judgment about what to do next — is transmissible. What cannot be transmitted is the boundary conditions accumulated over years of cases, decisions, mistakes, corrections, and watchings, which make their current read interpretable as judgment rather than as a guess.

It is why senior judgment is expensive. It is why it gets lost when experienced people leave. It is why institutional culture cannot be written down, though many organizations keep trying.