The post-mortem is a premeditatio malorum
The Stoics rehearsed loss before it happened. Engineering calls this a pre-mortem — and almost never practices it.
The unexpected weighs heaviest. What has been foreseen wounds less when it arrives.
Seneca wrote that letter after a fire consumed Lyon in a single night. An entire city, no rollback plan — the RTO was a generation. His advice to his shaken friend was not "this will never happen again" (every sprint retrospective's favorite lie) — it was the exercise the Stoics called premeditatio malorum: walking through everything that can go wrong, in advance and with open eyes.
The software industry rediscovered this exercise twice and gave it two names. When we do it after the disaster, we call it a post-mortem. When we do it before — rarely — we call it a pre-mortem. The ratio between the two in your calendar history says a lot about your organization.
Rehearsing failure is not pessimism
The objection to premeditatio is two thousand years old and still being made, these days usually by whoever estimates every project at "two weeks": doesn't dwelling on the worst attract the worst? Seneca would answer that the alternative is worse — being surprised. The exercise is not anxious rumination; it is visiting the scenario precisely, once, so it loses its power to shock.
Engineering has one advantage over life: here, rehearsing the failure changes its probability. When a team asks "how could this launch fail?" before the launch, it is not just preparing emotionally — it is finding the missing index, the optimistic timeout, the fallback-less dependency everyone swore "never goes down."
The pre-mortem ritual
The format I use is stolen half from Gary Klein, half from Seneca — neither will complain:
- Declare the disaster as fact. Not "what could go wrong?", but "it is six months from now and the project failed. What happened?" The change of tense disarms institutional optimism: nobody has to defend the plan, because the plan is already dead. It is remarkable what people will admit about a corpse.
- Everyone writes alone. Five minutes, private list. The senior who speaks first contaminates the whole room — yes, you.
- Sort by embarrassment, not probability. The useful question is: which of these causes would embarrass us most for not having foreseen it? That one almost always deserves a test today. Anticipated shame is an underrated linter.
Blameless is a Stoic word
Everyone says their post-mortems are blameless. Then you read the minutes and there is a first name in the second paragraph.
The blameless post-mortem is, at bottom, a philosophical position: whoever pressed the button was operating a system, and it was the whole system that produced the outcome. Epictetus would say the same in other words — judging a person by what was not in their control is aiming the judgment at the wrong target. If your process allows one command typed at 6:47pm on a Friday to take everything down, the incident wasn't caused by the command; it was scheduled by all of you, months in advance, with full ceremony.
A good post-mortem reads the past the way premeditatio reads the future: no drama, no culprit, with the single question that matters — what does this scenario teach us to prepare?
The fire of Lyon was not prevented. The next one, perhaps.