"A simulation shows you what could happen if the world behaves like your assumptions. It never, ever tells you what will happen."
The line that must not be crossed
Everything in this track built a powerful tool: reproducible, calibrated, percentile-banded scenarios. And now the discipline that governs it, stated flatly: a scenario is never presented as a forecast. "Presenting scenarios as forecasts" is a named non-goal, listed right alongside "pretending fallbacks or stale quotes are real-time truth." A simulation is a structured exploration of possibility under stated assumptions. It is not a prediction, not a guarantee, not a range the portfolio "will" stay within. The math is honest; the framing must be too.
Why the framing is a moral choice, not a caption
The exact same percentile fan can be presented two ways. "Under these assumptions, here is the distribution of outcomes the model explored" is honest — it foregrounds the assumptions and the word explored. "Your portfolio will be worth between X and Y in ten years" is a lie wearing the same chart — it launders a conditional exploration into a confident promise. The numbers didn't change; the claim did. And the false version is exactly the kind of confident-sounding future-number that manufactures the urge to act — which is why an observe-never-advise tool refuses it.
The deepest thing simulation teaches
The point of running thousands of paths isn't to find the future — it's to internalize that there is no single future to find, only a distribution of possibilities under assumptions you chose. Done honestly, a scenario tool makes you more humble about the future, not less. It shows you how wide the uncertainty really is and how much the outcome depends on assumptions you can't verify. That humility is the actual deliverable. A forecast pretends the future is knowable; a scenario, framed honestly, teaches you it isn't — and that's the more valuable lesson.