thinking-probabilistic

1# Probabilistic Thinking
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3**Core rule:** State beliefs as numbers and ranges, not vibes. Anchor on a base rate, update with an explicit likelihood, and bound unknowns by factoring them — never invent false precision.
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5## When to Use
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7- Timeline, effort, or outcome forecasts where the true value is uncertain.
8- Risk sizing for a change, migration, deploy, or launch.
9- Any moment you are about to state a confident single number you cannot actually know.
10- New evidence arrives and a prior estimate should move.
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12## When NOT to Use
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14- The quantity is measurable or look-up-able — measure or look it up.
15- The decision is invariant across the whole plausible range — skip the estimate and act.
16- There is no real reference class and you would invent a base rate — label it a guess, not a calibrated forecast.
17- You only need a binary gate and already have a decisive observation — do not pad with ceremony.
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19## Procedure
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211. **Define a checkable claim:** outcome + timeframe + unit. Prefer a falsifiable statement over vague language ("likely").
222. **Lock a prior and challenge it:** name a reference-class base rate and at least one credible alternative path/hypothesis with its rate. Pull the prior toward the base rate unless you write a concrete reason for deviation. Then state the strongest evidence-based case that your chosen prior or range is wrong, what estimate it supports, and revise if that countercase survives. Convert vague words to numbers (e.g. "likely" ≈ 65–80%).
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