Definition
Calculation is the cold accounting Sun Tzu performs in the temple before the army marches: a tally of moral influence, weather, terrain, command, and doctrine, weighed against the same factors on the other side. The side with more in the ledger wins; the side with fewer loses. The outcome is largely settled by this exercise, not by the fighting that follows.
The word translates poorly. It is closer to reckoning than to arithmetic — a sober inventory of advantages and disadvantages on both sides, conducted with no flattery toward one's own position.
Why it matters
How it works
Sun Tzu lists five factors to weigh: the moral law (whether the people are aligned with the cause), heaven (weather, season), earth (terrain, distance), the commander (their virtues), and method and discipline (the operating system of the force). For each factor he asks a comparative question — which sovereign has more moral authority, which side has the abler general, which has terrain advantage. The answers fill a balance sheet.
The point is not to compute a number but to expose where conviction is doing the work that evidence should do. If the reckoning comes out unfavorable, the right answer is usually not to fight, or to change the conditions of the fight until the balance shifts. Acting first and calculating later is the signature of the doomed campaign.
In modern decision-making the same discipline appears as pre-mortem analysis, base-rate forecasting, and the simple habit of writing the opposing case before defending one's own. The forms differ; the requirement is the same — give the unpleasant facts a seat at the table before committing resources.