Ada Palmer

What emerges is a probabilistic model of the political situation of 1492.

Not Florence will be sacked but Florence survives in 70% of runs.

Not France will invade but French intervention occurs with near certainty, though the target varies.

This is the kind of knowledge ensemble prediction provides.

Not certainty about specifics, but clarity about the shape of the possible.

Interestingly, Palmer has independently arrived at both major methods where the forecasters use for ensemble prediction, though for entirely different reasons.

For one, she perturbs the initial conditions by moving historical figures in time.

cardinals who never overlap now competing for the same throne, creating configurations that never actually existed.

And she also runs multiple models, each time different students inhabit the same roles, bringing different judgment and risk tolerance.

One student playing Cardinal de la Rovira might ally with France.

Another might seek Spanish protection,

Same constraints, different decision-making models.

Palmer developed these techniques for pedagogical reasons, to prevent students from seeking incorrect answers and to explore the range of human responses, but the result is structurally identical to what meteorologists spent decades developing to work around chaos.

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Military planners have long grappled with the same problem.

Wargaming exists because commanders cannot predict how battles will unfold.

Chaos, friction and human decision-making make deterministic prediction impossible.

But unlike meteorologists, military planners lack the resources to run true ensemble predictions.

A major wargame is expensive, it involves hundreds of personnel and equipment over weeks and a single scenario can be executed once, rarely twice.

History, we are told, is more like wargaming than meteorology or physics.