Why the Experiment Still Matters More Than the Model Previously, in Part 1 (skip ahead if you’ve just read it) Any piece of causal human biology sits in one of three tiers: known (established in the published literature), hidden (latent in data we’ve already generated but not yet extracted), or unknown (not yet revealed by any data, because the experiments haven’t been run). Which tier applies depends on the question. For drug discovery, there are three: the disease-level question (is this gene causal, and in which direction?), the mechanistic-driver question (through what pathway, in which tissue?), and the therapeutic-intervention question...