Alfred North Whitehead

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1. 01

   Do not pay for reasoning where no thinking is needed: route cheap calls to cheap models and keep the reasoning model for the hard decisions.

   An Introduction to Mathematics · 1911

   The expensive model is called on exception, not by default.

   An agent's cost architecture: tiering (a cheap model by default, escalation on low confidence or a hard task); routing reports in 2026 about 95% of frontier-model quality while sending only 14–26% of calls to the expensive model, a 75–85% saving on routed traffic; prompt caching cuts the price of repeated input by up to ~90%; batching for whatever is not urgent; caps on reasoning effort. The order of measures: static tiering, caching, effort caps and batching first (50–70% typical savings), a learned router only after. The trap: the cheap model's failure mode is confident error — every tier needs its own evaluation (lesson 15).

   “It is a profoundly erroneous truism, repeated by all copy-books and by eminent people when they are making speeches, that we should cultivate the habit of thinking of what we are doing. The precise opposite is the case. Civilization advances by extending the number of important operations which we can perform without thinking about them.”

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