THE CLAIM. the Conceptual Reasoning Index scores models 0 to 100 on reasoning about hard-to-verify topics like AI alignment and decision theory, with Opus 5 on top at 73.6 against an estimated ceiling of 91.

THE CHECK. the methodology is unusually honest for a launch: confidence intervals, a ceiling estimate, inter-rater checks, and a validated question set. But the core of the index compares model judgments to the authors' own ratings, primarily one researcher's, 2,140 in total. The work was done in collaboration with Anthropic, the domain is unverifiable by design, and the sponsor's model is number one. Hacker News needed one sentence for the prosecution: a benchmark Anthropic paid for that Anthropic ranked highest.