Claude Opus 5 Shows Erratic Behavior in Probability Tests

Benchmark screenshots reveal that Claude Opus 5 exhibits unstable reasoning, repeatedly changing its answer up to 30 times on a single probability question before converging, raising concerns about its reliability.

2026-07-25 ~ 2026-07-25 · 3 related posts

• Claude Opus 5 flips between 1/3 and 2/5 before finally settling on an answer — Sauers_ · 2026-07-25
• Claude Opus 5 flips 30 times on a probability problem before settling on one answer — scaling01 · 2026-07-25
• A second Claude Opus 5 screenshot shows the same kind of reasoning instability — scaling01 · 2026-07-25