GoKawiilTLA+ advocate pushes back on claims formal methods will fix AI coding
Following Claude Code creator Boris Cherny's comment that the Opus model used TLA+ to detect race conditions, online discussion has surged around formal verification as a fix for agentic software bugs. A longtime TLA+ educator and advocate argues this enthusiasm is overblown, noting that formal verification only checks properties that engineers explicitly define, and many important properties can't even be expressed in TLA+.
GoKawiil's interpretation of the reporting above, not reported fact.
The commentary suggests that even as AI models get better at applying formal methods, the core limitation remains human-defined specifications—tools can't verify properties nobody thought to state. This framing could temper expectations that AI plus formal verification will fully automate bug-free software development, positioning the debate as one about scope rather than capability.
- Boris Cherny noted Opus used TLA+ to find race conditions, sparking wider interest in formal verification
- A TLA+ educator warns formal methods can't guarantee correctness without correctly specified properties
- Correct formal designs don't automatically translate into correct code, a known limitation of TLA+
Practical TLA+ by Hillel Wayne — If you're curious about the limits and power of formal verification discussed here, this book is the most approachable way to actually learn TLA+ from the ground up. It walks through designing and checking real concurrent systems, which is exactly the skill needed to understand what specs can and can't express.
See Practical TLA+ by Hillel Wayne on Amazon → Affiliate link — we may earn a commission on purchases, at no extra cost to you. Product picked by AI based on this article; it is not a tested recommendation.Source: buttondown.com, 2026-09-30
Published there as: “What TLA+ can and can't check”
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