§ 81
Mechanisms, Not Good Intentions
Asking people to try harder after a failure changes little, because the failure happened to people who were already trying.
Keep in mind
Replace "be careful" with something that works without anyone remembering
What to do
When a postmortem action item says "be more careful", "remind the team" or "double-check", replace it with a change that works without anyone remembering: a CI check, a safe default, a field that cannot be skipped. Give each one an owner and a date to inspect whether it is used and whether it worked. Retire mechanisms that no longer change outcomes.
Why it happens
Many mistakes are made by people who meant well and knew the rule, so telling them again adds nothing they lacked. Attention is finite and fades, so a fix that depends on someone remembering often fades, and the same error comes back. What changes behavior is a mechanism: a tool, its actual adoption, and inspection that checks whether it works. A checklist nobody reads is not a mechanism; a gate that blocks the merge is.
In practice
On July 2, 2019, a single regular expression in a Cloudflare WAF rule backtracked catastrophically and exhausted CPU on its HTTP-serving cores worldwide, taking traffic down for 27 minutes. Instead of asking engineers to write safer regexes, Cloudflare's fixes were mechanisms: switch to the re2 or Rust regex engine, which give run-time guarantees, add performance profiling of every rule to the test suite, restore the CPU-usage protection that had been removed, and require staged rollouts for rules.
Read the accountWhen it stops applying
Resist Proxies: a mechanism can harden into the goal; once following the process is what gets judged, people defend a bad outcome by saying they followed it, and nobody asks whether the process still serves the result.
Source
An internal Amazon saying, not a published Bezos text. Gregor Hohpe, Strategy Is a Winding Road. Mechanisms Keep You on Track. (AWS Enterprise Strategy blog, 2021) records "At Amazon we have a common saying: 'Good intentions don't work—mechanisms do'" and defines a mechanism as tools, adoption and inspection; attributions of the line to Jeff Bezos are secondhand. The counter-force is from Jeff Bezos, 2016 Letter to Shareholders (Amazon.com, Inc., 2017): "The process is not the thing."
Read the sourceCite this
Hammurabi, § 81, “Mechanisms, Not Good Intentions.” https://kanywst.github.io/hammurabi/laws/mechanisms-not-good-intentions/
BibTeX
@misc{hammurabi-mechanisms-not-good-intentions,
title = {Mechanisms, Not Good Intentions},
author = {{Hammurabi contributors}},
note = {Hammurabi, § 81},
url = {https://kanywst.github.io/hammurabi/laws/mechanisms-not-good-intentions/}
}Read in a column
- Before and after an incident Next in the column: Chaos Engineering
Related laws
- 74Blameless PostmortemPunishing the person nearest a failure teaches people to hide what they did.
- 14Goodhart's LawA number stops measuring well once people are rewarded for moving it.
- 77You Build It, You Run ItWhen the team that writes a service also operates it, the cost of every operational weakness lands on the people who can fix it.
- 85Context, Not ControlAs an organization grows, rules and approvals tend to scale worse than shared understanding; Netflix's argument is that people given the reasons behind a goal make better local decisions than people given a procedure.