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Comment by jwmerrill | Hacker News Reader

The paper on "normalization of deviance" that this post links to is also really good. It's written from a medicine perspective, but its observations and conclusions are pretty generalizable.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2821100/

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Sidney Dekker's _The Field Guide to Understanding 'Human Error'_ has a bit about this (which he calls drift). One thing I liked in that section is a sort of anti-Murphy's Law: What can go wrong will usually go right, and then we'll assume that it will go right again and again, even if we borrow more from our safety margin.

That said, it's a trade-off, and if you're a startup, it's usually far better to do it dirty today than perfect next year.

Diane Vaughn wrote about 'normalisation of deviance' in her book The Challenger Launch Decision. The original Space Shuttle SSRB design had redundant O-rings for safety, and while a small amount of O-ring erosion (from the hot gases of burning propellant) had been observed on several occasions prior to 1986, it had never resulted in failure, so after a while, they began to accept it as normal. But as Richard Feynman pointed out, those O-rings had never been designed to erode. The first time erosion was seen was a deviance; it indicated that the protective thermal putty was not doing its job, and should have been corrected then.

An interesting (to me) recent piece of writing from the aviation world also points a finger at the "normalization of deviance." Written by Ron Rapp, a charter pilot:

http://www.rapp.org/archives/2015/12/normalization-of-devian...

Thanks for this...lots of great examples...the one about the stoned-out music student who, as a museum guard, accidentally enabled a ~$500 million art heist, was a good laugh, with links to more interesting reports and post-mortems.

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