Throughout this thread, commenters are assuming that circuit breakers are helpful and useful. Yet no evidence in favor of that assumption is presented in the WSJ article. The CNN article quotes someone named "Dennis Dick" claiming they are useful without providing evidence.

Under economic theory, interference in markets prevents them from correcting prices and is therefore never a good thing. Certainly Milton Friedman [1] thought they were harmful rather than helpful.

Is anybody interested in sharing positive evidence that they are helpful? Helpful is presumably defined to mean they help prices stay as accurate as possible.

[1] https://books.google.com/books?id=5NQvv_Z-zKcC&pg=PA151&lpg=...