Wikipedia guidelines instruct editors to assume good faith. The idea that this should not be taken to foolish extremes stems from a statement made by Jimmy Wales in March 2005:
Our social policies are not a suicide pact. They are in place to help us write the encyclopedia. [...] We need to take due process seriously, but we also need to remember: this is not a democracy, this is not an experiment in anarchy, it's a project to make the world a better place by giving away a free encyclopedia [...] We can cut some serious slack to administrators who are doing the good work of defending us from nonsense.
The inspiration was likely the American political phrase, "The Constitution is not a suicide pact". Since 2005, the words "not a suicide pact" have been commonly quoted in relation to Wikipedia's policies, particularly "assume good faith". "Our social policies are not a suicide pact" is essentially a restatement of Wikipedia:Ignore all rules as applied to editor behavior: "If a rule prevents you from improving or maintaining Wikipedia, ignore it."
Remember this principle is an exception to allow admins to protect the encyclopedia without getting bogged down in bureaucracy, not a general invitation to breach our behavioral guidelines. Quoting this essay is not a get-out-of-jail-free card. You shouldn't assume that every single harmful edit is intentional, but you don't have to pretend that all bad actions were accidents and mistakes, either.