The criticism of ENV only allowing strings has no bearing on his argument. ENV comes from the OS environment. Code in any other language--strong or weakly typed--would have the exact same issue. And not being able to coerce arbitrary strings to booleans is fine because there is no principled way to do that except through convention. And everybody makes up there own convention: true, yes, YES, OK, TRUE, ok, ON, ENABLED, which just goes to show that there's no principled way to do it.