when you find a statistical relation between A and B,
you cannot assert it is a cause-effect relation, until you find some other evidences to support it. If you donot have such kind of evidences yet, guess what? You have to assume A does not have a cause-effect ralation with B by default. i.e. you always assume something is not existing until you have an evidence. This kind of "default logic" is a common practice of human being's logic and it is happening everyday.