 But in some cases, the specifics of the agent explanation in question may make appeal to some prior level less plausible or sensible. For example, suppose that one held the view that crop circles were to be explained in terms of direct alien activity. One could, upon getting irrefutable video proof of human production of crop circles, still maintain that aliens were from a distance controlling the brains of the humans in question, and that thus the responsibility for crop circles did still lie with alien activity. While this retreat of levels preserves the basic explanation, it of course comes with a significant cost in inherent implausibility.