 It is widely agreed that downward or top-down explanation of this kind is required in science. The controversial and unsettled question is whether these cases also involve causation in a substantial sense, or whether it would be more appropriate to just designate them as some form of downward determination or explanation (see, e.g., Hulswit 2005). It should also be noted that both this approach and that of Craver and Bechtel are largely silent on the issue of downward causation understood as causation across levels of organization or scales in a broader sense, for example, between a nerve cell and molecules that are not part of that same nerve cell, or between psychological states and behavior.