 We noted above that a free action need not meet the conditions for an intervention, on any of the conceptions of intervention described in  §5.  It is also true that a process or event can qualify as an intervention even if it does not involve human action or intention at any point. This should be apparent from the way in which the notion of an intervention has been characterized, for this is entirely in terms of causal and correlational concepts and makes no reference to human beings or their activities. In other words, a purely “natural” process involving no animate beings at all can qualify as an intervention as long as it has the right sort of causal history—indeed, this sort of possibility is often described by scientists as a “natural experiment”. Moreover, even when manipulations are carried out by human beings, it is the causal features of those manipulations and not the fact that they are carried out by human beings or are free or are attended by a special experience of agency that matters for recognizing and characterizing causal relationships. Thus, by giving up any attempt at reduction and characterizing the notion of an intervention in causal terms, an “interventionist” approach of the sort described under  §§4–5  and  7  avoids the second classical problem besetting manipulability theories—that of anthropocentrism and commitment to a privileged status for human action. For example, under this approach \(X\) will qualify as a (total) cause of \(Y\) as long as it is true that for some value of \(X\) that if \(X\) were to be changed to that value by a process having the right sort of causal characteristics, the value of \(Y\) would change. Obviously, this claim can be true even if human beings lack the power to manipulate \(X\) or even in a world in which human beings do not or could not exist. There is nothing in the interventionist version of a manipulability theory that commits us to the view that all causal claims are in some way dependent for their truth on the existence of human beings or involve a “projection” on to the world of our experience of agency.