 Several statisticians (e.g., Holland 1986; Rubin 1986), as well as similarly minded epidemiologists (e.g., Hernan and Taubman 2008) who advocate treatments of causation in terms of manipulation-based ideas (in this case in terms of “potential outcome” theory) have held that causal claims involving causes that are unmanipulable in principle are defective or lack a clear meaning—they think of this conclusion as following directly from a manipulationist approach to causation. What is meant by an unmanipulable cause is not made very clear, but what these authors have in mind are not candidate causes that cannot be manipulated as a practical matter, but rather candidates that are such that we lack any clear conception of what would be involved in manipulating them or any basis for assessing what would happen under such manipulations—cases in which manipulation seems “impossible” for conceptual or (if you like) “metaphysical” reasons. Proposed examples include such candidate causes as race, membership in a particular species, and gender. Other examples discussed in this connection involve cases in which there are many different things one might have in mind by “manipulation” of the candidate causes with different results flowing from such manipulations so that the claims in question are taken, from a manipulationist or interventionist standpoint, to be unclear or ambiguous. All such cases contrast with the case involving  (G)  above, where the notion of manipulating the moon’s orbit seems perfectly clear and well-defined, and the problem is simply that the world happens to be arranged in such a way that an intervention that produces such a change is not physically possible.