 Alexander Staudacher (2006) has given a critical discussion of Pauen’s paper. Among several points, perhaps the strongest is a comparison between Pauen’s challenge and the challenge to prove I am not a brain in a vat. Inability to decisively answer this latter challenge is not generally taken to impugn our knowledge concerning tables and chairs, nor are physicists expected to lay it to rest before proceeding with their science. Analogously, it may be that worlds without causal laws are not “relevant alternatives” for epiphenomenalism, i.e., not alternatives that epiphenomenalists are fairly required to rule out. Staudacher points out that if we are allowed to raise skeptical challenges of the kind Pauen raises, it will be possible to construct analogous, unanswerable skeptical challenges for interactionism. And, although Staudacher does not provide an analogous case for physicalism, it seems that parallel difficulties are constructable. For example, according to physicalism, it would seem to be a conceptual possibility that qualia are identical, not with neural properties, but with a combination of neural properties and phases of the Moon, while memory traces depend only on neural properties. For reasons parallel to Pauen’s, it seems we could never have evidence that would rule this possibility out. But it is not clear that physicalists need to admit the necessity of providing evidence against such a view, in order to responsibly affirm their view. If that is right, parallel reasoning may be able to support Staudacher’s way of resisting the force of Pauen’s challenge.