 As Schaffer (2000c, 2012b) argues, many paradigm cases of causation turn out, on closer inspection, to be instances of double prevention. Pam uses a catapult to hurl a rock through the window. It seems clear that Pam’s actions caused the window to shatter. But suppose the catapult works like this: a catch prevents the catapult from launching, and Pam’s releasing the catch prevents it from preventing the launch. Thus, the relationship between Pam’s releasing the catch and the shattering of the window is one of double prevention. Here, it is less comfortable to deny that Pam caused the window to shatter, though not all agree. Aronson denies that there is any causation in a similar case: