 It is doubtful whether Putnam’s causal constraint alone can be used to show, in a manner that does not beg the question, that any arbitrary person is not a BIV. However, it is possible to show, using Putnam’s causal constraint, that the argument (SA) for skepticism mentioned above that uses both the BIV scenario and the closure principle (CP) is, in a sense, self defeating. Here, recall, is (SA):