A Knock-Down Argument against the Soul

I came across the following compelling argument from Keith Campbell while reading contemporary material for my dissertation. The following is a quotation from Hoffman and Rosencrantz, "The divine attributes," p. 43:

"Atoms, and material things generally, are individuated and counted by their positions. Non-spatial spirits cannot, of course, be individuated and counted in this way. But then, in what way can they be individuated and counted? If there really is no difference between one spirit and two spirits of exactly similar history and contents, then spirits are a very suspect sort of thing indeed."

To be fair, he did write a whole book about the subject, this is just one quote.