The metaphysical question having been disposed of, it becomes apparent that the epistemological question is less significant than it may appear to be at first. How do we re-identify immaterial souls over time? Under normal circumstances, we do this by re-identifying the embodiment of the soul, but this is not always possible: prior at least to the advent of DNA testing, cases of disputed identity could not always be settled by re-identifying bodies. Sometimes the subject’s memory of events is an important clue, though not of course an infallible one. But can any tests establish the identity of...