 We saw a number of ways of dealing with coincidence and indeterminacy more generally, in  section 4  and  section 5.  But any talk of either partial or total coincidence involving people can seem problematic, because of concerns about the use of first-person pronouns (who does your ‘I’ refer to before your brain-splitting operation, if there are two of you?), and about multiplying conscious entities (could two people have literally the same headache? if you merely coincide with a human organism, are you sure it’s you who has the headache, and not the organism?). It’s not clear, however, whether we should revise our theories of persistence as a consequence of these problems, or whether we should revise our ideas about people. This ‘too many thinkers’ problem is discussed in more detail in the entry on  personal identity.