There are some very well-known explanations of multiplicity, and some not-so-well-known ones.
The mainstream psychology methodology for dealing with multiples is by far not the only valid method of viewing multiplicity. If anything, there could be a great deal of argument about whether or not it is valid at all.
This section is for giving at least brief alternative explanations of multiplicity from other cultures, philosophies and psychological schools of thought, whether they're proven or not. Please try to give proper attributions to other people's theories of multiplicity.