original_query: What is mirror theory in theoretical linguistics?
query: What is mirror theory in theoretical linguistics?
answer: In theoretical linguistics, mirror theory is an approach to the architecture of the language organ developed by Michael Brody. It's a purely representational theory, unlike most generative theories.  A key principle, 'mirror', states that the syntactic relation 'X complement of Y' is identical to the inverse-order morphological relation 'X specifier of Y'.