Treatment of relations too rigid
In SME, relations are treated as n-place predicates that can only be mapped to other n-place predicates. But it is unlikely that human mind is so rigid in its treatment of relational mappings.
For example, attraction is a 2-place predicate tha can be represented as 'attracts' (sun, planet) and then mapped to 'attracts' (nucleus, electron).
David Chalmers, Robert French, Douglas Hofstadter, 1995.