This in  itself  is  actually  a non-trivial claim.
Although it  would be  interesting to  speculate on
what a system  of reasoning would be  like in which
justified inferences were  seperate and independent
of  the application  of the  rules of  a particular
science,  no single science deals with every aspect
of all phenomena.  Therefore, it is of relevance to
the student  (who engages the act  of  research) to
become familiar with the  results of other systems.
Theoretical  overlap  occurs   when  the  topic  of
another  system  deals  in   some  respect  to  the
elements (although  purely cognitive) of  which you
are concerned.  What you are  doing is showing some
concern  with  the  theoretical  foundations  of  a
discipline.  Skurai,  you are right  to think this,
and it's actually very intuitive.