Full Idea
If you think you need a rule to infer q from 'p and (if p then q)', then you would also need a rule to infer p from p.
Gist of Idea
If complex logic requires rules, then so does basic logic
Source
John Searle (Rationality in Action [2001], Ch.1.II)
Book Reference
Searle,John R.: 'Rationality in Action' [MIT 2001], p.19