If you take Social Studies 10a, it may count as one Gov elective, but not for a subfield requirement. If you take BOTH Social Studies 10a and Social Studies 10b, you may count those courses together as either the equivalent of Gov 97 OR for the subfield requirement in political theory, but not both.
Generally, students can count only one Harvard Summer School Government course, taught either on campus or abroad, towards their Government concentration requirements. If that course is not taught by a Harvard Government Department faculty member, the student must petition the Government DUS before the course is taken.
The foundational courses are designed to provide you with a firm grounding in the fundamental concepts and themes of the subfield. If you are unfamiliar with the subfield, or intend to study it in greater depth later, you may find it useful to take the foundational course rather than a 1000-level course in order to ensure that you have a good overview of the subject matter. This breadth of study will give you a firm base for upper-level work in the subfield, and will help you if you need to take oral exams for your final honors determination.