With regard to the basics: an idea that is acceptable in principle.
on principle
According to or because of principle.
[Middle English, alteration of Old French principe, from Latin prncipium, from prnceps, prncip-, leader, emperor; see per1 in Indo-European roots.]
principle /prnspl/ n.1 [C;U] a standard, such as a guide to behavior, rule: One of his principles is to have no debts.2in principle: regarding a principle, in theory: In principle, he has no debts, but in actual fact he has a mortgage on his house.