What motivations are assumed to underlie the “public interest” and the “economic” theories of legislation (self-interest paradigm)? Must a theory be accurate 100 percent or even 80 percent of the time...

What motivations are assumed to underlie the “public interest” and the “economic” theories of legislation (self-interest paradigm)?

Must a theory be accurate 100 percent or even 80 percent of the time to be judged useful for understanding legislative outcomes?