Responding to Dani Rodrik’s praise Costa Rica’s CAFTA referendum, Brad DeLong aptly summarizes the argument for representative government over directly democratic government:

Here in California we have referendums. LOTS of referendums. It is not an inspiring sight. It is much better for voters to elect representatives who share their values, and for the representative to then study and think and so develop informed opinions on the issues.

This idea–“the representation of the people in the legislature by deputies of their own election”–is, as Alexander Hamilton wrote 220 years ago, a great innovation in the

science of politics… [which] like most other sciences, has received great improvement. The efficacy of various principles is now well understood, which were either not known at all, or imperfectly known to the ancients…. [W]holly new discoveries… [and ideas that] have made their principal progress towards perfection in modern times… are means, and powerful means, by which the excellences of republican government may be retained and its imperfections lessened or avoided…”

Referendums have advantages as symbolic actions raising the issue decided to a higher place as far as the consent of the governed is concerned. But for making good decisions? Very doubtful.

This is just the simple  principle that you should be able to outsource your political decisions.