Direct democracy may work very well among a small group of people, but the larger the group the more difficult it is to run effectively. Representative democracy eliminates this difficulty by operating on a much smaller scale the majority of the time (via elected representatives of the electorate as a whole).

Political issues can be exceptionally complicated and take MPs a lot of time and consultation with experts to fully understand themselves, before they can be considered informed enough to vote. Educating the whole electorate on such issues would be exceptionally difficult for a number of reasons, and if an uninformed electorate were to vote on issues the results could be incredibly damaging.

The average individual voter would put his or her needs before those of society as a whole. This self-interest is perfectly natural, but if a law that benefits a smaller group does not benefit a larger group (for example, the protection of minority interests) then that law is not likely to be passed.