Ranciere views the scandal of democracy as the possibility that anyone could rule. As it eliminate qualifications for rule, qualifications associated with money/property and virtue/excellence, democracy contains the radical notion of a rule without qualification. Qualifications do not provide criteria for rule. It's a wild premise, a crazy idea, captured already in the practice of the lottery in ancient Greece.
What can we do with this idea? It's an odd one, one at odds with the idea that democracy is something struggled for and claimed. It's not the case that those fighting for democracy fight for the opportunity to be ruled by idiots. People are not in the streets pleading for the unqualified to govern them. What Ranciere points to, then, is this odd nugget in democracy--that it takes the form of a governance for which no one can argue.
Oligarchy, technocracy, aristocracy,monarchy, and socialism do not have this form. Each can be argued for on the basis of a claim or demand: rule of the wealthy, the competent, the best, the one, the workers. Each of these can be argued for and appealed to by those who want to be governed--there are histories of people asking for a king, asking to be ruled (histories likely written under monarchies and at the behest of monarchs, but I digress). People can say--I don't want to bother with this, leave it to the experts.
Democratic theory has foundered mightily on how it might coherent as a demand: rule by the people, but who are the people (insert here Schmitt's critique of the string of identifications at the basis of democracy). The struggle then is over including, counting, hearing, or viewing, trying to find some way to materialize or manifest the people. The democracy to come crowd gives up (takes the easy way out) as they mumble about necessary but impossible ideals the fulfillment of which is necessarily postponed. Twentieth century versions have been either hypocritical--elite democracy, the limitations and regulations installed by progressives, various systems of representation and election--calling themselves democracies even as they rely on the premise that many don't participate, or horrifying: fascism as mass mobilization, as the effort fully to give body to the people.
What if the scandal of democracy is that it cannot be comprehended properly in terms of claims and demands, that any such effort to confine it to either a position of enunciation or an enunciated content will necessarily fail? What if the democratic invention is not an empty place (which thus relies on the present absence of the king) of enunciation at all?