Arrow's impossibility theorem

To put it another way, if we assume everybody should count equally, then there is no method of voting which will avoid some possibility of violating the rules.

— Arrow's impossibility theorem

Contrary to the rationalist followers of the American economist Kenneth Arrow, for whom the instability of majority rule was a problem, Dahl’s Madisonian insight was that instability is actually an advantage. It keeps majorities fluid in ways that stop politics from becoming winner-take-all contests in which losers might as well reach for their guns.

— Arrow's impossibility theorem