Arrow's theorem

A mathematical look at democracy.

Unfortunately the answer is no, not perfectly. Find out more here.

Why a perfect voting system is mathematically impossible.

Is there a perfect voting system? In the 1950s the economist Kenneth Arrow asked himself this question and found that the answer is no, at least in the setting he imagined.

With the day of the referendum on the UK voting system drawing nearer, Tony Crilly uses a toy example to compare the first past the post, AV and Condorcet voting systems, and revisits a famous mathematical theorem which shows that there is nothing obvious about voting.

Election issues