Two-party systems are the inevitable product of a First-Past-The-Post voting in a democracy[1]. There would be no Democratic and Republican party under a sortition system.
Not quite. rdancer's saying that the options people have to choose amongst/between are a consequence of how their votes are counted. Proportional representation tends toward a larger number of parties; first-past-the-post tends toward two. And "tends toward" can be read as "definitely leads to" in the case of fpp.
