There's some evidence that presidential democracies are inherently less stable than parliamentary democracies: https://www.washingtonpost.com/opinions/is-the-u

There's some evidence that presidential democracies are inherently less stable than parliamentary democracies: https://www.washingtonpost.com/opinions/is-the-us-presidentialist-democracy-failing/2016/02/10/37fa9ec8-d018-11e5-abc9-ea152f0b9561_story.html https://www.washingtonpost.com/opinions/is-the-us-presidenti... America was thought to be an exception because both parties used to be more centrist with wide overlap, but it seems they've become increasingly polarized, which makes the whole system less stable.