Conversation

Arrow's impossibility theorem:

https://www.investopedia.com/terms/a/arrows-impossibility-theorem.asp

So, basically, in an instant-runoff voting system (where voters rank candidates by preference), the outcome (who the winner is) could change if one candidate wasn't running, even if that candidate hadn't won if they did participate.

My immediate conclusion is that instant-runoff voting systems work best if there is an abundance of good candidates, and voters can always pick the best ones for them, not the ones they hate the least.