Algorithms Seminar

The Power of Public Spirit in Voting

November 16, -
Speaker(s): Bailey Flanigan


Lunch will be served at 11:45 AM.


A key promise of voting is that, by accounting for all constituents’ preferences, it produces decisions that benefit society overall. It is alarming, then, that all deterministic voting rules have unbounded distortion — i.e., arbitrarily suboptimal social welfare — even under realistic conditions. In our paper Distortion Under Public-Spirited Voting, we show that this impossibility is circumvented when voters are public-spirited: that is, when deciding how to rank alternatives, voters weigh the common good in addition to their own interests. We first generalize the standard voting model to capture public-spirited voting behavior. We then show that public spirit can dramatically — and in some senses, monotonically — reduce the distortion; for some rules, it even drops the distortion from unbounded to constant. We further find that these benefits are robust to practically-motivated imperfect conditions. Taken together, our results suggest an implementable approach to improving the welfare outcomes of elections: democratic deliberation, an already-mainstream practice shown to increase voters' public spirit.

Speaker Bio:

Bailey Flanigan is a fifth (and final) year PhD student at Carnegie Mellon University, advised by Ariel Procaccia. Her work uses the tools of algorithms, social choice, and social science to design and support more effective democratic processes. Outside of research, she is passionate about equitable education and led the creation of CS-JEDI, a CMU grad course on diversity, equity, and inclusion. She is funded by a Hertz Fellowship, a Siebel Scholarship, and an NSF GRFP.


Kamesh Munagala