Rejoinder to “Understanding our Markov Chain Significance Test”

We thank Chikina, Frieze, and Pegden for their reply to our article. We offer just a short clarification rejoinder. In particular, we would like to be clear that we are not challenging the CFP test as a partisan gerrymandering test. We also do not “cast doubt” on the CFP paper. We have clearly stated that “we take no issues with the mathematics behind the CFP theorem or its proof.” In addition, we do not “prefer” one partisan gerrymandering test over another or advocate a single test. We firmly believe that there is plenty of room for multiple partisan gerrymandering tests. In this space, one test need not be “worse” than another. At the same time, it is indisputable that whether the CFP test would constitute a legal test for partisan gerrymandering is a legal question for the courts to decide. Legal questions cannot be decided by mathematicians. Mathematicians may make proposals, but judges decide whether to accept those proposals. Our point is simply that judges must clearly understand the mathematical concepts (even if not the mathematical details) in order to make a reasoned judgment. However, when the science is unclear, we have only miscommunication, from which no one benefits.