@andy-dienes said in An argument against committee monotonicity:
There are rules which are committee monotone which will elect AC (e.g. SAV)
That means that SAV elects C for k=1, which is definitely illogical. As for MES, part of that might be because it's a little unclear for which values of x the following generalization should elect AC instead of BC:
A (1-x)/2
AB x/2 - epsilon
BC x/2 + epsilon
C (1-x)/2
All-at-once d'Hondt PAV elects AC for x < 2/3. I think my argument is more persuasive if x is closer to (but still more than) 1/2, and epsilon is small compared to x-1/2.