24 may be too much for a downvoting decision. I think more than 3 because it adds more voices to the decision and leaves less room for gaming the outcome. Random selection and anonymous jurors would do much, but if I'm adjudicating your downvote of @prydefoltz and like her more than I like you, I may decide it's more important to vote with my affinity for prydefoltz rather than on the side of justice. If one other juror did that and there are only three, the majority is on the side of injustice. The more jurors you have, the less likely such thinking will rule the adjudication process.