Four of the 26 students in my Economics of Life class proposed delaying submitting their draft term project reports by one week. I emailed the whole class and gave them one day to let me know if they disapproved of this postponement.
The question was how heavily to weight the negatives — those who disapproved — compared to those who wanted to postpone. I couldn’t just require a Pareto improvement; why should one person’s problem with the proposal be allowed to veto an improvement for the other 25?
Instead, I decided that my little social welfare function would weigh losses more heavily than gains, so that if three people objected I would not make the change. Perhaps unsurprisingly nobody objected, and I went ahead with the change, presumably now generating a Pareto improvement for my class.