Sam invites me to a home-sewn costume party. While I'd love to come, I would much rather not spend the time to sew costume. Sam offers to do it for me. I know that it would take many hours for him to do it, and I would feel bad having him put this effort in when I could do it myself.
This generates a circular preference structure if we restrict to pairwise comparisons, assuming in each case that the third option is not available:
- Not coming to party beats sewing a costume.
- Sam's sewing a costume for me beats not coming to the party.
- My sewing a costume for me beats Sam's sewing a costume for me.
But if all three options are available, then I think I am stuck sewing a costume for me. For I just can't let Sam do the work for me simply because it's a lot of trouble for me, assuming I can do the work myself. Initially my choices were between sewing for myself and missing the party, and I preferred missing the party. But Sam's offering of a third option forced me to switch.
This kind of thing is a way for Sam to manipulate my behavior if I am a nice guy who doesn't want to put Sam to the trouble. In the case at hand, this means that Sam probably should not make me the offer to sew the costume, since by offering, he brings it about that I will go to the trouble myself. In cases where it is important that I go to the party, this manipulation may be perfectly fine—I've used it in an important case several years ago.