Can I use someone else as a "mere means" in Kant's words without coercing or deceiving them? Is the use of someone as mere means possible when there is consent?
Some of the examples I have in mind are:
(1) Prostitutes sell their bodies, hence "objectify" themselves even though they consent to this action. We could consider two sub-cases, one in which a prostitute is forced to prostitution due to poverty, the other in which she or he has other options.
(2) Two people, even though they don't like each other, meet regularly to play tennis. The only reason they meet is to play tennis. In short, they "use" each other to play tennis.