The Boatman Puzzle

A friend once sent me this puzzle:

A man (M) and a lady (L) who are very much in love and devoted to one another, are separated by a river with no way of getting across to the other side. On L’s side of the river, there is a boatman (B) who is able to take her over to the other side of the river but refuses to do so unless she pays him $20, twice his normal fare. L has no money. Another man (S) then tells L that he will giver her $20 if she sleeps with him. L agrees to do so and on receiving the $20, pays B who takes her over to the other side of the river. She is reunited with M and they are very happy together. However, a friend of M (F) finds out what L did with S and immediately tells M. On learning the news, M finds L and ends things with her, stating that he wants nothing more to do with her. Your task is to rank these five people, M, L, B, S, and F, from best person to worst person.

I find this an intriguing puzzle because your answer reveals a lot about your moral philosophy.

Of course, in a shallow sense there is no “correct” answer, because your answer is not solely constrained by the internal conditions of the puzzle: it depends on how you evaluate the characters’ actions in the light of your own ethics. In a deeper sense, however, there is a correct answer: because morality is objective and ethics are true or false, valid or invalid, depending on how they correspond with reality. So the correct answer is one that stems from a valid moral philosophy.

Actually, it is not quite that simple, as there is some ambiguity in at least some of the actor’s motivations, and how you rank them will depend on your evaluation of that. So the reasons for your answer are as important as your answer.

I’ve found that a person’s answer to this puzzle is a good indicator about him or her. People who give similar answers tend to be compatible – not surprisingly, since your moral philosophy is an important part of your character and a determinant of your values. People who give opposite or mutually random answers tend not to get along at all well.

So think about it and see what you think! How would you act under the conditions described, and why? If you’ve been following Philosophical Reflections, what do you think the answer would be according to its ethics? My answer is given elsewhere.

To constrain it a bit, you should take the puzzle at face value: assume that L indeed has no other way to get back across the river, and that if she doesn’t accept S’s offer, she will probably never see M again. That is, the point of the puzzle is the application of your moral philosophy to the circumstances stated, not to find alternative physical solutions to L’s problem!

For my answer to this puzzle see An Indecent Proposal.

© 1998 Robin Craig: first published in TableAus.