I am a virgin, but shortly to be married. I am looking forward to our wedding night but I am a little anxious about the risks. My fiance has had previous girlfriends, so I have asked him to take a test for sexually transmitted diseases. He says that he took a virginity pledge as a teenager and so there is no need. Should I accept this?
Yours, Miss M., Virginia
Dear Miss M.,
This so-called pledge doesn’t sound too solid to me. First, it is time-inconsistent. Nobel laureates Finn Kydland and Edward Prescott have explained that certain promises are likely to be broken when the time of trial arises. Time-inconsistency plagues government promises to run sound monetary and fiscal policy, but applies equally to more exciting forms of temptation.
Second, this is a non-verifiable contract under asymmetric information – that is, your fiance knows the truth, and you never will. If he is lying to you, you should be worried, since pledgers are less likely to use condoms if they do break their pledge.
Many pledgers promise to remain “sexually pure until the day I enter marriage”, but what does that mean? This is the third problem: the contract is incomplete. Even if you knew that he had stuck to the letter of his pledge, the risk is that your fiance may interpret “sexually pure” to allow certain practices which carry a high risk of STD infection. All in all, economists were hardly surprised when researchers from Columbia University’s Institute for Social and Economic Research and Policy found that virginity pledgers are as likely to pick up STDs as other teenagers.
You need a credible signal that your fiance is true. This would be an action which he could easily take if faithful, but which is costly if he is lying. His reticence to be tested should already tell you all you need to know.
First published at ft.com.