According to Steven Landsburg, writing in Slate, people who are NOT promiscuous should take on a couple more partners a year. Doing so could slow the spread of sexually transmitted disease.
The idea is that they’d still be conservative, but slightly less so. They wouldn’t increase their own chances of getting sick very much, and they’d ensure that the people they sleep with are choosing them (healthy people) over more promiscuous and possibly unhealthy ones.
And how can we help those people get out there and spread the love? Cheaper condoms.
The articles says that society should subsidize condoms in order to encourage people to be a little more slutty.