I was reading Will Saletan’s most recent piece (on conservatives and contraception) and got to thinking about two arguments with the same basic structure:

• Contraceptives and abortion lower the expected costs of sex, such that many people will be more willing to have more sex with more partners than if these things didn’t exist. In aggregate, it’s at least possible for this to have the paradoxical effect of producing more cases of STDs or unwanted pregnancies.
  
• Ending an unhappy marriage is often extraordinarily expensive, time consuming, and emotionally straining. There’s also a strong social stigma attached to divorce in many communities. Many people who are weighing whether to marry a current partner may be deterred by these high costs, though they would have taken a chance were the costs lower.

Presumably it’s a very difficult empirical question what the magnitude of the effect in each case is, though Saletan cites research suggesting that contraceptive use is associated with more sexual activity, it still leads to fewer unintended pregnancies. What’s interesting to note is that while conservatives make the first argument all the time, they often argue as though it’s unambiguously “good for marriage” if divorce is more difficult, costly, and stigmatized. As I noted in a review of two books about marriage a few months back, something like the logic of the second argument is expressed by lots of low-income single mothers (for whom conservatives say getting married is most important): They often conclude that however difficult single motherhood is, it’s better than risking divorce. Obviously, conservatives want to encourage more stable marriages, so they’re not going to be particularly impressed if lower exit costs just increase the total number of weddings but make the couples all much more likely to break up. But to the extent their worry about a “marriage crisis” seems to center on single mothers not marrying the biological fathers of their children, you’d think they’d at least be interested in the magnitude of the effect here. Paging Maggie Gallagher: Is there any research on this out there?