Might there soon be a pill for men? Standard theories of tax incidence (borrowing from the Coase theorem) say that if so, it shouldn’t much affect the quantity of intercourse. Either the gains from trade are there or they are not. The initial burden of taking the pill might change the distribution of those gains across the sexes, but at the end of the night the final result should still be the same.
If you are a man who can credibly signal he is taking such a pill, it is like paying the woman for that final result you so desired. The woman no longer has to perform the costly pill-taking action herself. And indeed the typical equilibrium is in fact that the man does the paying. But with the male pill you are paying her in a way that will flatter her, not insult her. Nice, eh?
The funny thing is, I don’t expect the male pill to be popular at all. The key question is to figure out which assumption of the basic model is not satisfied.
One possibility is that women will infer that a man taking the pill is essentially paying other women for sex and she values him less highly.
Another possibility has to do with credibility combined with lags. If it’s focal for the woman to be taking the pill, the woman is in any case taking her pill in advance. The male pill would have impact, at the margin, only on women who weren’t really planning on having sex at all. And what kind of man spends his energy targeting such women? Yes, some men indeed do target such women, but then we’re back to the male pill not really being so popular.
A third possibility is that women in any case want the man to use a condom, if only to prevent STDs. If the man is on the pill, it is harder to make that request without insulting him and thus a woman doesn’t want her new paramour to be on the male pill.
Addendum: Megan McArdle adds a fourth explanation.