International Harry, meet Sally.
Can men and women be just friends?
The answer matters more than you think.
Men and women can't be friends because the sex part always gets in the way.
This gloomy view expressed by Harry in When Harry Met Sally,
a romantic comedy released in 1989, is still widely shared.
Turkey's state religious authority recently issued a more scolding version of it to be read out in the country's 90,000 mosques.
Friendships between men and women,
which begin with thoughts of companionship or confiding in one another,
drag people into the pit of adultery.
The notion that sex sometimes gets in the way is not absurd.
A study of Americans by April Bleski-Ricek of the University of Wisconsin-Eau Claire finds that in platonic couples the men are far more likely than the women to find their friend sexy and far more likely to think she finds them attractive too.
Indeed,
a man's assessment of how much his female friend fancies him matches how much he fancies her and is unrelated to how she really feels.
Clearly, men are prone to wishful thinking.
Yet it does not follow that male-female friendships are doomed.
Most people can control their urges.
Furthermore, cross-sex friendships are extremely valuable.
And not just because friendship is the golden thread that ties the hearts of all the world,
as John Evelyn, a diarist, once put it.