Prince William and his bride, Catherine Middleton, exchanged vows. You needn’t be a royal watcher to join wholeheartedly in the rejoicing at a wedding. And we should celebrate — not because the principals are royalty, but because marriage itself badly needs reinforcing.

For the past several decades, we’ve been conducting an experiment to determine whether marriage really matters all that much to society. The results are in. But the news hasn’t yet been taken on board.