In short, more people may work when countries offer public services that directly make working easier, such as subsidized care for children and the old; generous sick leave policies; and cheap and accessible transportation. If the goal is to get more people working, what’s important about a social welfare plan may be more about what the money is spent on than how much is spent.

That is the argument that Henrik Jacobsen Kleven, a professor at the London School of Economics, offers to explain the exceptional rates of participation in the work force among citizens of Sweden, Norway and his native Denmark.

If correct, it could have broad implications for how the United States might better use its social safety net to encourage Americans to work. In particular, it could mean that more direct aid to the working poor could help coax Americans into the labor force more effectively than the tax credits that have been a mainstay for compromise between Republicans and Democrats for the last generation.

In Scandinavian countries, working parents have the option of heavily subsidized child care. Leave policies make it easy for parents to take off work to care for a sick child. Heavily subsidized public transportation may make it easier for a person in a low-wage job to get to and from work. And free or inexpensive education may make it easier to get the training to move from the unemployment rolls to a job.