Gas prices are tumbling, but that’s not necessarily a good thing

At first glance, it seems that the decline from more than $100 a barrel to $80 a barrel would be a good thing for the U.S. economy. It is like a tax cut, putting more spending power into the hands of consumers, but without the messiness of political wrangling. But how good is it actually?

There are two reasons to put that question forward – one having to do with what is happening outside the United States and the other, inside.