"We may never be able to point to a single cause for why this happened."

Did you know that drugs are the single biggest cause of crime in western society?

People who claim to know have said there isn't any single cause of the trouble.

It would not be possible to isolate a single cause without a lot of research.

But there is not enough evidence to support any single cause.

Some suggested that it might not in the end turn out to have any single global cause.

There does not seem to be any single cause, or treatment for this condition.

Man was their common foe and thus they were united in a single cause.

The need for basic education is the single most important cause of global poverty.

No one can yet be sure there is a single cause.