'sheer folly' is a correct and usable phrase in written English.
It is used to refer to a foolish action or idea. For example: "The plan he proposed was sheer folly; it could never work".
It's sheer folly to even suggest.
Letting him do that would be sheer folly.
It is sheer folly to resist closing them now.
This may strike some as sheer folly, a waste of time and foamcore.
But to suggest that American farmers no longer need a safety net would be sheer folly.
At a time when public policy should be supporting health and fitness, it's sheer folly.
Wise and responsible voices have suggested that it is the sheerest folly to threaten default on the nation's debt.
Just for the sheer joyous folly of it.
And how do you measure the sheer romantic folly of his ambition.
Closing Hazelwood before cost-effective and reliable alternative supplies could be established was "sheer, avoidable folly", Abbott wrote.
It's a dismal picture: a combination of intellectual confusion, narrow-minded officials and sheer fiscal folly has removed most of the tools that the world's major economies might be able to use to help us get through these troubled times.
