I have a query in regard to a paper I am writing. We know that the 
explicit distinction between risk and uncertainty is found in Frank 
Knight's "Risk, Uncertainty and Profit" first published in 1921. What 
I would like to know is whether this explicit distinction is found 
amongst economists before its use by Knight, whether the term 
"uncertainty" was used by economists prior to Knight's use, and 
whether the concepts surrounding uncertainty have an older provenance 
in the economic literature under a different name.

I might just note that Heisenberg did not publish his own paper on 
the Uncertainty Principle until 1927. The explicit use of 
"uncertainty" in economics predates its use by physicists.

Steven Kates