I recently embarked on an ambitious research effort with Adam Knott to find who and in what work that the original distinction between "constitutive" and "instrumental" means was made.
I'm happy to announce that in just 16 hours I was able to uncover that it was Leonard Hugh Graham Greenwood who made the distinction in the introduction to his translation of Aristotle's Nicomachean Ethics, Book VI, the 1909 version.
The entire book can be downloaded here. If you are just interested in reading the excerpt where Greenwood makes the distinction, then you can just download "Scans 1-100" where the excerpt begins in the bottom paragraph of page 46 or pdf page 55. I have also posted a recap of the research journey at http://twitter.com/praxeology so you can experience the excitement as me and Adam did in the search and successful uncovering of the original source.
In addition, Adam has posted "an analysis of the concept as it was originally introduced by Greenwood in 1909". The first post is here.
Only ideas can overcome ideas...