This would go nicely in the Philosophy subforum, but I seem to have arrived just in time to see that being closed. So I guess it goes under General Discussion. This is not quite a "philosophy of science" question, but more a history of science question anyway. There seem to be plenty of knowledgeable discussions about science and the nature of scientific theory here, and I see the term "theoretical construct" used frequently. But does anyone know the history of the concept itself? When does a "construct" as a tool of science first appear? The ability to distinguish between an observable phenomenon and a concept in the mind would seem to point to Kant as the earliest backstop for the origin of this usage. Kant's definition of science and scientific progress certainly looks like a good source for someone to develop the idea from. Is a "construct" directly related to a "category of the understanding"? Perhaps some "scientist" around the time the word "scientist" was coined by William Whewell (1833) realized that the broad and apparently undefinable "category" (philosophers were still fighting over the "right" number and definition long after Kant's death) could be reduced to a more manageable "construct of the mind" for the purpose of discussing scientific uncertainty? There doesn't seem to be any readily available source for the history of the term. All of the encyclopedias of science I can find do not give an origin, only a definition.