"Construct" implies to me something more or less arbitrary, that could just as easily be something else.

Languages, for example, are clearly "constructs," since no word or syntactical form has a direct relationship to reality. (If it did, there'd be just one universal language.)

I see no reason then to believe that human logic ("reason")is only a "construct," because its connection to reality seems to be clearly and irrefutably confirmed everywhere all the time. Unreason, magic, superstition, etc., can be shown, however, to be completely unreliable.