… is from chapter 1 of William Graham Sumner’s 1885 book, Protectionism: the -ism Which Teaches that Waste Makes Wealth:
Protectionism then is an ism, that is, it is a doctrine or system of doctrine which offers no demonstration, and rests upon no facts, but appeals to faith on grounds of its à priori reasonableness, or the plausibility with which it can be set forth.