Remember:  occasionally, it may be an interesting question to ask why a man says what he says; but whatever the answer, it does not tell us anything about whether what he says is true or false.  We take no stock in the cheap political device of political warfare — unfortunately too common also  among economists — of arguing about a proposition by attacking or extolling the motives of the man who sponsors it or the interest for or against which the proposition seems to tell.

———————  Joseph Schumpeter in a History of Economic Analysis (Its cheapness must be why it’s used so much)