… is from pages 17-18 of Gordon Tullock’s 1987 essay “Public Choice,” the original of which appeared in The New Palgrave: A Dictionary of Economics, and is reprinted in Virginia Political Economy, which is Vol. 1 of The Selected Works of Gordon Tullock (Charles K. Rowley, ed., 2004) (footnotes deleted):
One of the earliest discoveries of the new Public Choice was that a rational voter would not bother to be very well informed about the votes that he cast. The reason is simply that the effect of his vote on his well-being is trivially small. Apparently voters have always known this, since empirical studies of voter knowledge show them extremely ignorant, but it was something of a revelation to traditional professors of Political Science. Further, this general ignorance of the voter is not symmetrical. The voter is likely to know a good deal about any special interest which he has. Further, organized special interest groups will put effort into propagandizing the voter in such areas. Thus the voter is not only badly informed, but what information he has tends to be biased very heavily in the direction of his own occupation or avocation.