Quotes from book
Considerations on Representative Government

Name: Considerations on Representative Government
Author: John Stuart Mill

Considerations on Representative Government is a book by John Stuart Mill published in 1861.

“I did not mean that Conservatives are generally stupid; I meant, that stupid persons are generally Conservative. I believe that to be so obvious and undeniable a fact that I hardly think any hon. Gentleman will question it.”

John Stuart Mill book Considerations on Representative Government

In a Parliamentary debate with the Conservative MP, John Pakington (May 31, 1866). Hansard, vol 183, col 1592. Pakington was referring to Footnote 3 to Chapter 7 of Mill's "Considerations on Representative Government".
Misquoted as "I never meant to say that the Conservatives are generally stupid. I meant to say that stupid people are generally Conservative. I believe that is so obviously and universally admitted a principle that I hardly think any gentleman will deny it." in "Life of John Stuart Mill" (1889) by W. L. Courtney, p. 147.
This seems to have become paraphrased as "Conservatives are not necessarily stupid, but most stupid people are conservatives." which was a variant published in Quotations for Our Time (1978), edited by Laurence J. Peter.