“Historically, the claim of consensus has been the first refuge of scoundrels; it is a way to avoid debate by claiming that the matter is already settled.”

Source: Theses on the Philosophy of History (1940), II
Context: There is a secret agreement between past generations and the present one. Our coming was expected on earth. Like every generation that preceded us, we have been endowed with a weak Messianic power, a power to which the past has a claim. That claim cannot be settled cheaply.

Source: The Door Into Summer (1957), Chapter 5

April 7, 1775, p. 253
Boswell's full mention of this statement reads:
:Patriotism having become one of our topicks, Johnson suddenly uttered, in a strong determined tone, an apophthegm, at which many will start: "Patriotism is the last refuge of a scoundrel." But let it be considered, that he did not mean a real and generous love of our country, but that pretended patriotism which so many, in all ages and countries, have made a cloak of self-interest.
Life of Samuel Johnson (1791), Vol II

" O, Synecdoche, my Synecdoche! http://blogs.suntimes.com/ebert/2008/11/o_synecdoche_my_synecdoche.html," (10 November 2008)
Context: I was instructed long ago by a wise editor, "If you understand something you can explain it so that almost anyone can understand it. If you don't, you won't be able to understand your own explanation." That is why 90% of academic film theory is bullshit. Jargon is the last refuge of the scoundrel.

Spark (2014)

"Family Values," The Worst Years of Our Lives: Irreverent Notes from a Decade of Greed (1991)

Letter to Leopold Mozart (24 November 1781), from Mozart: The Man and the Artist, as Revealed in his own Words by Friedrich Kerst, trans. Henry Edward Krehbiel (1906).