Why not to believe Buchanan's ranting...

On immigration, there is a lot of heat and little light. So, let's take a look back at other times when immigration was an issue. Pink Flamingo has a great series of quotes from back then.

“…Immigrants will not be able to assimilate:

Where the
Italians wanted to be part of our family, millions of Mexicans are determined to retain their language and loyalty to Mexico. They prefer to remain outsiders. They do not wish to assimilate and the nation no longer demands that they do so. [Buchanan, p. 28, 2006]

VERSUS

Why should Pennsylvania, founded by the English, become a Colony of Aliens, who will shortly be so numerous as to Germanize us instead of our Anglifying them, and
will never adopt our Languages or Customs, any more than they can acquire our Complexion. [Benjamin Franklin, 1751]

Immigrants are responsible for crime:

Many Hispanics, as a matter of fact, you know what culture they are assimilating to? — the rap culture, the crime culture, anti-cops, all the rest of it. [Buchanan, 8/22/06]

VERSUS
“The Irish fill our prisons, our poor houses. … Scratch a convict or a pauper, and
the chances are that you tickle the skin of an Irish Catholic. Putting them on a boat and sending them home would end crime in this country.” [Chicago Post, 1868]

Immigrants plan to commit treason against America:
Mexican-Americans can now become citizens of Mexico again. The whole idea is to create this giant fifth column in the United States which can leverage the American government in elections and pressure them to do what is in the interest of the nation of Mexico. [Buchanan, 8/22/06]

VERSUS

[A] set of citizens, German and Irish, wanted to get the Constitution of the U. S.
into their own hands and sell it to a foreign power. [Theme of an American Nativist Party rally, 1844]

Immigrants come from inferior cultures:

[A]lmost all immigrants today, legal and illegal, come from countries and cultures whose peoples have never before been assimilated into a First World nation. [Buchanan, p. 221, 2006]

VERSUS

Today, instead of a nation descended from generations of freemen bred to a knowledge of principles and practice of self government, of liberty under the law, we have a heterogeneous population, no small proportion of which is sprung from races that throughout the centuries have known no liberty at all… In other words our capacity to maintain our cherished institutions stands diluted by a stream of alien blood, with all of its misconceptions respecting the relationships of the governing power to the governed. [Rep. Albert Johnson, 1927, justifying the 1924 National Origins Act]

Immigrants will dilute the white race:
If we do not get control of our borders, by 2050 Americans of European descent will be a minority in the nation their ancestors created and built. No nation has ever
undergone so radical a demographic transformation and survived. [Buchanan, p. 11, 2006]

VERSUS

The number of purely white People in the World is proportionally very small…in Europe, the Spaniards, Italians, French, Russians and Swedes, are generally of what we call a swarthy Complexion; as are Germans also, the Saxons only accepted, who with the English, make the principal Body of White People on the Face of the Earth. [Benjamin Franklin, 1751]”

I see a 256-year track record of nativism getting it wrong. If they have been so far off for so long, why should they be believed now?