I'm sure this book is full of scholarly errors.
However, clearly there are many, many American words related to gambling, physical labor, violence, conversation, affection, poverty etc. that the professional scholars cannot - or have not bothered - to trace. Reality dictates these words had to have come from SOMEWHERE.
Where did they come from then? There isn't an infinite number of potential sources.
If these words did not come from native languages, Spanish, French, German or Dutch, maybe, just maybe they came from one of the biggest waves of immigrants ever to hit American shores.
Is that such a leap of logic?
How is it these scholars can trace some words back thousands of years, but words that sprung up in the 19th and early 20th century in America remain "of obscure origin?"
The problem is, of course, that there wasn't a whole lot of vernacular writing going on in the US when most of these words came to be and were Anglicized. People who wrote were rare and they were trained in the King's English (or French, Spanish or Dutch.)
Remember Mark Twain guys?
His writing was SHOCKING because he attempted to document the way real people spoke. No one else of prominence even attempted this and he came along very late in the game. The reality is there are a few centuries of American English we know little about - because it was never written down. Does that mean we stop thinking about word origins from this period?
Language begins with speech and then makes its way to print often long after the fact. It amazes me that people presenting themselves as professional linguists don't seem to know or appreciate this.
The scholars bitch and moan that since there is no clear written record of given Irish terms making an orderly, traceable transition to given American English terms, then Cassidy's guesses as to the origin of various American slang words are completely invalid.
That's absurd.
Where I live in the Hudson Valley, there are many odd place names that are Dutch adaptations of original Native American place names. The Dutch grabbed words from their own vocabulary that sounded like the Native words and applied them to these places and they stuck - even if they made no sense in Dutch and they almost never do.
Come to think of it the French and English did the same thing. What's an "Iroquois" for example. You won't find the word in pre-Columbian France. It's the grabbing of one word (native) with another tongue (French.) It happens all the time.
(Thanks to the Jesuits who were linguists and did write things down we can trace what happened in this particular case. Otherwise, I can see the same scholars who trash Cassidy running around trashing anyone who suggests "Iroquois" might have native origins.)
Clearly there are many common American-English terms of 19th century origin that make no sense whatsoever in English. We use them daily, we know what they mean, but if you analyze them they're odd at best.
"Longshoreman" for example.
What the heck is a "longshore"? There is no such word in English, but there is an Irish word that sounds a lot like it and it means "maritime worker." Who were the maritime workers in America? In the 19th century, overwhelmingly the Irish.
Circumstantial evidence? It sure is and it's damn good circumstantial evidence. Enough to hang a pompous scholar on.
Reality check for the ivory tower types:
How many Irish-speaking famine victims who arrived in the US in literal rags and worked in far-worse-than-slavery conditions on the docks and elsewhere do you think kept journals, wrote letters to the editor, or even wrote letters back home?
These were profoundly impoverished people most of whom didn't even have a home to write back to as they came from villages that were destroyed by famine.
They were also severely penalized for speaking Irish (it was legally banned in Ireland by the British). Not conditions conducive for generating literary traces that professional linguists can track from the comfort of their stuffed chairs.
I think the professional linguists have a lot of explaining to do as to how they missed this obvious and obviously fertile contributing source of the American language.
I guess it's easier to dump on a gifted and insightful amateur than it is to do worthwhile work.