I recently came across an interesting little comment from a certain Bob Fagan, who ran into Cassidy in an empty classroom in New College of California in 2005 or 2006. As Fagan says:
When I heard he was Professor of Irish Studies, I asked him if he had ever heard the theory that much Jamaican/reggae slang comes from Gaelic words that had entered their language centuries earlier, when Irish immigrants and indentured servants settled in Jamaica. Forgetting about his papers, he walked up to the blackboard and for the next ten minutes, wrote down every Jamaican slang term I threw at him, and figured out its Gaelic origins. It was obvious to me that this was a man in love with language, with teaching, as well as with learning. It was an unexpected, brief but truly delightful and memorable encounter.
I would love to have been a fly on the wall listening to Cassidy bullshitting that day. There is, of course, no evidence for Irish influence on Jamaican slang. A quick search on Google fails to turn up even one clear instance of an Irish or Gaelic slang term used in Jamaican patois. Even Monserrat, which has a much stronger claim to direct Irish connections, has almost no Irish influence on its speech patterns. (This source mentions one word which is found in Monserrat which is not found elsewhere and has a clear Irish origin, but generally finds the evidence of an Irish influence on the speech of Monserrat very underwhelming: http://www.phon.ucl.ac.uk/home/wells/brogue.htm)
I wonder what kind of rubbish Cassidy produced as he ‘figured out’ the Gaelic origins of these words for Bob Fagan that day. I’ll have a guess. No doubt, according to Cassidy, jah (in the real world, a shortened form of Jehovah) came from the Irish Dia (God), pronounced jeea. And I think he could well have suggested that irie, meaning good or excellent, comes from éirí, meaning rising or succeeding, though nobody has ever said “Tá sé éirí” in Irish.
Or perhaps (because Cassidy really didn’t know any Irish at all and I’m sure couldn’t have come up with even ludicrous fake Irish candidates without access to a dictionary) he just invented a load of random nonsense, plucking fake Irish words out of his arse to impress a total stranger. Because that’s what hateful ignorant narcissists like Cassidy do, invent a load of lying nonsense in a desperate, needy attempt to impress strangers, then leave the messes they create for other people to clear up.