As I was reading through The Collected Papers of Charles Sanders Peirce, I came across the following sentence:
I doubt not that readers have been fretting over the ridiculous-seeming phrase “indecomposable element,” which is as Hibernian as “necessary and sufficient condition” (as if “condition” meant no more than concomitant and as [if] needful were not the proper accompaniment of “sufficient”).
(Punctuation modified; emphases and inserted conjunction in original edition.)
What did he mean by the statement in parentheses? How would amending the phrase “necessary and sufficient condition” to “needful and sufficient concomitant” change its connotation?
Regarding the first distinction, I have in mind Hume's criticism of the proposition that induction can serve to show a conditional (causal) relationship between concomitant events, but I don't know if it's justifiable to read that into Peirce's words.
Regarding the second distinction, I suspect but haven't been able to confirm that his preference for “needful” over “necessary” here may simply reflect a difference in common usage that existed at the time, rather than a technical distinction. Is this suspicion accurate?
(Ancillary question: What does he mean by "Hibernian"? Is there some antiquated stereotype that the Irish use ridiculous-seeming verbose phrases?)