When I was in college, my instructor said “grammatic” and “grammatical” were redundant. The -ic and -al suffixes both made “grammar” an adjective. I never really noticed a problem as “grammatic” and “grammatical” both seemed to be correct by native speaker intuition.
However, my native speaker intuition choked on “systemic” vs “systematical.”
Is -ic and -al exclusive?
Oh dear - The English language consistently refuses to be corralled into some rigid system of grammar. While there are many things that are totally unacceptable - putting an apostrophe in the wrong place for example) there are many others that are a matter of custom and practice, or even local usage.
“Systemic” and “systematical” are not the pair your prelude talks about.
“Systemic” and “systemical” are a pair based off the root “system”. Whereas “systematic” and “systematical” are a pair based off the root “systemat”.
I don’t have the formal grammar to take this any further. But so far IMO the OP has a false comparison going.
Said another way, “systemic” and “systematical” are not synonyms. So they’re not interchangeable and aren’t just a matter of either redundancy or of preference.
The olde-tyme anti-Commie Cold Warriors were fond of using the word “Communistic”.
I wonder if the “-ical” usage is just plain and simply erroneous. At least sometimes. You can make a lot of adverbs by adding “-ly” to other words, but if the word already ends in “-ic”, then you add “-ally”. Example: “systematic” -> “systematically”. This may lead people to think that the adjective, before you add the “-ly” is “systematical”.
OTOH, I’m not sure that “grammatic” is a correct word. And I’ve never heard of “systemat”. Or “grammat” either, for that matter.
List of words ending with “-ic”.
Another list of words ending with “-ic”.
List of words ending with “-al” (Note some of these end with “-ical”, e.g., angelical. How is that different from angelic?)
Another list of words ending with “-al”.
List of words ending with “-ical”.
Another list of words ending with “-ical”.
I would just say that it’s the historical weirdness of the English language. Sometimes it’s proper to add “-al,” other times “-ical.” There may be deeper reasons, but it would take a descriptivist to go out and discover them.
One thing I’ve noticed is that “-ical” tends to be added to roots that end in “mat.” There’s no reason we couldn’t use “mathematic” instead of “mathematical.” The reason we don’t is that “mathematics” is a noun.
And, checking the etymology of grammar, it comes from the Old French grammaire, which itself comes from the Greek γραμματῐκή (grammatikē), which was a noun meaning “the art of letters.” In other words, a noun version of “grammatic.”
SImilarly, “mathematics” comes from the Greek μαθεματικος (mathematikos), which was both an adjective meaning “fond of learning” and a noun meaning “advanced student.” (-ῐκός [ikos] is the masculine form of -ῐκή [ikē]).
So, while mathematics survived as a noun in English, “grammatics” went through French and came out as “grammar” instead. But we still have the historical artifacts of “mathematical” and “grammatical.”
Or, at least, that’s my amateur etymological and linguistic hypothesis, using publicly available sources on the Internet.
English is weird. If you drink too much you’re an alcoholic. If you work too much, you’re a workaholic. A-what? Should be “workic” but that doesn’t sound right to anybody.
Must be a grammatic thing.
I’m pretty sure that “workaholic” is just a cutesy neologism, derived from splicing together the root “work” plus the suffix “-aholic” taken from “alcoholic” to mean “addicted to”. (ETA: Of course, the “hol” syllable belonged with the root of alcoholic instead of being part of the suffix, but when we’re making up words we can have some fun, right?)
Just like “Watergate” referred to a presidential scandal that happened at the Watergate apartment complex, then the suffix “-gate” has come to mean “scandal” ever since.
More ETA: Any anyway, you’re right. English am weird.
“Electric” and “electrical” have significantly different meanings. You can have an electric stove or an electric bill. You can read an electrical diagram or use electrical connectors.