Suffix-o-rama
Grammar maven Patricia T. O’Conner responded via email to my query about suffix orthogonality. I don’t think she will mind my reprinting it here.
Hi, Chris,
You’ve done a lot more thinking about this suffix business than I have. Most of the shades of difference with adjectives ending in “-ic” and “-ical” seem to have developed idiomatically and there are no general rules governing them.
Suffixes in general can be quite mysterious. For example, two opposite suffixes (”-less” and “-ful”) give similar meanings the case of “shameless” and “shameful.” But I may be able to come up with some rough guidelines for certain kinds of suffixes.
In the case of agent nouns formed by adding “-er” and “-or,” there’s a generality to be made. Often the “-er” ones come from Old English (like “singer,” with roots in ancient Germanic), while the “-or” ones are derived from Latin (like “editor,” from the Latin edere*, “edit”). Even here, though, there are exceptions. When an English word has both endings (like “adviser”/”advisor”), the “-er” ending is often the older one. In the case of some legal terms, it appears that lawyers historically have been fonder of more pompous-looking Latinate endings than of simple Germanic ones. (Historically, English academics, jurists, and churchmen always respected Latin more than Old English, which explains much of the confusion about English grammar.)
Then there’s the “-ible”-vs.”-able” ending. If there’s a generality to be made, it’s this: Often a word derived from Old English or another Germanic source (like Old Dutch, Old Icelandic, Old Norse and so on) will end in “able” (“forgivable,” “lovable,” “readable”). But a word derived directly from Latin will end in “ible” (“terrible,” “audible,” “legible”). Again, this is only a rough generality, since there are exceptions. And oddities too: “eatable” is from the Old English etan (”eat”) while “edible” is from the Latin edere* (”eat”).
I can understand how a mathematician might be frustrated by all these generalities. As the grammarian Otto Jespersen once said, this isn’t Euclidean geometry.
Pat O’Conner
*The Latin edere can mean to eat, to publish, to edit, to give forth.
Thanks!
Filed under 
Chris, I think you’re onto something, but I don’t know what! I am disappointed to see that the so-called Grammar Mavens did not go into specific detail on the ic/ical dichotomy. What does Fowler say?
IANAL(inguist), but I think there’s a degree of indirection distinguishing the two; surely it seems that “ic” (roughly) corresponds to “having the quality or essence of” while “ical” (again roughly) corresponds to “of or relating to”, like classic/classical or historic/historical. I would also say there is a similar but perhaps slight difference between symmetric/symmetrical and diabolic/diabolical. I’d say a bunch Rorshach images are symmetrical but not symmetric, unless the images themselves were specifically arranged…
Obviously not a real rule, and usage clouds the issue, but interesting. Possibly of interest
http://icame.uib.no/ij25/gries.pdf