Dear Grammar Mavens,
In English, the suffixes ‘-ic’ and ‘-ical’ both form adjectives from nouns. An object exhibiting symmetry is ‘symmetric’, and the aims of a devil are ‘diabolical’.
My question is about how we use each suffix. For some roots, they seem interchangeable (diabolic vs. diabolical). For others they produce distinct shades of meaning (mythic vs. mythical). In some cases, one conceivable variant is absent from the dictionary and never used (chaotic vs. *chaotical, or *chemic vs. chemical). And in other cases, one variant seems to be preferred but the other can be found in the dictionary and is often heard (cyclic vs. cyclical).
To me personally, words like ‘cyclical’, ‘symmetrical’, and ‘fantastical’ clearly have redundant suffixes, because ‘cyclic’, ‘symmetric’, and ‘fantastic’ are already perfectly good adjectives. Unfortunately, I don’t seem to apply my own rule consistently, because I would use ‘parenthetical’ over ‘parenthetic’.
Nouns ending in ‘-ic’ confuse things too: ‘magic’ is both a noun and an adjective, but we also have ‘magical’ to make slight semantic distinctions. A “magic journey” is supernatural (perhaps enabled by a magic carpet or enchanted broomstick), whereas a “magical journey” is merely extraordinary.
‘Logic’ is strictly a noun (we need -al to form the adjective), but mysteriously, both ‘gynecologic’ and ‘gynecological’ are listed in my dictionary as adjectives. Similarly, ‘graphic’ and ‘graphical’ are both adjectives, as is ‘cryptographic’, but not *‘cryptographical’. In the former case, there might again be different shades of meaning: is a graphic depiction the same as a graphical depiction?
Is there any pattern or method to this madness? As a borderline mathematician, I would prefer orthogonal grammatical characteristics (orthogonalistical grammatic characterisms); as a language user, perhaps I must submit to its haphazardly evolved nature.