The same alternation occurs in other words pairs: medicine/medical, criticize/critical, electricity/electrical. (There is also g/j alternation as in allege/allegation.) Although it can’t be a full explanation, speakers may have a high-level model of some consonants with the sound dependent on context (especially the following vowel).
Originally Posted by Ulfreida:… [same example] …
Su-weet.
If there was still any doubt, I’ve now confirmed that most of you have me set to Ignore.