This is not a straight translation question. I am asking this because the above phrase, from 'Concede parum, nega frequenter, distingue semper' seems to be rendered by some unofficial sources (see here - the man who owns that blog is a priest and has a doctorate in Medieval philosophy, for what it's worth) as 'Seldom affirm, rarely deny, always distinguish', although it seems it would be better rendered 'Seldom affirm, frequently deny, always distinguish', which is quite a different expression. The only reason I'm not jumping to conclusions, is my Latin is rather rusty, and I wonder if I'm forgetting some idiom. A web search seems to pull up only that source, some forums, and the Latin expression quoted in older scholarly writings (in Google books) without translation. Any help is appreciated! Thank you.
You are right, nega frequenter does mean "deny frequently". I would guess that there was a confusion between frequenter (frequently) and infrequenter (infrequently).