Well, I’ll see what the big tome* I’ve been browsing through lately has to say about complementary infinitives…
Intro 34. “Some Latin verbs have as their object the infinitive of another verb.”
-possum i.e. possum id facere - I can do it
-nequeo i.e. nequeo id facere - I can’t do it
-desino i.e. desino id facere - I cease to do it/stop doing it
-volo i.e. volo id facere - I want to do it
A list from the same source. Categories:
a) Possibility - possum (can), nequeo (can’t)
b) duty, habit - debeo (ought to); soleo, assuesco, consuevi (am accustomed to)
c) wish, purpose, daring, endeavor - volo (wish to), nolo (don’t wish to), malo (prefer to), cupio (desire to), opto (choose/wish to); statuo, constituo (resolve/decide to); audeo (dare to); conor (try to) [also, tempto]
d) beginning, ceasing, continuing - coepi, incipio (begin); desino, desisto (stop/cease); pergo, persevero (keep/continue)
e) hastening, hesitating - festino , propero, maturo (hurry); dubito (hesitate)
f) learning, knowing how - disco (learn), doceo [can doceo mean to learn?]; scio (know how)
But I don’t suggest you try to memorize the list. If you just learn the meaning, most of the time you’ll be able to guess that they can take an infinitive, just as nearly all of them do in English. Some of them will rarely be seen without an infinitive - like possum for instance. Others can be used in multiple ways - debeo, as discussed already; dubito, which can mean “to hesitate” with an infinitive but also to doubt (whether)
-David
*“Bradley’s Arnold”: Latin Prose Composition, revised by Sir James Mountford, published by Bristol Classical Press