A learner recently asked me to confirm that we use the base form of the verb after “nothing but” and only infinitives after a phrase like “no choice but.” Hmm. I could have created greater complexity by throwing out the fact that gerunds could also appear after nothing but. After all, if but functions as a preposition, then we know that gerunds could also be indirect objects. Consider this example: “There is nothing but whining and arguing at those committee meetings.” (See comment below about dummy subjects.)
However, I felt it best to limit discussion to the two constructions [nothing but + base verb] and [no choice but + infinitive]. The latter phrase has a noun, and nouns can have infinitive complements: the right to remain silent, the need to express oneself, the choice to be free. The infinitives help us define those nouns, those ideas. It doesn’t matter if the phrase is affirmative or negative: no rights to exercise, no needs to speak of, no choice but to fight. Agreed?
As for nothing but, dictionaries prefer to use examples with noun and pronoun objects. We could start with such examples to help students discover the meaning of this phrase: They serve nothing but healthy food. = They serve only healthy food. We can then start offering more examples to show the range of objects: They serve nothing but the best. = They only serve the best. / The food critic did nothing but complain.= The food critic only complained. (He did nothing else.)
I think it’s easier to see nothing but as an equivalent of only, as noted in the Longman Dictionary of Contemporary English. Comparing it to except creates confusion for learners because we also have except for and constructions like except do something and except to do something. I also think it’s helpful to show the patterns that are most frequent. We usually see [nothing but + base verb] after a form of do: He did nothing but complain. She plans to do nothing but sleep. We‘ve done nothing but work, work, work. Sometimes the most helpful explanation to a question is not about targeting the why aspect, but rather targeting what the standard is.
If you’d like to help your students learn some standard patterns with but as a preposition, please check out my Nothing but the Truth_handout.
If you’d like to help me gain greater clarity on this topic, please post a comment. Thank you!