What isn't a split infinitive?

[M56]

Semantically, there's a marked difference between, say, A. and B.

A. To be perfectly clear (linking verb + adjective)
B. To be perfectly understood (verb + participle)

In A. the adjective is not part of the verb proper ([ . . . ]), whereas in B. the participle is part of the verb proper:

A. [to be] perfectly clear
B. [to be perfectly understood]

Now the verb proper happens to be an infinitive, and its structural integrity
hasn't been violated in A., and it hasn't been violated in B. The adverb doesn't come between the infinitive marker (to) and its base verb (be). If it did, we'd be looking at a split infinitive.

With our examples, the adverb is outside the verb proper (A.) and inside the verb proper (B.), but not inside the infinitive itself:

A. [ to be] perfectly clear
B. [ to be [perfectly understood] ]

If you want to agrue that B. is an example of a split, I'd be the first to agree with you, but you'll have to use a different term because "split infinitive" B. is not.

Now if we moved the adverb out of the verb proper ([ . . . ]), then it would serve to modify the verb proper:

C. [ to be understood ] perfectly

With structural change comes a change in meaning, so C. and B. don't express exactly the same thing:

B. [ to be [perfectly understood] ]
C. [ to be understood ] perfectly

In short, B. is not a split infinitive; no "infinitive" has been split.

Thanks for so detailed an explantion.


<In short, B. is not a split infinitive; no "infinitive" has been split.>

I agree.

[tuangpi]

Grammar is a stellar grade. It has two A's.

So long as there are different people.