Split Infinitives

 In section 6 of the essay "Morality and Convention" of Morality and Conflict by Stuart Hampshire, there appears the sentence

The kind of 'must not' that arises within this [local] area of morality can be compared with a linguistic prohibition, for example that you must not split an infinitive: a particular rule of a particular language, which is not made less binding by the fact that it is not a general rule in language.

Morality and Conflict was published in 1983. In Alison Lurie's Foreign Affairs, published in 1984, an American professor reflects on the conversation of a man who says that he "[used] to really enjoy baseball" with

A person without inner resources who splits infinitives ...

The first edition of H.W. Fowler's Modern English Usage, published in 1927, gives almost three pages to the question of split infinitives, and sorts writers by attitude into five divisions. Clearly Fowler is with the fifth:

5. The attitude of those who know and distinguish is something like this: We admit that the separation of to from its infinitive .. is not in itself desirable ... We maintain however that a real [split infinitive], though not desirable in itself, is preferable to either of two things, to real ambiguity, & to patent artificiality.

 Presumably Lurie's character belonged to Fowler's division 1, "those who neither know nor care what a split infinitive is".