Originally Posted By: zmjezhd
 Quote:
To is no more an essential part of an infinitive than the definite article is an essential part of a nominative, and no one would think of calling the good man a split nominative. (Otto Jespersen. (1905) Growth and Structure of the English Language.)

That's possibly the best anti-prescriptivist argument on the issue of split infinitives I've seen. Certainly shows up the selective nature of prescriptive purism.