The New York Times blog takes up the question of split infinitives, and begins with this item from the Times stylebook:

split infinitives are accepted by grammarians but irritate many readers. When a graceful alternative exists, avoid the construction: to show the difference clearly is better than to clearly show the difference. (Do not use the artificial clearly to show the difference.) When the split is unavoidable, accept it: He was obliged to more than double the price.

So far, not bad. I like the "to clearly show" version more, but at least the stylebook rejects the "split infinitives are ungrammatical" myth, while acknowledging that authors should keep in mind some readers' preferences.

Still, look at what even a measured preference against split infinitives yields:

The Treasury has promised to independently evaluate potential conflicts, but it appears that officials plan to start with the firms' own self-assessment of any problems.

This may be a closer call [than the previous example], but a slight rephrasing like "promised independent evaluations of potential conflicts" would avoid the problem.

Yes, it will avoid the problem of irritating some readers who dislike split infinitives -- but only by changing a verb phrase to a noun phrase. Verb phrases ("promised to independently evaluate potential conflicts") tend to be more active and engaging than their nominalized forms ("promised independent evaluations of potential conflicts"). They tend to be slightly simpler grammatically (note that the nominalization requires an extra prepositional phrase). And they often make clearer who is doing what: In this very example, for instance, the original indicates the Treasury will independently evaluate potential conflicts, while the revised version leaves that uncertain (since it just says there would be independent evaluations).

That's why avoid nominalization is itself common usage advice, and in my view better advice than avoid split infinitives, because it deals with real lack of clarity and vigor rather than just with accommodating the views of some readers. Again, I acknowledge that accommodating reader preferences is something that writers, especially writers at for-profit institutions, often need to do. But it's important to recognize, I think, that this particular preference against split infinitives can be costly.

Perhaps it's possible to rewrite the sentence in a way that avoids the split infinitive without nominalizations or other clunky constructions. But even if that's so, it's still worth focusing on the rewrite suggested by the Times blogger, a professional editor "who is also in charge of The Times's style manual." If the desire to avoid split infinitives pulls this experienced editor into making the sentence less active, more complex, and more opaque, it's a fair bet that it will often do the same to other, less experienced editors, even if enough thinking can yield a supposedly better solution.

Thanks to Prof. Sam Levine for the pointer.