I have commented elsewhere on the fact that writers in The Economist are required to write unnatural or even ungrammatical sentences rather than risk the wrath of the semi-educated public by "splitting an infinitive" (putting a preverbal modifier immediately before the verb in a to-infinitival complement clause). The magazine published a sentence containing the phrase publicly to label itself a foreign agent where clarity demanded to publicly label itself a foreign agent.
It wasn't a one-off occurrence. Look at this sentence (issue of June 1, 2013, p. 57):
The main umbrella organisation, the Syrian National Coalition, was supposed to do three things: expand its membership, elect a new leader and decide whether unconditionally to attend the Geneva talks.
What an appalling decision about modifier placement!
They meant "decide whether to unconditionally attend the Geneva talks." The best phrasing in a case like this has the adverb immediately before the verb it modifies.
You just can't prepose manner adverbs to the beginning of to-infinitival clauses introduced by whether. These examples are outright ungrammatical:
*The question for the managing editor is whether immediately to change the policy.
*The style guide manager should think about whether voluntarily to retire or resign.
In the 44 milion words of the ever-convenient Wall Street Journal corpus that I keep on my laptop, there is not a single occurrence of an -ly adverb between whether and infinitival to.
The Economist would do slightly better if it changed to using The New York Times Style Guide. I don't approve of the fussy NYT guide at all (I have to observe it when I write for the Lingua Franca at The Chronicle of Higher Education's site), but although it is idiosyncratic, old-fashioned, and occasionally benighted, its guidance is slightly better than the blanket ban that seems to be in force at The Economist right now:
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.
This explicitly opposes the "artificial" pushing of preverbal adverbs into the position before the to. And it should be noted that that the decision about trying to avoid the construction is openly admitted to be pure political cowardice: there is nothing grammatically wrong, they admit, but hush, it might "irritate" readers to use this familiar possibility in English syntax.
The Economist has a style guide of its own, and that is even more open in its cowardice and the totality of its avoidance policy:
Happy the man who has never been told that it is wrong to split an infinitive: the ban is pointless. Unfortunately, to see it broken is so annoying to so many people that you should observe it.
A pointless ban on a natural syntactic possibility that has never been authoritatively declared to have anything wrong with it in grammatical terms, but you should observe the ban anyway. Is this a sensible way for a great magazine (my favorite magazine) to make its decisions about how its writers should phrase things in their native language?