This letter to the editor of the Australian newspaper The Age, from Brian Cole of Yarragon, a small town in Victoria, ran under the title "What the…":
WHILE I recognise the evolutionary nature of the English language, I listen with increasing despair to the inappropriate use of the word "what".
"What" has an interrogatory sense, that is, it is a word looking for an answer. I have learned to cope with sports commentators using expressions such as "they moved the ball better than what the other team did". But in the second paragraph of The Sunday Age's editorial: "and that their culture was the opposite of what Mr Costello suggested"? No interrogative anywhere to be seen.
There are many ways to improve this phrase. It would be acceptable to simply replace "what" with "that" but nicer usage to write "and that their culture was the opposite of that suggested by Mr Costello".
Mr. Cole is the victim of a mistaken generalization. He starts by complaining about a genuinely non-standard usage, in which "than what" introduces an ordinary comparative clause where "than" is the standard form:
Kim is taller than (*what) Leslie is.
He apparently concludes that the key problem here is the use of "what" in a clause that's not a question, and decides that this practice should be banned. But the other example that he complains about is an entirely different (and unproblematic) structure:
… and that their culture was the opposite of what Mr. Costello suggested.
Here "what Mr. Costello suggested" is a fused relative (sometimes called a "headless relative clause" or a "nominal relative"). In this case it's serving as a noun phrase, the object of the preposition of. The result is parallel in structure to
… the opposite of Mr. Costello's suggestion.
This construction is discussed starting on p. 1033 of The Cambridge Grammar of the English Language. The authors suggest the term "fused relative" because "it is not possible to separately identify antecedent and relative clause", which we can think of as having been "fused", as in
|It would mean abandoning that which we hold most dear.||[antecedent + clause]|
|It would mean abandoning what we hold most dear.||[fused relative]|
Fused relatives are a perfectly standard construction in formal written English. And as for the "evolutionary nature" of English, the "evolution" in question took place quite a while ago, since (the precursors of) current English fused relatives were, I think, a feature of Indo-European. The equivalent construction is common in Latin proverbs, mottoes, and fixed expressions:
Qui transtulit sustinet.
Qui bene cantat, bis orat.
Quod erat demonstrandum.
Certainly this construction has been in use ever since English became English. We can start with Chaucer:
'Cosin,' quod she, 'if that I hadde a space,
As I have noon, and namely in this place,
Than wolde I telle a legende of my lyf,
What I have suffred sith I was a wyf
With myn housbonde, al be he your cosyn.'
And go on to Shakespeare:
Good name in man and woman's deere my Lord;
Is the immediate Iewell of our soules:
Who steales my purse, steales trash, tis something, nothing,
Twas mine, tis his, and has bin slaue to thousands:
But he that filches from me my good name,
Robs me of that, which not inriches him,
And makes me poore indeed.
In the classic literature of the 19th century, we can find a number of examples that are very similar to the case that set Mr. Cole off, e.g. this from George Eliot's Daniel Deronda (1876):
Doubtless her husband had meant to produce a great effect on her: by-and-by perhaps she would let him see an effect the very opposite of what he intended; but at present all that she could show was a defiant satisfaction in what had been presumed to be disagreeable.
Mr. Cole's letter is likely to have little influence. But the process that led him to peeve in public about a perfectly normal construction is worth documenting. We see similar things again and again, and if the mistaken generalization somehow goes culturally viral, this sort of thing gives rise what we've called "zombie rules".
[Tip of the hat to Brendan Corney.]