Complementing an adjective

There are very few examples of English adjectives that take noun phrase (NP) complements. The CGEL lists four: due, like, unlike and worth.

Prepositions typically take NPs as complements (e.g., up the ladder) as do linking verbs (e.g., It remains a difficult problem.). Adjectives don't do that, at least not typically. But we do have the few listed above, for example: he's very like his mother or it's worth the world.

The reason I mention this is that Rodney Huddleston brought one to my attention yesterday morning: underweight. (Geoff Pullum has already blogged about it here and I've added it to the English Wiktionary.) The example that he sent is: "It's a long-run trend of foreign investors -- typically being underweight the banking sector in Australia," Mr Baker said. 

To most of us who aren't in finance, though, this will sound rather odd. You may even have a burning desire to put an in between underweight and the the. But as Geoff points out, you can find lots of other examples in the financial papers if you go looking. It's feature, not a bug.

As I was marking essays this morning (which is what I should really be doing now), I realized this is another piece of evidence that to-infinitives do not "function as nouns" despite the common claim that they do. The fact is, English is endowed with plenty of adjectives that take to-infinitives as complements, (e.g., able to, likely to, hard to, etc.) In none of these cases can an actual NP take the place of the infinitive. Moreover, of the adjectives that actually do take NP complement, only due takes to-infinitives complement. Even then, the meaning of due somebody is not the same as due to go.

So what do these to-infinitives function as? Oh, this and that: mostly subjects, adjuncts, and of course, complements in adjective phrases.