The law requires every driver to drive safely.

In that case, the subject of the infinitive to drive is every driver—every driver is to drive safely. So, what you've got is:

• Main verb: requires
• Subject of main verb: the law
• Object of main verb = infinitive clause: every driver to drive safely

But that doesn't work for Pennebaker's sentence. Social skills to use properly is not a complete clause because (a) there's no object of the verb to use (to use what properly?), and (b) social skills is in a position where it could be the subject of to use (as in the driving example), but it's not.  The sentence could be "fixed" in a number of ways that involve making it clearer that function words are the things being used.

1. Make the infinitive into a passive, so it's clear that function words is the object of use: Function words require social skills to be used properly.
2. Move use closer to function words so that it's clear how they relate to each other: To use function words properly requires social skills. (Or Using function words properly requires social skills.)
3. Move function words closer to use:  It takes social skills to use function words properly.

Number 1 is a little ambiguous (it sounds a bit like function words are bossing social skills around), so I'd prefer 2 or 3, where it's really clear that function words is the object of use. 

But there are sentences with require that do work more like Pennebaker's sentence:

Crops require water to grow.

Here, it's not the water that's growing, it's the crops. So it doesn't work like the driving sentence—the object of require is not water to grow. In both sentences, I've put the object of require in blue, so you can see that the sentences have different structures. Another way that you can tell they're different structures is that you can replace to with in order to in one and not the other and can rephrase one with that and no to, but not the other.

The law requires every passenger in order to drive safely.
Crops require water in order to grow.

 The law requires that every driver drive safely. [or drives if you're not a subjunctive user]

Crops require that water grow.

So one of the reasons I wanted to write this post is to make this big point:
Grammar isn't just where words go in a sentence, it's how they relate to each other.
The fact that the crops sentence is the same shape as Pennebaker's sentence doesn't mean that Pennebaker's sentence is grammatical, because it still has the problem that there is no subject for to use. Notice that it can't be rephrased in either of the ways that the other two can:

Function words require social skills in order to use properly
Function words require that social skills use properly

The last possibility is to interpret use as being in middle voice (as opposed to active or passive voice). This is when the verb acts kind of like a passive (where what would have been the active object becomes the subject), but doesn't get the passive be +past participle form. English has some verbs that work this way.

I cut the bread easily. (active voice: subject is the cutter)
The bread is cut easily. (passive voice: subject is what's cut)
The bread cuts easily. (middle voice: subject is what's cut)

Grammar Girl has a podcast and post on middle voice in English if you're interested. English has more of a 'middlish' voice than a 'middle', as we're really limited in how we can use it and it doesn't have a special verb form, as it does in some other languages. As Grammar Girl notes:

[English] middle-voice sentences usually include some adverbial meaning, negation, or a modal verb, or a combination of the three. “The spearheads didn’t cast very well” has both negation (“didn’t”) and an adverb phrase (“very well”). “The screw screwed in more easily than I thought it would” has the adverb phrase “more easily than I thought it would.”

While Pennebaker's sentence does have an adverb, properly, it's not one that I'm super-comfortable using with a middle construction (?The bread cuts properly), but maybe some people would like it better than I do. (Proper is used more as an adjective and adverb of intensity in some colloquial BrEs than in my AmE.)

So, are the 25% who like the sentence reading it as having middle voice? I'm not totally convinced, because I think that the English middle doesn't do well with fancier sentence constructions as with require:

?That bread requires a good knife to cut easily.
?That bread requires a steady hand to cut easily.

Putting an object between requires and to makes it confusing—is it the bread or the knife/hand that is cutting easily? If it's the knife or hand, then the sentence would usually require an it to stand for the bread: The bread requires a good knife to cut it easily. 

So, anyhow, when I put the Pennebaker sentence up, some people wondered if it was like this dialect phenomenon, found in some parts of the US (particularly western Pennsylvania) and some parts of the UK (particularly Scotland):

The car needs washed.

It was natural for them to make that connection because both Pennebaker's sentence and the needs washed sentence would work in other dialects if the final verb were made passive. But note that what needs to be added to the sentences to create a passive is different in the two cases. In needs washed, the washed is in the past participle needed for a passive. But in Pennebaker's sentence the infinitive verb is not in any way in passive form.

The car needs to be washed.
The function words require social skills to be used properly.

So, I asked the 25% who accepted the sentence to write back and tell me where they were from. And it turns out they're from anywhere.... New Jersey, California, New England, southeastern US, eastern and western Canada, up and down the UK, the Caribbean. That makes it look like it's not a dialect feature. 

An interesting thing about the 25%, though, was that a few got in touch to say: "I clicked that the sentence was fine for me, but once I started thinking about it, I was less sure."

After the dialect idea didn't pan out, I joked that the next step was to give personality tests to people who didn't like the sentence. And while it was a joke, I think there is probably something to the idea  that some people read for meaning and don't get the grammatical 'clang' that I got because getting the meaning is good enough. If they can get the meaning without a deep look at the grammar, the grammar is irrelevant. I'd wonder if people who get a 'clang' with this sentence are also more likely to also notice misplaced modifiers and dangling participles. A lot of us who notice these things notice them because we've been trained in looking at language analytically, or we're just very literal readers. Had I heard Pennebaker's sentence, I probably wouldn't have noticed that there was no workable subject for the verb use. I would have just understood it and gone merrily on my way. But in reading, CLANG.


Anyhow, the main reason I wanted to blog this was to make that point that Grammar is how words relate to each other. That two sentences with the same shape can be working in very different ways. And on that note, I'll leave you with an experiment that Carol Chomsky did way back when. She gave children a doll with a blindfold over its eyes and asked them if this sentence was true—and if not, to make the sentence true.

The doll is easy to see. 

Notice how that sentence doesn't work like this sentence:

The doll is eager to see.

In the first, the doll is being seen. We can paraphrase it as The doll is easy for me to see. In the second, the doll is who will do the seeing. We can't paraphrase it as The doll is eager for me to see, because it means The doll is eager for the doll to see. The words easy and eager determine how we interpret the relations of the other words in the sentence. In linguistic terms, they license different relationships in the sentence. (In these sentences it's adjectives doing that relationship-determining, but in most sentences, it's the verbs. In our requires sentences above, we can see that require licenses a range of possible sentence structures—words do that too.)

Understanding that a blindfolded doll is easy to see is something that most kids don't master till they're into their school years. When asked to make the doll easy to see, the younger kids take off the doll's blindfold. This shows us that kids take a while to fully take account of the grammar, not just the words, in sentences.

Hope you didn't mind my little grammatical foray...