Survival of the frequent
Why roofs, not rooves? Roofs, after all, are old enough to be irregular.
You remember the story behind irregular plurals:
1. In Old English, /f/ surrounded by voiced segments became voiced as well.
2. The Old English plural included a vowel preceding the /s/
So singular lif had the plural lifas, leaving us with life and lives. Same holds for leaves and hooves. But not reef — reefs are tropical, the Anglo-Saxons nordic, so they didn’t have this word. English acquired the word late, after the old plural formation had long been replaced with the regular plural of today.
But what about roof? It’s an Anglo-Saxon word, why doesn’t it have an Anglo-Saxon plural? My shot in the dark: the plural of roof is not much used.
Every creature with a hoof
has three more,
And many lives are lost in war,
as leaves they fall aplenty.
But the only roof you care about is the roof over your own head.
Falling out of use, rooves didn’t survive into the age of the regular reef/reefs plural and now speakers, when forced to pluralize it, treat it as if they’d never heard the irregular form.
And so they never do.
Dwarfs are rare too.
Informational direction of shift
Latin prefixed verbs are usually stressed on the root syllable. Stress shift to the prefix derives a noun:
reJECT a REject, conVERT a CONvert, reWRITE a REwrite.
Did these words enter English as verbs or nouns? Well, there’s an empirical answer for those tireless foot soldiers dedicated to searching for truth, but for instant gratification here’s an argument: the verbs tend to be general in meaning while the nouns are often quite specific. The noun “reject” is specifically a pejorative. A convert is specifically someone who has adopted a religion — any other kind of convert is metaphorical. A convert to cooking with a wok draws an analogy between styles of cooking and religion, implying a kind of exclusive commitment or, at least, devotion and conviction. But the verb can be used literally for electricity, chemistry, cooking, housing, you name it, without a hint of metaphor. Even a rewrite is more specific than something that has merely been rewritten, though this may just be the difference between the concreteness of nouns and the imperfectness of verbs. But think of the many things that can be perverted from their natural course or use compared with the extreme specificity of “a pervert.” Same with retard. Not all are pejoratives: previews, contacts, prefixes.
I speculate that these nouns were derived from general verbs for specific uses. A general concept already automatically covers all of its specific instances. So adding information (conVERT/change=>change + religion=CONvert) should be less disruptive than subtracting information, which is the nature of metaphor (changing religious conviction=> change of conviction) where select semantic features are transferred out of their context (neglect the religion part and just transfer the change conviction features). I wonder if that’s a general rule of coinage: adding information — leaning to the specific — is more common than subtracting (generalizing).
Of course there’s an empirical answer to this question. If it were to turn out that these words entered English as specific nouns, then there’d have to be a theory of why nouns are more specific than verbs or why it’s more common for information to be stripped from a word than added to it. Something for the OED fans to look up. My copy of the OED is on the opposite side of the room from my computer, so it’s not happening now.