2.3 Anomalous cases
The following verbs do not fit exactly into any of the above categories:
The modal verbs, which are defective verbs – they have only a present indicative form and (in some cases) a preterite, lacking nonfinite forms (infinitives, participles, gerunds), imperatives, and subjunctives (although some uses of the preterites are sometimes identified as subjunctives). Moreover, they do not add -s in the third person singular – this is because they derive either from preterites, or from Germanic preterite-present verbs, which were conjugated using the (strong-type) preterite form with present tense meaning. (Additional "true" preterites with past tense meaning were formed with the addition of dentals in the manner of the weak verbs.) The chief verbs of this class are can–could, may–might, shall–should, will–would, and must and ought (These last two have no preterites. They were originally preterites themselves). There are also dare and need, which follow the same pattern (no -s) in some contexts: "Dare he jump? She needn't worry" (dare derives from a preterite-present verb, but need is from an Old English regular verb).
Two verbs (be and go) that contain suppletive forms, i.e. one or more of their parts came from an entirely different root. With go this applies to the past tense went, which is originally from the verb wend. With be it applies to a number of different forms. Derived from be is the defective verb beware, which does not inflect in normal use and which appears only in those forms in which the plain form of be would be used, namely the infinitive, the imperative, and the subjunctive.
The verb do, which has the reduplicated form did for its past tense (an irregularity that can be traced back to Proto-Germanic). Its past participle done can be compared to typical strong participles in -[e]n; however both this and the third person present tense does feature a short vowel in modern pronunciation: /dʌn/, /dʌz/.
3. History of irregular verbs in English
The next time you try to decide whether you had run or had ran home, thank the Angles and the Saxons. Those old guys were members of the Germanic tribes who invaded England about 1500 years ago. Their languages blended into Anglo-Saxon, which came to be called Englisc. Nowadays it's called "Old English."
Old English lasted about 400 years; this English would look and sound like a goreign language to English-speakers today. Although it's gone, Old English isn't forgotten. Remnants remain in modern speech. You can thank (or blame) the Anglo-Saxons for most of the irregular verbs, including the fact that you say ran instead of runned.
In the Middle English period (1100 to about 1450) England was speckled with local dialects, each with its own vocabulary and sentence structure. Nobody studied grammar in school, and nobody worried about what was correct or incorrect. (There were a few more important items on the agenda, including starvation and the bubonic plague.)
In the fifteenth century the printing press was invented and the era of Modern English began. At this time, folks were more interested in learning to read ad also more interested in writing for publication. But writers faced a new problem. Sending one's words to a different part of the country might mean sending them off to someone whose vocabulary or sentence structure was different. Not to mention the fact that spelling was all over the place! Suddenly, rules seemed like a good idea. London was the center of government and economic life - ad also the center of printing. So what the London printers decided was right soon became right. However, not until the eighteenth century did the rules really become set. Printers, in charge of turning handwriting into type, were guided by "printers' bibles," also known as the rules.
Schoolmasters tried to whip the English language into shape by writing the rules down. But they grafted Latin concepts into English, and it wasn't always a good fit. In fact, some the loonier rules of English grammar come from this mismatch. In Latin, for example, you can't split an infinitive because an infinitive is a single word. In English, infinitives are formed with two words (to plus a verb, as in to dance, to dream). Nevertheless, the rules was handed down: no split infinitives.
Conclusion
Today, less than 3% of verbs are irregular but they wield a disproportionate power. The ten most commonly used English verbs – be, have, do, go say, can, will, see, take and get – are all irregular. Lieberman found that this is because irregular verbs are weeded out much more slowly if they are commonly used.
To get by, speakers have to use common verbs correctly. More obscure irregular verbs, however, are less readily learned and more easily forgotten, and their misuse is less frequently corrected. That creates a situation where ‘mutant’ versions that obey the regular “-ed” rule can creep in and start taking over.
As Lieberman says, “We measured something no one really thought could be measured, and got a striking and beautiful result.” Using this model, the team managed to estimate how much staying power the remaining irregular verbs have and assigned them ‘half-lives’ just as they would to radioactive isotopes that decay over time.
Which will be next? Lieberman has his speculative sights set on ‘wed’. It is one of the least commonly used of modern irregular verbs and the past form ‘wed’ will soon be replaced with ‘wedded’. As he jokes, “Now is your last chance to be a ‘newly wed’. The married couples of the future can only hope for ‘wedded’ bliss.