Defective Verb - English

English

The most commonly recognized defective verbs in English are auxiliary verbs — the class of preterite-present verbs — can/could, may/might, shall/should, must, ought to, and will/would (which was not historically in Old English a preterite-present but has joined the class in modern English). Though these verbs were not originally defective, in most varieties of English today, they occur only in a modal auxiliary sense. However, unlike normal auxiliary verbs, they are not regularly conjugated in the infinitive mood. Therefore, these defective auxiliaries do not accept each other as objects. Additionally, they do not regularly appear as participles. The defective form "ought to" is used with a "bare infinitive" verb, since the "to" goes with "ought," and not with the verb.

For example, can lacks an infinitive, future tense, participle, imperative, and gerund. The missing parts of speech, however, can be expressed by using the appropriate forms of to be plus able to. So, while I could do it and I was able to do it are equivalent, one cannot say *I will can, *I have canned, or *canning do it, but instead we have to say I will be able to, I have been able to, and being able to do it. Likewise, the role of must, which has only a present tense —technically, it is the past tense of the archaic verb to mote—, can be filled in by to have plus to. This way, one can say things like he had to clean the room last week, which would be impossible to do with must.

Some verbs are becoming more defective as time goes on; for example, although might is etymologically the past tense (preterite) of may, it is no longer generally used as such (*he might not pass for "he was forbidden to pass"). Similarly, should is no longer used as the past of shall, but with a separate meaning indicating possibility or advice. (However, the use of the preterite form should as a subjunctive form continues, as in If I should go there tomorrow, ..., which contrasts with the indicative form I shall go there tomorrow.) The defective verb ought was etymologically the past tense of owe (the affection he ought his children), but it has since split off, leaving owe as a non-defective verb with its original sense and a regular past tense (owed).

Beyond the modal auxiliaries, beware is a fully-fledged defective verb of English: it is used as an imperative (Beware of the dog) and an infinitive (I must beware of the dog), but very rarely or never as a finite verb, especially with inflectional endings (*bewared, *bewares). Another defective verb is the archaic quoth, a past tense which is the only surviving form of the verb quethe, "to say" (related to bequeath). Certain other verbs are defective only in specific constructions.