Writing my section on morphology, I spent some time thinking about the nature of the binyanim in the Semitic languages. Namely, to what extent are the binyanim derivational and to what extent are they inflectional?
In short, derivation is the process by which the addition of an affix to a base morpheme creates a new word, either by giving a new meaning or shifting the lexical category. For instance, in English the suffix -er can be applied to a verb to create a noun meaning “one who does X”. Thus paint + -er > painter, “one who paints”. Another example is the use of the suffix -ize to change a noun into a verb, item + ize > itemize.
In contrast, in inflection an affix is used to to indicate grammatical information about the base morpheme, often called the stem. The type of information marked includes gender, number, case, tense, aspect, etc. Thus the plural marker -s in English is inflectional, not derivational.
In biblical Hebrew, we usually learn the binyanim in the section on verbs so that we memorize them in the verbal paradigms together with person, number, tense/aspect, strong and weak forms, etc. Because we associate them so strongly with verbs, I think most students consider the binyanim to be inflectional. In fact, when we parse a verb we give binyan along with all the other inflectional information. However, the binyanim are really derivational in nature. That is, they are part of the system in Semitic to build new words. This can be seen partly by the fact that generally Hebrew verbs do not appear in all of the possible binyanim.
The difference between drinking and causing someone else to drink has to do with the meaning of the verb, not its grammatical category. Dr Kaufman stressed this in class and urged us not to translate the hifil as “to cause X”, but rather to find an appropriate English verb in order to stress the lexical nature of the binyan. Of course, there is not always an appropriate verb. “To feed” is the causative of “to eat”, but what is the causative of “to drink”?
Arabic has several stem forms beyond Hebrew. Most interesting is probably the IX stem which is used with stative verbs denoting the inherent possession of qualities, such as color or physical defect, in order to express “to become X”. Thus, for instance, if the root ḥmr = ‘red’, iḥmarra = “to become red.” The rare XI stem has the same function, but is only limited to colors. This form lengthens the medial vowel of the IX form, thus iḥmārra.
Now, here is where inflection and derivation begin to blur. Is “to become red” really a new lexical meaning, or is it an inflection of aspect? That is, “to become” is really ingressive, a category of aktionsart or, as some call it, “lexical aspect”. With certain types of verbs in certain syntactic contexts, the binyanim may give Semitic languages an option for expressing aktionsart by varying the lexical nature of the verb. For example, in biblical Hebrew, the niphal may also have an ingressive sense when describing the subject as coming into a particular state.
This is still derivational in nature, but over time the process of grammaticalization (simply put, shifting a word/form that primarily has a lexical function to a grammatical one) may shift a binyan from a lexical derivation to an inflection of tense/aspect/mood. There are two possible examples from Akkadian.
The first example is the perfect iptarras in Akkadian. This form had always puzzled me since it is identical to the Gt form. However, it is common for a passive form to be grammaticalized into a perfective inflection. Thus, it makes sense that the Gt passive has been incorporated into the Akkadian TMA system as a perfect.
The second, and more complicated, is the iparras present-future form, which Akkadian shares only with Ethiopic and other modern South Semitic languages (yənäggər). The normal present-future form in Semitic is derived from *yaqtulu. Note the doubled middle radical in the Akkadian form, similar to the D-stem or piel. Could these forms be unrelated innovations in Akkadian and South Semitic which have grammaticalized the lexical meaning of multiplicity/repetition into a tense form? That is, repetition first shifted to progressive aspect before finally becoming a present-future tense?