The normal arrangement of the verbal paradigm in Semitic grammars was inherited from the Arabic grammarians. They used the 3ms perfect fa’ala form (Hebrew פעל) as the base stem (I), since it had no affixes, and assumed that all other stems were derived from it. The Arabic grammarians described the function of the II stem as “intensification” or for expressing “plurality” (also called “frequentative”). Analogous forms are found in the other Semitic languages (ie Heb. piel, Arm. pael, Akk. D-stem). In all cases, grammarians seem to have assumed the primary “intensive” function of the stem from Arabic. However, Goetze laments that exactly what “intensification” means is poorly understood. Further, Semitists recognize that the stem has other functions, but they attempt to derive them from the assumed original meaning based on what Goetze calls the “romantic notion” that somehow doubling of the middle radical symbolically strengthens the meaning of the base stem. Goetze suggests instead that the function of the form should be determined by a synchronic analysis of its usage. Surveying Akkadian, he finds that the D-stem actually has more in common with the stative than the base stem (G-stem), and he suggests that the original function of the stem was as a denominative.
The Arabic-Hebrew grammarians had already realized that the intensive-frequentative force of the II-stem only applies to one group of verbs. These can be divided into both transitive (Ia) and intransitive (Ib) forms such as: (Ia) qāṭal “to kill” / qiṭṭel “to massacre” and (Ib) rāqad “to leap” / riqqed “to dance”. In a second group the stem has a causative-factitive force, that is it results in transitivization. If the verb is already transitive (IIa), it becomes doubly transitive (ie causative): lāmad “to learn” / limmed “to teach”. If the verb is intransitive (IIb), it becomes factitive: gādel “to be big” / giddel “to make big”. Note that a causative verb causes action while a factitive causes a result. The last group of verbs the grammarians recognized are denominatives – that is verbs derived from a noun.
The Akkadian verbal system differs from West Semitic in that there is no qatala perfect form and no distinction of fientive from stative verbs throughout the paradigm (ie qāṭal but qāton and kābed). On the other hand, Akkadian has an independent stative form, paris, which obviously has some relationship with the West Semitic stative (cf Akk. šalim, Arb. salima, Heb. šālem “he is well”). This Akkadian form is obviously of nominal origin, being a predicate adjective. Thus, there are two basic sentence types in Akkadian The nominal-descriptive sentence uses paris as the base verbal form, while the narrative-action sentence uses iprus. Goetze suggests that the best way to understand the D-stem is not necessarily in relation to the active verbs, but to the stative.
The Akkadian stative can be broken into three groups: (1) The durative stative which denotes an inherent quality of a person/thing, šalim “it is well” or rapaš “it is wide”. Whenever a verb occurs in a stative of this type, the corresponding iprus form is resultative, išlim “he became well”. (2) The perfect stative which denotes a condition which resulted from the subject’s action, šakin “he has placed (something)”. In some cases this can be used with an intransitive verb, in which case it denotes rest after motion - wašib “he is seated”. (3) The passive stative denotes a state which results from another, unspecified, agent. This is always used with transitive verbs.
Interestingly, the use of the D-stem seems to correspond well with these three categories. Thus (1) durative – šalim “he is well”, šullumum “he makes healthy”; (2) perfect – labiš “to have put on (clothes)”, lubbušum “to make someone to be clothed”; (3) passive – ziz “is divided (ie an estate)”, zuzzuzum “make (somebody) divide (an estate)”. The difference between the D- and G-stems in (3) is very slight, in the G the emphasis is on the action performed while in D it is on the effect. As the use of the D-stem seems to correspond so closely to the stative, Goetze concludes that the D-form is derived from the G stative. Further, since the stative is basically a nominative form, the primary function of the D-stem seems to be as a denominative. That is, if the stative is basically an adjective, the D-stem denotes “to make something/someone what the adjective indicates.”
However, there are some active verbs which in the D-stem do not seem to be related to the stative, for example ruqqudum, “to dance”. These verbs tend to express continuous action, and seem to be the counterpart for group (Ib) in West Semitic. Normally in Akkadian such action is expressed by the -tan- infix. Goetze suggests that the continuity is not related to the t, which is normally reflexive, but to the n. He thus suggests an older Gn form that was related to the Gtn just as the G is related to the Gt. The doubled middle radical is thus a result of assimilation of the n, and not gemination. These forms were assumed by the D paradigm, but they should be considered only quasi-D and not impact the understanding of its basic denominative function.