Abstract :
[en] The Germanic languages boast two morphological strategies for past tense formation. The strong inflection is based on an ablaut in the verb’s stem (e.g. sing ~ sang, drive ~ drove) and is the oldest, largely descendant from the Indo-European mother tongue (Harbert 2007). The weak inflection, by contrast, adds a dental suffix to the stem (e.g. laugh ~ laughed), and constitutes a Proto-Germanic innovation. In the history of the Germanic languages, this dental suffix has had considerable success in taking over past tense formation, to the detriment of the strong inflection (Harbert 2007; Lieberman et al. 2007; Cuskley et al. 2014). To account for this success, three explanations are given in the literature (Ball 1968: 164; Bailey 1997: 7–8). First, while each separate strong ablaut class is only applicable to a subset of verbs, the weak suffix can, in principle, be attached to any verb indiscriminately. Second, some verbs escaped ablaut formation altogether, for instance because they had a vowel that fitted in none of the ablauting patterns. Such verbs would then create a save nest for the nascent weak inflection, free of competing strong forms. Third, the strong inflection was ravaged by the effects of several sound laws, which severely undermined its transparency. This would have rendered it vulnerable to competition from the seemingly more transparent weak inflection. We will claim that the first explanation is already sufficient to account for the rise of the weak inflection. Moreover, it may explain why the weak inflection first took over the low frequency verbs and low frequency ablaut classes (Carroll, Svare and Salmons 2012). Since we then no longer need the irregularization of the strong inflection to explain these effects, this irregularization may be the result of the rise of the weak inflection, rather than its cause. To support these claims, we have built an agent-based simulation. In this simulation, computational agents communicate with each other by referring to past events, thereby employing either the strong or weak inflection. The agents preferably use the forms that they hear most often from their fellow agents. The simulation was composed in Babel2, a framework for building agent-based models of language evolution (Steels 2012). In the simulation, the only difference between the strong and weak inflection lies in the first explanation given above. Any other possible advantages for the weak inflection were excluded from the model. Under such conditions, it can be observed that a rise of the weak inflection will come to pass in both type and token frequency, accompanied by a Conserving Effect of both the verbs and the ablaut classes (Bybee 2006; Carroll, Svare and Salmons 2012). This rise even takes place if the weak dental suffix starts out as inferior in both type and token frequency to any individual strong ablaut class.
