Aurelio M. Espinosa’s scientific contributions

... In lieu of these two explanations, Silva-Corvalán promotes a hypothesis of complex causation in which it is a combination of semantic ambiguity and language contact that causes the shift [12]. She postulates that the shift of -ra, which as Espinoza noted historically alternated with conditional forms in certain contexts, from indicative to subjunctive caused a lack of clarity in the meaning difference between subjunctive forms in -ra and indicative forms in -ría [14,15]. Additionally language contact plays a role, she claims, as in Lavandera's study it was Spanish speakers of Italian origin, and in her own study Spanish speakers of Basque background, who most frequently employed the conditional forms in a parallel manner to their language-of-origin. ...

Reference:

On the Acceptability and Use of -ra and -se in Conditional Phrases in Galician Spanish