by Qimmik » Sat Mar 22, 2014 2:28 pm
OK, y'all (more on that later) have prompted me to satisfy my pedantic curiosity.
Chantraine (Morphologie historique, sec. 199, p. 175) writes that the sigmatic aorist goes back to an old Indo-European athematic type with vowel gradation (alternance).
Sihler (sec. 459, p. 510): "The only stem-formation which is uniquely aoristic is an athematic stem consisting of an element *-s- directly affixed to the root perhaps because of its distinctiveness it enjoyed considerable productivity in the daughter languages."
Neither of them mentions that the -s- was a causative marker--it was simply a normal proto-Indo-European aorist marker.
The -α- of the personal endings apparently developed as an epenthetic vowel between the stem ending in -σ- and the athematic personal endings. According to Sihler (sec. 504, p. 560), the -α- was generalized from the 3rd pers. plural form, which ended up as -σαν (after various changes from an original -σντ (ν = syllabic ν), except for the 3rd sing. form, which was borrowed from the thematic conjugation.
A note on non-standard English: For those to whom it's unfamiliar, "y'all" is southern US English for the plural 2d person plural pronoun. The generalization of "you" as the number-less 2d person pronoun in English is a perpetual embarrassment to speakers of standard English, who are helpless to indicate whether they are addressing a single individual or a group. In the southern US, "y'all" (non-standard but not sub-standard) fills the morphological void (that's not my dialect, but I do use "you all" when I need to make things clear); elsewhere, "youse" (definitely sub-standard) serves this function. Once long ago in the Army, I heard a sergeant address us privates as "youse mens" (one notch below substandard).