For what I know a little
(Brittany in the Middle Ages), it seems to me than until the 11th century, each
person (male or female) bore a unique anthroponym, which could
be a saint's name (either Roman or local), but also a name among
various names (with various meanings). Some of these names were from Celtic
origin and the others were "gallo-frankish". In the 12 th and 13th
centuries, more and more saints'names were given to people, even if others names
were still in use. After the 13th, and during 14th and 15th, it's very rare to
find somebody bearing a name which is not a saint's one ; at the same
time, due to the decreasing of anthroponymic "stock", everybody begun
to bear, in association with his/her "baptismal" name, a surname
which was very often the one of his/her dad, but could be also a
nickname. By the end of the 15th century, all these surnames have become
hereditary.
For what concerns Abelard and
Astralabius, may I observe that :
1. The "baptismal" name of the
philosopher was Peter
2. Abelard is a surname (not the
name of the philosopher's dad)
3. Astralabius could
have been a surname.
4. If the case, why the
"baptismal" name of Astralabius could not have been Peter ?
I agree with Brenda on the fact we
have no medieval testimony about the "double name" of Abelard's son : that means
we have to verify identity of all clerics bearing the name Peter at this
period, to check if one of them isn't ours.
ANDRE-YVES BOURGES