In the book which I use there is a passage combining this noun with a plural verb and the book states " the plural form is used , since the verb implies that the people were individually affected." Is this construction common in Classical Latin and does the reverse occur(plural noun with singular verb) ? Thanks, Paul
Allen & Greenough, 317d:
d. A collective noun commonly takes a verb in the singular; but the plural is often found with collective nouns when individuals are thought of (§ 280. a):—
(1) “senātus haec intellegit” (Cat. 1.2) , the senate is aware of this.
“ad hīberna exercitus redit ” (Liv. 21.22) , the army returns to winter-quarters.
plēbēs ā patribus sēcessit (Sall. Cat. 33), the plebs seceded from the patricians.
(2) “ pars praedās agēbant” (Iug. 32) , a part brought in booty.
“cum tanta multitūdō lapidēs conicerent ” (B. G. 2.6) , when such a crowd were throwing stones.
The example with plebes illustrates the opposite phenomenon–a plural noun with a singular verb–but it works the other way, too.
http://www.perseus.tufts.edu/hopper/text?doc=317&fromdoc=Perseus%3Atext%3A1999.04.0001
I would say it’s just the alternate form plebes, -is or plebes, -ei (still singular) rather than a plural noun with a singular verb. See the L+S entry for plebs.
Perhaps we have here the root cause of the conflict of the orders. None could agree on the proper usage of the word. 