Plura or pluria?

Question

Before answering this recent question about the US motto, I had to check whether the neuter version of plures is plura or pluria. I had recalled right: plura appears to be indeed the sole form used in classical Latin. The same corpus search for pluria gave results of grammarians discussing the choice between plura and pluria. Some seem to defend the form pluria, but I found no attestations of it in a context that does not discuss the very form itself.

So, what's the deal with pluria? Was it a valid alternative spelling, but later all manuscripts were conformed to plura? Is there a good reason to choose plura over pluria? Judging by the same corpus, the genitive is exclusively plurium, not plurum, and this makes me expect pluria insead of plura. All this leaves me somewhat confused.

Answer 1

The usual form used in Classical Latin seems to have been plura. I don't know of any "good reason" to choose plura aside from that.

The discrepancy between plura and plurium was noted by past authors. The main historical source I've seen mentioned¹ that discusses pluria is Aulus Gellius, who in Noctes Atticae 5.21 recounts an anecdote where a friend of his says pluria, is criticized for using this instead of plura, and then appeals to historical usage of pluria (and compluria) and an alleged letter by Sinnius Capito that says pluria and not plura should be used. An English translation of the passage can be found here.

The critic argues that plura should be used based on the rule that comparatives take the ending -ra rather than -ria, but Gellius's friend disputes that plus is a comparative. (From a strictly etymological standpoint, de Vaan 2008 indicates that plus did in fact originate as a comparative form.)

1. Nox Philologiae, by Erik Gunderson, 2009; p. 123-124 and Readers and Reading Culture in the High Roman Empire, by William A. Johnson, 2010, p. 131.