3rd conjugation verbs with -i

Latin Learning Latin
1

I’m sure I should know this but sometimes I can’t understand why certain classes or subclasses of verbs are defined as such…

In LLPSI Orberg Cap XV orberg explains the 3rd conjugation as follows:

[3] Ut ‘dico dicimus’ declinantur verba quorum infinitivus desinit in ‘-ere’, praeter ea quae ‘-i-’ habent ante ‘-o’ et ‘-unt’, ut ‘facio faciunt’: accipere, aspicere, capere, facere, fugere, iacere, incipere, parere, cet.

Now here’s the thing. Why are these latter verbs exceptions? After all if the verb is ‘facio’ then surely you can just say that the stem ends in -i as opposed to, say, ‘g’ as in rego. What is the point of defining as an exception a verb which if we just regard the part before the ending as the end of the stem…is perfectly regular…?

Also what does Orberg mean by singling out ‘-o’ et ‘-unt’ when this verb has ‘i’ before all of its endings in the present tense…?

Is the point here that facio, facere doesn’t have an i in the infinitive…and so the stem cannot be said to end in ‘i’? I see that ‘i’ makes appearances in this verb depending upon tense etc… so I suppose the stem ends in ‘c’…

2

If facio were a regular third declension verb, it would conjugate thus:

facio faciimus
faciis faciitis
faciit faciunt

It’s a small and understandable irregularity, but an irregularity nonetheless.

3

The verbs you’ve given are all a subclass of 3rd conjugation called “-io conjugation”(that’s their ending in 1st person singular). They largely decline like 3rd conjugation verbs, but have some “irregularites” they all share.
And you cannot say their stems end in “i” because that’d make them a part of 4th conjugation, which they do not follow.