In Greek, my understanding on Voice has been largely shaped by Kemmer, Allen, and R. Aubrey. To whit, Ancient Greek operates with an Active-Middle voice system, and the sooner you come to grips with that and jettison concepts like a distinct morphological passive, and ‘deponent’, the better.
But what about Latin, what’s going on in Latin? I don’t have all the answers for Latin, but here’s where my thinking is at.
Latin really does have an active <> passive system. Active voice verbs are what you’d expect, and Passive verbs generally involve syntactic transformation to replace the agent-subject with patient-subject, and demote agent to an optional oblique phrase.
daedalus ordinatrum programmat – the hacker programmed the computer >
ordinatrum programmatur [a daedalo] – the computer is programmed by the hacker
But Latin has two groups of verbs that we want to think about today. The first are those traditionally called ‘deponent’, that is “active in meaning, passive in form”. I prefer to call this “passiva tantum” or passive-only verbs. The second are those that have active forms but rarely use them. I call these “passive preferred”.
To my mind, there are two problems with calling verbs ‘deponent’ in the traditional sense. Firstly, the idea that they deposuerunt, ‘set aside’ their active forms and started using passive forms with active meaning is [mostly] a fiction (though there are some verbs that have switched over in the history of Latin). Secondly, it suggests that there is a mismatch of form and meaning in deponent verbs, which I think risks missing why they are passive in form.
While I’d want to hold back from imposing Ancient Greek as the grid in which we understand Latin, just as much as we shouldn’t understand Latin on English’s terms, this is where a bit of awareness of Middleness in Greek really helps. Because a large number of Latin passive-only verbs correspond to Greek middle-only verbs, and presumable for the same sets of reasons.
ornor, perluor, lavor – middle forms denoting bodily grooming and adornment.
progredior, etc. – middle forms denoting translation body movement
apiscor, potior – middle forms involving the subject as indirect beneficiary
osculor, amplector, luctor, etc. – middle forms involving reciprocal 2-party action
congregor, colligor – middle forms involving collective action
delector, misereor, vereor, meditor – middle forms of cognitive experience in which the subject is experience and the ‘object’ acts as stimulus
morior, nascor, orior, etc. – middle forms of spontaneous change of state
And so on. By understanding prototypical Latin passive-only verbs as historical middles, helps understand ‘why’ they are middle – they fit a certain logic. It stops us thinking that they are someone odd, breaking the rules, or exceptional. And in doing so, I think this helps students a great deal – you don’t need to make a big fuss about this and just getting people used to the fact that these verbs use passive-type endings.
It also helps understand some active/passive alternations, e.g. veho>vehor, mergo>mergor, moveo>moveor – in each of these cases the active verb is causative and prototypically involves a change of state on the accusative complement. The morphologically middle form involves the same change of state or movement through space, but it may be either middle (self-movement) or a true passive (with external agency).
So broadening our conception of ‘deponency’ in Latin to put aside the idea that these verbs are ‘oddities’, and instead understand them within a scheme where semantic middleness occurs with morphological passive forms, does a better job of situating these verbs in their linguistic system. I think.