1 /I/ as an Abstract (Nonsurfacing) Vowel of Latin

An interesting body of data worth discussing in elementary phonology classes begins with the examples of the finite forms of the Latin verbs in (1).1



As shown by the 1st person plural examples in (1a), the present tense forms consist of a Verb Stem followed by a Theme vowel and end with the 1st person plural Agr(eement) morpheme /-mus/. In the contrasting 1st person singular forms, shown in (1b), although the Theme vowel appears in /de:l-e-o:, aud-i-o:, cap-i-o:/, it does not appear in /port-o:, leg-o:/. How does one formally account for this difference?

In traditional treatments of Latin grammar—for example, the summary of Latin grammar appended to The Pocket Oxford Latin Dictionary (Oxford University Press 1994) or to be found in Barron’s Latin Grammar (Maidhoff 2009)—the verbs are assigned to the same classes as in (1). The first three classes are classified by their long Theme vowel, and the last two are analyzed here as having the short Theme vowels /i/ and /I/. (Barron’s Grammar calls the /i/-verbs the mixed conjugation and the /I/-verbs the consonantal conjugation.)

In the examples in (1), the Theme vowel /e:/ is never deleted (/de:l-e-o:/). By contrast, the Theme vowel /a:/ always deletes (/port-a:-o: → port-o:/) and /i/ varies: it deletes in /leg-o: ← leg-i-o:/, but not in /aud-i-o:, cap-i-o:/.

At this point, it is essential to recall that phonemes are not further unanalyzable atoms; rather, they are clusters of phonetic features as illustrated in (2).



The insight that phonemes are distinctive feature complexes of the kind illustrated in (2) requires us to state the deletion rule as shown in (3), where the deleted phonemes are represented as distinctive feature complexes.


  • a.

    Delete [+back, −round, −high] in env. __ + V(owel)

  • b.

    Delete [−back, −round, +high] in env. __ + V (in the verbs in Barron’s consonantal conjugation (List L))

At this point, it is worth remarking that this idea is taken with complete seriousness below and that whenever phonemes are mentioned in the exposition, this is due to lapsing into informal language. In the representation that appears in actual computations of the pronunciation of words and utterances, phonemes are always understood as complexes of features, never as anything else.

An important principle governing scientific accounts of all kinds is that they must be concise. Since the accounts proposed here are formulated in terms of feature complexes, conciseness in the present context implies that the accounts must use as few features as possible. From this perspective, rule (3b) would be especially problematic because it would require a very large number of features to represent the different words in List L. By contrast, rule (3a) is unproblematic, as it uses only three features. In accounts of actual languages, we expect to encounter rules like (3a), but not rules like (3b).

One way of avoiding the need for a rule such as (3b) in Latin is by representing the Theme vowel /i/ that deletes (e.g., in /leg-o: ~ leg-i-mus/) with a different feature set than the vowel that does not delete (e.g., in /cap-i-o: ~ cap-i-mus/). In particular, it is assumed here that the vowel that deletes prevocalically is assigned the features [+back, −round, +high], which distinguish it from the nondeleting vowel, which is assigned the features [−back, −round, +high]. Once this is done, we assume that phonological theory requires us to restate the deletion rule (3a) in the (featurally more parsimonious) form shown in (4).

(4) Delete [+back, −round] in env. ___ + V

The solution just sketched has a cost: it requires that we add a rule to account for the fact that when not deleted, /I/ surfaces as /i/. The additional rule, which mentions four features, is stated in (5).

(5) [+back] → [−back] in env. [ ___, −round, +high]

In view of the economies noted above, the extra cost of rule (5) can readily be borne.

A crucial aspect of the account just presented is that rules were applied in a specific order; in particular, the fronting rule (5) was ordered after the deletion rule (4). To see that rule ordering is essential, recall that rule (5) turns /I/ into /i/. Therefore, if rule (5) had applied before rule (4), it would have fronted all underlying /I/ segments. There would have remained no [+back, −round] vowels to be deleted by rule (4). Since we know that underlying /I/ is not deleted by rule (4) in /leg-I-mus → leg-i-mus/, for example, we conclude that rule (4) must be ordered before rule (5), and from this we draw the further general inference that rules apply in a specific order.

2 The Constituent Structure of the Latin Verb

The perfect active forms of six verbs are given in (6a,c), along with their present forms in (6b,d) (all in 1st person plural).


  • a.

    port-a:-v-i-mus ‘carry’ de:l-e:-v-i-mus ‘destroy’ aud-i:-v-i-mus ‘hear’

  • b.

    port-a:-mus de:l-e:-mus aud-i:-mus

  • c.

    sec-u-i-mus ‘cut’ mon-u-i-mus ‘warn’ aper-u-i-mus ‘open’

  • d.

    sec-a:-mus mon-e:-mus aper-i:-mus

The verbs in (6a) preserve the Theme vowel in the perfect (cf. (6b)), whereas those in (6c) systematically fail to preserve the Theme vowel (cf. (6d)). To account for this fact, let us examine the abstract constituent structure of the perfect forms of two of the verbs in (6).



As shown graphically in (7), we assume that the form on the right is subject to a transformation that links the /u/ to the Theme constituent and simultaneously delinks /a:/ from it, and that this is accompanied by the deletion of /a:/. We also assume that the sequence /u-i/ and its postvocalic alternant /v-i/ are reflexes of the Perfect morpheme.

As illustrated in (8), the same formal delinking treatment accounts for the remaining perfects of the Latin verbal system.



The s-perfects in (8a) all undergo the linking transformation illustrated in (7). The examples in (8b) demonstrate what we have already seen in (7): when the perfect takes the form /ui/, sometimes it undergoes a linking transformation as in /secuimus/, causing the Theme vowel to delete, and sometimes it does not, as in /porta:vimus/. The form /ce:pimus/ in (8c) exhibits the same effects of linking as, for example, /secuimus/. We mark this by assuming a Perfect morpheme /i/ augmented by the null segment: /Ø-i/ (i.e., Ø-I-Perf ). Finally, the forms in (8d) demonstrate that when the Theme vowel is /I/ and the Perfect morpheme is unaugmented, the Theme vowel always undergoes deletion.

To summarize the account of the Latin perfect morphology illustrated in (8), we note that the Latin verbal system contains five Theme vowels, /a:, e:, i:, I, i/. We postulate that the Perfect morpheme is /i/. We further postulate that the Perfect morpheme /i/ can be augmented by three different segments: /s/ (see (8a)), /u/ (see (8b)), and /Ø/ (see (8c)). Each of these augmentations produces its own class of perfect. Given this analysis, we may say that linking always occurs with s-perfects and Ø-perfects. With u/v-perfects, it sometimes occurs and sometimes does not. Unaugmented perfects (see (8d)) never link.2

3 The Latin Verbal System: Perfect and [αFut]

An aspect of its morphology that Latin shares with many other languages, though not all, is that unmarked categories are (often) signaled by the absence of any phonetic marker. This is illustrated by the forms in (9), where each perfect form (in (9a)) includes the Perfect morpheme (/vi/ (or /ve/)), but the unmarked nonperfect forms in (9b) do not.

(9) (Unmarked) [–Fut] (Past) [+Fut] (Future)

  • a.

    Perfect port-a:-vi-mus port-a:-ve-r-a:-mus port-a:-ve-r-i-mus

  • b.

    Unmarked port-a:-mus port-a:-b-a:-mus port-a:-b-i-mus

This difference is formally expressed in (10) by enclosing the Perfect and [αFut] morphemes in angled brackets, which reflect the optional status of these two morphemes in the finite verb forms of Latin. Their status is “optional” in the sense that unlike the “obligatory” Verb Stem, Theme vowel, and Agr ending, the Perfect and [αFut] morphemes do not appear in every finite form of the Latin verb.

(10) VbSt - 〈Perf〉 - 〈[αFut]〉 - Agr

In actual (pronounced) forms of the Latin verb, each of the four morphemes in (10) is supplied with its own sequence of phonemes.

The morpheme [αFut] in (10) stands for [–Fut] and [+Fut], which are semantically interpreted as past and future, respectively; the absence of the [αFut] morpheme in the forms in the left column of (9) is interpreted semantically as present.

The phonetic exponence of the [αFut] morpheme, which precedes the Agr morpheme in (10), is moderately complex. There are distinct phonetic exponents for [–Fut] and for [+Fut]. As shown in the second and third columns of (9), the phonetic exponent of [–Fut] is long /a:/, and that of [+Fut] is short /i/. Moreover, in the (marked) perfect forms of the verb in (9a), the consonant /r/ is preposed before the [αFut] morpheme (/port-a:-ve-r-a:-mus, port-a:-ve-r-i-mus/), but in the unmarked perfect forms in (9b), the consonant /b/ is preposed before [αFut] (/port-a:- b-a:-mus, port-a:-b-i-mus/). These facts are accounted for formally by the two rules in (11), which have not usually been recognized as parts of the phonology of Latin, but actually perform a distinct role in the morphology of the language.


  • a.

    Insert /r/ in env. Perf + — [αFut]

  • b.

    Insert /b/ in env. + — [αFut]

I assume the /r/ inserted by rule (11a) is the surface manifestation of an underlying /s/ by a rhotacism rule left unspecified.

The phonetic exponents of the morpheme [αFut] are spelled out by the two Vocabulary Insertion rules in (12).


  • a.

    [–Fut] → /a:/

  • b.

    [+Fut] → /i/

This completes the present review of the finite active forms of the Latin verb. As shown in (10), these forms all begin with the Verb Stem and end with the Agr (Person) ending. Between these two terminal morphemes, there appear optionally a Perfect morpheme and/or a [αFut] (or Tense) morpheme. The abstract underlying structure of the Latin active verb forms is therefore as shown in (10), which abbreviates the six distinct sequences in (13).


  • a.

    VbSt - Perf - [–Fut] - Agr port-a:-ve-r-a:-mus

  • b.

    VbSt - Perf - [+Fut] - Agr port-a:-ve-r-I-mus

  • c.

    VbSt - Perf - Agr port-a:-vi-mus

  • d.

    VbSt - [–Fut] - Agr port-a:-b-a:-mus

  • e.

    VbSt - [+Fut] - Agr port-a:-b-I-mus

  • f.

    VbSt - Agr port-a:-mus

In (13), the Perfect morpheme is actualized phonetically as /i/~/e/. This alternation is formally captured by rule (14), which turns short /i/ into /e/ before /r/ and is ordered after rules (4) and (5).

(14) Short [+high] → [–high] in env. [ ___–round] /r/

4 Vocabulary Insertion and the Generation of the Phonetic Form of an Utterance

Among the rules discussed to this point—that is, (4), (5), (11), (12), (14), and the linking transformation—rule (11) stands out in that it alone includes mention of a nonphonological feature: [αFut].

Rule (11) accounts for the augmentation of the morpheme [αFut]: where [αFut] is directly preceded by the Perfect morpheme, the rule preposes the phoneme /s/ before the [αFut] morpheme, and it preposes the phoneme /b/ elsewhere (i.e., where [αFut] is not preceded by the Perfect morpheme).

In (10), the Latin verb is represented as a sequence of abstract morphemes: the string VbSt - 〈Perf〉 - 〈[αFut]〉 - Agr. The information about how these morphemes are pronounced is provided by special Vocabulary Insertion rules, of which two have been stated in (11). We have also postulated that the Perfect morpheme has three distinct exponents, whose underlying representations are /uI/ (illustrated also in (6)), /SI/, and /ØI/. These facts are formally reflected by the Vocabulary Insertion rule (15), which assigns particular sequences of phonemes to the Perfect morpheme. (16) provides examples.


  • a.

    Perf → /SI/ in env. VbSt(W) + —

  • b.

    → /i/ in env. VbSt(X) + —

  • c.

    → /ØI/ in env. VbSt(Y) + —

  • d.

    → /uI/ in env. VbSt(Z) + —


  • a.

    du:k-si-mus ‘have led’ (linking after (15a))

    scri:p-si-mus ‘have written’ (linking after (15a))

    carp-si-mus ‘have plucked’ (linking after (15a))

  • b.

    le:g-i-mus ‘have read’ (rule (4) after (15b))

    vi:d-i-mus ‘have seen’ (rule (4) after (15b))

    prand-i-mus ‘have breakfasted’ (with lengthening of stem

    vowel in open syllable) (rule (4) after (15b))

  • c.

    ce:p-i-mus ‘have taken’ (linking after (15c))


    spo-(s)pond-i-mus ‘have pledged’ (linking after (15c))

  • d.

    port-a:-vi-mus ‘carry’ (no linking)

    aud-i:-vi-mus ‘heard’ (no linking)

    mon-ui-mus ‘warn’ (with loss of Theme vowel /e:/ in the perfect)

    (linking after (15d)))

  • e.


    tet-ig-i-mus ‘have touched’ (rule (4))


    tu-tud-i-mus ‘have struck’ (rule (4))

What makes the account of the perfect inflections somewhat complex is that in some verbs perfect stem formation is accompanied by the deletion of the Theme vowel (see (16b)) and that in other verbs perfect stem formation is accompanied either by lengthening of the Verb Stem vowel (see the first two examples in (16b)) or by its reduplication (see the second example in (16c) and (16e)). These details are not fully covered in the present account.

In the present account—and this is a new proposal not found in other accounts to my knowledge—the phonetic actualization of the [αFut] morpheme depends crucially on the feature [high] of the Theme vowel. Specifically, as stated in the Vocabulary Insertion rule (17), the [–Fut] morpheme is actualized as /e:-ba:/ after stems with [+high] Theme vowels (see (18a)), and as /ba:/ elsewhere (i.e., after stems with [–high] Theme vowels; see (18b)). The obvious similarity between these two rules is not fully reflected in their representation in (18), as it involves abbreviatory devices that are left aside here.

(17) [–Fut] → /e:-ba:/ in env. [+high] ___

/ba:/ (elsewhere)


  • a.




  • b.



The deletion of the Theme vowel /I/ in /leg-e:-ba:-mus/ (from underlying /leg-I-e:-ba:-mus/) is due to the (subsequent) application of the vowel deletion rule (4). The feature [+high] of the Theme vowel also plays a role in the forms of the future [+Fut]. In these forms, [+Fut] is actualized as /e:/ after [+high] Theme vowels, and as /bI/ (→ /bi/) after [–high] Theme vowels. This is formally implemented by the Vocabulary Insertion rule (19), exemplified in (20).

(19) [+Fut] → /e:/ in env. [+high] ___

/bI/ (elsewhere)


  • a.




    leg-e:-mus ← leg-I-e:-mus

  • b.



It is to be noted that in /leg-e:-mus/ (in (20a)) the Theme vowel /I/ is deleted by rule (4), just as in the [–Fut] /leg-e:-ba:-mus/ in (18a). Although rules (17) and (19) exhibit striking formal similarities, these further inferences are not incorporated into the present account.

5 The Passive Forms of the Latin Verb

In nonperfect forms, the exponent of the Passive morpheme /r/ is placed at the very end of the word, as shown in (21) (putting aside here some further modifications).

(21) 1Sg port-o-r port-a:-ba-r port-a:-b-o-r

The situation is radically different in the perfect passive forms shown in (22).


  • 3SgMPres port-a:-t-us es-t ‘has been carried’

  • 1PlF [–Fut] port-a:-t-ae er-a:-mus ‘had been carried’

  • 3PlN [+Fut] port-a:-t-a er-u-nt ‘will have been carried’

The underlying structure of the Latin active verb assumed throughout is as follows:

(23) VbSt - Theme - 〈Perf〉 - 〈[αFut]〉 - Agr

In the passive forms in (22), the verb is split into two parts. One part consists of the optional 〈[αFut]〉 morpheme and the Agr ending, which are attached to the inserted auxiliary verb stem /es/ ‘be’. The second part, consisting of the Verb Stem and the Perfect morpheme, is merged into the perfect passive participle, which surfaces as /t/ ← /s/ after underlying stops and which, like the Perfect morpheme, may trigger deletion of the Theme vowel of the verb. The two pieces are shown in (24).


  • es 〈[αFut]〉 Agr(Number-Person)

  • VbSt Perf Agr(Number-Gender)

The question to be answered at this point is where, in light of the facts just discussed, the Passive morpheme is to be placed with respect to the other morphemes in (23). Since the newly generated auxiliary verb /es/ ‘be’ is not a passive, the Passive morpheme must not be placed into the first of the two substrings in (24). We assume that the Passive morpheme is placed directly after the Verb Stem, so that the string underlying perfect passive verbs consists of the sequence in (25).

(25) VbSt - Passive - Theme - Perf - 〈[αFut]〉 - Agr

To generate the correct surface sequence of morphemes from (25), we need to posit a transformation that moves the Passive morpheme to the end of the sequence in cases where the Perfect morpheme is absent, but leaves it in place elsewhere. This transformation, which is not further detailed here, will generate the sequences in (21) and (22).

6 On the Structure of the Auxiliary Verb in German and English

Note that the sequence of morphemes in (25) is identical to that of the auxiliary verb in modern German, illustrated here in detail in the form that it takes in subordinate clauses.



This sequence of morphemes, where EnP stands for the Perfect Passive morpheme, is subject to a transformation that pairs each verb with the abstract morpheme on its right, generating the sequence in (27), which correctly reflects the German morpheme order.

(27) (VbSt-EnP) (werd-EnP) (sei-Inf) (könn-te-st)

The essential identity of the structures in (25) and (26) evidently reflects the common Indo- European ancestry of Latin and modern German. To my knowledge, this parallel has not previously been observed.

I conclude this review with a brief look at the parallel facts in English. As shown first in Chomsky 1957, the auxiliary verb in English has the underlying structure illustrated in (28), which is the reverse of the German order in (27).



Like auxiliary verbs in German, auxiliary verbs in English are subject to the pairing transformation, with the effects shown in the bottom line of (28). Unlike its German counterpart, this transformation produces pairs with the elements in the wrong order—that is, pairs where the affixes precede rather than follow the verb. As shown in (29), this misformation is readily corrected by applying the “Affix-Hopping” transformation (Chomsky 1957).



Setting aside the effects of Affix-Hopping, the auxiliary verbs in English and German are composed of identical elements and differ only in the left-to-right order in which the elements appear. The order of morphemes in German is the same as in Latin, and the main difference between Latin, on the one hand, and German (and English), on the other, is that in Latin the auxiliary verb /es/ is inserted only in the perfect passive and placed before the [αPast] morpheme, whereas in German and English each morpheme modifying the verb—[αPast], Modal, Perfect, Passive, and so on—constitutes a separate word, and each verb auxiliary is limited to taking just one affix.

Whereas the order of the morphemes in Latin, German, and English is identical, the differences are noteworthy. In Latin, the verbal morphemes are simply added to the Verb Stem, one after the other, in typical agglutinative fashion. In German, however, there appears to be a limit to the number of morphemes that can be added to a Verb Stem: namely, one. This limitation has led to the development of the auxiliary system of the VP. The accompanying tree in German is obviously left-branching. In English, on the other hand, the tree is right-branching. If we assume that head dominance is a parameter, we can argue that the switch from the Germanic left-branching VP to its right-branching English counterpart is what necessitated the rule of Affix-Hopping in English. In other words, English Affix-Hopping is a repair rule required when the head dominance of the VP switched from left to right in English.

7 Conclusion

Perhaps a methodological comment is appropriate in bringing this note to its conclusion. I remarked at the outset that I was committed to a theory of phonology that takes seriously such notions as distinctive features, parsimony of accounts, and simplicity, saying “An important principle governing scientific accounts of all kinds is that they must be concise.” Following in the spirit of these constraints, I arrived at an abstract morphological account of Latin whose resemblance to German was as striking as it was unexpected. That, in turn, led to the account of Affix-Hopping in English as a morphological repair rule, again an unexpected result. I take this latter insight as corroboration of the phonological theory that gave rise to it.

In sum, as the Mishnah tells us:


and there is much work, and the master keeps urging on . . .


Editor’s note: Thanks to Noam Chomsky for contributing this footnote.

1 This note is best construed as an addendum to Embick and Halle 2005.

2 Additional examples of delinking are as follows:

  • (i)
    • a.

      /mon-u-i-mus/ ‘harm’ perfect, instead of */mon-e:-v-i-mus/

      (present /mon-e:-mus/ shows Theme vowel /e:/)

    • b.

      /plac-u-i-mus/ ‘please’ perfect, instead of */plac-e:-v-i-mus/

      (present /plac-e:-mus/ shows Theme vowel /e:/)


On July 23, 2013, Morris Halle celebrated his 90th birthday. To honor that occasion, a two-day conference was held at MIT on September 20–21 of the same year. Morris gave a brilliant talk on Latin morphology, a topic that has been investigated in depth for too long to remember. Astonishingly, Morris made some surprising new discoveries, and in the style that he pioneered over many years of outstanding work, the discoveries enabled him to provide a deep explanation for phenomena that had, basically, been listed. And as an aside, he provided important new insight into one of the earliest syntactic problems addressed in modern generative grammar 65 years ago.

Working together with Jay Keyser, Morris prepared successive drafts of a paper to be submitted for publication, with steady improvements. Tragically, he was unable to bring this work to a conclusion. The latest draft, virtually complete, is presented here—a fitting testimonial to the distinguished career of a remarkable person, whose legacy is an inspiration for all of those who seek to follow in his footsteps.

In his letters, Isaac Newton famously wrote that “[i]f I have seen further it is by standing on the shoulders of Giants.” Morris’s colleagues, students, grand-students, and others who aspire to extend his legacy will be able to say the same.


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