Why is the first person singular the citation form?

Question

In both Latin and Greek, the most common citation form for a verb is the first person singular present indicative active. In other words, dictionaries will generally be indexed by amō and λύω rather than amāre and λύειν. There are some exceptions, but this seems to be the most common practice.

Why is this? Is it a modern practice, or did the ancients cite words by their 1S too?

(I know why the 1S (first person singular) form is included as one of the principal parts in Latin, because it distinguishes the third -ō verbs from the third -iō verbs. But that doesn't explain why it's the citation form—after all, there are three other principal parts too, none of which are used as the citation form. And in Greek, I can't think of any information the 1S provides that the infinitive doesn't.)

Answer 1

For practical reasons, I imagine the index form is often (but not always) given in the first-person since it comes first in the principal parts and is usually the first in a paradigm memorized.

There is however ancient precedence. In discussing Latin verbs, Varro chiefly (but again not always) gives the first person unless he was specifically discussing another person. See e.g. De Lingua Latina 9.96-100, 105, 107, etc.

Ultimately I think it's just familiarity and convention.

Answer 2

Let me try to approach this from a slightly different angle: What would work as a citation form?

A good citation form would be such that you could deduce all other forms (from the present stem) from it. I will look into the six personal forms of present active indicative and the present active infinitive. The exercise can be extended to other forms, but these are a natural set of candidates and the conclusion will remain the same.

For reference, here are these forms of the five regular conjugation patterns:

	I	II	III-o	III-io	IV
inf.	laudāre	vidēre	trahere	facere	audīre
1S	laudō	videō	trahō	faciō	audiō
2S	laudās	vidēs	trahis	facis	audīs
3S	laudat	videt	trahit	facit	audit
1P	laudāmus	vidēmus	trahimus	facimus	audīmus
2P	laudātis	vidētis	trahitis	facitis	audītis
3P	laudant	vident	trahunt	faciunt	audiunt

Each has its problems:

• If you are only given the infinitive, you cannot tell the difference between III-o and III-io. [Nor between II and III if there are no macrons.]
• If you are only given the first person singular (1S), you cannot tell the difference between I and III-o nor between III-io and IV. (You might also confuse III-io or IV for I or III-o, as in facio > *faciare or audio > *audiere. This is ruled out if you know that certain stems are impossible, but this is a potential source of confusion for students.)
• If you are only given the 2S, you cannot tell the difference between III-o and III-io. [Nor between III and IV if there are no macrons.]
• If you are only given the 3S, you cannot tell the difference between III-o, III-io, and IV.
• If you are only given the 1P, you cannot tell the difference between III-o and III-io. [Nor between III and IV if there are no macrons.]
• If you are only given the 2P, you cannot tell the difference between III-o and III-io. [Nor between III and IV if there are no macrons.]
• If you are only given the 3P, you cannot tell the difference between III-io and IV.

The conclusion is that no single form will work perfectly. You can, however, dissolve all ambiguity if you are given two forms or one form and the conjugation number. For example, you could give the pair (2P&3P) (eg. trahitis & trahunt and facitis & faciunt and audītis & audiunt), and you could find all else from those.

The canonical choices seem to be infinitive with 1S and 1S with conjugation number. These work but are but are not the only ones that do. If the dictionary has no macrons, the chances of confusion increase somewhat, but there are still several pairs of forms that resolve all ambiguities.

If you want to choose a single citation form, it makes sense to pick one with minimal overlap between the different conjugations. But from a practical point of view, it is wise to choose a relatively short form for which cannot cause confusion between two existing verbs.

Conclusion: The citation form wouldn't have to be what it is. Therefore any explanation must have a cultural aspect to it; it is a matter of convention rather than necessity.

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Related older posts you might find interesting in connection to this:

• The Romans did use 1S mostly but not exclusively: What did the Romans consider the “basic” form of a verb?
• The ancients had the same concept of first, second, and third person as we do now: Numbering of persons

Answer 3

This isn't a full answer, but brianpck provides some interesting evidence for how the Romans thought of verbs, in his answer to a related question.

From Varro's De Lingua Latina VI.5.37:

Primigenia dicuntur verba ut lego, scribo, sto, sedeo et cetera, quae non sunt ab ali<o> quo verbo, sed suas habent radices. Contra verba declinata sunt, quae ab ali<o> quo oriuntur, ut ab lego legis, legit, legam et sic indidem hinc permulta.

We call verbs like 'legō', 'scribō', 'stō', 'sedeō', etc "primitive": the ones that don't come from another verb, but have their own roots. On the other hand, "declined" verbs are the ones that arise from another, like from 'legō' [arise] 'legis', 'legit', 'legam'; in this way a whole lot [of verbs] come from the same place.

In other words, the grammarians seem to have thought of a verb paradigm somewhat like a noun paradigm, and cited it by the first form on the list.

This doesn't explain why the 1S has now become so thoroughly predominant in modern times, when (as we can see in brianpck's question) Quintilian also cited verbs by the 3S, but it might help someone else in tracking down the origins of the modern convention.

Answer 4

It's interesting to note that for many ancient Greek grammarians, the infinitive was not a real verb (ῥημα) "on the grounds that it is not part of a basic sentence or λόγος". See 'Whence and Whither Greek Verbal Lexicography and Pedagogy' (at http://bagl.org/files/volume3/BAGL_3-3_Kraeger.pdf)

About the disadvantages of using the 1st singular as citation form: in addition to the ones mentioned by Joonas, there's confusion between 'video' (vidēre) and 'creo' (creāre), and someone might add possible confusion between verbs on the one hand and nouns + adverbs ending on -o on the other.