In a modern language the valency of a predicate can quite often be determined by using the linguistic intuition of speakers of that language. This is, of course, excluded in the case of Latin. Another way to establish the valency of a predicate is to study the occurrences of that predicate in a `corpus' of adequate size and variety and to decide on statistical grounds what its valency is. Latin does not differ from other languages in this respect, apart from the fact that the corpus we have contains a relatively high number of stylistically marked texts (many are literary texts). Furthermore, our corpus consists solely of written documents. Written language differs from spoken language in several respects. These limitations, however, are to a large extent outweighed by the availability of lexicons for very many authors, the work done at the Thesaurus Linguae Latinae (TLL) in Munich, the presence of computer corpora and, recently, the compact disc corpus of the Packard Humanities Institute. (b) The role of context
If in Latin some entity is known or supposed to be known on the basis of contextual or situational information, a writer or speaker need not refer to that entity in an explicit way. This general rule also holds for entities
that must be regarded as arguments in relation to a specific predicate. An example is:
(1) orabo ut mihi pallam reddat quam dudum dedi (sc. ei) (`I'll beg her to give me back the mantle I gave her a while ago', Pl. Men. 672)Examples like (1) are especially frequent in certain context types: 
(2) (C. Piso … orator) minime … tardus in excogitando (`(the orator Gaius Piso …) by no means slow in invention', Cic. Brut. 239; cf. defensionem/causam excogitare)
(3) ne quis te invitum polliceri … cogat (`that no one shall compel you to promise against your will', Cic. Ver. 2. 148)
(4) nullo hoste prohibente aut iter demorante (`no enemy to hinder him or delay his march', Caes. Gal. 3.6.5.)
(5) at enim veteranis suspectum nomen est M. Bruti? … equidem non arbitror (`but the name of Marcus Brutus is suspected by the veterans? … I myself think not', Cic. Phil. 10.15)
(6) suscepi causam, Torquate, suscepi (`I have undertaken the case, Torquatus, I have undertaken it', Cic. Sul. 20)
In all these examples the context provides the information the reader needs in order to understand which elements are associated with the predicate. In our grammars and dictionaries the predicate in these cases is often labelled `absolute' or `used absolutely'. For details concerning the omissibility of elements in a continuous text, see also chapter 12.(c) More predicate frames, more valencies
Many predicates have more than one meaning. As a consequence they also have more than one predicate frame which may also differ in quantitative valency. Sometimes a predicate has several predicate frames even though the semantic differences involved are only small. I will discuss this problem in some detail.
(i) Some predicates have more than one predicate frame without having different valencies. A predicate's having more than one predicate frame often follows from its having more than one meaning, as in the case of reddere:
(7) orabo ut mihi pallam reddat quam dudum dedi (`I'll beg her to give me back the mantle I gave her a while ago', Pl. Men. 672)
(8) haec (fama) itinera infesta reddiderat (`this rumour had made the routes full of danger', Caes. Civ. 3.79.4)
In (7) reddere means `to give back'. It is quite obvious that reddere in this case, just like all verbs of `giving', is a three-place predicate. In (8), however, reddere
means `to render'. As such it can be compared to facere and creare, where in addition to a Subject constituent and an Object constituent, a third argument is required which agrees with the Object in case (a so-called Object Complement).  In other cases of predicates with more than one predicate frame, the differences are much more subtle. In the examples (9) and (10) the difference in construction does not correlate with a difference in meaning. However, we will see below that they are not simply exchangeable in their contexts (see crosssection 5.2.4. (b), p. 50, and crosssection 12.3.3., p. 255):
(9) arma umeris circumdare (`to throw the armour around the shoulders') (cf. Verg. A. 2.510)
(10) filo collum circumdare (`to circle the neck with a riband') (cf. Catul. 64.377)
(ii) Many predicates have more than one valency and more than one predicate frame which correlate with a difference in meaning. A good example of this is the verb dicere. With this verb we may distinguish two-place dicere (= `to speak')  and three-place dicere (= `to say, tell'):
(11) est oratoris proprium apte, distincte, ornate dicere (`it is the orator's peculiar ability to speak with propriety, clearness, elegance', Cic. Off. 1.2)
(12) tum mihi Roscius … alia multa … dixit (`then Roscius told me many other things', Cic. Quinct. 78)However, distinguishing two predicate frames for the verb dicere is not sufficient. There is another three-place dicere, when it means `to appoint someone as'. There is even another two-place dicere, which, again, differs from dicere in (11):
(13) prooemium dicere (`to pronounce') In view of such variation one might object that it does not make much sense to speak about the valency of a predicate. One might also ask how the frames are related to each other and how the meanings are related to each other.
One reason for establishing the frame or frames of a certain predicate (say, dicere) is that we may use it or them for describing properties of other predicates or classes of predicates. In (11), for example, dicere can be compared to loqui. In (13), however, dicere is comparable to pronuntiare. Such a paradigmatic comparison enables us to distinguish various predicate frames and various valencies for a verb, while at the same time giving us criteria to describe the frames of other verbs that do not show the same variety of frames. One more example will illustrate this point. Consider examples (14a) and (14b):
(14a) John was eating his hamburger
(14b) John was eating
If we simply compare the two sentences in (14), we might conclude that to eat is a one-place verb, since the (b) sentence is grammatical, and therefore his hamburger is an optional constituent. However, eating in the sense of eating up resembles other verbs which indicate `taking through the mouth and oesophagus into the stomach' like to swallow and to devour, which are strictly two-place predicates. Eat in (14b), however, resembles verbs like to dine and to feast, which are strictly one-place predicates. John was dining resembles (14b) in this respect. Combining these two things it seems better to assume that the verb to eat has two valencies. Other verbs of `processing food' are either one-place or two-place.
If a predicate has more than one frame and valency, these frames and valencies can quite often be shown to be related to each other in a systematic way. Many verbs, for example, can occur both as a `neutral/unspecified' activity and as a specific activity, such as sing/sing the national anthem. The unspecified activity is one-place, while the specific one is a two-place predicate. A related example is the verb to paint, which is two-place when used in a specific sense, but one-place when denoting professional activity: paint a wall/paint (i.e. `be a painter').(d) The relationship between active and passive (valency reduction)
In most languages that have an active/passive distinction the Agent or Cause of the action indicated by the verb is absent in passive sentences. Furthermore, it is often the case that the Agent or Cause cannot be retrieved from the context. Recent studies on the use of the passive in English and German texts have shown that in c. 80% of sentences with a passive verb the Agent or Cause is not indicated. In Latin texts too, the Agent or Cause is most often not expressed. On the basis of these observations one might assign different predicate frames to the active and passive forms of verbs. One might state this in a different way saying that passivization is above all valency reduction. It has been shown, however, that at least in English there are also cases where the Agent or Cause must be expressed. Since no research on this particular aspect of Latin has been carried out, a few English examples will serve to illustrate the point: 
(A) (15) An irresistible desire to run away possessed me
(16) *I was possessed
(17) I was possessed by an irresistible desire to run away
The Cause constituent cannot be left unexpressed with the verb to possess.
(B) (18) Somebody followed me
(19) I was followed
(20) Curse one followed curse two
(21) *Curse two was followed
With the verb to follow the inanimate Cause has to be expressed. The animate Agent, however, can be omitted.
(C) (22) His parents brought him up
(23) He was brought up by his parents
(24) *He was brought up
(25) He was brought up in Cambridge
The Agent can be omitted only if some Adjunct is present in the sentence.
(D) (26) This sonnet was written by Shakespeare
(27) *This sonnet was written
The fact that a sonnet was written is so trivial, that the information makes no sense without further specification. I will return to the active/passive relation further on ( crosssection 2.4. on p. 19).(e) The cognate object (valency extension) 
In Latin certain one-place predicates can be extended into two-place predicates. An example is mirum somnium somniare (`to dream a wonderful dream'). In standard grammars mirum somnium is often said to be an `internal' or `cognate' Object. The objecthood of the constituent appears from the fact that it may be passivized. The noun in such noun phrases has a meaning that is semantically related to the meaning of the verb. Usually there is also a close morphological relation between the nominal and verbal expressions. The noun is normally accompanied by an adjective or another expression as its Attribute. It is usually the Attribute which contains the most important information. This appears among other things from its position with respect to the Head noun: it normally precedes, as is the rule for Attributes carrying Focus function (see crosssection 9.4. on p. 186). Examples can be found in K.–St. I.274–8.
Pinkster, Harm (1942-) , Latin Syntax and Semantics [info], xii, 320 p.: ill.; 24 cm. [word count] [Pinkster].