In this section I will discuss the syntactic functions arguments may fulfil. The semantic functions of arguments will be taken up in the next section. I will not
consider the so-called impersonal verbs and impersonally used verb forms like pluit, licet, miseret and concurritur, parcitur, respectively. For these I refer the reader to table 2.4 on p. 23.
(i) Subject. With monovalent predicates like ambulare the single argument occurring in an active sentence fulfils the function `Subject'. The finite verb form agrees with this constituent in Number and Person, for example ambulat with pater in pater ambulat. With bivalent and trivalent predicates the function `Subject' is fulfilled by the constituent that determines agreement of the finite verb form in Number, Person and sometimes also Gender (in complex verb forms, for example laudaturus est).
N.B. 1. Finite verb forms in Latin also manifest agreement with persons or things which are to be understood as Subject in a given situation or context, for example laudat (laudaturus est). In such cases we may speak of an `internal Subject'. N.B. 2. In the Accusative and Infinitive construction the expression of agreement is restricted (only Number and Gender in periphrastic forms).
N.B. 1. Finite verb forms in Latin also manifest agreement with persons or things which are to be understood as Subject in a given situation or context, for example laudat (laudaturus est). In such cases we may speak of an `internal Subject'.
N.B. 2. In the Accusative and Infinitive construction the expression of agreement is restricted (only Number and Gender in periphrastic forms).
(ii) Object. The constituent that becomes Subject in passive sentences with two-or three-place predicates will be called Object.
(iii) Indirect Object. In active sentences three-place predicates will usually be accompanied by a Subject and an Object argument. Three-place predicates meaning `transfer', in the sense both of `communication' and of `handing over', normally also require a third argument (the `Addressee' or `Recipient'). This argument, which typically is expressed by the dative case, will be called the `Indirect Object'.
(iv) Complement. This label will be used to refer to those arguments that cannot be defined as Object or Indirect Object in the sense indicated above. As a consequence it is used both for third arguments (for example, filo (`riband') in filo collum circumdare (`to circle the neck with a riband')) and for second arguments that cannot become Subject in passive sentences, for example the argument expressed by a dative case form as with favere (`to show favour to').
(v) Finally I will also distinguish the functions Subject Complement (see ch. 1, n. 3) and Object Complement (infesta in ex. (8) on p. 7).
There is no consensus among linguists about the terminology to be used for the syntactic functions fulfilled by arguments. In fact, only the notion Subject is used more or less consistently.  The notions Object and Complement are also used to refer to any non-Subject argument of a predicate. Hence one finds expressions like `Dative object', `Ablative object', etc. The label `Indirect Object' is used quite often to denote simply any argument constituent marked by the dative case, so for example the argument of a two-place predicate
marked by the dative, which we defined as `Complement' above, as in favere alicui. In this book I have chosen formal criteria to define the syntactic functions of arguments. Agreement is such a criterion, used to define the Subject (however, this criterion is not always sufficient as we noted above). Passivization is another criterion which can be used to define the Object and to distinguish it from the Complement. However, this criterion has certain defects that we will discuss shortly. Finally, the Indirect Object is not without problems either. I will discuss the matter in some detail below.
(a) If we take the possibility of passivization as a decisive criterion for identifying an argument as an Object, the italicized items in (39) cannot be considered Objects. As a consequence they will be regarded as Complements.
(39) nimis plebem amplecti videbatur (`he seemed to support the people too much')
pater gladio utitur (`father is using a sword')
pater litteris studet (`father devotes himself to literature')
pater filii miseretur (`father feels pity for his son')
me paenitet imperii nostri (`I feel ashamed of our empire')Conversely, the italicized constituent in (40) is considered an Object, since passivization is possible:
(40) hostes in custodia habebant Romani (`the Romans kept the enemies in prison')
(40a) hostes in custodia habebantur a Romanis (`the enemies were kept in prison by the Romans')If, however, habere does not mean `to keep', but rather `to own' (as in (41)), the constituent in the accusative will be described as a Complement, because there is apparently no passive like (41a):
(41) librum habeo (`I have the book')
(41a) ?liber habetur (in the sense of: ?`the book is owned by me')The criterion of passivization thus forces us to assume different syntactic functions for the second argument depending on the meaning of the predicate. But the problem is even more difficult. It is not self-evident which verb forms are to be considered passive verb forms. In our final example in (39) me paenitet imperii we took imperii as a Complement. However, expressions like res paenitenda are completely viable. If we do not regard the gerundive as a passive form, as many people would prefer,  only finite passive verb forms can be used as a criterion for establishing the function of a second argument.
(b) With three-place predicates I made a distinction above between third arguments in the `Indirect Object' function and other third arguments, by
definition occurring in the function Complement. However, in the definition a semantic element has been introduced which is lacking elsewhere. The label was said to apply to arguments of predicates with the meaning of `transfer' expressed in the dative case. The notion would apply, therefore, to arguments of verbs like dare (`to give'), adimere (`to take away'), dicere (`to tell'), that is, verbs of `giving' and `saying', as well as to third arguments with verbs like necem moliri (`to meditate murder'), copiam facere (`to create an opportunity'). However, the notion does not apply to the third argument, expressed by the ablative, with verbs like circumdare (`to circle'). My reason to use this half semantic/half syntactic definition is that it is more or less in line with the terminology in Latin grammars and in itself is not ambiguous.
Pinkster, Harm (1942-) , Latin Syntax and Semantics [info], xii, 320 p.: ill.; 24 cm. [word count] [Pinkster].