All Tamil verbs can be broadly classified into two, namely, intransitive and transitive. Transitive verbs are capable of taking an object whereas intransitive verbs are not capable of taking it.

    Transitive verbs can be further classified into two. Those  verb which are derived from corresponding intransitive verbs from one class and those which do not have any overt marker to denote transitivity from another class. the former can be DERIVED TRANSITIVE and the latter INHERENT TRANSITIVE.

        Dr.Caldwell derives transitive from the corresponding intransitive in three  modes

      Robert Caldwell, while dealing with "Transitives and Intransitives" says that "Dravidian grammarians divide all verbs into two classes, which are called in Tamil pira vinai and tan vinai, transitives and intransitives, literally outward action words and self-action words". This statement does not hold good as there are many transitive verbs which are, according to Tamil grammarians, only tan vinai, as the action expressed by the root of the verb is done by the subject itself.

        Another important issue is whether the classification of verbs into pira vinai and tan vinai is necessary for the description of Tamil. Many scholars hold the view that there are many verbs which morphologically show a two way contrast and this must be treated in the grammar. Their main objection to treating this contrast as intransitive and transitive, is that like unta:n 'ate-he' and u:ttina:n 'fed-he', me:yntatu and me:yttatu, kanta:n and ka:ttina:n show tan vinai and pira vinai though both the sets are transitive verbs. And also the relation that exists between the two sets are found to be the same as that of atanku Vs atakku, nanainta:n Vs nansitta:n etc.

There are some other scholars who consider that a few cases like unta:n  Vs u:ttina:n need not be taken seriously and therefore the contrast can be considered as intransitive and transitive. These forms can be taken as exceptions. This contrast is found only in a small number of verbs and " the classification of verbs into   pira vinai and tan vinai  is vague and unnecessary.........." .There are many verbs where the contrast is not found, and therefore it is better to take them as intransitive Vs. transitive rather than  pira vinai and tan vinai.

[1] There is a set of intransitive verbs which end in stops like a:t[u] 'dance', a:ku 'become' and stops precede by homorganic nasals like atamk[u] 'be submissive', tirmupu 'turn' etc. These "Intransitive themes become transitive by the hardening of the consonant of the appended formative".

                a:ku 'become'                       -------    a:kku 'to make'

                alamuku 'be submissive' -------   tiruppu 'turn[tr.]'

                tiruntu 'become correct'   --------  tirttu 'correct'

[2] There is another set of intransitive verbs like nanai 'become wet', ce:r 'join', kurai ' diminish'. These "Intransitive verbs become transitive by the doubling and hardening of the initial consonant of the signs of tense".

                nanai-nt-e:n                               'become wet-he'

                nanai-tt-e:n                                 'wet-he'

                kurai-nt-atu                                'become diminish-it'

                kurai-tt-atu                                  'diminished-it'

                eri-nt-atu                                      'burnt-it[int.]'

                eri-tt-tau                                        'burn-it[tr]'

                nanai-v-a:n                                  'will become wet-he'

                nanai-pp-a:n                               'will wet-he[tr]' .

[3] There is till another set of verbs like nata 'walk', ti::r 'finish', aru 'cut' etc. which are converted into transitive "by adding a particle of transition to theme of root".

                nata        'walk'                 -------- nata-tt[u]     'conduct'

                uzar        'rise'                     ------- nzar-tt[u]    'raise'

                nimir       'become erect'   ------- nimir-tt[u]     'erect'

                ta:l            'become low'     ------- ta:l-tt[u]        'lower'

    There is an important differences between the derived transitive and inherent transitive. Consider the following sentences.

        1.   avan atankina:n                            "He subdued[int.]"

        2.    na:n avanai atakkine:n                "I subdued him"

        3.    avan nanainta:n                           "He was wet"

        4.   na:n   avanai   nanaitte:n             "I wet him" 

    These sentences clearly show that the subjects in the intransitive sentences are converted into objects in the corresponding transitive sentences. But this is net the case in the case of inherent transitives. It is impossible to have sentences like

            5. puttakam patittatu

            6.  puttakam pa:rttatu

       corresponding to the sentences like

            7.  na:n puttakam patitte:n

            8.   na:n puttakam pa:rtte:n

        It is worth mentioning that in Tamil there are certain verbs which can be used both as transitive and intransitive. Verbs like velu 'wash' may be used both as transitive and intransitive. In these cases also the subject of the transitive is used as the object of the corresponding transitive verb. Sentences like

            9. tuni veluttatu                             'The clothes become white'

            10. avan tuniyai velutta:n                'He washed the clothes'  

are found in Tamil.