Sophia University Junior College Division Faculty Journal
第 37 号, 2016, 57-72

On “Thook” as a Main Verb in Thai
Timothy Gould
1. The Problem
This paper will focus on determining the nature of the lexical item “thook” in Thai.
“Thook” has traditionally been considered an auxiliary, or a kind of “helping verb” used
to form passive sentences. Mary Haas, in her “Thai-English Student’s Dictionary,”
defines it as “[a] verbal element; used in making passive constructions”(Haas 1964 p.219).
The issue of classifying “thook” is not a straightforward one, however, in that Thai does
not make any use of inflection on nouns or verbs. Danvivathana’s (1987 p. 7) claim that“there are no hard and fast rules that make Thai words belong to a particular part ofspeech,” though possibly too strong, captures, I believe, the native speaker’s difficulty inplacing “thook” in a specific grammatical category. Intrasai and Boonmee (2015 personalcommunication) agree that in Thailand, “thook” is presented as the analog to English
passives, and that most Thai speakers accept the notion that “thook” serves exactly thesame function as the auxiliary “be” in English passives.

2. The Hypothesis
I will examine two Hypotheses in order to determine exactly which lexical category“thook” should be considered a member of. The first, which I will call the Infl Hypothesis,
supports the traditional view in Thai that “thook” is used to make passive constructions.
Under this view, as the name implies, “thook” is an auxiliary verb. The second, which
I will call the V Hypothesis, supports the notion that “thook” is a main verb which
requires a CP complement. Basing my arguments on the patterns exhibited by othernon-controversial verbs and auxiliaries in Thai, I will show that “thook” is, indeed, amain verb. Below, for clarity, is a restatement of the two Hypotheses under examination.

INFL Hypothesis“Thook” is an auxiliary element used to form passive voice sentences in Thai.

─ 57 ─

Timothy Gould

V Hypothesis“Thook” is a main verb which requires a sentential complement.

3. Brief Outline of Thai Syntax
The canonical word order of sentences in Thai is Subject, Verb, Object. Since there
are no overt case markers, word order is crucial.
(1) khaotii chanhe/she/they hit I“He/she/they hit me.”
Notice that when the order of the subject and object in (1) is reversed, the form of
the pronouns remains the same.
(2) chan tii khaoIhit he/she/they“I hit him/her/them.”
These sentences clearly show that Thai does not make use of overt case marking on
NP’s. Additional syntactic features of Thai will be explored as they become relevant todevelopment of the following arguments.

4. The INFL Hypothesis
The Infl hypothesis proposes that passive formation in Thai is virtually identical topassivization in English and that “thook” occurs under Infl. A passive verb then, will not
subcategorize for an external argument and it “loses” the active verb’s ability to assign
accusative case. To satisfy the Case Filter, overt NP’s in Thai must receive abstract case,which in passives is accomplished by moving the direct object NP to [Spec,IP], wherecase is assigned by Infl. An auxiliary verb is also needed in both languages: “be” inEnglish and “thook” in Thai. Following are examples of simple active sentences and tree
structures of their passive transformations in both languages.
(3) Mom hit me.

─ 58 ─

On“Thook”as a Main Verb in Thai

(4) Mae tii chan.
mom hit I“Mom hit me.”In both Thai and English, as shown below, the agent of the active verb may
optionally be omitted in the passive sentence.
(5) Chan thook tii.				
I(6) I was hit.

suffer hit“I was hit”(5i)						

		

(6i)

			

A number of issues immediately surface. First, notice that while the English Infl
carries tense and number, the Thai Infl is uninflected. This is relatively uninterestingin this sentence, but the lack of any overt marking on “thook” prevents use of the Infl
Hypothesis to confirm or deny this placement of the word. More straightforwardly, since
there is no inflection, we cannot ascertain if “thook” really belongs in Infl. Additionally,
while “be” is semantically neutral, “thook” carries a connotation of negativity. The
translation of “thook” is usually “suffer,” but as I will show in later arguments, it may
sometimes be translated more accurately as “experience” or “undergo.” This “negativity
condition” on the verbs with which “thook” appears, though, is indicative of a constraint
on Thai “passives” which does not hold for English. Consider the sentences in (7) and (8).

─ 59 ─

Timothy Gould(7) chan kap rot.
I drive car“I drive a car.”(8) *rot thookkap.

car undergo drive“The car was driven.”
The English passive of (8), “the car was driven,” is perfectly acceptable, but while
the construction in (8) is syntactically identical to (5), the sentence is ungrammatical.
This is an unexpected result; passive markers are not usually employed to convey
their own semantic notions. Even more surprising, however, is the fact that the verb
appearing with “thook” is not solely responsible for the unpleasant interpretation Thai
speakers give “thook” constructions.
(9) chan thook John jup
Isuffer John kiss

“I was kissed by John.” (and it was not a pleasant experience)
For (9) to be an acceptable sentence, the kissing must be given a pejorative reading.
But the verb “kiss” does not carry any negativity itself, so the unpleasant meaningcomes from “thook.” Although none of the above examples constitute a direct indictmentof the Infl Hypothesis, they certainly raise suspicion of its validity. So far we haveseen that when the agent of the verb is omitted, passivization seems to operate in Thai
as in English, with a couple of important caveats. First, we are unable to determine
if movement of the direct object to [Spec,IP] has occurred because there is no overt
marking of case on Thai pronominal NP’s. As I mentioned above, this merely eliminates
a potential confirmation of passivity in Thai, it does not deny it. Second, unlike mostother languages which use a semantically neutral auxiliary type verb to form passives,“thook” conveys a distinct pejorative meaning. Again, this simply raises suspicion of theaccuracy of classifying “thook” as an auxiliary element. Based on these suspicions, thefollowing arguments will confirm that “thook” cannot appear in Infl. In both Thai andEnglish, the agent of the passive verb can be optionally omitted in the S-structure of apassive sentence. In English, the agent NP appears in a prepositional “by” phrase, but
in Thai the agent always follows “thook”. (5a) and (6a) below are (5) and (6) above with─ 60 ─

On“Thook”as a Main Verb in Thai

overt agents.
(6a) I was hit by mom(6ai)

Since the verb “hit,” in its passive form, cannot assign accusative case, the direct
object must move to [Spec,IP], where it gets nominative case from Infl. This casemarking of the NP makes the chain of which “I” is the head visible so the tail of thechain can receive the verb’s theta role. The overt agent NP “mom,” then, receives
accusative case from the preposition “by.” In this way, all overt NP’s in English passives
satisfy the Case Filter. Thai also has a word that translates as “by,” but it cannot be
used to capture the verb/agent relation in a “thook” construction.
(10) Chan pai doi rotI

go by car

“I go by car.”If we try to place the agent in a “by” phrase adjoined to the verb, we get theungrammatical (5a)(5a) *chan thook tii doi maeIsuffer hit by mom“I was hit by mom.”─ 61 ─

Timothy Gould(5ai)*		This sentence is deceptively well formed for English speakers, but it is simply
unacceptable in Thai. The grammatical “thook” construction which includes an overt
agent is (5b).
(5b) Chan thook mae tii
Isuffer mom hit“I was hit by mom.”
The tree diagram for (5b) exposes a real problem for the Infl Hypothesis.
(5bi)

As the tree above is drawn, “mae” ‘mom’ is in [Spec,VP], the only available position.
The problem presented here is that the Infl Hypothesis assumes that passive verbs,

─ 62 ─

On“Thook”as a Main Verb in Thai

indicated by the appearance of “thook” in Infl, do not have an external argument, so[Spec, VP] in this sentence should be empty. Even if we do allow it, “mae” ‘mom’ shouldhave to move to [Spec,IP] to get case. Obviously this is an impossible move, as “chan” ‘I’is already occupying that position. An attempt could be made to rescue the structure byadjoining a “mae” headed NP between I’ and VP or between VP and V’. Either of these
options, though, would only exacerbate the problems already noted. If we adjoin anotherNP phrase above the VP, we will have an overt NP that cannot get a theta role and isblocked by the NP “chan” from moving to get case. We would also lose the informationthat “mae” is the logical subject of the sentence and that [Spec, VP] is exactly where
we find it in active sentences (assuming the “subject in VP hypothesis”). An adjoined
NP above V’ would violate X’ Theory and cause the same problem. The Infl Hypothesisis thus unable to account for the overt agent’s grammatical appearance in a “passive”
construction.
Sentences containing other auxiliaries can appear in constructions containing“thook.” The following arguments will show that because these elements are “real”
auxiliaries which reside in Infl (except for negation), “thook” must belong somewhere
else. First, I will consider the progressive auxiliary “kamlang,” best translated as “V-ing.”
Consider the following sentence with tree diagram.
(11) Chan kamlang kap rot muwan.
I-ing

drive car yesterday“I was driving the car yesterday.”(11i)

─ 63 ─

Timothy Gould

This sentence is uncontroversial. “Kamlang,” under Infl, always precedes theverb and in this sentence makes “kap” ‘drive’ progressive. Unless we invoke the Split
Infl Hypothesis to open another node in the tree, “kamlang” occupies the only space
available, namely Infl. Now consider (12) in which “kamlang” and “thook” occur together
in a grammatical sentence.
(12) Rot kamlang thook chan kamoy.
car -ing

suffer I

steal“The car is being stolen by me.”
Again, under the Infl Hypothesis, there is no place in the structure to support both“kamlang” and thook. Additionally, as shown above, “kamlang,” in all other instances,
precedes main verbs, so we must conclude that “thook,” contrary to the Infl Hypothesis,
is not in Infl.
Another argument along the same lines uses the future auxiliary“ja”‘will.’
The lexical item “ja” always precedes the verb in Thai sentences, which gives us
active sentences like (13).
(13) Chan ja kamoy rot.
I

will stealcar“I will steal a car.”Which can be made into a “thook” construction.
(14) Rot ja

thook chan kamoy

car will suffer

I

steal

“The car will be stolen by me.”The Infl Hypothesis is unable to explain this construction. According to the Infl
Hypothesis, two auxiliaries “thook” and “ja,” would have to occupy Infl at the same time.
Since this is impossible, we must conclude that “thook” is not an auxiliary in Thai.
We have seen that the Infl Hypothesis fails in a number of ways to account for
constructions in Thai which contain “thook.” All of the problems stem from the inability─ 64 ─

On“Thook”as a Main Verb in Thaiof a syntactic structure which posits “thook” as the head of Infl to account for lexical
items appearing in grammatical sentences. I first showed that overt agents are unable
to be case marked when “thook” is in Infl. Then I showed that since other auxiliaries(“kamlang” and “ja”) always appear before verbs, the fact that they also precede“thook” makes it impossible for them to belong to the same lexical category. “Thook’s”
appearance after negatives raises the same problem for the Infl Hypothesis, so thenegation argument will not be fully explored in this section. Based on these findings, I
dismiss the Infl Hypothesis as a possible accounting for “thook.” The following section
will explore a more likely hypothesis.

5. The V Hypothesis
Under the V Hypothesis, “thook” is a main verb which requires a sentential
complement. I will show in the following arguments how this structure can accurately
account for all grammatical occurrences of “thook.” Consider (5b) rewritten as (15); the V
Hypothesis structure for a “thook” construction with an overt agent.
(15a) Chan thook mae tii
Isuffer mom hit“I was hit by mom.”(15b)

proi/＊j─ 65 ─

Timothy Gould

In (15a), “chan” is base generated as the subject of the main verb “thook” (In these
representations I assume the subject has already moved from [Spec,VP] to [Spec IP]).
In this position it receives case from Infl and an external theta role from the verb
“thook.” In the embedded clausal complement, the overt agent “mae” ‘mom’ is no longer
problematic, it receives case from Infl and a theta role from the “active” verb “tii” andit remains the understood, and real subject of “tii.” Under the V Hypothesis, the direct
object of the embedded verb is the covert NP “pro” which does not require case. Sincecovert NP’s are not bound by the Case Filter, we no longer have to posit movement.
This gives the V Hypothesis a theoretical advantage in that movement in Thai is highlymarked (only rarely occurring in topicalization and possibly in the UG “subject in VP
hypothesis”). The above argument satisfactorily addresses all the difficulties faced by
the Infl Hypothesis, strongly suggesting that “thook” is a main verb. The following
arguments will confirm this status.
Remember from arguments presented against the Infl Hypothesis that auxiliaries
in Thai always come before main verbs. Under the V Hypothesis, “thook’s” consistentappearance in that position is naturally accounted for. Consider again sentence (12),which the Infl Hypothesis was unable to produce. (12) is repeated here as (16a) and thetree diagram (16b).
(16a) Rot kamlang thook chan kamoy.
car

-ing

sufferI

steal“The car is being stolen by me.”─ 66 ─

On“Thook”as a Main Verb in Thai

(16b)

proi/＊j

Referring back to (11), we see that “thook” patterns in exactly the same way as a mainverb when it appears with an auxiliary element. “Kamlang” “V -ing’’ always appears before
the verb it modifies. Since it also appears before “thook,” we can be certain that “thook”
is a verb. At this point, the V Hypothesis seems to account ably for the patterns “thook”
exhibits in grammatical Thai sentences, so before I make additional arguments confirming
this via the future auxiliary “ja” and negation, I will address the issue of the “gaps” foundin “thook” constructions. This gap, thus far found in the direct object position of theembedded clause, is coindexed with the base generated subject in the matrix [Spec,IP]. A
pattern begins to emerge here that may partially account for the “special” status of “thook.”

6. Digression concerning the “gap” in “thook” constructions.
Thai speakers are taught in the course of their formal education that “thook” is used
to form two types of passives, direct and indirect. All of the examples so far ((5), (9), (12),(14), (15), (16)) have demonstrated the effect of “direct passive” “thook” constructions,
namely that the direct object position of the embedded verb is left empty. For example,
in the trees for (15b) and (16b), the NP’s that are coindexed with the subject of “thook”
cannot be overt. And as shown in (17), if the coreferring NP is overt, the sentencecrashes.

─ 67 ─

Timothy Gould(17) *Chan thook mae tii chan.
I

suffer mom hit I*“I was hit me by mom.”
While the ungrammaticality of the English translation for (17) is easily defined asa violation of the Case Filter, the situation in Thai is not so clear cut. If we look again
at the tree diagrams in (15b) and (16b), it is not apparent exactly why the direct object
NP of the embedded clause must be covert. Since the lower verb is active, it should
assign accusative case and a theta role to its direct object NP, essentially licensing the
NP to be overt. Recourse to Government and Binding Principles does not provide muchinsight. PRO must be ungoverned, and this sister of V position is obviously governedby V, disqualifying it as a potential candidate for PRO. Little pro can appear in object
position, but according to Haegeman (1994), it must be recoverable. In Italian,“recoveryof the content of object pro [ ] is due to a rule of arbitrary interpretation” (p. 462) whichassigns the features [+masculine, +plural] to pro (Haegeman 1994). But Thai pronouns
are not marked for person, number, or gender (cf. (1) above) and the empty coreferrential
position may also be coindexed with an R-expression, making it irrecoverable without
recourse to the matrix [Spec, IP] position. Forced to a draw I have chosen to “abstractaway” from the issue and use the combination term “Pro” to refer to the gap in the
direct object position (and sometimes in the subject position, as shown below) which iscoindexed with “thook’s” [Spec,IP]. The distribution of the empty category, though, iseasily captured with the following stipulatory condition: Any NP’s coindexed with thesubject of “thook” must be covert.
This definition predicts that the grammatical position of a coreferrential NP in a“thook” construction is irrelevant; a prediction borne out by (15) and (16) and further
confirmed by the following sentences. These sentences are considered in traditional Thaigrammar as “indirect passives”.

(18a) Chan thook samiIprakatwa mii chuu.

suffer husband announced that have lover“I suffer the fact that my husband announced that I have a lover.”─ 68 ─

On“Thook”as a Main Verb in Thai

(18b)

proi/＊jIn (18), the subject of the doubly embedded CP is coindexed with the subject of“thook,” and as predicted, it must be covert. A reading where “sami” ‘husband’ is the
person with an illicit lover is impossible unless an overt pronoun replaces “Pro.” Inthat case, no NP’s would refer to the subject of “thook” and the sentence would begrammatical. The “Pro” gap can also occur in possessive NP’s as shown in (19).
(19) Chani thook joanj kamoy waan Proi/*jI

suffer thief steal

ring (I/*thief)“My ring was stolen by a thief.”
The combined force of (15), (16), (18), and (19), provides powerful empirical evidence
that “thook” constructions are not divided into direct and indirect “passives,” indeed they

─ 69 ─

Timothy Gould

are not passives at all, but are the sole reflex of a (subcategorization?) constraint barring
overt NP’s that corefer to the subject of the main verb “thook.”

7. Three final arguments for “thook” as a verb.
These final arguments will solidify the accuracy of the V Hypothesis claim that“thook” is a main verb. The first refers to the tree (18b) above. Notice that the doubly
embedded CP is a complement of “prakat” ‘announced.’ The single lexical item that canappear alone between a subject and an embedded CP is a verb. Since “thook” appears as
the only word between the matrix subject and the first embedded CP, it, too, must be averb.
The second argument is that the modal “ja” ‘will’ cannot occur without a verb, as
evidenced by (20).
(20) *Chan ja
Irongrian

will school*“I will school.”
In a grammatical sentence it always precedes the main verb.
(21) Chan ja pai rongrianIwill go school“I will go to school.”
When the modal “ja” is in a “thook” construction, it precedes “thook.”(22) Chan ja
Ithook mae tii.

will suffer mom hit“I will be hit by mom.”Based on this pattern, “thook” is a main verb.
The third and final argument is based on the fact that main verbs always follow
negation in Thai.

─ 70 ─

On“Thook”as a Main Verb in Thai

(23) Chan ja
Imai pai rongrian.

will not go school“I will not go to school.”“Thook” also follows negation when they appear in the same sentence.
(24) Chan ja
I

mai thook mae tii.

will not suffer mom hit“I will not be hit by mom.”Once again “thook” patterns like a main verb, confirming that that is exactly what it is.

8. Conclusion
In this paper I have shown that the V Hypothesis, which claims that “thook” is amain verb in Thai, is empirically and theoretically superior to the Infl Hypothesis, whichclaims that “thook” is an auxiliary element used to construct passive voice sentences.
The preponderance of empirical evidence supporting the V Hypothesis also entails that
there is no “passive” as such in the Thai language. The Infl Hypothesis collapses as soon
as it is pressed into service to explain any but the simplest Thai “passive” constructions
with covert agents. Although my conclusion is resoundingly in favor of the V Hypothesis,“thook” does have some special properties not found in other main verbs.

9. Two further issues.
The first of these, which was noted in the digression, is that NP’s coindexed withthe subject of “thook” must be covert. This feature is not found with any other verbs inThai (Boonmee and Intrasai 2015 personal communication). The second unique property
is that “thook” is the only main verb that can and must appear without an overt
complementizer.
(25) Chan chuaIwaa khao pen khon

believe that hedii

is person good

“I believe that he is a good person.”─ 71 ─

Timothy Gould(26) John puut waa Mary ja maa sai
John said that Mary will come late“John said that Mary will come late.”
Although these unique properties of the verb “thook” are not specifically the focus
here, I believe that they are probably responsible for “thook’s” traditional treatment as
an auxiliary element.

Acknowledgements
I wish to thank my Thai informants: Jiraporn Intrasai and Sirintip Boonmee

References
Danvivathana, N., (1987), The Thai Writing System, Hamburg: Buske.
Haas, M. R., (1964), Thai - English Student’s Dictionary, Stanford: Stanford University
Press.
Haegeman, L., (1994), Introduction to Government and Binding Theory, Cambridge:
Blackwell.
Carnie, A., (2011), Modern Syntax: A Coursebook, Cambridge, Cambridge University
Press.

─ 72 ─