Zero Complementizers after Speech and Thought

Vietnamese often puts the content of speech or thought directly after a verb, with no overt equivalent of English that. Tôi nghĩ anh ấy bận literally has the sequence “I think — he is busy,” yet listeners readily understand anh ấy bận as what the speaker thinks. Grammarians describe the missing linking word as a zero complementizer, written Ø.

Zero marking is not careless or incomplete Vietnamese. It is an ordinary way to package a short, predictable message in conversation, personal writing, and even clear neutral prose. The choice among rằng, là, and Ø tells the listener how strongly the speaker wants to mark the clause boundary and often signals register. This page stays with declarative content after speech, thought, knowledge, and perception verbs; Fact, Question, and Command Complements treats the different internal shapes selected by verbs such as biết, hỏi, and bảo.

The zero pattern

The structure is:

subject + speech/thought verb + Ø + proposition

The symbol Ø is an analysis aid; it is never written in an actual Vietnamese sentence. On the page or screen, the real forms are simply Tôi nghĩ anh ấy đang họp, Lan bảo mai Lan về quê, and Bọn mình tưởng quán còn mở.

Verbs that commonly permit this tight packaging include nói “say,” bảo “say/tell,” nghĩ “think,” tưởng “assume,” biết “know,” thấy “find/feel,” nghe “hear,” nhớ “remember,” quên “forget,” and hy vọng “hope.” The complement is understood through meaning and order rather than through a visible linking word.

Choosing rằng, là, or zero

All three versions below can describe the same belief, but they package it differently:

Zero marking becomes less attractive when the matrix clause contains several modifiers or the embedded content is long. An overt marker then helps the reader or listener locate the start of the report.

This sentence is possible without rằng, but the formal verb thừa nhận, long introductory phrase, and substantial complement make the explicit boundary useful.

The clause after Ø remains complete

Omission removes only the complementizer. It does not strip the embedded proposition of its subject, negation, aspect, or time reference.

Vietnamese does permit an understood subject when context makes it recoverable, but that is a separate omission. In Anh Nam bảo mai sẽ gọi lại, the caller may be Nam or another salient person; if the distinction matters, state it: Anh Nam bảo mai anh ấy sẽ gọi lại.

Zero content clauses within the larger connector system

Bare juxtaposition occurs elsewhere in Vietnamese, but the logical relation must still be recoverable. Compare this compact reference set:

The pairs nếu...thì, vì...nên, and tuy...nhưng may lose one half when context is clear: trời mưa thì ở nhà, vì bận, tôi về sớm, tuy mệt, chị ấy vẫn làm. Time relations likewise use khi, trước khi, or sau khi when needed. None of those shortened patterns automatically becomes a complement clause. A complement is selected as the content of a verb such as nghĩ or nói.

Here Ø follows nghĩ, while trời mưa thì... is an abbreviated conditional inside the complement. Two levels of clause linkage coexist.

Here Ø introduces everything after nói, and vì...nên expresses the internal cause-result relation. Keeping those levels distinct prevents connector mismatches.

How interpretation changes in a real exchange

The compact first sentence is natural, but it leaves the subject of nghỉ underdetermined. Hạnh asks for clarification. Phương then uses là and supplies công ty as the embedded subject. Zero marking did not itself cause ungrammaticality; it simply relied on shared context that the two speakers did not actually share.

This illustrates the communicative principle: choose less marking when the relationship is predictable and more marking when the listener needs guidance.

Reported content, not exact quotation

A zero complement normally introduces a summary of content rather than a word-for-word quote. Pronouns and time expressions can be adjusted to the current speaker’s viewpoint:

If the original words were Chiều nay mình sẽ ghé qua, the reporter may replace mình with Linh to prevent ambiguity. Vietnamese verbs do not undergo English-style tense backshift; this is developed on Reported Speech without Tense Backshift.

Common Mistakes

1. Inserting rằng after every English “that”

The speech verb nghĩ and the following subject cậu already make the boundary clear, so zero marking is natural.

2. Omitting so much that the subject becomes unclear

Zero complement marking is fine, but the repeated name repairs the separate problem of ambiguous reference.

3. Copying English relative-pronoun order

A relative follows its head noun. This is not the same structure as a zero content clause after nói or nghĩ.

4. Dropping mismatched halves from paired connectors

The complementizer after nghĩ may be zero, but the concessive relation inside the complement must still be tuy...nhưng.

5. Treating two adjacent clauses as automatically equivalent

Zero complementizers are licensed by a content-selecting verb. Without one, use the connector that names the intended relation.

Key Takeaways

• After familiar speech and thought verbs, Vietnamese can introduce a full proposition with no overt complementizer.
• Rằng, là, and Ø often preserve the same core proposition but signal different degrees of boundary marking and formality.
• Zero marking is safest when the complement is short and its subject is clear.
• Bare linking does not erase the distinct roles of relative mà, conditional nếu...thì, causal vì...nên, concessive tuy...nhưng, purpose để, or time markers khi, trước khi, and sau khi.