understanding tgg

Created in June 14, 2025

2025   ·   tgg   deep   surface   x-bar   ·   hi-linguistics   theo-linguistics   explanations

What is TGG?

  • Transformational Generative Grammar(TGG) is a specific type of generative grammar. Introduced by Chomsky in his book “Syntactic Structures” (1957).

  • It introduces transformations — operations that convert one syntactic structure into another. For example, converting: “John is eating an apple.” → “Is John eating an apple?” (yes-no question)

  • It makes use of “phrase structures”. When linguists talk about phrase structure, they are referring to the hierarchical organization of words into larger units (phrases) within a sentence. Thus, this concept provides use of alternative names to this viz. Phrase Structure Grammar (PSG), also known as Constituency Grammar.

Which other grammatical theory is it affiliated with? - X-bar theory (A refinement of phrase structure rules that introduced intermediate phrase levels (e.g., X′ or X-bar), ensuring a uniform structure across all phrases (NPs, VPs, etc.).), Minimalist Program (While it reduces reliance on phrase structure rules, it still assumes hierarchical phrase structure via Merge operations.)

  • Chomsky introduced deep structure (basic sentence structure) and surface structure (what we actually say/hear), both built on phrase structure in TGG. Chomsky talked about these structurs especially in the Standard Theory (1965), while discussing TGG.

🌱 What are the differences between Deep and Surface Structure?

Term Meaning
Surface Structure The final, actual form of a sentence that we speak or hear, after transformations are applied.
Deep Structure The abstract, underlying form of a sentence that captures its core meaning and basic grammatical relations.


🌱 Why Two Levels?

  • Some sentences may have ambiguous surface forms that deep structure helps clarify.
  • Different surface forms can express the same underlying meaning.


🌱 Examples

A. English Examples

1. Active and Passive Voice

  • Active: The cat chased the mouse.
  • Passive: The mouse was chased by the cat.

✅ Same Deep Structure: “cat chases mouse”
✅ Different Surface Structures due to transformation.


2. Question Formation

  • Statement: You are eating an apple.
  • Question: Are you eating an apple?

✅ Deep structure stays the same.
✅ Surface structure changes through auxiliary movement.

B. Hindi Examples

1. Active-Passive

  • Active: राम ने सीता को देखा।
  • Passive: सीता राम द्वारा देखी गई।

✅ Deep structure: Ram sees Sita
✅ Surface structure: Changes with voice


2. Question Formation

  • Statement: तुम बाज़ार जा रहे हो।
  • Question: क्या तुम बाज़ार जा रहे हो?

✅ Deep structure = “You are going to the market”
✅ Surface structure = Adds “क्या” to form question