Concept:
Postmodern architecture emerged as a reaction against the simplicity and rigidity of modernism. Texts that questioned functional purity and embraced historical reference, ambiguity, and symbolism became foundational to this movement.
Explanation:
Robert Venturi's book \textit{Complexity and Contradiction in Architecture} (1966) challenged the modernist principle of “less is more” by proposing “less is a bore.”
The book argued for richness, ambiguity, and historical reference in architectural design.
\textit{The Timeless Way of Building} is by Christopher Alexander.
\textit{The Poetics of Space} is written by Gaston Bachelard.
\textit{Architecture: Form, Space and Order} is authored by Francis D.K. Ching.
Thus, the book that played a pivotal role in shaping postmodern architectural thought is \textit{Complexity and Contradiction in Architecture}.