A new interpretation of a 2,500-year-old Sanskrit text upends millennia of debate and affirms an ancient linguist’s remarkably sophisticated grammatical system.

Around 500 BCE, the Indian scholar Pāṇini wrote a treatise on Sanskrit, the Aṣṭādhyāyī, describing a kind of language machine: an algebraic system of rules for producing grammatically correct word forms. The enormity and elegance of that accomplishment—and the underlying computational methodology—cemented Pāṇini’s place as a founder of linguistics. Even so, centuries of commentators have insisted that there are glitches in the machine’s ability to tackle rule conflict (that is, a situation in which two or more rules are simultaneously applicable) and have responded with complex rules and tools aimed at resolving the issues apparently besetting the ancient system.

In one fell swoop, this book renders the overwhelming majority of that work obsolete. Linguist Rishi Rajpopat lays out a novel interpretation of Pāṇini’s grammar, focusing on Pāṇini’s only rule dealing with rule conflict, known as 1.4.2. Pāṇini’s Perfect Rule shows that the Aṣṭādhyāyī indeed functions like a well-oiled machine, capable of handling challenges without any of the complications introduced by later scholars.

Rajpopat thus solves an ancient and important problem in Indology and linguistics that will fascinate anyone interested in how language systems—including those of computer programming—operate. In addition, Pāṇini’s Perfect Rule offers meditations on the history of the early Pāṇinian tradition, its philosophy, the relationship between rule conflict and accentuation, and aspects of theoretical phonology. A nontechnical preface lays out key findings and foregrounds the deep history of Sanskrit scholarship. This volume opens new horizons for the study of Sanskrit, inviting seasoned experts and novices alike to behold its majesty.

This is a wonderfully interesting, enjoyable book on a new solution to an ancient problem of word construction in Sanskrit. As a longtime admirer of Pāṇini, I join Rishi Rajpopat in inviting general readers – not just grammarians and linguists – to the fun hidden in the great Pāṇinian rules. -- Amartya Sen, winner of the Nobel Prize in Economic Sciences
This book resolves a major dilemma in the long history of the reception of Pāṇini’s grammar, centering on its metarule devoted to rule conflict. Rishi Rajpopat's ingenious and revolutionary reinterpretation of the metarule emanates from an accurate and elegant analysis of the usus scribendi of Pāṇini’s grammar. He brilliantly demonstrates that the metarule far more effectively resolves rule conflicts than was previously thought possible. -- Tiziana Pontillo, University of Cagliari
Pāṇini’s Perfect Rule is a splendid book. With understated boldness, Rajpopat steps around the work in Pāṇinian studies that has obscured rather than illumined Pāṇini’s straightforward directive. Not only grammarians but also scholars in a wider range of Indian intellectual systems will benefit greatly from this magisterial demonstration of how best to reappropriate the great sūtra texts of the tradition. -- Francis X. Clooney, Harvard University

Rishi Rajpopat holds a PhD in Sanskrit Studies from the University of Cambridge. His research on Pāṇini’s grammar has been covered by the BBC, Daily Mail, The Telegraph, Times of India, The Hindu, and other global news outlets.