We celebrate the linguistic contributions of Anthony (Tony) Kroch, Professor Emeritus of Linguistics at the University of Pennsylvania, who died on April 27th. Together with William Labov and David Sankoff, Tony was a co-founder of Language Variation and Change, which he co-edited from 1989 until 2006.

Tony graduated from Harvard in 1967, having majored in anthropology, and undertook graduate studies in linguistics at MIT with the aim of furthering his understanding of the narrative structure of myth. At MIT, his interests broadened, and his doctoral thesis was one of the first investigations of quantifier scope in natural language. The thesis, completed in 1974, was published in 1979 by Garland Press. Following appointments in the Anthropology Departments at the University of Connecticut and Temple University, Tony obtained a fellowship in 1978 with William Labov to conduct sociolinguistic interviews with upper-class Philadelphians, which were important in rounding out and confirming the description of the intricate pattern of Philadelphia speech that had emerged from interviews with working-class and middle-class speakers. In 1981, Tony joined the faculty of the Linguistics Department at the University of Pennsylvania, where he remained for the rest of his career, apart from periodic visiting professorships in the United States and abroad. He retired in 2020.

Tony's work in linguistics was notable for the breadth of its range and the depth of its insight. The great bulk of his work, both published and unpublished, was carried out in collaboration with others, in accordance with his convivial character. Working with Aravind Joshi in the University of Pennsylvania's Computer Science Department, Tony applied Joshi's formalism of Tree-Adjoining Grammar to provide mathematically precise characterizations of theoretically important constructions in natural language. Perhaps most widely known is his work on syntactic change, which led him to discover a mathematical result known as the Constant Rate Effect. The result was published in 1989, in the very first volume of Language Variation and Change. At around the same time, together with David Lightfoot and Ian Roberts, Tony helped bring into existence a conference called Diachronic Generative Syntax (DiGS), which continues up to the present. In order to provide a suitable infrastructure for the work on syntactic change, Tony pioneered the construction of large syntactically annotated historical corpora. In this, he was assisted from the 1990s on by Ann Taylor, who continued to construct historical corpora after her appointment at the University of York, England, and by Beatrice Santorini. With Beth Randall, Tony developed a powerful and versatile tool to search the corpora, which formed the empirical basis for his own work, but even more importantly from his point of view, the basis for replication and extension by other researchers. The conceptual beauty of the results that he and his students were able to obtain resonated with researchers to the point of motivating the construction of an increasing number of parsed corpora for other languages, both historical and modern. Tony's desire to exploit the existence of ever larger corpora in order to increase the statistical reliability of his results led him to collaborate closely with computational linguists, often students of Aravind Joshi's. A final strand of Tony's research investigated the syntax-semantics interface, with a focus on various types of copular sentences, with the aim of elucidating the overarching architecture of grammar.

Though he made his career in linguistics, Tony felt himself to be less of a traditional linguist than an applied mathematician. Early on, as a college freshman, he realized that his mathematical talent, though it turned out to be versatile, was not of a caliber sufficient to support a career in mathematics. Instead, Tony marshalled the forces at his disposal in the service of driving linguistics in a scientific direction by mathematicizing the field wherever he saw or could create the opportunity.

Tony loved life, and especially, he loved the life of the mind as it expresses itself in dialogue. We knew him as a gifted student and researcher, talented teacher, generous mentor, careful listener, skillful debater, engaging presenter, effective negotiator, genial and witty conversation partner, shrewd counselor, seizer of the main chance and procrastinator extraordinaire, haven in the storm and secret worrywart, a bundle of paradoxes like life itself. He was not one to suffer fools gladly, and he could be tart. But he was neither arrogant nor mean, and he was a very good man to have in your corner. To many of us, he embodied the concept of mensch. To the best of his ability, he attempted to strengthen the life of the communities that he belonged to and to defend and further their interests. Beyond what he had to say to us about linguistics, it is the model of this posture that many of us who knew him treasure as a gift beyond words. Tony will be missed by scores of us, both in the United States and around the world. We remember him with gratitude, respect, and affection—with sadness, but also with laughter. It is to be hoped that the various strands of his linguistic work will be carried forward. Nothing, but nothing, could give him greater joy!