Special issue on formal diachronic semantics Introduction

It is a pleasure to present this collection of articles which make up the first-ever special issue dedicated specifically to formal diachronic semantics. This young subfield is in its formative stages, and is concerned with using the apparatus of "formal", that is, logical semantics, for understanding meaning change, particularly of grammatical meaning.

Formal diachronic semantics is not strictly delineated from other types of historical semantics, just as modern formal semantics is informed by the insights in usageconscious, cognitively-oriented, or sociolinguistically-aware research. Choosing the logical approach to linguistic meaning is not so much a matter of dogma or ideology as it is one of convenience: as it turns out, the logical perspective can often lead to interesting discoveries about how language functions which often complement those made by pursuing other lines of linguistic inquiry.

There have arguably been two key moments in the gradual emergence of formal diachronic semantics as a research field. The first one was the publication of Eckardt (2006), a book which, in hindsight, can be said to have created formal diachronic semantics as a field. Eckardt addressed both formal semanticists and historical linguists and tried, with several case studies, to show how starting from a logical analysis of meaning can contribute to a better understanding of the diachronic semantic processes.

An important insight of Eckardt's concerned the nature of a minimal change, and was addressed more to the formal semanticists in her audience: she noted that when speakers and hearers conduct semantic reanalysis—potentially leading to a lasting meaning change—the primary objects they operate on are sentence meanings, not those of individual lexical items or morphemes. A reanalysis by the hearer (from the speaker's perspective, a misanalysis of her words) must result in a different yet reasonable meaning for the whole utterance. From that global meaning, the hearer can then work out the meanings of the sentence's parts, which may involve assigning innovative lexical/morphemic meanings to some of them. When we write down the innovative meanings for words and morphemes using logical formalisms, they might look quite different from the original formulas describing the speaker's intended meaning. The insight here is that this change happens through the interaction between the speaker and hearer, at the discourse level, and not at the level of specific subformulas. The level of subformulas simply follows from the change that happened elsewhere; subformulas themselves are used as a tool for us to understand the relevant meanings, but not as objects directly manipulated by speakers and hearers in meaning change.

Thus, when we try to understand a meaning change, we should look for the actual contexts of reanalysis, rather than try to manipulate the symbols of our logical representations. This realization may go against the instinct of a semanticist used to working with formulas for individual lexical items and how they compose with each other; nevertheless, it is completely at home in a more holistic, and no less formal-semantic, tradition of studying both semantics and pragmatics with mathematical and philosophical tools. Moreover, Eckardt's insight also brings formal diachronic semantics immediately into close dialogue with the practices used in historical linguistics, where working with specific reanalysis contexts is a long-established practice.

The second foundational moment for the field was Ashwini Deo's organization of the workshop "Systematic Semantic Change" at the University of Texas at Austin in April 2013. This workshop brought together formal semanticists with historical linguists and typologists like Östen Dahl and Elizabeth Traugott. It was so successful that it sparked a series of subsequent events. First, a special session was organized at "Sinn und Bedeutung 19" in 2014 at the University of Göttingen by Regine Eckardt, Igor Yanovich, and Hedde Zeijlstra, with Hedde the main driving force behind it; and then in 2015, at the "22nd International Conference on Historical Linguistics" held at the University of Naples, another special session was organized by Cleo Condoravdi and Ashwini Deo. Subsequently, Regine Eckardt, recognizing that there was sufficient interest in this new subfield to warrant a regular conference series, organized the inaugural "Formal Diachronic Semantics" conference (FoDS...