# Syntactic change in diachrony versus contact-induced change: two sides of the same coin?

## TL;DR

This paper explores whether language change due to contact or over time follows similar or different paths, focusing on syntax.

## Contribution

The paper introduces a new heuristic to distinguish syntactic change in contact and diachrony based on feature types.

## Key findings

- Changes involving ϕ-features show similar patterns in contact and diachronic settings.
- Discourse-driven features lead to divergent change patterns in contact and diachrony.
- Empirical evidence from indexicals, clitics, and DOM supports the proposed heuristic.

## Abstract

Recent studies (e.g. Kupisch, Tanja & Maria Polinsky. 2022. Language history on fast forward: Innovations in heritage languages and diachronic change. Bilingualism: Language and Cognition 25. 1–12) have rekindled an old debate concerning whether language change in contact (CIC) and language change in diachrony (CID) proceed along the same developmental path, or whether they diverge from one another in fundamental and predictable ways. This paper contributes to this ongoing debate; we propose a new heuristic to determine similarities and differences in syntactic change in CIC and CID. We postulate that the primary distinction boils down to the type of features related to the domain of syntax under investigation, i.e., situations involving (formal) ϕ-features lead to similar trajectories of change in both CIC and CID, while those driven by discourse-features show divergence. We test our hypothesis on a host of different empirical data, e.g., indexicals, (subject) clitics, and differential object marking (DOM) as evidence for our claim.